4" Is Out!

My research has been slowed down considerably but has not been stopped. I believe that I have established that the 4" stroke is not feasible for phase 1 of project #001. I still have not read anything about the reliability of the engine but I have seen plenty on the difficulty of assembling such an engine in a stock block. Some very knowledgeable and experienced builders said, I think verbatim, you are fool if you try to build a 4" stroke engine in a stock block.

First, there is A LOT of grinding of numerous places on the block so that the crank and rods won't hit anything. This entails assembling the bottom end, finding where there is interference, disassembling the engine, grinding (but not too much!), cleaning the block, reassembling, finding that you didn't grind enough, and repeating the process only to start all over again with the next place of interference.

Second, the block holds the cam too close to the crank with a 4" stroke and requires the use of a smaller diameter camshaft. This is referred to as a "reduced base circle" camshaft. This also means that the lobes can't be too high or they will hit the connecting rods. I'm not sure if I will be running a camshaft with high enough lift for that to be an issue. It is looking like I will be using a high lift short duration camshaft for low end torque so interference may be an issue. Since I don't know just how far I want to open the valves, I don't know how much total lift I will need but some of the guys were having to run higher ration rocker arms to get the lift they needed. With the higher ratio the valve springs can push harder on the camshaft (more leverage) and in some cases cause the reduced base circle camshafts to flex. I don't know exactly how this ended up being bad for the engines. The two bad things I can think of right off the bat are breaking the camshaft from flexing it and the flexing giving inconsistent opening and closing of the valves.

Third, as mentioned before, special "clearanced" connecting rods had to be used. There was even discussion of using crankshafts with smaller rod journals to bring the outer circumference of the crankshaft down. Clearanced rods don't seem like a big deal to me but reducing bearing surface is not in line with the kind of reliability I am after.

I don't think any one of those things alone or in concert are way beyond my capability but they sound like A LOT of work and definitely not the engine to start out with.

There was a simple (and expensive, for me) solution. Buy an after market block with a raised camshaft location and a taller deck height that was designed to accommodate a 4" stroke. This makes sense to me! There are some other headaches that come along with this solution but none that get in the way like the PRICE. I looks like these block sell for $1,000-$2,000.

So there's an end to that. There was a discussion of using a 3.82" (I think that dimension is correct, I know it is close) stroke but, at the moment, I'm inclined to go with the 3.75" stroke. I'm guessing that there is greater parts availability for it and I know I can get decent rod/stroke ratios. I guess that is the next thing to check on.

Builder

Out of the frying pan

I am out of China and in Spain. I was thinking that I would now be free to research to my hearts content. two issues have arisen.

First, I do not have regular Internet access and have to pay by time. Not a good way to go about hours of research per day. that said I will be researching as time (and money) allow and am focusing right now on the reliability of the 4 inch stoke engine.


Second, being in Spain seems like a good time to focus on improving my Spanish. I am in a good situation to do this and I don´t often spend a month at a time in Spain. This will curtail my research and posts but it will not end them.

I´ll write when I do.

Builder

More Circling Around - Questions

More Circling Around

I know that this is largely just more talking about things that have been talked about before but I am finding that the process of just massaging the information is helpful. What I'm going to do here is look at all my questions and explore each one. The answers come later.

1. What are ALL the reasons that manifolds come stock with coolant and exhaust passages?

I know that this is done to heat the manifold but why do they want to heat the manifold? I have read that this maintains a consistent air temperature to aid in more precise air fuel mixtures in carburetors. This also aids in fuel atomization or evaporation so it may help with mileage. I think it may also help with carburetor icing by warming up the manifold and heating the carb on top of it.

Heating the air before it enters the cylinder is anathema to performance engine builders. Warmer air is not as dense. The denser the air, the more power you can make. I, however, am not building a performance engine. I am building an engine to deliver the maximum of a specific type of performance. This leaves me with three questions to answer. Actually four questions.

1. Is there any fuel mileage to be gained by heating the air fuel mixture and if so how much?

   1. Is the gain great enough to offset the loss of power?

   2. How much power is to be gained by cooling the temperature?

2. Is the improved atomization worth it?

   1. Can I get the same or at least sufficient fuel atomization from a well designed and chosen carburetor that has a very high vacuum signal at the booster venturi and that shreds the fuel as it is released?

3. At what temperatures does carb icing become a problem?

   1. Will the Jeep ever be operated in these temperatures?

   2. What effect does heating the intake manifold have on the range of temperatures that an engine is serviceable in?

   3. Are there other solutions to this problem (if it is indeed a problem)? Especially solutions that do not always have to be in use or can be switched off?

4. Why else is the manifold heated?

I guess that is more like a slew of questions than four and they are to answer this one question:

How much heat do I want or need in my manifold?

2. What, if any, reliability issues are there with a 4" stroke?

I really need to find out what the trade offs are with this long of a stroke. A 4” stroke significantly reduces the rod stroke ratio. I need to have rods almost 6” long and an accompanying compression height just over 1”. These are certainly obtainable specs with parts like this quite available but how reliable are these parts. I'm not really concerned with the rod length but the piston is definitely and issue. It also occurs to me that the length of the rod effects the size of the piston skirt. So is the 4” stroke a candidate for the project? This leads to the next question.

3. What is the minimum durable compression height (or distance)?

As the compression height is reduced the rings start getting packed tighter together which reduces the amount of metal in the piston to support them. There is an amount of metal that is the most that makes an improvement in strength and any more is not necessary but I don't know what that measurement is. Additionally, I don't know how thick the rings need to be in order to be reliable and seal for a long time. This leaves me with two questions.

1. How much metal is needed to support the rings?

2. How wide to the rings need to be for high mileage durability?

This leads me to the next question.

4. What is the lightest durable piston?

In looking to improve fuel economy I want to find every opportunity to reduce weight. Rotating weight, reciprocating weight, and overall weight. In that order

5. How much flow do I need for my application?

   1. What heads/ports/port size will barely flow that?

      1. And have good flow characteristics (e.g. Swirl)

   2. What influence does stroke have on this?

   3. What magnitude of difference does swirl make?

      1. How much difference will it make on power, torque, fuel efficiency, etc.?

   4. What other head questions should I be asking?

Gears. Not so much questions but numbers that need to be determined.

6. What is (and should) the engine speed be at 70 MPH?

   1. Automatic or manual transmission and which specific one.

      1. Transmission gear ratios (especially at 70 MPH).

   2. Differential Ratios

   3. Tire diameter (and circumference)

Carburetor Selection.

7. What carburetor should be used? (Things to consider)

   1. Price

   2. Tunability

   3. Fuel Atomization

   4. Squarebore vs spreadbore

   5. Mechanical vs vacuum secondaries

   6. Flow capacity

   7. Anything else?

Clearly this plays into the manifold heat question. Frankly, right now the finely atomized mixture going into a heated manifold appears to offer the best possibilities for both complete fuel use and consistent air/fuel ratios. On the other hand, a higher intake air temperature will likely lead to needing a lower compression ratio which brings me to:

Compression Ratios

8. What is the maximum compression ratio that I can reliably use with poor quality fuel in all anticipated air temperatures and applications?

I know that this rig will be operated off road at low vehicle speeds (crawling) in higher temperatures. Engines can get pretty hot in these conditions. This means I'm going to need a good. . .

Cooling System

9. What radiator and water pump am I going to need to make sure that this engine never runs hotter than it wants to?

   1. What other parts should I be looking at for this?

      1. High volume water pump.

      2. Big radiator (but how big?)

      3. High flow T-stat.

      4. Anything else?

Rings

10. Are total seal rings durable enough?

ANWSER – Yes! It would appear that Total Seal rings are durable enough in some variation. Supposedly good for 100k miles.

1. How much do they cost?

2. What would the ideal setup be? (i.e. What should the top, second, and oil control rings be?

   1. What is the difference between standard and low tension rings?

3. Are there suitable cheaper alternatives for the first build?

   1. Are these alternatives worth the decreased performance for the decreased price? (And vis versa)

Engine Block

11. Price and availability of good used 350 and 400 blocks.

    1. I'm thinking that the 400 is more trouble than it is worth but I should definitely check it out.

       1. Reliability of the siamesed cylinders.

          1. What problems are there? (Specifically with regard to over heating)

          2. What solutions are there to these problems?

          3. Are these solutions adequate for my reliability standards and the temperature extremes likely to be encountered by the Jeep?

I am inclined to think that the 350 is the best choice for this application. First there is, as far as I know, a large supply of 350 blocks but not 400 blocks, so a 350 block will be cheaper. Second, the cylinders in the 350 block will have coolant circulating all around them and more surface area is always good for cooling. Third, the 350 block does not, to best of my knowledge and unlike the 400, have a reputation for having cooling problems. That said, I would like to know all I can about the 400. I may be using a 400 type block in the future (I have an idea for project #004 or #005 where I build a high reving high output engine for a corvette but that is way out in the future).

Oil Pumps

12. High pressure pumps. Why and why not.

What is the deal with oil pumps? Some engines run 15 psi and others run 60-90 psi. Why? What is the deal with high volume oil pumps? Only so much fluid can be pumped through a restriction at a given pressure. I hear people say that you can pump the pan dry with a high volume pump. This seems unlikely to me if the pressure is the same. People who I look to as a “Christ-like” source for automotive information like David Vizard say that high volume pumps can flood the engine with oil and should only be used if there are things like oil coolers in the line. I have yet to hear David Vizard discuss exactly what theory supports his assertions. As I said before, you can only force so much fluid through a restriction at a given pressure.

As I see it now there are two things about high volume pumps. One, you may get oil to all the parts faster with the higher volume. Two, it seems like the pressure relief bypass will get a work out relieving all the pressure from trying to pump more oil than will fit at the pressure.

What applications are universally agreed upon to need high volume pumps?

High pressure. Why? I have heard that if you don't do it right, the high pressure oil can blow the face off your bearings.

Since your engine will rapidly become so much scrap metal if it doesn't get the oil it needs, this seems like an important question to answer. This rig will be going deep off road. Reliability must be absolute.

Oil Pan

13. What kind of oil pan should I use?

This falls in a similar category as the oil pump. The pump can't deliver oil that isn't at the pick-up. So how does the oil pan influence that? Do I want extra volume? Is there a particular pan shape that will more reliably keep oil at the pick-up when the vehicle is being operated at extreme angles? Are extreme angles analogous to high cornering forces? Will the pan interfere with the high travel suspension? What about windage trays? What about baffles? What about oil scrapers? I believe that the 4” stroke will require a different pan.

I think that actually covers it for now.

Today I leave this city, wait in another city for a few days, and then fly out to the next country. I feel reasonably confident that I will have the time and resources to begin researching these questions in depth.

I will be off-line for the next four or five days so the three of you who are reading this will just have to wait for the next thrilling installment!

Builder

Man! Still busy!

I thought I was going to be free for this week to write and research to my heart's content. No such luck. I am now moving out of my apartment to go to yet another country and it is taking a lot more work than I thought.

I did correspond with my engine partner and he said that he thought my multiple engine idea was great. So that change in the plan is official, project #001 now has three phases:

• Phase 1
• Build an engine as cheaply as possible without sacrificing reliability in any way and taking every affordable step to improve fuel mileage and low-end torque.
• Phase 2
• Build an engine to whatever specs my partner wants.
• Phase 3
• Build an engine using everything that I have learned to build the engine for reliability, durability, efficiency, and low-end torque like a racer builds an engine for power.

I have compiled a pretty thorough list of questions and am in the process exploring each of the questions. Just more circling around really but it helps me organize my thoughts and find structure. That's always a good thing.

More to come when this current storm of busyness blows over.

Builder

Ahhhhhh

It is done. That load of work is completed leaving me free. . .yes free. I am still decompressing, de-adrenalizing, and just plain relaxing. So naturally I'm looking at engines.

Lets see if I can't sketch out a battle plan here.

My resources are uneven. I don't have access to any of my books (although I did find a copy of Vizard's How to Modify Ford S.O.H.C Engines) I can't call around and get prices, and I can't buy anyone lunch, sit down, and pick their brain. On the other hand I do have places like Speedtalk and I have managed to amass a fair number of online articles from knowledgable people (like Vizard).

Questions.

The first question I have is about intake manifold heat.

• What are ALL the reasons that manifolds come stock with coolant and exhuast passages?
• What effect does heating the intake manifold have on the range of temperatures that an engine is serviceable in?

Then

• What, if any, reliability issues are there with a 4" stroke?
• What is the minimum durable compression height (or distance)?
• What is the lightest durable piston?
  

Of course I have many more questions than these but these are some critical ones. I need to know what camshaft to use. In order to select the camshaft I need to know how much air the engine needs. To know how much air the engine needs I need to know what RPM it is running at and its displacement. I must know the stroke in order to know the displacement. I think I will start with that.

I am also reading Vizard's SOHC book. I couldn't figure out who the market was for a while. I guess this was the engine in the Ford Pinto. A great deal of the information is specific to this engine but Mr. Vizard also goes into the theory behind the specifics and that applies to everything and is what I need!

That isn't much of a battle plan but it is a few good first steps. I shouldn't expect too much from myself when my brain is still fried (all the work).

And I'm off!!

Builder

Finished the Lump

I had a BUNCH of stupid crap paperwork type stuff to do that I have now finally knocked out. I will now be free to throw myself fully into researching all my questions. I will lay out the plan tomorrow but I am planning on posting once a day for the foreseeable future provided that I have something to say. I'm not going to post crap for the sake of posting.

Whooooooooooooooohh. . . . . . .

Breath deep and release a deep sigh of relief.

See you tomorrow!

Builder

It's All in the Cylinder Heads

It is all in the cylinder heads. Port shape, port volume, valve size, valve shrouding. . . They all have an impact on the way the air/fuel mixture enters the cylinder. How does the port flow as the valve is opened? What is the maximum volume the port can flow? You’d think that the larger the port the more it will flow and the more power the cylinder will make. No, and here is where there is a bunch of disinformation and arcane references to “witchcraft” and flatly incorrect statements like “the bigger the better” or just as incorrect “some restriction is good” come from.

First thing to do is to get the air moving. Since this an intake port for an engine the air will begin moving when the valve opens and the piston goes down (For this port we will pretend that the valve is always open). Apparently the maximum pressure drop created by the cylinder descending is 28” of water¹. This isn’t very much. This translates to 2.06” Hg. This means that the port shape is critical to having good flow. I should also say that I don’t see how this is accurate seeing that the manifold vacuum of an engine can easily reach 25” Hg! Of course this is with the throttle plates closed at idle or on deceleration. As you open the throttle plates and put the engine under load the manifold vacuum will easily drop to 10” Hg and at WOT (wide open throttle) I know I have seen manifold vacuum drop to 4” Hg. It has been almost a year since I did any of this testing but I think I have seen vacuum numbers as low as 2” Hg at WOT and heavy load. WOT with high load is when you want maximum power so I guess it makes sense to measure port flow at this pressure drop. But I am getting ahead of myself.

First, let’s consider a port. Let’s think about an imaginary port that is simply a section of pipe. To make things easier we will not even consider how the air enters or leaves the pipe. We also don’t care how long the pipe is. All we care about is its diameter, or more specifically, its cross-sectional area. Let’s look at two pipes. One pipe has an inside diameter (ID) of 1” and the other pipe has an ID of 4”. Now, let’s pick a flow number. I am choosing arbitrary numbers. I don’t know the real numbers for any of this (YET!). Let’s say that we’ve determined that our cylinder needs to be fed 100 cubic feet per minute (CFM). This 100 CFM needs to pass through our straight pipe port.

The formula for determining the velocity for an ideal gas (one without friction, turbulence, etc.) is as follows:



CFM
------------------- = Velocity of flow
Area of opening

So let’s look at the 1” ID pipe.

Area = πr²

Area = π1² = π

Well isn’t that handy.

For this we will just say that π (pi, pronounced “pie”) is 3.14. π is actually an irrational non-repeating decimal that goes on forever. Some folks have calculated it out to millions of places but that’s about as useful to us as the number of angels that can dance on the head of a pin. So the cross sectional area of the 1” ID pipe is 3.14 in². When we convert that to feet we get 0.02180555555ft². We plug that into the formula and we get:

100 CFM
---------------------- = 4585.99 ft/min
0.02180555555ft²

The 1in ID pipe flows 100 CFM at the rate of 4585.99 ft/min.

Let’s look at the 4in ID pipe now.

Area = π4² = 16π = 50.24 in²

Convert 50.24 in² into 0.3488888889ft², plug it in and you get:

100 CFM
-------------------- = 286.62 ft/min
0.3488888889ft²

The 4in ID pipe flows 100 CFM at the rate of 286.62 ft/min.

4585.99 ft/min vs. 286.62 ft/min. That is a pretty big difference in velocity! Of course that is also a big difference in diameter. I chose such different diameters to make the difference clear.

“Big deal. There are two different velocities.”

Yes, it is a big deal when you consider that air has mass and therefore the faster it goes the more momentum it has. It is a pretty simple formula:

P = mv

Or momentum equals mass times velocity. This means that when the air flows into the cylinder from the 1in ID port it will have about 16 times the inertia as the 4in ID port. This ramming effect is helpful in getting air to continue to enter the cylinder even after the piston has started coming up. This improves volumetric efficiency (VE). Improving VE improves torque. Getting good cylinder filling at low RPMs is essential for good low end torque. This is where the misguided statement about “Some restriction is good” comes from.

This means we want the smallest ports possible right? Let’s really get that air moving!
Not exactly. This is where that 28” H₂0 comes into play.

After a fair amount of searching on the internet I was unable to find a formula that approximates the pressure differential required to produce a given volume of flow through a pipe. No doubt such a thing exists but I have been unable to find it. Fortunately it is not critical for us to understand the basics of what is going on.

As we just saw, smaller ports are good. However, we do not want ports too small or else they won’t flow enough (it was here that I was hoping to show the difference in the pressures required for the 1in ID and 4in ID pipes to flow 100 CFM).

“So what do we want?”

We want the smallest ports possible that will still flow the volume we need at 28” H₂0.

“So is that it? Is that all we need to know?”

Of course not! And the truth is that I don’t know what all the things are to pay attention to, but here is one more thing.

Port shape.

We want to port to be shaped to accomplish three things (that I’m aware of). First, we want the shape to match the way the air wants to flow. We don’t want there to be sharp bends where the air piles up or where the inside of the bend is so sharp that the air wants to shoot past and make flow disturbing eddies. Second, we want a shape that sets the air to flow smoothly over the valve and into the cylinder. Third, we want the head to promote swirl into the flow so that the air is swirling around in the cylinder. This is supposed to do lots of good things (increase torque, help the mix burn faster thus reducing the spark advance, improve fuel mileage, I think there are more things but I don’t know).

So that is what I know. Now let’s see what questions I need to answer.

- How much flow do I need for my application?
- How big do the ports need to be in order to do that?
- What influence does stroke have on this?
- Ramming and airspeed are important but how important is the swirl? How much difference will it make on power, torque, fuel efficiency, etc.?
- What other questions should I be asking?

"What about exhaust ports?"

Obviously similar things apply but the flow is mainly in the opposite direction.

"Mainly?"

Yes both intake and exhaust ports can have flow on both directions but this, like exhaust ports, is something that I will need to learn more about.

"Hey! What about valve shrouding?"

I'll talk about that later. It isn't really a part of what takes place in the port.

Well that took a while but it was worth it. I really feel like I have a much more solid grasp of what I know and a better understanding of what I don’t.

Builder

¹The way inches of water is computed can be described easiest by telling you how to make a gauge. Take a board attach a clear tube to it (without puncturing the tube!) so that the tube forms a ‘U’. Then fill the tube until water is halfway up the ‘U’. Then attach one end of the ‘U’ tube to a port connecting to an area with a pressure drop and keep the other end open to the air. Keep the ‘U’ vertical. If there is a pressure drop then one side of the ‘U’ will be higher than the other. Measure the distance from the top of the two water columns. This is how many inches of water the port is pulling. The name of this device is a manometer.

Happy Birthday to the Best Damn Country in the World

O say, can you see, by the dawn’s early light,
What so proudly we hailed at the twilight's last gleaming,
Whose broad stripes and bright stars, through the perilous fight
O’er the ramparts we watched, were so gallantly streaming?
And the rockets’ red glare, the bombs bursting in air
Gave proof through the night that our flag was still there;

O say, does that star-spangled banner yet wave
O’er the land of the free and the home of the brave?

On the shore, dimly seen thro’ the mist of the deep,
Where the foe’s haughty host in dread silence reposes,
What is that which the breeze, o’er the towering steep,
As it fitfully blows, half conceals, half discloses?
Now it catches the gleam of the morning’s first beam,
In full glory reflected, now shines on the stream

’Tis the star-spangled banner. Oh! long may it wave
O’er the land of the free and the home of the brave!

And where is that band who so vauntingly swore
That the havoc of war and the battle’s confusion
A home and a country should leave us no more?
Their blood has washed out their foul footsteps' pollution.
No refuge could save the hireling and slave
From the terror of flight, or the gloom of the grave,

And the star-spangled banner in triumph doth wave
O’er the land of the free and the home of the brave.

Oh! thus be it ever, when freemen shall stand
Between their loved homes and the war’s desolation,
Blest with vict’ry and peace, may the Heav’n-rescued land
Praise the Power that hath made and preserved us a nation!
Then conquer we must, when our cause it is just,
And this be our motto: "In God is our Trust"

And the star-spangled banner in triumph shall wave
O’er the land of the free and the home of the brave.

- Francis Scott Key

I have an Idea!

I’ve been making plans to build my ultimate engine first crack out of the box. While I have been around and nothing that I am planning on doing is outside of my abilities, the fact is that I have never opened up this particular engine and I’ve never built an engine from scratch. So what I am thinking is that I should build an engine or two before I dive in with a big project.

What I plan to propose to my project partner is that I just build an engine without too much focus of the goals (outside of reliability) and do it on the cheap. Having been a repair business I know people and have accounts with parts suppliers that offer me smokin’ deals on some stuff. So I would build a solid 50k mile engine. Then I would take the engine that is already in the Jeep and build it how my friend wants it. And then I would build the engine and take it to the limit.

Even with this plan though I need to know what I am trying to learn so I can build an engine that will work for the application.

I’ll have to run that by him and see what he thinks.

Builder

Disclaimer

It needs to be clear that I have little to nothing original to add to this or most any other subject. While some of the thoughts and ideas to originate with me (i.e. I thought them up on my own), if they are even remotely helpful in making things work better you can be damn sure that I am not the first to think of it. There is nothing new under the sun and the lucidity that can be found (if any) in my writing is the result of David Vizard, many excellent techs I have worked with, and my physics professors.

Additionally, this blog is about my thoughts and what I am doing. What I come up with may or may not work for me. If you try it then it is up to you to make it work, not me. If something I say here doesn't work then I will refund you what you paid me to read it. . .nothing.

Builder

WOW

I’ve been reading up some at the Speed Talk forum. While there are some idiots there for the most part it is a bunch of guys who REALLY know their stuff. The amount you have to know in order to truly know something is staggering. I’m hoping to acquire a level of expertise with the small block Chevy and I feel intimidated by it. These guys are as familiar as I would like to be with the SBC on many engines.

WoW!!

Builder

Not a Clue

After spending a few hours on the Summit website I gathered a rough price list for most of the parts involved in assembling an engine. I should qualify this list by saying I did not search for the best deal and simply looked for things that seemed like a good idea. I estimated the price for a core block and core heads. I’m not sure but I suspect that after doing the numbers I may find that it is nearly as expensive (maybe even cheaper!) to buy pre-assembled after market heads.

So what was the damage?

$5,473

Here is the list.

Part	Notes	Price
Engine Block	Used core (Price estimated)	150
Cylinder heads (2)	Used cores (Price estimated)	150
Crankshaft	Scat cast steel crank. Price for crank is pretty much the same regardless of stroke	190
Connecting rods (8)		200
Pistons (8)		275
Piston rings		100
ARP Studs		150
Headers		400
Carburetor	Thinking about a Speed Demon. Tunability and reliability are essential	500
K&N Air filter and housing	4” High 14” diameter. I’ve had good experience with K&N. KNN-60-1290	85
K&N substack	Won’t work on the Speed Demon but will use it if I select a different Carb	25
Camshaft	Flat tappet	125
Lifters	Hydraulic	100
Pushrods	Custom length (preassembled)	160 (90)
Rocker arms (16)	ST-2740	200
Valve covers (2)		50
Timing Chain	Double roller	90
Timing cover		20
Valves (16)		340
Valve springs and retainers		160
Valve seats	No idea what the price is but at this point pre-assembled after market heads are starting to sound like a good idea
Gasket set	Supposedly all the gaskets I’ll need	125
Intake manifold		200
Harmonic balancer	St-3995	270
Machine Work
- Bore and Hone		250
- Align hone	If needed. No price.
- Balance		200
Cylinder head Machine work. Guides, seats, deck.	No ideas on pricing but again, after market is looking better all the time
Bearings
- Cam		18
- Main		27
- Rod		32
Fuel pump	High volume low pressure	75
Fuel filter		10
Oil filter		10
Oil pan	MOR-20190 I'll need a different pan for a 4” stroke	136
- Windage tray		25
- Oil pickup		40
Oil pump	Standard volume ST-4398	30
Oil pump driveshaft		18
Water pump	High volume	175
T-stat		10
Ignition system
- Distributor	HEI	300
- Plug wires	Good stuff	110
- Spark Plugs		12
Total	And not all expenses are accounted for	5473

I should also point out that this does not include the price for specialized tools like micrometers and burettes.

This has been an enlightening exercise. I hear people discuss buying parts and refer to their costs that don’t make sense until you start really adding up the costs. If you are spending $6,000 to $8,000 on an engine then $1,300 for a block doesn’t seem like so much. This is especially true if you are building a high output motor. Well, I’m not. I’m looking for a modest power output hovering around 1 HP and 1lb ft per cubic inch.

However, I have an idea!

Builder

More Thoughts Re Budget

Wow. I thought I had a good idea of what I would be spending.

Not a clue.

I repeat, “I did not have a clue”

I was planning on forking out about $1,000. Well. . .I am about two thirds of the way through pricing out the parts list and I think I’m already over $2,000. The truth is that most of this is just idle circling around until I can get my hands on the necessary information for determining what the engine needs to give me the performance I want. Carburetors, crankshafts, connecting rods, pistons, oil pumps. . .they are all fun but the source of the engines power, or lack thereof, is the cylinder heads, more on that later.

Builder

Connecting Rod to Stroke Ratios

I spent some time, in the last post, discussing rod-to-stroke ratios but never actually looked at them. So here is a quickie.

First, rod-to-stroke ratios are determined by dividing the rod length by the stroke length.

For example, the stock 350 connecting rod is 5.7” from center to center. Rod lengths are determined by measuring the distance between the center of the big end hole and the small end hole. The stroke for a stock 350 is 3.480”.

We then compute the ratio as follows:

5.7”
-------- = 1.64
3.480”

1.64 is the rod-to-stroke ratio.

I have yet to see a reason for not putting the longest rods you can in an engine. The longest length you “can” fit depends on the purpose of the engine. If you stretch the rod lengths too far then you get troubles with the piston. As you increase rod length you have to decrease compression height (compression height [or distance] is the distance from the center of the wrist pin to the top pf the piston*). As you decrease compression height you begin crowding the rings and that can lead to reliability issues. There are various tricks to reducing compression height, like using a smaller diameter wrist pin, but these tricks are both expensive and relatively short lived. So for me the longest rods I “can” fit are with pistons with compression heights that permit reliability and a long service life. For the purposes of this evaluation I’m choosing (somewhat arbitrarily) 1.2” for the minimum compression height. Further research will determine what my true minimum is.

Back to rod-stroke ratios. All of the previous to say that I am presently trying to put the longest rods possible in the motor and want to see how these ratios look compared to each other.

Stroke	3.480”	3.750”	4.000”
Max Rod Length	6.08”	5.95”	5.82”
Rod-Stoke Ratio	1.747	1.587	1.455

It is ironic that as the stroke increases, and you need a longer rod to maintain rod-stroke ratio, the maximum rod length decreases.

Well, I don’t know what to do with these numbers but I know I don’t like the ratio for the 4.000” stroke.

More study is needed

Builder

* This isn’t strictly true with domed pistons but if you cut the dome off so the piston was flat, then you would have the compression height.