Thread: Need Help with this build please!

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Hi guys, new member and my first engine build. i have a 350 5.7 Chevy Vortec engine. its been bored out .60 and has a 383 stroker kit. it has a camshaft with Duration 288/298, Lift .444/.466 . here are some specs on the kit. i also have a quickfuel 750 cfm double pumper carb.

Bore (in): 4.060 in.
Bore (mm): 103.124mm
Engine Stroke (in): 3.750 in.
Balanced: Yes
Pistons Included: Yes
Piston Rings Included: Yes
Piston and Ring Oversize (in): 0.060 in.
Piston Material: Hypereutectic aluminum
Piston Style: Dish, with a D-shaped cup
Piston Head Volume (cc): +12.00cc
Wrist Pin Style: Floating
Piston Ring Facing Material: Plasmamoly

i plan on running nos but no turbo. should use a copper head gasket or MLS?

should i go with a thinner or thicker gasket


the engine still has the stock valves and they are in decent condition, will putting in some new ones give me more hp or can i get away with the stock ones?

i know its a lot so any feedback would greatly be appreciated. thanks guys!

What is the intended use of the engine ?

You didn't say what heads you will be using, but assuming 64cc combustion chambers, 0.025" piston deck height and a 0.015" compressed steel shim head gasket such as a Fel-Pro 1094, I have your SCR (static compression ratio) at 10.41:1. If you're using iron heads, you probably won't get away with this on pump gas, as the motor will likely want to detonate. It should be fine at this SCR with aluminum heads though. Problem with using aluminum heads with a thin steel shim gasket is that the heads will fret against the steel gasket and wear away, so you need a thicker composition gasket for use with aluminum heads. Problem with this is that if you didn't cut the block decks for "zero deck", then the piston deck height added to the gasket thickness will put the crown of the piston too far away from the underside of the cylinder head and the resultant wide "squish/quench" will contribute to detonation.

See, here's the thing.....you started buying parts before you engineered the build, so now you have painted yourself into a corner.

Start with the "STACK" of parts that you will use.
1. Crank radius.... half the stroke. Half of a 383 stroke is 1.875"
2. Rod length....you didn't tell us this.
3. Piston compression height....you didn't tell us this either.
These 3 values added together equals the "stack" of parts that you will fit into the block. From the factory, this value was 9.000" for all Gen I small block Chevy motors. To compensate for different stroke lengths, the compression distance on the piston was changed. For instance, on your stroker, the piston compression height was changed from stock 1.560" to 1.425" if your kit provided a 5.7" rod or to 1.125" if your kit provided a 6.000" rod.

Anyway, this is where you start, with the stack measurement. Then you measure the block deck height of the cylinder block. Stock from the factory, the blueprint dimension is 9.025". Now, if you measure a small block block and find that exact measurement on all four corners of the block, you should run right out and buy a lottery ticket. Not only will it not be 9.025" on any corner, but no two corners will have the same block deck height. This leads to problems when you get farther into the build. If the block is not square, then the heads cannot sit squarely on the block and the intake manifold has no chance in hell of sealing up at the manifold/head interface. That's why some fellows end up with a motor that uses oil. If the interface if gapped open on the bottom, no amount of trying to find a vacuum leak will work and the cylinders will suck in oily crankcase vapors every time the intake valve opens.

So, let's say that you find your stack at 9.000" and your block averages 9.023". This gives you a piston deck height of 0.023". When you finish off the motor, you add this piston deck height to the compressed gasket thickness and you have the squish/quench figure. In this case, with a 0.015" steel shim gasket, the squish/quench works out to 0.038", solidly in the range of 0.035" to 0.045" that is recommended by those who know what they are doing. And that will work great with iron heads. But aluminum heads need a cushion to prevent fretting the aluminum against the much harder steel of the gasket. If they fret long enough, the action can wear away enough material that the heads get loose on the block and the next thing you have is a blown head gasket.

Let's say further that your stack is 9.000" and you take the block to the machine shop and have the decks cut to 9.000". Now, you have a "zero deck" block and you can use a thicker composition gasket for use with aluminum heads and still maintain the 0.035" to 0.045" squish/quench that will prevent detonation.

I'm going to copy one of old bogie's posts from another forum instead of writing all of it out.....

" You're rather limited in what you can do since the block isn't decked and the heads are aluminum. Aluminum really prefers a composition gasket or a MLS stainless gasket. None of which come thinner than .028 inch so you end up with a quench of .053 which with an aluminum head isn't too bad as they are more tolerant of what you could think of as excessive chamber temperature simply because aluminum pulls heat out of the chamber and into the coolant faster than iron.

The problem with shim gaskets is structural because aluminum has a higher coefficient of expansion than iron it expands and contracts more than the iron block and a shim gasket causing the head to wear a groove into itself around the combustion chamber. The composition or MLS gasket provides a surface that allows the head to move around in relation to the block with the shearing stresses taken in the material layering so to a big extent the face against the head moves with it reducing the rubbing wear on the softer aluminum called fretting or brineling.

Copper can make a good gasket but it should have an O ring either built in to the gasket or modify the block or head to install an stainless O ring that is used to bend the copper up sufficient that the head installation causes a crush fit. The copper moves more like the aluminum helping reducing the wear on the soft aluminum.

One of my favorites is the composition GM gasket 10105117 or 14096405 these are .028 inch thick and carry stainless both sides or graphite on one side and stainless on the other.

Again nothing eliminates the wear issue of the aluminum this is just a case of finding better solutions to reduce it certainly if the aluminum is brought to a T5 or T6 hardening it is useful in reducing this wear but often import heads like White's might not have this done."

So, you have two things to measure before going any further, your stack and your block deck heights on all four corners.

1. Never, ever use a thicker head gasket to lower static compression ratio. The motor will detonate worse than if you used a thinner gasket and a little higher static compression ratio because the thinner gasket will make a thinner squish/quench.
2. You will likely need at least a 3000 stall torque converter to prevent bogging the motor when you lean into that double pumper.
3. Never, ever bore a small block Chevy to +0.060". Thin walls will contribute to overheating. Don't believe it? Read Smokey Yunick's Power Secrets.
4. Give us all the info you have on the cam. Advertised duration and lift are not even half the story. Is this a flat tappet cam or a roller? The lift looks weak for a roller.

.

My kneejerk .02 (and Tech will correct me if I'm wrong) : if you're planning nitrous, then the cam choice MUST accommodate the juice, which means a reduced performance when the button is off.

This might explain why "the lift looks weak", or perhaps there is a particular reason you chose this cam.

Unless I missed it, you didn't state your application: street or strip?