340 stroker 422

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Miszny

Miszny

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Hi

I recently started building a 340 stroker.
The block was rough so we went with 4.100 bore. Walls are still thick so it should be fine.
I got:
- Molnar 4.000” crank
- Scat 6.123” rods
- Wiseco k0144a100 flat top pistons
- Very nicely ported RPM heads
- Performer rpm intake
- Felpro 1008 head gaskets .039” thick
- Hydraulic roller cam 232/[email protected] 108lsa .565” lift

Cam card calls for 104 icl, after retard of 2 degrees it came up at 104.5 degrees.

It was all nice till I realized my compression status. It’s going to be 11.83:1 static and 10.12:1 dynamic…

Is there any chance for this to work on premium pump gas?

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E2FFA81D-BAB4-4E1F-B4CD-966F83FD9F13.jpeg
 
Did you cc your heads and pistons? Those are some pretty big eyebrows in those pistons.
 
If those compression ratios are accurate, I believe you will be ok. If not you can mix a gallon of race gas to 10 gallons of premium.
 
Or you could get a thick pair of cometic head gaskets, they are like.060.
 
Cometic has head gaskets up to .080 at least, contact them and see if they can accommodate your bore.
Or have the pistons shaved to get the CR where you want it.
 
What's your goal with the build? Cam seems small for the displacement.
 
thats a pretty small cam , thicker gaskets or go bigger on your cam to lower your dynamic , race fuel is a poa in a street car, I'm at 10.85 static & 8.87 dynamic , fine on 93 ----240-244 @ .050 and sounds tame. You will regret that small cam.
 
Select a bigger cam, better yet give a cam grinder a call and never go with a thicker gasket.
The gasket should always be figured in when mapping the build.
 
Unless you did a downfill on the cylinder you don’t really know what you have.

IMO, for your displacement you are at least 15 degrees too small on your cam timing and probably 3 degrees too wide on your LSA.

What heads are they?
 
Professor Fate said:
Cometic has head gaskets up to .080 at least, contact them and see if they can accommodate your bore.
Or have the pistons shaved to get the CR where you want it.
Click to expand...
Cometic did me a .100 thick.
Rat Bastid said:
Unless you did a downfill on the cylinder you don’t really know what you have.

IMO, for your displacement you are at least 15 degrees too small on your cam timing and probably 3 degrees too wide on your LSA.

What heads are they?
Click to expand...
He said nicely done RPM’s which leaves a little to the imagination. If he still has the 2.02 valves, a 104 LSA would be in order. If he has 2.08, a move up 1 is the math. If I did the math right.

The increased duration is a look for more overlap I assume?

@Miszny, do you already have the camshaft?
The cam you have listed above is right around a nice street grind and really doesn’t require a lot of compression.

Go through your math again on compression and see what you need for head gasket thickness to drop it some.
 
Don't you lose the quench effect using a thick gasket? It seems like a waste to build a good motor and then do that.
 
Thicker head gasket will cause you to lose the quench effect and quench helps reduce detonation. I think losing quench is the wrong way to reduce compression.
 
Running that cam, needed to start with a dish piston.

Flat tops, put a bunch more cam in it to settle down dynamic compression

I think location might be an issue with parts from the pictures. Auto Lic Plate
 
Given the location. And their 98 ron is similar to 93 in the US right?
If no option for parts swaps. I would run the numbers on 106 and 108 installed centerline with that cam and a .050” gasket (still utilize quench properties). Double check all the measurements to be sure on compression. But 11.8 sounds right with a stroker and flat top piston right?
 
Which ede head, the open chamber or closed chamber.

If it's the open chamber, you aren't likely going to have quench anyways, so go with a thicker gasket.

Closed chamber... nevermind.
 
1MeanA said:
Don't you lose the quench effect using a thick gasket? It seems like a waste to build a good motor and then do that.
Click to expand...
Yes but that doesn’t mean the engine will run bad or like crap.
340sFastback said:
Thicker head gasket will cause you to lose the quench effect and quench helps reduce detonation. I think losing quench is the wrong way to reduce compression.
Click to expand...
True it does help reduce detonation. However, IF and that’s a big IF he already has the cam, it is already know that a cam that size will work and very well I have to add at even a 9.0-1 ratio. Been there done that in the ‘80’s and many before me and a lot older than me have done that.

Ideal, no, an easy way to get up and going? YES!
A good working ratio is all that’s needed.
Not quench!

Quench is a great thing but never worry if you have it or not. Ignore that fact you don’t have it. I haven’t run the numbers on his set up but there’s 3 ways to reduce the “CRANKING” pressure. Cam change, chamber enlargement, thicker head gasket. Of course and I’m sure a piston change is out.

Otherwise, how do you plan to retain the quench but reduce the cranking dynamic compression?

How much of that chamber is going to be carved away and yet still be a good chamber nevermind it’s less than great design as cast.

Detonation can be helped by quench but there is a whole lot more to detonation than just a good quench area.
 
.070 head gasket will equal 11-1. If I calculated correctly

For what it’s worth, I’m running a .030 - 360 w/a zero deck flat top pistons from sealed power (C116HP), TF heads (60cc) .039 X 4.04 head gasket which works out to 11-1 (11.09-1 actual) and a Hyd roller comp w/a 224 intake duration in pump 93.

No problems, no worries.

He will have to work with the distributor timing. That’s it.
The only way he can run what he has set up now is with a mix of not straight race fuel. That will allow the best timing curve and power output but… but….. that will take a bunch of money to run race fuel all the time. I don’t care if miszny is super rich! Needing that kind of fuel is not at the local gas station and limits driving the car and it’s fun since he will need a gasoline truck following him everywhere.
 
People are telling the OP to go to a bigger cam, but nobody has asked him what the intended use of the engine is....& if idle quality & vacuum [ power brakes ] are a concern.

Will it detonate? Won't know until it is running. Every engine is different. DCR is a useless calculation, don't know why people use it.
 
DCR is more accurate in the probable fuel octane needed.
 
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