Head gasket advice

[Davesdart]

So I have a 383 stroked to 496, +6.5 dome pistons. The block has been heavily decked in order to square and parallel the head surface. This was done by the same trusted machine guy I always use. So here is my dilemma, and I could be over thinking this. The flat of the piston comes out of the hole .023. I clayed the dome, with 1/2" of clay. Doesn't even touch the clay. Clayed the valve pockets, with .040 of clearance. This was done with a .040 thick gasket. Should I be ok? Am I over thinking this? Heads are Trick flow 270 max wedge comp port. Any knowledgeable insite welcome. Thanks

 

[RemCharger]

You are not overthinking this.
Race gas engine?
Where you're at now, you would have .017 piston to head clearance.
No good.
I would shoot for the .040 area, so you'd call that a .063 headgasket.
Not sure what the closest cometic would be to that.

 

[steve340]

Provided the dome will fit in the combustion chamber and clear the valves at full lift you need too check the flat or squish areas of the cylinder head for clearance.

 

[Davesdart]

You are not overthinking this.
Race gas engine?
Where you're at now, you would have .017 piston to head clearance.
No good.
I would shoot for the .040 area, so you'd call that a .063 headgasket.
Not sure what the closest cometic would be to that.

Yes race gas engine.I was running .060 cometic gasket and I was told that maybe I was leaving a little bit on the table

 

[RemCharger]

So at .060, you're at .037 correct?
I would say that's perfect but I'm not much of a gambling man.( to go tighter)

 

[Davesdart]

Provided the dome will fit in the combustion chamber and clear the valves at full lift you need too check the flat or squish areas of the cylinder head for clearance.

I am not sure I quite understand what you are saying

 

[WileE]

I'm not sure how much meat you've sliced, but I also thought of intake geometry.

 

[Davesdart]

I'm not sure how much meat you've sliced, but I also thought of intake geometry.

I was concerned about that too. But, I guess enough but, not too much. My indy 400B fits fine

 

[Davesdart]

So at .060, you're at .037 correct?
I would say that's perfect but I'm not much of a gambling man.( to

So at .060, you're at .037 correct?
I would say that's perfect but I'm not much of a gambling man.( to go tighter)

That was the way I was thinking it to be. Talking to a couple of people at the track, a couple of suggestions was I can go as low as .035 on quench. Another suggestion was flat top pistons.

 

[RemCharger]

That was the way I was thinking it to be. Talking to a couple of people at the track, a couple of suggestions was I can go as low as .035 on quench. Another suggestion was flat top pistons.

What CR do have, how much are you trying to get?
Can't see .002 more quench add much on a dyno sheet.

 

[Davesdart]

What CR do have, how much are you trying to get?
Can't see .002 more quench add much on a dyno sheet.

I thought my CR @ 13.43 was fine, but it seems as if my car is under powered for my combination. So there were a few suggestions and comments made that I was trying to look into to find the issue. One was maybe I was giving up something somewhere in the engine namely head gasket. I believe my engine to have 700hp but my ET 9.71 @ 138MPH. 2800lb car says different. I was also told that it could be possibly the converter.

 

[Davesdart]

What CR do have, how much are you trying to get?
Can't see .002 more quench add much on a dyno sheet.

Sometimes I listen to people that I believe are more knowledgeable than I am, and I start to second guess myself.

 

[Geoff 2]

This engine has a big diam piston, which means it has a lot of 'rock'. I would use a head gasket that gives a minimum 0.020 " piston to head clearance, with about 0.025" being ideal for retaining quench.

If the 0.040" referred to in post #1 is valve to piston clearance, it is not enough. Should be 0.100/0.125" in/exh; going tighter with a 700 hp engine is risky.

 

[Davesdart]

This engine has a big diam piston, which means it has a lot of 'rock'. I would use a head gasket that gives a minimum 0.020 " piston to head clearance, with about 0.025" being ideal for retaining quench.

If the 0.040" referred to in post #1 is valve to piston clearance, it is not enough. Should be 0.100/0.125" in/exh; going tighter with a 700 hp engine is risky.

I am going to reclay it all again to make sure I am correct in my measurements.

 

[RemCharger]

I thought my CR @ 13.43 was fine, but it seems as if my car is under powered for my combination. So there were a few suggestions and comments made that I was trying to look into to find the issue. One was maybe I was giving up something somewhere in the engine namely head gasket. I believe my engine to have 700hp but my ET 9.71 @ 138MPH. 2800lb car says different. I was also told that it could be possibly the converter.

Doesn't sound too far off to me..
But it does sound like you're taking a perceived or guessed hp # and applying that to a slide rule or calculator..
Many guys at our track run a similar combo, right around the 10 0 mark.
1 guy actually dynoed right about 700 but is probably a tad heavier.
My 383 with a 3.38 stroke crank and -1s ran 10.50 at 130 in a similar weight to yours.
Converter and gearing left something to be desired. Not that there's a direct correlation.
Converters can definitely slow you down without noticing a problem
What is the converter?

 

[Davesdart]

Doesn't sound too far off to me..
But it does sound like you're taking a perceived or guessed hp # and applying that to a slide rule or calculator..
Many guys at our track run a similar combo, right around the 10 0 mark.
1 guy actually dynoed right about 700 but is probably a tad heavier.
My 383 with a 3.38 stroke crank and -1s ran 10.50 at 130 in a similar weight to yours.
Converter and gearing left something to be desired. Not that there's a direct correlation.
Converters can definitely slow you down without noticing a problem
What is the converter?

I have 4.250 stroke. Doing the math, first time ever trying it, says 720hp. Converter is 8" TCI. Couple of years ago I sent it to ptc to be tightened up a bit.

 

[RemCharger]

I have 4.250 stroke. Doing the math, first time ever trying it, says 720hp. Converter is 8" TCI. Couple of years ago I sent it to ptc to be tightened up a bit.

727 or glide?

 

[Davesdart]

727 or glide?

Glide.

 

[RemCharger]

Glide.

Getting the right converter isn't easy. But at least with a glide there's lots out there.
And there's the 1st gear ratio.
A data logger would probably help see what's going on. Haven't used one myself, but would sure like one.

 

[Davesdart]

Getting the right converter isn't easy. But at least with a glide there's lots out there.
And there's the 1st gear ratio.
A data logger would probably help see what's going on. Haven't used one myself, but would sure like one.

I would like one as well. A good friend of mine, whom drag races sometimes, mostly builds sprint car engines seems to think there is too much converter slip. He is also the one who says he doesn't believe I need domed piston. needless to say, currently I am in my head too much and am goung a little bonkers. I built my car with the purpose of running a
C gas class 9.60 at no more than 150mph. Rules state no faster on MPH. I figured I failed, but there are several people telling with my car and engine combination, they believe there is a lot more in it. I just don't have the knowledge or experience to find it. Other than machine work, and shortening/bracing of rearend, I have done it all myself. Engine build, car/chassis build, and transmission build. I am just at a loss right now.