Head Gaskets???

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DentalDart

DentalDart

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Thick or Thin head gaskets? Can I get some input on which ones I should run? Is this a controversial topic? If not I'll start a new thread with a more controversial topic :rofl:

Engine - 1968 340
Pistons- 30 over TRW pistons that are avg of 12 thousandths over? (I think that's how it was stated)
Heads- heavy *** X heads
Springs- comp 901
Rockers - Stock
Rods- straight pieces of metal that are stock?
Compression- pictured below 135-157
Camshaft- Summit 1789 (cam card pictured)
Hooker comp headers
RPM 7576 Air Gap
2.5in exhaust

Need anything else?

The car had some engine tech 7J gaskets on it (measuring thickness tomorrow) and I have some felt pro 8355pt which are .053 thickness. Or should I get thinner head gaskets?

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What does it have on it now?
 
Sorry cam card of 1789

Edit- Pistons were .012-.013 above deck height on drivers side

@RustyRatRod currently the headgaskets are/were enginetech and I havent been able find the specs of them

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Felpro 1008's will raise compression by about 0.2 points and cranking compression about 4 psi on average. Just noticeable in the butt-dyno.

Mr Gasket 1121G's will raise compression by about 0.4 point and about 8 psi of cranking compression. A definite change will be felt. These are thin and some have reported sealing issues; so I can only recommend that the heads and block be known to be good and flat before using these. If the heads and block have not been checked or surfaced, then you cannot count on them being flat.
 
nm9stheham said:
Felpro 1008's will raise compression by about 0.2 points and cranking compression about 4 psi on average. Just noticeable in the butt-dyno.

Mr Gasket 1121G's will raise compression by about 0.4 point and about 8 psi of cranking compression. A definite change will be felt. These are thin and some have reported sealing issues; so I can only recommend that the heads and block be known to be good and flat before using these. If the heads and block have not been checked or surfaced, then you cannot count on them being flat.
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I'm cleaning the heads, block, and intake currently... well not right now because I'm taking a little break and my cordless drill battery died and it's now charging. Also I ran out of brake cleaner and need to get more

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If you want to be pulling the heads again, run the Mr Gaskets.
 
go with felpro 1008
i seen on ebay mopar performance steel shim old stock time to time, mr.gasket equals trouble
also you can mill up to .045 on stock heads but you need to measure everything first.
 
Slantsix64 said:
go with felpro 1008
i seen on ebay mopar performance steel shim old stock time to time, mr.gasket equals trouble
also you can mill up to .045 on stock heads but you need to measure everything first.
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Mill .045 on stock heads. What do you mean?
 
DentalDart said:
Mill .045 on stock heads. What do you mean?
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you would have to check piston height the current cylinder head cc's in your chamber, how thick the head gaskets are, on my stock 318 302 heads i milled .045 to reduce chamber volume from 64cc to 58cc, but you would for sure need to know everything before you mill.
 
dano said:
Hell, at the point you're at now, just pull the short block out.
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Not today kemosabe. I'm to old for that kind of stuff and the short block is in good shape... plus I dont have a cherry picker anymore (is that a good excuse? Lol)
 
DentalDart said:
Mill .045 on stock heads. What do you mean?
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IMO, you don't need to mill anything except to make sure the heads are FLAT and TRUE. You have a 340 with two eyebrow pistons and positive deck height. You WILL HAVE plenty of compression AS IS. Use the stock FelPro blue gaskets and you'll never have trouble. Mill the heads JUST to clean them up and no more. This is a driver. You don't want too much cylinder pressure on a hot afternoon stuck in traffic with your family. You want a driver. Something that's not finikey. Something that won't detonate no matter WHAT. You're not building a hot street or race engine, just a driver. Don't lose focus on that.
 
RustyRatRod said:
IMO, you don't need to mill anything except to make sure the heads are FLAT and TRUE. You have a 340 with two eyebrow pistons and positive deck height. You WILL HAVE plenty of compression AS IS. Use the stock FelPro blue gaskets and you'll never have trouble. Mill the heads JUST to clean them up and no more. This is a driver. You don't want too much cylinder pressure on a hot afternoon stuck in traffic with your family. You want a driver. Something that's not finikey. Something that won't detonate no matter WHAT. You're not building a hot street or race engine, just a driver. Don't lose focus on that.
Click to expand...

Agree! Dont tell my daughter its not a race engine though, she thinks her purple car is the fastest car in the world :)
 
DentalDart said:
Mill .045 on stock heads. What do you mean
Click to expand...
He means taking the heads to a machine shop and having the surface that goes against the block shaved down by 0.045". It makes the combustion chamber smaller thus raising the compression ratio.

IMHO you are making changes to an unknown engine. You knew it worked before with the head gasket it had on there. (Or the valve s did not hit the heads, you could run on pump gas without ping, etc.) With the changes you are making it is unknown where you will end up with tune, drivability etc. I would get a head gasket as similar in thickness to what was on there. If you are using a cam with more lift then what was on there before you might want to make sure the valves don't hit the pistons.

Admittedly I'm no expert and others can say with some certainty that your combo will work without checking.
 
Dana67Dart said:
He means taking the heads to a machine shop and having the surface that goes against the block shaved down by 0.045". It makes the combustion chamber smaller thus raising the compression ratio.

IMHO you are making changes to an unknown engine. You knew it worked before with the head gasket it had on there. (Or the valve s did not hit the heads, you could run on pump gas without ping, etc.) With the changes you are making it is unknown where you will end up with tune, drivability etc. I would get a head gasket as similar in thickness to what was on there. If you are using a cam with more lift then what was on there before you might want to make sure the valves don't hit the pistons.

Admittedly I'm no expert and others can say with some certainty that your combo will work without checking.
Click to expand...

I think you are right on key. I believe all the OP is looking for is a bit of an upgrade and to make it sound good. Nothing wrong with either. Easy to get caught up in the "do this" and "do that". Heck, it's already a 340. It was a high performance engine from the get go. I say use the cam you have, make sure the heads are good......the power comes from the heads, after all clean that pup up and stick it back together.
 
Dana67Dart said:
He means taking the heads to a machine shop and having the surface that goes against the block shaved down by 0.045". It makes the combustion chamber smaller thus raising the compression ratio.

IMHO you are making changes to an unknown engine. You knew it worked before with the head gasket it had on there. (Or the valve s did not hit the heads, you could run on pump gas without ping, etc.) With the changes you are making it is unknown where you will end up with tune, drivability etc. I would get a head gasket as similar in thickness to what was on there. If you are using a cam with more lift then what was on there before you might want to make sure the valves don't hit the pistons.

Admittedly I'm no expert and others can say with some certainty that your combo will work without checking.
Click to expand...


If you do that, then you may need to mill the intake also, especially if you run the thinner gaskets - stay with the fel pro 1008's...
 
you know you guys..with all these questions I will spend a hour explaining this **** to him.....LOL.....have to draw more pictures...
 
Docs a sharp cookie. All of us didn't know what milling the heads was at one time. A little info points him in the right direction and he can reasearch from there.

I'm glad doc is here he inspires me to get off my butt and work on my car.
 
Dana67Dart said:
He means taking the heads to a machine shop and having the surface that goes against the block shaved down by 0.045". It makes the combustion chamber smaller thus raising the compression ratio.

IMHO you are making changes to an unknown engine. You knew it worked before with the head gasket it had on there. (Or the valve s did not hit the heads, you could run on pump gas without ping, etc.) With the changes you are making it is unknown where you will end up with tune, drivability etc. I would get a head gasket as similar in thickness to what was on there. If you are using a cam with more lift then what was on there before you might want to make sure the valves don't hit the pistons.

Admittedly I'm no expert and others can say with some certainty that your combo will work without checking.
Click to expand...

We have checked the deck height on the driver side head as that is the one he got off first...and the TRW L2316 F pistons are approximately .012 to 013 above the deck...the piston have very nice valve notches...his cam theoretical lift is going to be around .470 with the cam he really wants....we all know stock rockers are not 1.50 ratio ....I ran a MP 590 with those pistons so we will be no where near PTV problems..I will to bet the cam will probably have no more that 230 degrees duration at .050...and I think he will narrow the LSA from 114 to 110....he wants some lope....sound...lol
 
krazykuda said:
If you do that, then you may need to mill the intake also, especially if you run the thinner gaskets - stay with the fel pro 1008's...
Click to expand...
nope 0.45 is the max you can go without having to mill the intake any more than you would have too
 
will we do some calculations on the compression ratio tomorrow...like a best to worst case.......

we got new springs and valve seals to put on the heads.....

I think right now...it would weeks to get anything done in a machine shop....i think he wants this running soon....
 
70aarcuda said:
you know you guys..with all these questions I will spend a hour explaining this **** to him.....LOL.....have to draw more pictures...
Click to expand...

But you're such an artist! :poke:

Edit- and the more pictures and explanations you give me the better help I'll be when we put that AAR cuda together for you to drive around.
 
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