Big Block headgaskets - steel shim for racing?

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C

cudadenny

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I just picked up a new motor and pulled apart: it's a 400 w/steel crank w/ KB pistons and stage 5 iron heads, It had Felpro 1009 (.039") headgaskets , I have a set of MP 4286754 (.020") headgaskets in the package and am asking if the MP shim gaskets would be better for racing and nitrous ? or stick with the felpros , I am using stock style headbolts , thanks
 
As long as your block and heads have flat surfaces, the steel gaskets will work fine and give you about 1/2 point more compression which all 383's and 400's can always use.
 
The engine is supposed to be 9 to 1 compression and the pistons are at zero deck. I was planning on a 125 shot of nitrous when I come off the transbrake at 3500 rpms , and I have a dana 60 w 4.10 gears and 29x10 tires.

I called Mopar tech and the guy was like " well those gaskets are performance.. because they are thin to increase HP ... they should be fine "

I don't want to sacrifice durability or coolant leakage to gain a 1/2 point in compression since I can add more than that through the nitrous. Does anyone here use these type gaskets for racing ? how about a better reccomendation like the fel pro or detroits or cometics ?
 
You may not like that gasket for NOS. You want to make sure the gasket has adaquate bore size for the 400's largest bore of any big block, and that the fire ring does not sit out beyond the cylinder's taper. The 1009 fits ok (4.41 bore, your block at .030 over is 4.38). Otherwise you can burn them out in a few miles. The steel gasket with it's smaller bore will also act similar to a sharp edge, and could promote preigition if you are not careful.
 
I did not take the gasket bore size into account , thank you. The reasons you pointed out make perfect sense.
I looked closer at the engine block today and the area between 3+5 under the fire ring of the PT1009's looks to have been leaking (black). whereas everywhere else the fire ring left a clean mark. I checked the deck and it is flat.
 
Another thing to check is to tap the bolt holes with a bottoming tap, and blow the debris out. I've seen a heavily decked set f heads not bolt down tight becuase the holes were full of crud. Mopar holes are generally dry. So you want them clean and the threads good. And carefully torque with the right lube.
 
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