TwoFast4Lv

iTrader: (8)

I checked on this a while back.


DO NOT put FelPros back on. Call SDPC and get some Cometics. Those and some ARPs. I am coming out of the hole on a #82 jet and took out my FelPros. All the big boys told me to go to Cometics.

BTW If you lower the compression you just have to run more juice to make up for it . No myth there

SincalT/A

iTrader: (16)

The little compression you gain will be offset by the way better quench height.

BoostedZ28

Can you be more specific about the head gasket problem? You say the motor is lifting the head which is unusual for your combination. If this is what is actually happening, a new gasket isn't going to fix the problem. What does the head gasket look like after you notice the problem?

As mentioned earlier, Cometic gaskets require a specific "smoothness" on both the cylinder head and deck of the block. Unless you know for sure that they have been machined with this in mind, I wouldn't choose the Cometics for a replacement. Most people have choosen Felpro 1074's and don't seem to have any problems with them. If it is feasible, I would consider head studs and pay close attention to ARP's torque procedure AND the recommended lube to use on them...it makes a tremendous difference.

IH8FORD

iTrader: (6)

I was using a .064 Flat-out copper gasket. The #2 and #7 Bores in the gasket were pushed over at the triagle shaped water jacket at the corner of the block.The bolt holes on those cylinders also looked kind of oval shaped.

IH8FORD

iTrader: (6)

No my fuel system is a 255 intank walboro with a hotwire kit and a aeromotive presure regulator.

96capricemgr

iTrader: (1)

I would then wonder if a momentary lean at the hit [plays into this as well.

If you go too a small dedicated system you can use a low pressure carbed deadhead style pump and regulator for reasonable money and put as high an octane unleaded as you can find in there.

That was a thick gasket you were running, any idea on the bore. Wondering how much compression will be raised going too a thin gasket.

BoostedZ28

Is the block o-ringed and the head have a receiver groove? I've never known anyone to have any luck sealing a copper head gasket at the combustion chamber without these. From Flatout's website:

How do I prepare to use Copper Head Gaskets?
We recommend that all copper head gaskets be installed on engines with machined "o-ring" grooves and stainless steel wire o-rings. This groove is traditionally done in the engine block. Typical wire diameter is .041" in a .039" wide x .029" deep groove resulting in a wire standup of .012". This is used in combination with a .040" thick copper gasket (about 4 times the wire standup). For engines at or above 3 HP per cubic inch of displacement, the combustion seal should be enhanced. For this we recommend a receiver groove opposite the o-ring, typically in the cylinder heads. See your engine builder for other options and machining details

BoostedZ28

From the Cometic website FAQs:


What surface finish is required to us an MLS head gasket?
A surface finish of 50 RA (roughness average) or finer, is recommended for a proper gasket seal. Anything rougher may conflict with the gasket design.

IH8FORD

iTrader: (6)

The bore was 4.155 . If I go back down to like a.040 gasket I think the Compression will be about 12.5-1.

IH8FORD

iTrader: (6)

How would you be able to tell what finish you have on the block.I will be getting the heads redone anyway. And the machine shop I use probally does it that way because they said for about the last year cometics are all they put on anything now. They are what I have on my 408 for my 99SS.

BoostedZ28

There is a "tool" that will read the roughness I believe. There have been numerous threads regarding this topic. It seems the Cometics are pretty set in needing to see this finish, otherwise there are some noticable sealing issues.

You said you were using a "copper head gasket" from Flatout. Is the block o-ringed for this style of gasket???

gatorhead

iTrader: (4)

All nitrous systems require timing to be pulled a total of 1-1.5 degrees per 50 hp. Larger shots should use a programmable timing control.A general rule of thumb is that a stock engine can hold up to a 150 shot, but it needs a proper tune. Anything larger than that and you want forged everything!You want to run a colder plug when using nitrous, up to a 150 shot you need one to two steps colder and reduce the gap between .025-.030. Any larger shots need yet another two to three steps colder on the plugs and gaps should be closer to the .025.

IH8FORD

iTrader: (6)

The Block does not have an o-ring.

Ray@Nitrous Outlet

I have run both the Fel-pro's and cometics in my 12.2:1 motor with up to a 200 shot of nitrous

JonCR96Z

iTrader: (33)

Oh, ok. I say quench, you say quench-smench. I say cam timing, you say too much work. Let somebody else say it and you're all over it.

Running a quench height of .035 means gasket thickness of .028. That means SCR is gonna be 13:1, which don't really mean **** if your DCR is in check. And the added detonation resistance of low quench height means less head lifting (assuming that the heads are lifting and that it is caused by detonation). You better get your degree wheel and dial indicator out. And lets hope that you don't have to turn it so far back that it causes your other valve timing events to be out of whack. I'll come down and help you if you'll put my clutch in while I'm there.

TwoFast4Lv

iTrader: (8)

I must have gone over LOL!

I put the .088 jet in last night

BoostedZ28

If you are going through head gaskets (they are leaking cylinder pressure)and they are copper and the block is not o-ringed and the cylinder head does not have a receiver groove, I would tend to believe this is your problem. Why are you running copper head gaskets on the motor???

Ray@Nitrous Outlet

Ellis an .088 is weak....I will be running a .136 in the new kit



















but the solenoid is .093

TwoFast4Lv

iTrader: (8)

LOL On the next engine I plan on starting with a .032 jet. . on each hole

I am pushing this set of pistons already

Just gotta make it through April!

jakesz28

iTrader: (9)

Only a .032 in each hole, That must just be the first stage right?

Or at least that's thw way I'm doing it.

Man three months to go. Times running out and my wallet is alot thinner.