My car was in the shop for a month after breaking my rpm level 3 diff and putting a new one in and I have had it back almost a week. After a few hundred miles I decided to get on it once and I noticed a bunch of smoke behind me when I did (it was dark out but I think it was white). Next morning my battery was dead from sitting in the shop so I threw a new one in and was on my way to work. I looked down and noticed the temp was 255. I immediately turned the car off and coasted off the freeway into a parking lot. In the parking lot I replaced the tstat with a stock one and it would still overheat in about 2 minutes. Towed it to my buddies shop and he hooked up a machine that read 110+ hydrocarbons in the radiator resoirvoir.

(on a funny note he put it in the tailpipe of a chevy malibu and it appeared the air in my resoirvoir was more toxic than the exhaust of the malibu.)

I called west coast corvettes and they said it's $750 to do the head gaskets plus cost of gaskets, bolts, oil, coolant, etc. I had cometic .045 head gaskets in there before.

One question, can I go to stock head gaskets? I think they are .052 or something and I wouldn't mind lowering my compression a little for 91 octane (currently afr 205's milled to 59cc with the cometics). He also said the cometcs are a few hundred bucks when stock is $33 a piece. I don't want to cut corners though.

Anyone have any thoughts on this? I didn't think blown head gaskets was too common on these motors, but who knows.

Mod list:
2002 Z06 - AFR 205 heads milled to 59cc, upgraded double springs, Custom Grind Comp Cam 232/236 .617/.600 112 LSA, LG Pro Headers, Borla Stinger Catback, Halltech CAI, ASP Underdrive Crank Pulley, 7.400" Chromoly Pushrods, LS2 Timing Chain and Sprocket, .045 Cometic Headgaskets, B&M shifter, 42lb injectors , RPM level V trans, RPM level 3 diff, MT ET Streets. 440/406.

 

 

could be any number of reasons for a blown head gasket. Especially if the heads were replaced. Stock they almost never blow. These engines are touchy when it comes to head gaskets and torque. The head bolt holes need to be clean and dry all the way to the bottom. If they use new stock bolts, they need to do the torque to yield perfectly.

I just did mine myself because the shop that did the initial (long story) replacement tried to reuse the old bolts. Lasted about a year then blew the gasket. Lucky nuff did not get anything in the oil.

Make sure they go with the ARPs and then you don't have to do that torque to yield thing, just torque to ARP specs. Plus you can reuse the ARP bolts.

As far as stock gaskets vers others. The stockers are pretty high quality, other than thickness the stockers are the best value for the money.

 

You have the 0.045 head gaskets for a reason - to give you the desired compression and quench that your H/C was set up for. If you go to the stock gasket - you will save $$ but you will lose performance (especially lower RPM torque). I assume your tune was based on the 0.045 head gasket and the octane of the gas use normally use. So the new gaskets will not match with your tune.

If I were to do the fix - I would get the same thickness gaskets and not try to save a few $$. Also, have you thought about doing it yourself? It is not that hard.

Good Luck.

 

I guess I could do it myself, but I don't have another car to drive in the meantime. Would I need a lift to get to the longtubes?

I was thinking stock because my car was set up for 100 octane which an old owner used to run all the time and now it is tuned down to 91. I am not sure what the tune looks like. I think the last owner said my compression is 13.6:1 EDIT: IT'S 11.8:1, I'M AN IDIOT. I was wondering if stock head gaskets would be safer on it... it's my DD afterall

 

Having a highly modded car as your sole horse will leave you frustrated after a while.

I tried that with a mostly stock Zo6 and it didn't always work out as planned over two years. Then I bought a cheap beater car and things are a little better.

On the head gasket I would use a stock one. I've got my heads off the car and plan some stock ones, they work well.

 

i used stock gm head gaskets on my 94mm turbo car (4-bolt 6.0 prod block)with head studs of course....(1200rwhp......) no problems until the wastegate stuck and the car hit 37lbs of boost.........not good...lol..........i had cometics on my grand national, just because i couldnt find another good set of ml gaskets for it

my procharged t/a still has stock ones on it also

stock ones is the only way i would go

 

How much power would you guys guess I would lose going from a .045 gasket to a .052 or whatever stock is... will it be noticable?

 

I believe AFR has a chart showing how much head surfacing will reduce the chambers' ccs. IIRC, .006" deck removal translates into 1cc. So my thinking is that increasing HG thickness by .007" would give about the same result. If that's right, 1cc wouldn't be noticable.

You could check AFR's website to see if the numbers are posted there. I've got a couple of their catalogs laying around here somewhere. I can track them down if you need me to; let me know.

Jake

West Point ROCKS! Nation's TOP COLLEGE per Forbes Magazine!! Graduation Day Parade 20 May 2010!!!

 

if you didnt spray it, someone who did the install fuked up....afr heads have a very thick deck so the issue is not with them, it was with the torque pattern.

 

 

Re-think any kind of head bolts. The ARP stud system will not wear out the block threaded holes. We all like to play the game and pull cylinder heads more than on stock motors. Nice not to have to clean out the bolt holes.
If you go to stock head gaskets, recheck your rocker arm wipe pattern on the valve stems.
With the heads off, consider lifter change.

A reliable beater for work will give you great peace of MIND and not force you into a hasty decision on your motor. Why waste that motor driving to work every day. You'll enjoy your car more if you don't HAVE to drive it every day.

Wish you all the best.

 

definitely didn't spray it. I think I'll look for arp head studs. I'm hearing it's likely the heads will have to be resurfaced... you think?

 

if you purchased the heads new, i dont see how they could have warped or have an uneven surface. you should be able to install new gaskets and arp's and be all set.

 

While the head gasket is the most likely cause, you won't know until you get it apart...
That being said, If it's the head gasket, I would have the heads checked for damage, warping etc. If OK, I wouldn't hesitate using GM gaskets w/ARP hardware, your performance should be about the same.

Good luck.

Mike

 

the .045 head gasket creates a tighter quench area. a stock GM gasket is great quality but it can effect the tune (by changing the quench area) and pushrod length. Example if you have morel lifters the added height would effect pushrod length, you would need a slightly longer one (not rocker/valve stem center). If you have stock lifters or ones that are like stock ex. a .040 preload you should be ok with the GM gasket concerning pushrods.
do you know if stock head bolts were used when the heads were put on and did they reuse the original ones? I would stay with a .045 gasket and ARP studs or bolts. use studs if you plan on pulling heads again in the future. always clean the bolt holes and get the antifreeze out or them. a real pain
the heads should be torqued in small steps-flatten the gasket evenly.

 

As I said above I had to replace my head gaskets about a month ago. Some things I learned: Eventhough the heads are in good shape you should have them trued up. Aluminum heads have a tendency to be come "wavy" we checked mine and took off the bare minimum to get them perfect wound up removing 3 thou. this gives you a nice fresh true surface. With you changing gaskets etc. and the previous posts from others showing you probably won't notice the difference in compression change, I would say have the heads trued up, new stock gaskets, ARP bolts or studs, and you will have a really good reliable job done.

 

How many miles since the heads were installed? A blown headgasket could be a symptom rather than the root of the problem.

 

First let me say, I have no personal experience with the Cometic gaskets. From what I've read here on the forum, they are a quality product, but do require meticulous preparation of the mating surfaces. If you have the heads milled, you need to make sure they take a very fine cut. The smoother the surface, the better it will seal. Some of the guys use the Permatex copper spray gasket prior to assembly. Do a search here and on the LS forum. I'm sure you will find more info on using Cometic gaskets.

Here's some info.

http://www.cometic.com/faq.aspx

http://www.ls1tech.com/forums/genera...pros-come.html

 

Sounds to me like you may have detonated the engine due to a combination not designed for 91 octane (and the gasket failed from detonation).

Do you have notches in your pistons at all....are they OEM that were flycut or aftermarket pistons?

You might need to drop the CR of that combination some if you plan to continue to run 91 pump gas.

-Tony