[John Langer]

Originally Posted by 65nss4spdGTO

Are you saying the inserts didn't work?

I'm sure the water helps, but everyone that has used this mod showed a big gain in head gasket life.

Calvin Hill
Hill Performance
708-250-7420

I have said before and will say again, the rules are different when you are making over 1100hp na.

[60man]

I have the Tiger mod on my heads and checked compression(cold) today to see if I need to pull top end....
Lowest cylinder was 180 and highest was 185. There is 80 passes on them at close to 15-1 CR...
Well worth the price!!
Thanks Glen...

[Glenn Sedig]

Originally Posted by 60man

I have the Tiger mod on my heads and checked compression(cold) today to see if I need to pull top end....
Lowest cylinder was 180 and highest was 185. There is 80 passes on them at close to 15-1 CR...
Well worth the price!!
Thanks Glen...

You are welcome.

We have had good results with the new inserts. We have done 15 to 20 sets of heads and have not heard of any problems other than the ones mentioned below.

I got one set of heads back that was running nitrous and went lean. The alum around and under the insert was melted away and almost all of the way thru to the other chamber. The inset looked like it did when it was installed. My customer wondered if the melted area could be welded up without removing the insert. My first thought was no, then I said, it held up to nitrous, maybe it would hold up to welding also. I don't know how or if it was repaired. I would be interested in hearing if the head is fixed and how it was done.

A second set of heads had a problem after several initial dyno pulls. I'm not sure yet what caused the issue, but I will let you know when I find out.

If anyone else is having any problems please let me know.

Thanks

Glenn Sedig
815 441 0931

[65nss4spdGTO]

I've not had a single issue with any of the sets I've installed inserts in.

Calvin Hill
Hill Performance
708-250-7420

[65nss4spdGTO]

Originally Posted by badgto

I had Calvin put the insert in my cv-1 heads several years ago when I kept burning head gaskets and burn a gap between 4 and 6 chambers. I use cometic head gaskets. Went to mannual fuel injection fix problem and insert works great.

I'm being told of the first issue regarding this modification regardless of cylinder head type. Not having the chance to inspect the head to get to the root cause or corrective action, Keith indicates leakage between the two cylinders after running the insert for a number of years. I know the head was serviced by other shops, not sure if the decks were cut or insert was disturbed or removed. I did offer to inspect the heads at no charge.

All that being said, this is a performance modification that was designed to fix specific issues with the heat associated between the center exhaust ports on Pontiac head.

This modification doesn't come with a five year, unlimited off-road racing warranty.

Calvin Hill
Hill Performance
708-250-7420

[mysticmissle]

why, with the advertised superior cooling of the cv1 design, was this deemed neccesary in an alcohol application? Was he having head gasket issues before this mod? Not trying to fire up the natives, but i was unaware he had this mod on his heads.

[65nss4spdGTO]

Originally Posted by mysticmissle

why, with the advertised superior cooling of the cv1 design, was this deemed neccesary in an alcohol application? Was he having head gasket issues before this mod? Not trying to fire up the natives, but i was unaware he had this mod on his heads.

That is a great question.

Most people I know never have an issue with heat running alcohol, many have to run a separate fuel system just to create heat.

He burned out the center between the exhaust valves, sent the head in for repair. Decided to use the deck insert vs welding.

Is alcohol prone to creating heat issues? I would image it can be similar if the condition is too lean.

Calvin Hill
Hill Performance
708-250-7420

[BruceWilkie]

I've read that methanol can be more prone to preignition than gasoline at stoichiometric correct mixture.

Pre-ignition is far more damaging than detonation. It strikes faster than you can respond to it. Keep in mind diesel motors run in detonation continually.

Pre-ignition can have you lighting off before BDC and trying to compress burning mixture. EGT soars and piston looks like plasma cutter was in it's place. Total meltdown before a full revolution has completed. Been there done that.

[slowbird]

Originally Posted by BruceWilkie

I've read that methanol can be more prone to preignition than gasoline at stoichiometric correct mixture.

Pre-ignition is far more damaging than detonation. It strikes faster than you can respond to it. Keep in mind diesel motors run in detonation continually.

Pre-ignition can have you lighting off before BDC and trying to compress burning mixture. EGT soars and piston looks like plasma cutter was in it's place. Total meltdown before a full revolution has completed. Been there done that.

So he should have had messed up pistons and rod bearings would be beat to heck along with the head issues, correct?

[7T2]

Originally Posted by mysticmissle

why, with the advertised superior cooling of the cv1 design, was this deemed neccesary in an alcohol application? Was he having head gasket issues before this mod? Not trying to fire up the natives, but i was unaware he had this mod on his heads.

incident rate of cv-1's burning thru center cyl's is historically less than 1%-
pdude did it back in '09 when he forgot to turn his water pump on before a burnout / run- and keith's.
im not aware of any other cv-1's that have the deck inserts installed besides keith's, but calvin or glen may have other info

[BruceWilkie]

Originally Posted by slowbird

So he should have had messed up pistons and rod bearings would be beat to heck along with the head issues, correct?

On two stroke with. Oil diuted pump gas I had big hole in center of piston and aluminum sprayed on rings and cylinder walls. Chamber and plugs covered with some aluminum. Never actually hurt chamber it always cleaned up ok. Roller bearings weren't failed. After doing this probably a dozen times the bearings had beat up the case to point bearings rattled at idle and sypmptoms of failing seal between cylinders. I replaced entire bottom end with a good used one. My jugs were ported. Sometimes cleaned up ok enough to just bore to next oversize. Then just had to port match new pistons.. other times had to resleeve so back to std bore and port new pistons. Yeah I learned from it.