I've got a 408ci LS1..... iron block. My bore is 4.030

Mycar is turbo charged S91

Will LS9 head gaskets work well for me?


Thanks!!!

 

yes. 6.2 LS9 is 4.062

and ls9 gasket will go up to 4.075

 

I couldve sworn that i read they are a 4.1 gasket??

 

Im fairly certain that they are 4.100" as well either way they will work on your 408 OP

 

****. now that you guys say it. it might be a 4.100. either way you are fine. run it. lol.

 

Umm...anybody going to mention thickness/quench/compression ratio?

 

thickness is same as all of gm gaskets. .51

and compression is based off of more than just gaskets. a lot more

 

A LOT more? Deck height, compression height, piston dome/dish/valve relief, chamber volume (don't forget the volume of the valve faces...I've seen Ferrea ship different volume valve faces under the same PN), bore, stroke, and gasket bore/thickness...the OP didn't really say much other than that he has a 4.030" iron 408...nobody asked what heads, nobody asked if the block was zero decked and if so, what the piston tops look like...so my point was...rather than saying "yeah run those gaskets" maybe people could say "what are the rest of the specs on your engine?"...most GM gaskets are 0.051" and most STOCK gm bottom ends put the pistons out of the hole ~0.010" giving you very close to 0.040" quench...when you go to a built bottom end, I'd find it more likely that they were "in the hole" on paper, and the machine shop most likely milled the engine deck down to "zero" with the pistons...not always the case, but seems to be the most common...so then an off the shelf GM head gasket opens the quench up a lot...

I'm not trying to pick a fight...but there is a LOT more to head gasket selection than just "yeah, GM uses them with boost so go for it"...especially when it's a big bad built stroker that probably has a good amount of cash invested in it, and will have air forced into it, most likely with a fairly high HP/TQ goal...

 

^thank you

 

The block has been completely gone through.... All I ca say is that I had Cometic gaskets, and the heads are Patriot stg 3 72cc. The comp ration on the build sheet said 9.5:1

I know this is not an actual measurement, but the Cometic head gaskets are a 16th of an inch by dial caliper.. don't know what they are compressed.


Thanks for any help and input!!!

 

Calipers aren't accurate enough for thickness (could measure bore diameter with them though)...are there any part numbers on the gaskets that could be translated back to specs?

 

no markings on the Cometics to give me a clue. Builder is no longer in the bizz...... don't know what size the Coms were other than a 16th with dial caliper

 

Then at this point, you need to use a depth micrometer (borrow if necessary) to measure if your pistons are at zero deck, or in the hole, or out of the hole, and how much...then you really should also measure the displacement of their valve reliefs and of your chambers on your heads before you buy head gaskets.