Hi guys,

I`m putting a new set of heads on my stock bottom end, the heads have been flat-milled 20 thousandths, the cam I`m going to run is the 230/236 .544int/ .555ex lift w\ 1.6rr`s. I need to know if i will have any problem running the impalla gaskets 29 thousandths thickness when it comes to piston to valve clearance. Don`t want to damage a piston or valve.

please help.

 

It really should be measured, not "guesstimated". To even guesstimate it though, it would be helpful to know the "deck": how far down in the hole the piston crown is. Are the lift numbers with 1.6 rockers, or 1.5? Stock pistons? LT1 heads?

Rich Krause

 

Sorry,

little more info. The bottom end is completely stock 96 LT1 that is in my 96 trans am. As stated in the previous post the lift numbers are w\ 1.6roller rockers. The heads to be installed are stock ported LT1 aluminum heads also from a 96 LT1 Trans Am. The have been flat milled 20 thousandths. If I already had the stock heads off I could tell you how far down the piston crown is but they are still on and I`m driving my car currently. I am trying to order all the parts prior to tearing the car down. Since there are a whole lot of people running the cam I am going to see first post I assumed someone else has had their heads flatmilled 20 and obviously needed head gaskets and should be able to help me. Hence the post.

So has anyone w\ a LT1, w\ aluminum heads that have been flatmilled 20 thousandths, and a stock LT1 bottom end(shortblock) running the XE 230/236 .544in/ .555ex lift tried using the impalla head gaskets? and if so were there any piston to valve clearance problems? And are you currently running that setup now?

 

You're going to find a lot more people with LT1's on "LT1 Tech".

Moving to LT1 Tech.....

 

Any help?

 

I'm running the XL 230/236 with Impy Gaskets, the head has been shaved .010 and I have no problems at all.

It would be best to measure just to make sure but from what I can recall I still had plenty of clearance with mine. Where you run into problems if you zeroed clearance the block out plus shaved the heads down alot. Than you might have to go to bigger valve releases in the pistons.

When I did a compression measurements on mine it calculated out to be 11:1, yours chances are will be a little higher.

 

Thanks for the help Ken. The only diff in my setup would be the additional 10 thousandths milled off the headscompared to yours. I guess if I was to run the Felpro`s which are 10 thousands thicker than the impy`s then I would have the same CR as you. I`m not doing anything to the block other than scraping the old gasket if needed. So do you think 10 thousandths less than your setup would be OK? I`m ordering gaskets prior to teardown.

Thanks