My 86 heritage has a base gasket leak that has been getting progressively worse and this winter I'm going to take care of it.

While the motor is apart I would like to try and gain a little compression and basically just make the most out of the setup I already have without breaking the bank.

Here is kind of a rundown of what I'm planning. Any input would be greatly appreciated as to whether this looks OK or if there would be a better route.

The motor has about 30k on it and I've already been in the cam chest and replaced the, inner cam bearing, lifters, pushrods, breather gear, and installed an s&s 508 cam.

1) pistons
Depending on how stuff looks when I get it apart I may just hone and re-ring what I have or if need be use some new stock compression pistons. Is there a brand people prefer?

The reason im staying away from 10:1 pistons is that The cam grind im running has a fairly short duration so I was told to stay under 10:1 to avoid detonation problems. And I haven't been able to find any 9 or 9.5:1 piston options.

2) squish band and deck height.
I plan on using cometics .030 head gaskets so what should I shoot for for deck height? Would aiming for .000 and having a squish of .030 be too tight?

3) heads
I will have a valve job done and new seals and what not, but I would also like to have them decked so I could end up with about a 9 or 9.5:1 CR.

The research I've done online leads me to believe that if I took .040 off the heads and used a .030 head gasket that should get me close?

My question is with a .508 lift cam and a tighter squish band will I run into valve to piston clearance problems?

Any feedback would be much appreciated!

Thanks, FS

 

I am running Keith Black 9.5-1 hypereutectic pistons in mine.
Also I'm running a 30 thou head gasket and a 10 thou base gasket without issues.

After installing the EV-27 in mine I didn't notice that the stock springs were hitting the inside of my rocker boxes.
It wasn't until I went in for a top end rebuild that I found that out so as a precaution I suggest you have the beehive springs installed in place of the stock springs.

 

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Just built my1986 over the winter and what I discovered was Oem gaskets were .060" ,Oem pistons had no valve relief in them, yours may be the same. So shaving the heads and that cam you have and thinner head gaskets means new pistons in my opinion. Cast pistons and bore .010" over was recommended to me and that is what I did, some parts are listed in my signature for my rebuild , you could also read through my thread I had ," evo rebuild under way ".....

 

I played around some on the keith black website and their 9.5:1s look like a great way to go.

That would give me the c.r. I'm looking for without worrying about clearance issues with factory flat tops like glidein wide was talking about.

And yes some beehives would also be a good idea. So far I haven't had any issues with my 30 year old factory springs but I know I'm playing with fire running that lift with them.

Thank you both for the good info!