1BAD88

I am hoping to move to AFR 195's for my 88 with a Super Ram, headers, 222 cam, stock bottom end and pistons, etc. and have a couple of questions.

#1 What is the best way to deal with the loss in compression ratio without replacing the pistons? By my math it will drop to about 8.8:1 and a thinner head gasket won't be enough to compensate.

#2 If the heads are milled, what size chambers should I shoot for?

#3 Do the heads need to be angle milled to maintain intake manifold mounting geometry?

#4 For roller rockers on this set up would it be best to use 1.5 on the intake and 1.6 on exhaust or should I use 1.6 straight across?

#5 Has anyone else kept the bottom end and pistons with a similar set up?

tpi 421 vette

The smallest chamber size is 65cc's. You can flat mill to 60cc's. You have to angle mill to get the chamber smaller than that. Angle milling is almost twice the money after the surfaces are corrected, compared to flat milling. TPIS sells a .028" head gasket which is worth about 1/2 of compression. I have used them before, and haven't had any problems with them.

I personally would run 1.6 rockers on both sides. You will maximize all the flow you can out of the AFR 195's.

1989TransAm

I agree with the above. I just want to add that GM also sells the .028 head gasket at a decent price. Could be where TPIS gets theirs.

Calderone

TPIS sells the gasket but i found out they are Victor Reinz 5746
http://www.summitracing.com/parts/CLE-5746/

Bore (in) 4.125 in.
Bore (mm) 104.775mm / 4.125 in.
Gasket Material Nitroseal
Compressed Thickness (in) 0.026 in.
Compressed Volume (cc) 5.400cc
Lock Wire No

Im currently using those on my AFR195's with great success
1.6 Roller Rockers and Super Ram, 7.200 Chromemoly pushrods and 219 LPECamshaft

It's running GREAT with Zero problems !
Go for the AFR's ! you will be pleased !


as a note aside...if you are going to tear down the engine that much
i suggest to add forgedpistons rods and crank stroke it
and make it a bulletproof rotating assembly
im regreting that and i think i will tear everything apart
just because of this

88BlackZ-51

Let me know 1BAD88.

1BAD88

So if I have them milled to 60cc's and use a 0.028" head gasket it looks like I can get to 9.63:1

4" bore, 3.48" stroke, 4.03" head gasket diameter, 0.028" compressed gasket, 60cc chamber, 12 cc relief pistons, 0.025" deck

Does that sound correct? How would this affect intake manifold mounting?

-J

QuickBlack85

I have the 195's angle milled to 60 with TPIS mini-ram putting out 398HP at the fly wheel.
I've had it apart several times I highly reccomend the cometic head gaskets, had problems with the others.

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

GREGGPENN

Cometics are good stuff. That's for sure. (I used them on a zero-deck setup to get a .040" quench.)

But, I went the angle-milling route -- having my 195's cut to 56cc chambers. I had zero issue with intake mounting. There was still enough space for the china walls -- which (to me) means you'd have no issues with flat-milling to 60cc.

The difference in 4cc's isn't worth the extra cost though (in terms of power). I could have (and would have) used flat tops with the 65cc as-cast setup -- if I'd decided on the 383 before buying my heads.

When redoing a bottom-end, seriously consider a 383. Glad I did anyway.

1BAD88

Gregg,

You bring up an interesting point though, with the 56cc chambers you were able to use a thicker head gasket that is generally considered to be a more reliable option.

-J

Corvette0096

I would talk to your machine shop. Some of the gaskets listed above can leak without the right machine finish on the block and or heads.

GREGGPENN

You could still zero deck your block, flat mill to 60cc, use a .035-.040" gasket to get ~.040" quench, and get amazing performance.

If you really look at the power-level difference of specific dynamic/static compression levels, you won't find much difference in HP numbers. Raising a whole compression point only gives you 10hp or something very low like that.

cv67

Yes but it can make a combination either wake up or always be a little on the lazy side, thats important.

Firm believer in running compression whenever you can. 'Course theres always "too much" of a good thing too.

bjankuski

Use the Fel=pro 1094 gasket (coated steel shim .015 compressed thickness)

Mill the heads to 60cc or less to get compression near 10:1

GREGGPENN

I understand what you're saying. With the flexibility of the timing grid (SA), I'd think you could pick up off-idle response via the tune.

Of course, I'm pumped by the off-idle performance of my small-cam, 10.25 SCR 383 setup. (All 3, of which, create responsiveness)

1) chamber size
2) longer rod stroke
3) shorter valve-open events

The later being an option you can persue with smaller cams and better breathing heads -- and still get great TQ/HP numbers.

88BlackZ-51

I agree. For whatever reason the higher compression rides I have been in have never felt lazy.

1BAD88

Perhaps I'm thinking about this upside down. What about changing the pistons, rings, and rod bolts? This way the heads could be used as is and would have more options for future builds. Any other parts that would be needed for this swap?

GREGGPENN

I think it makes more sense to spend your money on RA parts vs milling the heads. Your choices are quite extensive and include stroking the motor.

If you just want to bore it to a 355 and put flat-tops in it, that'll work too. Then, leave the AFRs at 65cc.

Calderone

Yes,that's what i did !

1BAD88

Thank you everyone for your advice. I ended up with a regular pair of 195/1040's. A big thanks goes to Rick for all of his help. Now I just have to wait until the end of may.

88BlackZ-51

No problem. Hope it all works out for you.