J.D.78

pulled the heads of my 350. not quite the pistons in it I was hoping for . looks like 8.5 to1 compression with stock 76cc heads (462624) . it is a rebuilt engine with about 3000 miles on it. not really wanting to redo bottom end. what kind of compression you think I would get with the 64cc afr heads and maybe a thinner head gasket ? pistons are about .045 down at top dead center.

keithl1967

.045 at TDC? That is REALLY DEEP. Even on a stock engine set up, pistons were generally about .025-.035 in the hole...while I am a novice, I have never heard of a piston that deep.

Compression ratio will depend on the overbore as well--is this a stock setup (4.000), or was it rebuilt at one time, with an over bore (.020, .030, .040, etc)?

63mako

Cheaper rebuilder pistons are many times -.020 from stock which puts them .045 in the hole. Those are probably 17 CC Dish pistons (Stock replacement). With a .015 felpro 1094 gasket and 64 CC heads your compression calculates out to 8.77 to 1 at sea level figuring a .030 overbore. http://www.jeepstrokers.com/calculator/ Look at these 175 CC Trick Flow heads 56CC to bump compression. They flow 242/181 @ .500 lift and get you to about 9.5 to 1.
http://www.summitracing.com/search/p...8%2B4294918441

J.D.78

that's a little lower than I would like on compression . but I really don't want to redo the bottom end. you think I will make decent power with the 64 cc afr heads and a cam change ? or is there a lower cc head I should be looking at ? engine supposedly put out 292 rwhp the way it was. but I have doubts about that. lol

Jartanyon

Would decking the block be an option? If so, you could improve your compression more along with the other suggestions.

c3_dk

With only 3000 miles, would it then be ok to change the pistons and rings?
With 5cc pistons, 0.015 head gasket, 64 heads, 0.025 Down the hole, 0.30 over, you would get 10.39:1 quench 0.040

spikebot 81

I think you would notice a big improvement from the 624 heads to the afr's but a lot left on the table with such huge quench area. The engine that came in my Vette was .040 overbore with 882 smog heads, flat top pistons .040 down in the hole and a .040 head gasket. Very surprised it didn't rattle itself to death. A bit of fun with 2 kids in moms honda accord led to a engine swap. They didn't pull away but I couldn't pass them. Very embarrasing

J.D.78

was thinking I might have to change the pistons. new pistons light hone and rings. probably the cheapest way to go ? really didn't want to touch the bottom end. %&#$*(+@

bonesbrakr

Like the other suggestion. 56 cc heads. Unless you already have the 64 cc heads in which case then yes you need new pistons.

J.D.78

who makes the best aluminum 56 cc heads ? haven't bought the heads yet. I didn't see any afr 56cc heads measured bore. looks like 4.000 to me.

J.D.78

trick flow has some . probably get me up to 9 to1 compression ? would like to get around 400 hp out of this engine . doable ?
http://www.summitracing.com/search/d...rder=Ascending

keithl1967

what are your power goals?

Don't get so caught up in one number (compression)...Even with that short block and some 64 cc heads--with the right cam, you cans till get to 300-325 pretty easily...

And have it run on 87 octane...

63mako

Did you read my post????

J.D.78

evidently not all the way thru.

thinking one of these 2 with comp xe-274 cam . looking at howards cams too. not sure which one to get.
not sure how the angled plug holes will affect headers though.

J.D.78

ok , thinking the tfs30310002 heads(single springs)
and howards cl11004-12 cam. couple other cam choices listed. thoughts ?? looking to order soon.
oh , 700r4 trans with 3:73's out back
http://www.summitracing.com/compare

c3_dk

Nice set of heads, that will do the job :- )

diehrd

save cash get a set of L98 heads ,, even used if you have to , This way you are not throwing good money at a crappy lower end build..

The L98 head has 58cc combustion chamber , also used on the earlier ZZ4 motor and the TPI 350 motors from 87 and up ..

76strokervette

Iron eagle dart heads can be bought with 49cc combustion chambers which would bring you over 10 to 1 compression ratio.I believe they are only available in the cast iron line if that matters.

J.D.78

was all ready to pull the trigger on the trick flow heads. have to think about these now. pretty sure im going with the howard cam
279in\289 exh duration
465in\488exh lift . that's with stock rockers. I have 1.5 roller rockers.

the iron eagle heads do have bigger valves.

tektrans

Why don't you just find a used procharger or top mount mini blower since your cr is so low?
IMO to spend money on new heads (which will most likely be really hard to sell in the future because of the small chamber size) to just satisfy that old bottom end is not the best way to go about it. Jmo.
If the iron eagle heads have larger valves are you even sure they will clear the fly cuts on your current pistons?