Durango_Boy

I'm planning my 454 build, and was looking for some heads. Consider the starting point a stock rebuilt Gen6 454 long block. Stock crank, rods, and pistons. Stock deck, and a yet undetermined cam.

I'm looking into older generation heads, and was wondering what a good chamber CC to shoot for was. 118 seems very common, both in oval and small ports, but also seems a bit high.

What chamber CC should I be looking for?

Bullshark

Durango, my old iron heads (390hp oval) on the 69 427 and 70 454 were around 100cc for what it's worth.

Why are you going with the old tech heads anyway??

Bullshark

brngrhd

loking at head the 100cc chamber heads are called "high compression heads" the 110 heads are the "normal" heads for most aftermarket heads 118-120 sounds normal. imo the old heads work well unless your looking for huge numbers. talking to a bunch or engine builder friends of mine they told me that the stock heads that are on the 69 396 camaro engine that is in my car, would be fine for my 500+ hp build, so why spend 1500 on a new set of iron eagle or merlin heads.

Durango_Boy

Well, I was told the heads, 118 CC, on the Gen6 blocks are designed for torque and fuel economy and won't fit the bill very well for a Corvette engine.

The old tech heads are just an option for cheap used heads. I don't mind using Gen6 heads but I want something that'll flow well and not blow my SCR out the window.

So if I use 118 CC heads, I could deck the block, use a thin head gasket, and port if needed for better flow?

iree75

My ol' 9840 square ports are at 107cc closed chamber. They came with the motor I bought. But plan on replacing them with AFR 305s in a year or so. Save some weight, better flow and allow someone to have some 9840s that really needs them for their restoration. Check out Engine Masters for some ideas.. http://www.popularhotrodding.com/enginemasters/

Little Mouse

The 101cc 69/70 heads used on 390hp engines had a bathtub style
chamber the wall of the chamber was steep and kept the valves
shrouded pretty bad, the 118/119 heads are open chamber the
steep wall is leighed down angled away from the valves helps
unshruod the valves allowing the engine to pull air around the valve
easier. open chamber is the head to have for best overall breathing.
but if you want much compression with 118/119 open chamber you
will need a piston with at least a small dome.

Durango_Boy

Right, and I wanted to stay with stock pistons for budget reasons. I'm trying to build a good budget motor, changing the heads and cam. Will decking help achieve a decent SCR?

Jughead

Depends on whether your stock pistons are domed (probably not), dished, eyebrow or flat tops. I used 110cc chambered aluminums and use domed 1971 LS-6 TRW pistons, 14cc volume and ended up with about a 9.4 CR.

Little Mouse

DB the chamber on an open chamber head is so big decking the block
will do next to nothing to help you. think about it a small block
starts out with only 64cc chambers and the low comp engines had
only 76cc, open chamber factory big block 119.

Durango_Boy

Okay. So to use 118 CC chamber heads I pretty much have to get small domed pistons.

What would the CSR be with these heads, and stock possibly flat pistons?

Little Mouse

If your piston is a flat top you might find a way to squeak out a true 8.25/8.5
comp. with a 119 chamber.

Jughead showed you, he has smaller 110 chambers and a 14cc
domed piston and has 9.4 comp. with you using 119 chambers
and if you do happen to have flat top pistons you will be lucky
to have a true 8.25 comp. this is a change pistons for comp.
deal or do without comp. deal.

Durango_Boy

What CC dome pistons would be best with a 118?

Bullshark

Durango, back in my hell bent for leather days, my brother and I rebuilt the 390hp engines for more power. It was sort of a sybling rivalry thing I guess. We each had the stock head chambers machined between the valves to provide clearence for some high dome TRW pistons. Can't remember their part no, but they are still in the 69 today. If our calculations were correct back then, that resulted in ~12-1 CR. We had a pretty radical cam.....the old Crane Fireball. Back in the days when we could still buy the high octane Sunoco they were king of the hill...... at least the hill we lived on After teh gas went south in the early 70's it was a constant battle trying to find AV gas and keep them from rattling the tops out of the pistons. I finally tore the 454 down and replaced the pistons with a set with a lower dome. It calculated out to be around 9.6-1. The engine is sitting on a stand having never been started. That's when I started my second childhood and opted for the RamJet. Fuel Injection helped alot with preignition on the 69 but I still have to be real carefull and run high octane. Needless to say it doesn't get much use.

Bullshark

Durango_Boy

No mistake here, I want to use pump gas, and I think a 10.0 comp is what I'll want to shoot for.

I'm not a high RPM kind of driver. I like tooling around at lower RPMs, using the torque more the high RPM HP. I will have a 5-speed manual behind it, and it won't see much if any racing.

L88Plus

I've only seen 4 types of Gen 6 heads. First is the L-29 Vortec head, great exhaust but intake is lacking. 100cc chamber, great compression ratio and good for torque. Second is peanut ports, can't remember the casting number off the top of my head, good for trucks and doorstops. Third is good ol' rectangular port heads. Very similar to 990's but the short turn seems a bit tighter to me. Fourth is a semi-closed chamber true large oval. Except for the shape of the water passages, it looks identical to the old -215, -290 and -063 castings. If you have those, they might be a good starting point. Keep in mind that except for the rectangular port heads, all Gen 6 stuff I've seen has non-adjustable valvetrain.

Little Mouse

be carefull a 10.00 comp. iron headed big block will not be like
a 10.00 iron headed small block it will be more prone to ping
not good, stay at 9.25/9.5 and plan on 93 octain. I'm assuming you will
have a very mild duration cam.

Durango_Boy

Yeah I wasn't planning on anything radical. I have not decided on cam specs yet, but I don't go out of control when it comes to cams. I'm taking suggestions for that too by the way.

Little Mouse

Heres a mild cam for torque a small amount of mid range better
then a pickup cam, hydraulic flat tappit
Crane powermax
Power range 1600-5400
int. dur..050 216
ex. dur..050 228
adv. int. dur. 272
adv. ex. dur. 284
LSA 112
lift int. 515
lift. ex. 510

Cam Facts- good idle, daily usage, off road, towing,
8.75 to 10.75 compression ratio advised.
Cam part #133941, lifters part# 99277-16

Durango_Boy

Wow that's really good info. Something to keep in mind is the Gen6 454 is a factory roller. Should I look for a roller cam with those same numbers or will they need to change based on that difference?

Little Mouse

Just keep your int. dur. figures pretty simular so the power band
will be roughly the same hydraulic roller will have more lift, a hydraulic
roller will have a little broader power range then a flat tappit cam
so you could go up a little on duration and still be ok as long as
you have the comp. to support it say 9.25 to 9.50.