91RS5speed

Ive been working on a 383 for a while now. Originally I was playing on running AFR heads and just never can get the cash for them. I'm thinking about picking up a set of used ZZ4 heads. How would the engine run with these?

The cam I have in the engine now is comp
Lift .487 intake ,495 exhaust
Duration @ .050 212 intake 218 exhaust
Lobe separation 113.0

Ill be running the stock base for now
Have SLP runners and ported upper

SLP 1 3/4 headers

Orr89RocZ

iTrader: (20)

It will run ok, but you need to make sure you have a big dish piston or else compression ratio is going to be thru the roof.

11 to 1 is pretty much standard with a 383 flat top pistons and 64cc chamber. ZZ4's have 58 cc chambers so you are now over 11.86 to 1.

Thats too much compression for most street pump gas builds unless you have a giant cam to bleed off the cylinder pressures, and that cam you have is very mild for a 383.

So with stock base, moderate compression, and those heads/cam, it will be a low rpm motor but make a GREAT deal of torque.
SLP's siamesed alot will help gain some higher rpms when combined with AFR or other better heads and aftermarket base down the road. Also look into more cam when you go with AFR's or whatever heads you end up getting for that 383.

As it is, that TPI 383 wont be a hp powerhouse but make a great deal more torque than a standard bolt on L98. It should even run well on stock tune for the most part, but would need abit of tweaking since its Speed density assuming you are using 91 MAP electronics from the car in your sig.

Artisan

For the most part I agree except that I don't think you will be able to bleed off enough compression even if you changed to a very long duration cam. Thats just too much compression. Would run good on race fuel though.

91RS5speed

I am running forged dished pistons in the 383. I don't remember the exact ones though. the CR came out to 9.5 or so with the 64cc heads. Also it is running speed density. I attached a pic of the short block you can see the dish.

Orr89RocZ

iTrader: (20)

If you can keep it cool, it is possible to do this. Couple guys on the vette forum and one or 2 here running near 12 to 1 and getting away with it on pump gas. Limited on timing however. LT1's can easily do mid 11's to high 11's to 1 compression with a big cam because they can keep cool with reverse cooling.

Its risky however and definately need to pay attention to the tune.

91RS5speed

Sorry to bring this back up. I did end up buying the 16 cc dished pistons to keep the cr low. Would this still beto much compression to run ZZ4 heads with 58cc? Here is the link to the summit rotating assembly I bought.

http://www.summitracing.com/parts/ESP-13052030/

Abubaca

iTrader: (3)

I can't help thinking those zz4 heads aren't gonna flow nearly enough for a 383. Tons of potential with porting, but outta the box they're not all that much better than stockers. But if you got a good deal, even with porting, they could be a better deal than brand new AFRs

F-Body Demon

iTrader: (1)

I got a set of ZZ4s you can have for $600.

https://www.thirdgen.org/forums/engi...zz4-heads.html

thomas1976

The link describes 2 piece rear main seal, I think you have/need the 1 piece.

91RS5speed

Ya I called summit when I ordered it originaly and told him i needed a 1 piece for a 91 block. He sold me the wrong kit I had to send back the 2 piece and they sent me a 1 piece. Still the same setup though. I just need to know if the CR will be to high with 58cc heads.

F-Body Demon I got a shipping quote for ya a few weeks ago but I need to make sure they will work before I go any further.

vetteoz

iTrader: (13)

383 with 58cc heads, 16cc pistons , 40 thou gasket , stock deck height
CR 9.9:1

Need full cam details to calc DCR

watajob

iTrader: (29)

http://www.purplesagetradingpost.com...fo/heads1.html

The ZZ4 heads are comparable to a 113's so they don't have great flow numbers. For the cost of those, you could probably find a set of Vortecs, have them redone with springs to handle the increased lift and still have some, if not most, of the cost of a Vortec base. Plus, the CR would be a non issue then. The only downside is the weight, although small, you could save with aluminum heads. Just my $.02.

thomas1976

Ok, just thought to point it out, the order could have be changed if it was not shipped, too late.

Here some links to posts, were I was investigating about CR and DCR, not a 383 but could be hepfull.
https://www.thirdgen.org/forums/tech...-dcr-help.html
https://www.thirdgen.org/forums/post...67-post29.html
https://www.thirdgen.org/forums/post...25-post25.html