mich2112

iTrader: (1)

Here the deal:

I have a 88 Iroc with a 305 TPI motor with a rod knock. I can get a 89 Truck 350, 4 bolt main block (cast 638) with swirl port heads (cast 191). I don't plan to use the 191 heads because of what I have read here, but to save some $$$, might use the 305 heads instead.

This is what I had thought so far:

Rebuild the short block and convert to roller cam using ZZ4 cam.

Transfer or buy new the push rods, timing gear, roller lifters, spider, etc. (this block has the bosses for the spider).

Have the heads machined for 1.94 intakes and have them ported on the intake and exhaust (or would buying a used set of 083's be better).

Want to be between 9.5-10 comp ratio.

Using stock TPI for now with 350 injectors.

Will change the knock sensor and chip.

Will I need springs for the ZZ4 cam?

Does this sound good, or is there a better approach.

Thanks in advance.

Mike Jones

Odyssey

I'd look into some ZZ4/vette heads. They can be bought fairly cheap and if you sell both the 305 and the new 350s heads, with that money you can buy ZZ4 heads.

That way you'll have a better flowing head, and aluminum to boot.

Bort62

Sounds like you are on the right track.

The LB9 heads will be better than the TBI truck heads.

But I like the idea of selling both of them, and trying to find either a set of Aluminum or Cast Iron L98 heads. Ally preferably cut Cast Iron should be able to be had dirty Cheap.

I would reccommend upgrading springs with the ZZ4 Cam. Cheap Insurance.

All your Lb9 roller Hardware should transfer right over.

The ZZ4 Cam should run well In that combo w/ the stock TPI.

F-BIRD'88

The 305 TPI heads (081) you already own have just as much potential * when ported*
as the 350TPI heads (083) *when ported* and near the potential of the aluminum version *when ported*(better ex port)
You need to thourougly port them of course and get new 1.94 x1.60 valves.
When your done your chamber cc will be right about 61 cc's
so the cr will not be too high. ( chamber sweep)
Hey if the guides are ok and ya know they are not cracked
and ya don't mind porting them I say use them.
The 081 and 083 have the same ports. The difference is the chamber size and valve size but you can fix that.
All three of these heads are good. *when ported*

If the 89 truck motor has dished pistons of any kind and you want any where near 10:1 then the smaller chamber of the 305 head is the way to go.

hydric

My 5 cents -

aluminum is good, but from my exp... and many others I know around here that race the quarter daily, they are only good if u can replace them within a couple years or even shorter.

I suggest cast iron heads

mich2112

iTrader: (1)

1) How much will a shop charge to increase the valve sizes in the 305 - Lb9 heads?

2) When rebuilding the short block, what type of pistons should I use?

3) Don't want alum vette heads or vortec because of the hassel, expense of changing intake manifolds and no egr or installing external egr. Thats why I wanted to stay with 081 or 083.

F-BIRD'88

1. If you ask a shop that, they'll interpret that as "How much extra should they charge you"?
If you port the heads out to just below the valve stock valve seat and carve out the chamber wall a little so the larger valves
clear the chamber wall beforehand there is no reason they should charge you extra. The job is the same. If the shop trys to do so , find another.

2. Hypereutectic pistons are the best bang for the buck
federal mogul flat top hp345's are popular. If you can break these pistons, you can break any piston !:hail:

3. Cool, so port up your 305 heads your self and buy larger 1.94x 1.60 valves and take 'em in for a valve job.
You can read al about how to do this in David Vizard's book
"How to build a small block chev on a budget" Best $10 you'll
spend.