This is for a pretty mild 350 build. (extreme budget)
350 block, bored .040 over
Summit 1102 cam (Duration @.050 204 in. 214 ex. Lift .420 in.
.442 ex. with 112 lobe sep. )
head casting number 3998993 used on 72-73 307/350blocks 75cc and 1.94 intake 1.6 exhaust. Will be milled to 64cc.
Flat top pistons
Total seal rings.
using stock manifolds with AIR deleted and no Cat convert. Through a flowmaster muffler.
Sitting underneath of a TPI intake.

Desktop dyno is showing me about 283hp at 4500rpm and 376tq at 3000. this is using the l98 head profile, so this maybe off a bit. I think the hp and tq curve looks really good, but I'm a novice.
1. How does this setup sound?
2. Also what size injectors would you suggest? 24#?
3. What would we have to do with the computer, i know we would need a new knock sensor, but what else?

 

how cheap are you planning to be? If you go cheap now, I know you will regret it. Personally I started out cheap on my rebuild because I didnt think it would take as long as it is and I wouldnt have the money by the time it was done. All in all though Im going to be extremely happy with my engine except for the fact of not going forged bottom end. I kinda like the sounds of a nitrous kit but I cant now. Anyway, sorry about that. That cam sounds way too mild for even the mildest of 350's. You can have a ZZ4 cam for not much more than 100 bucks and they are a real nice upgrade for low - midrange power in a 350. As far as heads go, you could use and port those heads but Im not so sure how good they are. I think the stock L98 heads would even be better. To answer some of your questions, I think 24# injectors will be plenty for that setup. As far as computer tuning, it is always good to do tuning to get the most out of your engine. Since you are trying to work on a budget however, your setup as of now will work fine with the stock chip. A ZZ4 cam is best with a TPI and doesnt need tuning to run well. Im no expert on all this so feel free to correct me if Im wrong.

 

The reason is, a friend of mine just rebuilt the engine in his 86 Iroc, it too is a 305 tpi, and well the front pulley was out of balance and after about 150 - 200 miles it took out the front main. now he is looking into really cheap crate engines, or the possiblity of finding a 350 block and building it. I have the block that is .040 over, and he just put the 1102 in his 305. it doesn't even have 250 miles on the cam. and everything else we already have. This is going to be as budget, as budget gets.

 

you could run the existing 1102 cam as long as you keep each lifter matched to its cam lobe. flat-tappet cams establish a wear pattern between each lobe, and each lifter. if you change it, you'll notice accelerated wear to the camshaft or the lifters.

however, a 350 could possibly want more cam. i'm running a cam with just a hair more lift in a 305 with good results. it specs out at 204* @.050" and .427" of lift. it runs quite well for a 305.

i would try and pick up a pair of tuned port heads, some good casting numbers are 416, 081, and 083 (last three digits) i don't think i've ever heard good things about 993 heads.

 

He does have his 305 tpi heads, would those be better with the 1.8 in, and 1.5ex valves? and 58cc chambers? What kind of compression would that be with flat tops?
His heads are 86 IROC 305 TPI heads, aren't those 416's?

 

Hmmm ok I guess I see what you are doing. So he doesnt have any money to spend at all so you two are just taking whatever parts you have and throwing them together? If you arent worried about much performance at all then I'd say go ahead and do it. If he would have any extra money at all, I'd suggest a few other small things. The ZZ4 cam like I said is a perfect cam for the TPI. The low and midrange is supposed to be real good. Plus the TPI is tuned for exactly that so you wont have to worry about mismatched parts. I dont want to make it seem like you have to spend a bunch of money because I didnt like it when people put down my engine build. There are cheap things however which shouldnt be cut from a new rebuild. Even using the hedman headers that are under 100 bucks is a good idea too. For another 200 bucks or so then, I'd say the better cam and headers will make your friend alot happier with the rebuild. Trust me that you dont want to spend a good deal of time working on a rebuild and then to be disappointed because it isnt in the power range you would like. Just trying to help ya out some I hope.

 

The 305 heads are probabily the better choice.

have the 305 tpi heads fitted for larger 350sized 1.94x 1.60" valves and give them a moderate Home port job.
this will cost less than shaving those 993's to 64cc.
Durability is questionable when you shave 'em that much.
You'll need to remove more than .060" to get to 64cc on a 76cc head.
The 305 tpi heads will flow better and provide more compression and performance for less money than the 993's
*(Once home ported with larger valves)*.
You can deshroud the chamber around the larger valves too.
Finished chamber size will be right about 61cc's
Which 305 tpi heads do you have? Center bolt type or perimeter type valve covers?.Casting numbers should be 081 and 416 respectively. Both will work well.
If you have the 081 heads I'd definatly work with them.
Don't need to make huge ports but some bowl work, short side smoothing and guide boss streamlining will go a long way.
But don't wimp out and try to get there with the stock small 305 valves. It won't happen.

this won't cost you much more extra than your time.
Sell the 993's to some one else.

 

ok so the 993's are basically junk? How much does it normally cost to have the heads fitted for 1.94 intake valves, and should i worry about the exhuast valves?

 

One of these things is not like the other. Use normal rings.

Considering that a L98 came from the factory with 230ish HP, and those are grossly inferior heads to the L98 ones, I'd estimate that you might get 220 HP out of that combo, maybe. They won't cost you all that much power though because the main limit to how it will run will be the TPI. Deleting the AIR and the cat will make basically no difference whatsoever in its power output, maybe 4 HP max, surely not enough to make up for the no-flow no-compression heads and add 50-55 HP besides. You certainly won't need to be putting bigger injectors in it. That's also not a very good cam choice for a TPI motor, although it works OK in a real mild carb situation; the stock L98 cam is about 202°/207° or 207°/213° on about a 114.5° LSA (details vary depending on year model), just for comparison.

You'd get more power out of 305 TPI heads such as the 416 or 081 heads, but only with dished pistons, not with flat-tops; and buying larger valves and paying somebody to install them isn't exactly in the same "budget" league as using those "Hecho En Mexico" castings. I would not go that route in what you're proposing.

I would put less faith in Desktop Dyno, and instead look at known and familiar real world results. The parts you are proposing are very close to various factory ones and therefore are very easy to compare to well-known and well-characterized combos. DD is excessively optimistic on that one, even more so than it usually appears to be.

My recommendation would be to put the L98 back together using its original heads with a bit of port work, and pick a cam designed for TPI.

 

Incidentally, the absolute cheapest thing you can do, would be to simply crank-kit the 305, and get a new crank damper (which he's going to need anyway since his old one seems to be farkled). You can do that without even taking the heads off, which of course will save you the cost of head gaskets among other things. Any other option will be several multiples of the cost of simply repairing his existing motor (assuming it's any good in the first place, other than the one failure). At most, you may need to tear it down and clean the metal shavings out of its oil passages, if he was unwise and kept driving it until that happened to it.

 

Your combo is pretty well matc hed now, it will be a torque monster at low rpms. I think the 220HP estimate is a little low, I would think more in the 270-285 range.

The combo you are planning is nearly identical to mine. I have a 355 with world s/r heads with 1.94/1.5 valves that probably flow just as good as those heads(the flow #s I have seen for my heads give em 200 cfms intake/135 or so exhaust stock so they aren't much better then stock castings but do have more room for porting)...I have a 650 DP and an even tinyer cam at 203/212@.050 with .425/.439 Lift...best run in a much heavier 2nd gen Camaro with tremec TKO 5-speed and 3/42s is 14.3@96.5 w/ 2.1 60ft time...and if I throw on a vaccum secondary carb and use a vaccum dist. I would see 22+mpg on the highway.

 

The 993's are not junk. But you'll get more of what you want, for less by going with the 305 tpi heads that you already have.

With modern valve seat cutting equipment the cost of a new valve job is the same wether you replace the stock valve or go up the the next size. Your going to need new valves and a valve job
reguardless.
If the larger valves that are in the 993's are in real good shape
they can be reground but new budget valves and not that pricey.
late used factory valves are usually not very good to be reground. The margins are too thin.
Plan on new ones.

Don;t need a expensive race valve . a budget replacement
valve is good enough ( pep valves)


I'd go with 1.94x 1.60 valves.
But 1.94x 1.50 will due.

You should do the porting and deshrouding your self.

Find a good automotive machine shop in your area and get an estimate.

 

Here is another tid bit of info... both sets of heads, the 416 Castings, and the 993's both have less than 200 miles on complete rebuilds. The 416's have some home porting done to the intakes and some polishing on the exhausts. What kind of power would you expect using the 416's with a different cam.

 

Whats wrong with that cam?

Its a good cam for a mild torquey budget build up.

it will make more power than stock.

You'll have to decide how much compression you want to run
as to which head to use.

the 993's can be cut .060" which will get you about 68/69cc's from the origional 76cc.

the 416's are right about 58cc stock. You can "deshroud" the chamber surounding the valves to good effect which will increase the chamber size alittle and improve air flow to boot.
Should end up with about 61cc when your done.

The hot ticket is to combine the mild porting with larger 350sized valves.
This is a popular upgrade for these heads.
What size valves are in the 305 heads now?
Like I said sticking with the smaller stock 305 valve will only get you half way there.
The large valved, pocket ported 416's work very well for what your trying to achieve.

The difference is in the amount of preperation you put into it
not on how much time you waste playing with Desk top dyno.

If a 68cc head will get your all the compression you want then go with the 993's. If you need 58 to 61cc+/- then the upgraded 305 heads are the way to go.

trying to mill a 76cc head down to 64cc will likey let you down
You'll need to remove .100" or more.

The deck will be too thin.


The ports in both these heads are more simular than differnt.
They port up about the same all said and done.

I've used fully Ported big valved 305 heads with loads of compression and a big race cam and a race single plane intake. Made tons of power. But the motor is a whole different beast from what you're trying to build.