jeepboy180

I ve heard of a few ppl putting 305 heads on a 350. What I was wondering is, wont 305 heads be more restrictive then 350 heads??? Also how would this perform with a TPI setup???

91B2L

It should up the compression ratio a-bit. No way on earth I would put stock 305 on a 350, only route would be world products 305 heads. From World S/R Torquers

305 350
intake 170cc 170cc
chamber 58cc 67cc or 76cc
valve 1.94x1.50 2.02x1.6

some people has good results

five7kid

iTrader: (14)

There are two things different between 305 and 350 heads: The chambers, and the intake valves.

Guess what that leaves the same?

Right, everything else.

Now, we aren't talking about TBI heads. As long as the 305 heads are 416, 601, or 081 castings, then my first statement stands.

If your 350 has dished pistons, and you have 1.94" intake valves installed and do basic port clean-up on the 305 heads, they'll support a 350 as well as factory 350 heads.

(For the record, 3rd gen 305 heads all have 1.84/1.50" valves. And, 3rd gen 350 heads don't have 2.02/1.60" valves. In fact, most factory heads that did have 2.02/1.60" valves, don't flow as well as cleaned-up, 1.94" valve 305 heads.)

(And, even though I have them, the World S/R heads aren't that much better than the aforementioned 305 castings. The "S/R", after all, stands for "stock replacement".)

jeepboy180

well of course I cant use my TBI heads, I wouldn't even if I could. In my opinion The 305ci TBi is nothing more than a mere pickup truck motor.(which shouldn't be in my camaro to begin with)

Anywho, my dad gave me a '90 350ci remanned block, and I have the TPI manifold, wireharness, and ECU in my closet from my old z28. So I was just gonna build a new block for my RS.

I have already decided to used those world heads( I found them for a pretty good deal in Jegs) I just dont really know a whole lot when it comes to chamber sizes. I just didnt understand how a seet of smaller heads made more power then what the regular heads do.

sngreen

It comes down to intake runner size and port size, the chamber size is what you want to look at for the compression ratio your going for, the smaller the chamber the more static compression you will achive the bigger the chamber the oppisite will happen. most street cars are between 8to1 and 9.5to1. on thing you have to remeber is the more compression you run you will have to have a strong ignition system to spark the mix up and you have to use premium fuel, to reduce the chance od spark knock (or detination) lower the ratio you can use the cheap gas but youll loose a little horse power. hope this helps you a little bit!

jeepboy180

Ya it did now I have more of an understanding on how that works. Thanks man.

kd5icr

iTrader: (2)

Another thing, not all 305 heads have small chambers. Some are 60cc and some come as high as 64cc. Also bigger valve size doesnt always mean better flow. A 350 with milde worked heads a mild cam say .500 or even a 480 lift a preformer intake and a 650 carb can and will yeild ok numbers at the track, that is if that is your main concern. For a DD that can put up a fight, that combo will work as well there is no reason you cant get 200 plus HP out if that. IMO

five7kid

iTrader: (14)

2-1/2 years later...

If we're talking 3rd gen f-body 305's, then what you said is incorrect. All 3rd gen f-body 305's had 58cc heads from the factory.

kd5icr

iTrader: (2)

2-1/2 years later. Gee like I didnt see that. I just found it. I was looking for info. And as far as I can tell what I said was dead on as far as cc sizes. if you notice I said "not all 305 heads are 58cc" I said nothing about year and the OP never said a year. And not all 3rd gens had 305's and now that most people are putting in 350's and bigger, so what I said is still valid.

five7kid

iTrader: (14)

Since this is a board dedicated to 3rd gen f-bodies, and since the OP has a 3rd gen f-body 305, it is fair to assume he is starting with an f-body 305.

Of course, he has a TBI 305, with swirl port heads, and even though they will be 58cc, they aren't appropriate for use on a 350.

kd5icr

iTrader: (2)

I know this is a 3rd gen site, hell I am on my 3rd, 3rd gen, so I know this. And I know that no 58cc head is appropriate for a 350 but they can work. The point I was going with is, not all 305 heads are small like that and that there areoptions as far as that goes. Yes 350 heads on a 350 it ideal, but he can use 305's. Just the same 350 heads on a 305 will lose compression and thusly power. Thats the main point I was tring for. In the end I was not wrong in what I said. Yes I agree with you that all 3rd gen heads were 58cc they seemed to use 2 catings,416 and 601 the same head with different casting numbers. So you were also right. So, truce? I am not here to argue.

five7kid

iTrader: (14)

Never heard of 601's on 3rd gens, at least not U.S.-delivered. Maybe Canadian, but still not something I've heard of.

3rd gen 305 heads were 416's, 081's, and the swirl-ports.

SeriousGearhead

305 heads will fit and work on a 350 (except the aforementioned swirlport). Fact of the matter is, though they you could go with 305 heads, they may not produce the results you are looking for. If you have a short block 350 waiting for a build, my advice for what its worth, would be to shell the extra coin and get some better heads. Then you will have a stout performing engine and a step to build further from if you ever choose to. Just my opinion.

kd5icr

iTrader: (2)

You know the 601's could be canadian. all I can tell you are the year of them. 82-86 and there are 415 castings used from 80-85 and are also the same head. There are so many 305 head castings that it is hard to pin down any one casting used. It was the same way back in the 80's when the SS454 truck was made, they ran out of 454 blocks and used 500ci blocks, while they were rare that is what was used. So to say that all 3rd gens just used only 1 or 2 castings may not be true. Like some 350's used bow tie heads that were cast iron on trucks as well as car's. at the time they were just as sought after as vortec heads are now that is if a person wants to deal with getting a special intake for those of us that like carb's it may not be worth the money. and in some cases still are.

DRock89RS

my brothers 84 we are finishing up now HAD 305 heads on the 350 and with the TH350, shift kit and 3.73s you never would of thought they were 305 heads. not something i would do obviously but it works if thats what floats your boat...

kd5icr

iTrader: (2)

I dont think it is about what ever floats your boat. Not all of out here have the money to spend on heads.Think budget build, Like in my case. I got a set of 305 heads to replace the burned up set on my 85 z28. Turns out the rings are bad. These are not the 416's they are 450's and they are 60cc heads used on 75-81 305's yes I know some people call these smogers, so what. I have a 350 4bolt short block in the machine shop now, because I didnt have 350 heads I am going to use the brand new heads I have now. That will save me over 150-200 dollars. I get to use that on other parts. Not a bad deal really. Ok so they they run out of steam at 5500rpm and higher. Well I dont see this build getting reved that high. I am not out the beat everybody, but I think I can still put up a fight. I can see getting 250hp out of this setup maybe more. And thats not bad for a DD that wont be at the track as much as some here if at all.

SeriousGearhead

Got a good point about the budget build. I got nothing against using 305 heads, I have heard of people getting decent results. I think my bro-in-law uses them on the 350 in his '89 Cheyenne. I just offered up an idea if the OP ever decided he wanted more under the hood.