Alright, here is the famous "what should it do" Question.

Ive got a 91 RS that i converted to carb with some other goodies and was curious as to what it should be capable of as far as horsepower and times.

Its a 305 with ported 081 heads, bigger cam, 214/224 450/465 lift. Edelbrock performer RPM intake and Edelbrock 600 (1406) Carb. Then for the exhaust, hedders, custom Y Pipe, 3 inch cat back and flow muffler. High performance tranny, 2800 stall and 3.42 posi.

Let me know what you all think.

 

You are probably looking at 300 to 325 hp. It will be a fun daily driver. With that cam, I would pick a smaller stall. Maybe 2000 to 2300 rpm stall

 

Sounds decent. That stall is gonna be good for performance, but may be a drag for the street.

 

Well, it definitly doesnt feel like it has that much power, although i havent worked all the kinks out yet

 

its a 305, power is in the high end.

 

You mean in the RPM's?

 

I didn't realize you had already built this combination.

I have a few questions. What did you do to the heads and what size are the valves? I'm not familiar with that casting number. Does your stall really go to 2800? This is pretty big for such a small cam. Your powerband should be 2000 to 5200, or something like that. You may be running out of powerband.

 

Those heads are 305 TPI heads.

You might need to tune the combo. That torque converter should stall 500-800 rpm below your peak torque output, which i'm guessing occurs around 3500 rpm. So that should be good for performance.

 

The heads have been ported and have stronger springs and stock valves.

As far as tuning, i got the timing set on it finally, i have it set at 18 degrees base, for a total of 36. Then i set the IMS with a vacuum gauge and got them set just right. However it still seems like its running a little rich. Im gonna pull the plugs and look at them later.

 

If those are 305 heads with stock 1.72 valves then your powerband is not going to be very long and definately won't be very high.

 

True compression ratio should be at or near 10:1.
I'll bet you actual measured cr is a lot less.
A 350 .015" shim gasket works just fine on a 305.
Worth 1/2 a cr. If you installed the heads with a typical .040" composite replacement gasket there is room for improvement there.

You need way more rear gear. 4.10's are just right.

A 750cfm carb is not too much for this motor.

Should have installed 1.94" intake valves in the ported heads. Makes a big difference. Most of the porting effort is a waste without the larger valves.

The converter stall speed is not too much.

Uncap the exhaust system and see if it is holding the motor back... or.? It 's all in the details.

 

All the 305 heads used in thirdgen have 1.84" valves. The 305 heads used in 3rd gens are also some of the best SBC heads cast by GM. The only thing they lack is larger performance valves.

 

Ok, well let me ask you guys a question. Yesterday i was going to work and i was getting ready to pull across a busy street so i had to hurry. When traffic clear i nailed the crap out of it and i started to go then it cut out, and barely stayed running. Then it came back to. then i nailed it again and same thing happened. It only does it when i just absolutely stomp the crap out of it. Do i need to adjust my float levels?

 

It sounds like the float level to me. I would definetely check that first. If that is not it, I would hook the vaccum gauge back up. I can not remember what carb you said you have but sometimes when the weather changes some holleys will act up.

 

Im running edelbrock 1406 carb

 

There is one of your problems. Get rid of the edeljunk. Buy a road demon. It will impress you.

 

"All the 305 heads used in thirdgen have 1.84" valves. The 305 heads used in 3rd gens are also some of the best SBC heads cast by GM. The only thing they lack is larger performance valves."




I dont think swirlport heads fall into a "Best" category...

 

ME Leigh, If you like 305 heads so much, why do you have LT1 heads on your 305?

 

Because i wanted some aluminmum heads to save weight.

 

i wasnt trying to start something, i just dont think 305 heads are great....i actually despise them. If i had known then what i know now i never would have bought my car. I have the slowest, fastest LOOKING car i have ever seen. But i have a 170 hp, 230 ft. lbs. torque 305...seriously whos the ******* that thought of giving a V8 that little of power WITH a 2.73 rear end AND an automatic that can barely handle 250 horsepower? with the ****tiest heads ever made in my opinion? Makes me want to go buy a 5.0 mustang...which i have nothing against since two of my cousins owned pretty sick ones, then they traded them for civics...ok sorry about that im done.

 

Blame the feds. Yes stock our engines are very hindered by all the smog crap. So there is many area for big improvement.

I don't know what your complaining about he late 70's camaros and firebirds were way slower and made less power with a much larger engine.

 

This is true, but it still sucks having less torque and horsepower than most v6 sedans now. of course having a 1976 vette with a 350 and 160 horsepower must suck worse than my situation

 

You don't know much about the 305 heads at all do you? It also appears that you don't understand the technology and emissions history that directly affects the design of each new generation small block.

The RS wasn't suposed to be a performance option for the f-body. I guess GM took care of that with the whole Z28 thing. The LO3 was an economy V8 that was an option over the V6. It was good on gas, had decent power, and was cheap to insure.

Do you know that most swirl ports will outflow any stock 3rd gen cast head on the exhaust side and minimally lag behind it on the intake side? There is a lot of new information and tests that show that slightly ported 193 and 187 (350 and 305 TBI swirl ports) will flow the same as a stock vortec head. People who don't know anything about head design are quick to naysay though. If your motor needs more and your wallet is thick enough than you can get better performance out of ported TPI heads or go with an aftermarket set. If you don't have large power goals with a lot of money to spend, a ported set of 350 heads can take you pretty far.

 

if swirlports are so great why does everyone on here that ive seen knock them for being so ****ty? from what ive read on here they onlt feed air up intil 4500 rpm, i dont know much about them because from everything that everyone has said i didnt think it was worth even reading about them.

 

The reason the swirl port equiped engines don't pull is not the heads. The cam is the biggest power drainer. My 355 with somewhat worked over "193s" was still pulling strong at 6,300 rpm, that was with the stock TBI, TBI intake, and LT1 roller cam. The stock TBI and intake was building vacuum and begining to hold me back though.

 

No one is saying they are great but instead just horribly miss-understood. People are quick to bash them because they don't understand them. I too was once in this category. Then certain people like Fast355 took the time and money to have stock heads flowed. He then ported them and had them flowed again. He has since posted numerous threads devoted to his progression with his combo as well as his data. He then spent more of his time to properly learn how to match a cam to the heads and then do the necessary chip work and then share it with us for free. Guys like JPrevost, Dewey316, Dimented24x7 and a few others paved the way for TBI chip work. All this knew knowledge resulting in great track times, documented flow data and a better awareness of what make these set-ups tick. Guys like Dewey still run the stock swirl port heads and run 14.5's all day at the track with a full exhaust, cam and tuning. Only a few people have actually taken the time to "play" with these heads and understand why they were created. No one is saying they are perfect. They have limits and those limits aren't that far up in the power category. The point we are trying to focus on is correct tuning measures as well as part selection. With some port work these heads can be used in extreme "budget" situations. As mentioned above the 193 heads outflow the stock L98 heads on the exhaust side. The L98's flow better on the intake side but you have to choose the lesser of two evils. Swirl ports make 100% use of the intake side. No stock TPI head can do that. Ported TPI heads are better performers in the end but TBI heads aren't pure junk. The intake, cam and tune are what plagued these motors from the get-go. The key to any TBI set-up is extensive chip work with proper parts selection. Without that you just have people with miss matched and untuned combos that run slower than stock. They then deem TBI as garbage. Everyone who then reads their posts takes that as verbatim and spreads it around without doing any testing or learning of their own.

 

del91_305

How is the car runnig now? We got off the subject. Did you reset the float level? Have you tried more timing?

 

Well, its running pretty good. I pulled one of the plugs and it was pretty white. As far as performance, is doesnt perform like it should but it doesnt seem like anything major is wrong with it.

 

sorry for making this go off subject, i appreciate the information from everybody though, it was more insiteful than everyone else ive talked to about this subject just telling me to get rid of the TBI heads and get new ones.