88ROC1LE

iTrader: (4)

I have a 92 305 with TBI in good shape, just wondering if a swap to the L31 vortec heads(just the stock ones, no uprated springs or anything like that) and the GMPP TBI/vortec intake would be a giant pain in the ****? Not looking for monster gains or anything like that, just pleased with the vortecs on my 350 and would like to try them on my 305 while keeping it as close to stock apperances and such as possible. Guess I'm asking if I should be ready for some kind of chip mod ect... Thanks!
Me = TBI noob

BMmonteSS

You'll need to learn to burn your own chips, anything you do to increase power on a speed density FI setup will require a reburn. The mail order guys won't have a prayer of getting your motor to run right.


The head and intake swap will do wonders for your 305, but be warned the true bottle necks of the system is the stock tiny cam and exhaust. You'll still pickup 30+ hp with the heads, but with a cam and exhaust you could be looking at over 100+ hp more than stock and appear like it did from the factory.

88ROC1LE

iTrader: (4)

Sweet, that's what I needed to know

Fast355

iTrader: (2)

I would personally use L30 305 Vortec heads with the 059 casting.

S105.7

i like how they failed to mention L30 heads in CHP when they did the Project 305 Camaro. doesn't seem to make sense to mill them to the valve seats, when you could have baught TFS heads for probably the same money after machine work. must be nice to have an unlimited budget.

1991 RS 305

I did extensive mods with no burn... car runs like a bat out of hell with no driveability issues. I used the 062 vortecs milled to 56cc's. That's the only machine work I needed. I swapped the cam to a 97 LT1, threw the RPM Air Gap Intake one her and Hooker 2460's with 3" exhaust. The car runs great. I also did the "free" ultimate TBI mods. I know I could get more gains with a burn, but many searches on this board will revel threads insisting that the car will run like crap without a tune. Not true by a long shot! Do your mods, the heads etc, and as you have the cash flow available do the tune. From all the searches I've done, you may not want to run 305 heads. If anything get the 350's and run them as is, they do flow better. I'd get them milled if it's in your budget. I have even seen people on this board run them with 64cc vortec heads and be very happy with the gains. Yes, it would drop the compression, but you can run a .015" shim head gasket to make up for some of the loss. If you're willing to spend the extra $80, have the 350 vortecs milled. I had mine milled down to 56cc's, 2 cc's lower than stock. I also ran the .015" shim style head gasket. I highly recommend this combo. Compression is by no means too high and as we all know compression is "free power". I also would recommend a different intake. You can get a carb intake for cheaper and all you need at that point is get a TBI adapter plate. I suppose all said and done you would be close in price (Vortec intake plus TBI adapter plate), but their are many carb intakes to choose from, and you would end up making far more power when compared to the TBI Vortec intake. I can't emphasize enough how well the car runs. Driveability is phenomenal!! I know you said you're not looking for monster gains, so I don't mean to bring you off track, but what I have mentioned should give you more power at a very similar price.

Good luck, Matt

Fast355

iTrader: (2)

The TFS heads weren't in production when CHP did their project 305 camaro. Another magazine recently put a pair on a tired 305 and got good gains while staying emissions legal.

Fast355

iTrader: (2)

The ones of us that are saying to TUNE the setup HAVE experienced driveability problems. Hell, this is what happened when I put a 204/214 duration cam, ported MPFI heads, and headers in my 3.1 build for my S10.

http://youtube.com/watch?v=gdQENVYISPs

The 059 casting L30 305 Vortec heads FLOW very well too, DESPITE what others have claimed. They work VERY WELL on a 305. I would not state this without having personally used them on a 305 TBI buildup.

Here is the bone stock flow numbers of MY personal L30 heads. 28 in/h20 pressure drop.

Lift-----Intake----Exhaust
.050------36-------28
.100------68-------47
.200-----128------103
.300-----179------138
.400-----205------152
.500-----221------163
.600-----225------165

1991 RS 305

And this has anything to do with the tune of a 305 TBI??

Anyways, your heads look to flow pretty well, I just gave my OPINION to the question asked. That is all this board is, OPINIONS! I'm not looking for an argument or a comparison to an IRRELEVANT engine to the question asked. My point simply was that he would be able to run his car on the stock tune if he needed to. As far as the heads, If I'm not mistaken, the 350 Vortecs have larger valves which is a good selling point for me. The numbers you posted aren't bad at all. I would say I'm actually impressed, especially with your exhaust flow numbers. With that said, this is what I've seen out of stock 350 Vortecs.

Lift-----Intake----Exhaust
.100------70-------49
.200-----139------105
.300-----190------137
.400-----227------151
.500-----239------160
.600-----229------162

They are reasonably close, but .500 flow is killer, especially considering that not many people run over .500 lift on vortecs. That is NOT to say you have bad heads by any means, like I said, I'm impressed by the numbers you posted... Not to mention, I have seen people on this board rip the Vortec heads apart saying they are overrated and they should get some real heads if they want to make power... So lets remember that again, this is just my opinion on the matter. I'm very pleased with my 350 Vortecs, as you are with your 305 vortecs.

Later, Matt

88ROC1LE

iTrader: (4)

Thanks for the replies!
My main concern was if I was still going to be able to drive the thing if I did put vortec heads on it. Since it's just the 305 TBI I myself figured I wouldn't be getting too far out of "stock" since it was just the plain ol' vortecs and intake, nothing in the way of new cam or nitrous ect...This is my every-other day driver so it can't be down TOO long hehe.
I understand that it would probably make a world of difference if I re-tuned it chip wise, I just wanted to make sure the TBI/ecm/ect... wasn't going to crap out on me totally by adding these type of heads and intake.
The vortec heads were just going on for the next couple of years or so until I finally make a jump to a 350, even then it will be a very plain 350 with vortec heads and the TBI setup.

I know, I'm boring lol

S105.7

well that would explain it.

rlh134

im running the vortec heads with weiand new vortec intake manifold a comp cam, headers y pipe and exhaust, a little upgrading in the tbi system and adjustable fuel pressure regulator, i drive it everyday i have a slight lope in idle but nothing major and i still get good gas mileage and its pretty damn quick

and yes i think its pretty funny that my shitty 305 tbi which is said to be garbage runs real low 14s without nitrous and with a good 60ft i can hit a high 13, if i make it out to the track next saturday ill make some videos of me running, there is a firebird runing almost the same setup he runs 14.1s consistently

88ROC1LE

iTrader: (4)

So you were able to make all those changes and it's still driveable and reliable...hmmm. Guess I'll just have to do the swap and see what happens, worst case it will run like crap and I'll just have to put the stock stuff back the way it was.

bluers91

I had pretty much decided not to use the vortec setup on my 305 TBI due to drivability issues and tuning. I always planned on getting a tuning setup, but still it seemed to be nearly impossible. After reading this thread I have since changed my mind back to doing it. Thanks for sharing your experiences in doing the swap and still having a good running car without a tune.

Who makes a vortec carb intake that retains EGR?

rlh134

yea the drivability after just putting the parts on isnt bad at all you make peak torque a little later but your making well above 300 from 2k and beyond, i did get tuned on the dyno i have a bunch of places around here to get tuned and reccommend, akron horsepower is awesome and so is hybrid dynamics, on is in akron ohio and one just south of pittsburg,pa.

i was looking for maxium power and tuning for street and track use that is why i got tuned period, it cost me about 350 to get tuned and dynod but it was well worth everything is nice and smooth beautiful power band and its a total sleeper looks wise

racer J

Did you not hear it stumble and try to die upon initial acceleration?

I know when I just did a cam in a fresh rebuilt 305 in my 88 it would die at every single stop once I began to decelerate. In fairness though I had warped the heads and had them milled down to 52 cc. It did however run like a bat out of hell and drive fine until it was time to stop. I had to stand on the brake and give it some gas to keep it running. It was a major PITA.

88ROC1LE

iTrader: (4)

Just an update, the head swap was finished last night. Other than having to mess with the exhaust leak at the headers all went well and runs well.
Gas mileage seems the same but has much more get up and go now.
Thanks for the help all.

1991 RS 305

Excellent! Glad to hear it went so well!!

bluers91

Hey 88ROC. Did you mill the heads down at all to keep your compression? Also, did you keep the peanut cam in there?

88ROC1LE

iTrader: (4)

Heads were untouched and the cam is the stocker.

After driving around today I did get a SES light, but it was for the O2 sensor which was easily fixed. Everything else seems pretty darn good now!

bluers91

Good to hear its running good for you. After I do my exhaust I plan to use vortec's milled down with an LT1 cam. Intake is the only thing getting me. I really dont want to spend $350 for the GMPP TBI vortec manifold. Need to figure out how to hookup egr with a carb intake and tbi adapter.

89IrocPballa

well i have two questions. where could i take the 350 heads to get them milled down to have a better compression? this setup seems like what i should get and for pretty cheap right. my other question is how much power do you think that brought you up?? also if I do it i think that i would put the vortec heads on with one of the mentioned intakes and an lt1 cam.

bluers91

Another thing to note is that there are 305 Vortec heads that would not need to be milled down. The casting numbers are 520 and 059. If you got the 350 Vortec heads you should take them to a machine shop to mill them to get them closer to 58cc or less to keep your compression up. Some people run them without milling, but why do that if you are going to go through all that work.

The GMPP Vortec TBI intake is the expensive part, but you get to keep your EGR that way.

How are you guys plumbing your EGR with the carb intakes? I'd like to get a Weiand Stealth and use a spacer instead. I know someone has the answer. Plumb what? Run something from the intake to exhaust but how?