Intake and Carb combo advice

[L695speed]

Alright guys, except for struts, the daily driver is squared away. Now to get the Trans Am up and running. Funding aside...I'm leaning towards just dropping in a Vortec 350, run and enjoy the car while I accumulate parts for the stroker build. This way I can sort out the chassis and trans and the rest of the wiring. When the time comes to pull to build the stroker, all I'll have to do is theoretically plug and play.

I'll get a distributor online off Ebay, there is one being sold for round 60 bucks that has been used with quite a bit of success. HEI naturally. But since I'm not running a computer and will be running a carb; I will need to swap the intake and the fuel delivery to a carb setup. The question is with the 383 build in mind, what would be the best carb/intake combination to run so I can just swap it over to the 383 with just a slight mixture adjustment.

I'm thinking electric choke is best off. I'm not drilling holes to run a cable. I was leaning towards the RPM Performer intake mainfold and a 750 carb. While 750 might be overkill for the 350 it should be perfect on the 383. So one carb and done. Question is what carb would be best? I saw Elderbrock had suggstions for the RPM Performer Intake and matched it to a #1411 electric choke carb. I am also looking at Holleys but am unsure what may be the best one.

Finally, could I run a stock LT1 clutch behind a Vortec with the above changes til I built the 400+ horse monster 383? Or will I destroy the clutch in spirited driving? If I can nail down this stuff, and get my hands on a Vortec, another F body may be on the road by the end of the summer if a few things go my way.

[zraffz]

Carb & Intake depend on your RPM range. A stock vortec 350 switched from FI would probably work best with a 600 cfm carb and a dual plane. Naturally, I would use a Holley and Edelbrock respectively.

I have very little experience with Edelbrock's carbs; I can tell you they are tuned via adjustment screws and I had no issue tuning one but the local shop cringed when he saw it under the hood.

As far as running a 750 on a stock 350 I'm not sure how well it will work. I never had any luck getting a 750 dialed in an old 305. No matter what we did it had a pretty bad flat spot at around 1,300 RPMs.

[L695speed]

Yeah I am trying to do the intake and carb so I can just take it off the 350 and put it on the 383 (likely will be the same motor stroked). The intake may work just fine either way, the carb is the bigger question. I would rather run Holleys based on their rep anyway. Question is if there is a carb that will work on both, which one is it? I may pose the same question on TGO with their wider base too. Any thoughts on the stock LT clutch holding up on a aftermarket carb/intake Vortec? As for 750 on a 305 correct me if I'm wrong but weren't the Q jets 750s?

[BonzoHansen]

qjets were various sizes. what is the RPM range for the engine? rear gears?

[WildBillyT]

Make sure your dizzy can do the advance curve and amount you want. A holley 3310 might work well.

[BonzoHansen]

don't buy an accel hei.

[L695speed]

I am going to run the factory 3.73 rear gear 10 bolt til it blows then maybe the same gear in a Moser or Strange rear end when I upgrade. LT1 T56 94+ spec. The desired RPM is around the same as the L69 but no reason to go above 6500, most likely to be 6-6200 redline. I hate engines that die at 4K. Based on that I'd say the RPM Performer (NOT THE AIRGAP ONE) will be ideal. Eventual power figures with the 383 will be in the 450 range. I will upgrade the clutch when I stroke the motor, but don't see a reason to do it with a 350 ft lb Vortec 350 starter motor hence asking about the stock clutch.

I've read on TGO that the 650 DP Holley would be good for the 350, but I think it would be too small for the final product.

[L695speed]

don't buy an accel hei.

Advice taken. There was a generic one that I've been told that works great when the gear at the bottom is changed to work with a roller cam.

[S.J.SLEEPER]

No Accel junk
msd billet (locked out)
start retard box
Msd 6al or better
Eldebrock Performer Rpm or Air Gap intake
HP750 carb
and start rowin gears

[L695speed]

No Accel junk
msd billet (locked out)
start retard box
Msd 6al or better
Eldebrock Performer Rpm or Air Gap intake
HP750 carb
and start rowin gears

So run the MSD stuff and RPM Performer and 750 carb on a Vortec 350 then slap it all on the 383 when done? Sounds good, excuse the next newb question but I'm not an electronics genius. Whats the point of a start retard box?
w

[S.J.SLEEPER]

So run the MSD stuff and RPM Performer and 750 carb on a Vortec 350 then slap it all on the 383 when done? Sounds good, excuse the next newb question but I'm not an electronics genius. Whats the point of a start retard box?
w

yes. As for the start/retard box, Locking out the msd distributor and setting it @ 35,37,43 degrees etc.. makes engine almost impossible to start especially after its up to running temps. The start retard box initially drops the timing down to say...6-8 degrees @ start up, and will remian there until engine rises above idle, then it will go back to your preset locked out timing.
Doing this allows for you to make more consistent runs, confirm timing is where you need it to be, eliminates playing around with different springs,spring failure on mechanical advance or vaccum issues on vaccuum advance distributors.
Also works great when running nitrous and you need to pull 4,6,8,12 degrees of timing, you can just set it to the desired timing, and elimate the extra $ & time wiring in retard boxes for the nitrous(allthough most are plug n play)

[WildBillyT]

No Accel junk
msd billet (locked out)
start retard box
Msd 6al or better
Eldebrock Performer Rpm or Air Gap intake
HP750 carb
and start rowin gears

Curt, why are you recommending a locked out dizzy for what appears (to me) to be mostly a street car?

[L695speed]

Curt, why are you recommending a locked out dizzy for what appears (to me) to be mostly a street car?

After what he explained to me, I was wondering the same thing. I admit to the extreme likely possibility that this thing will see the track both in quarter mile and either autocross/road course format. But its definitely a street car first and foremost. As I've said before, if I can run the same intake and carb on the 350 and 383 without changing much then it makes for less work later. Seems the intake is likely a yes, but the carb is up in the air. I was gonna get a vac advance distributor that could run up to my desired RPM and call it a day. Unless anyone else has input on that.

[WildBillyT]

After what he explained to me, I was wondering the same thing. I admit to the extreme likely possibility that this thing will see the track both in quarter mile and either autocross/road course format. But its definitely a street car first and foremost. As I've said before, if I can run the same intake and carb on the 350 and 383 without changing much then it makes for less work later. Seems the intake is likely a yes, but the carb is up in the air. I was gonna get a vac advance distributor that could run up to my desired RPM and call it a day. Unless anyone else has input on that.

I am a big fan of my MSD 8360. New ones even have a built in rev limiter.

What I don't like about the HEI stuff is that they can be wacky to limit total advance in. My Vortec engine likes 15-16 initial/18 mechanical for 34 total. I don't think HEIs can go less than 21-23* mech advance. Plus you may need an adjustable vacuum advance can if the HEI one adds too much.

[L695speed]

So you feel that the HEI might be a limiting factor in the final product? A quick search in the catalog for that particular one, and in the description it seemed to say that you could run it without any other "boxes" so to speak. In short it seems you could buy it hook up a line, and wire and drop and go. Straight swap it seems.

[WildBillyT]

So you feel that the HEI might be a limiting factor in the final product? A quick search in the catalog for that particular one, and in the description it seemed to say that you could run it without any other "boxes" so to speak. In short it seems you could buy it hook up a line, and wire and drop and go. Straight swap it seems.

I do not know a whole hell of a lot about an HEI setup so that's up to you or others who chime in. I just know from recent research that setting up a late 70's-mid 80's smogger HEI might limit some options without doing some work. Do not let my lone opinion sway you; that's just my thoughts.

The 8360 is a drop in and go. You'll have to change springs and possibly the stop bushing, but that's kind of it.

[L695speed]

I do not know a whole hell of a lot about an HEI setup so that's up to you or others who chime in. I just know from recent research that setting up a late 70's-mid 80's smogger HEI might limit some options without doing some work. Do not let my lone opinion sway you; that's just my thoughts.

The 8360 is a drop in and go. You'll have to change springs and possibly the stop bushing, but that's kind of it.

I will indeed wait for other opinions. I will keep both avenues open. Ideally I would want to get this stuff nailed down so when I do get the motor, I know exactly what I need instead of dwadleling on the boards trying to get answers when I could be stuffing a motor in the car. I know based on Sleeper's description a lockout and retard box don't belong on a street car but if there is something we don't know I'll gladly hear him out on it.

[BonzoHansen]

IMO locked out distributor, start retard box and MSD6al is over complication for a street car. But I also prescribe to the KISS theory and I take driveabilty & reliability over gaining the last 5% of performance.

[S.J.SLEEPER]

I know based on Sleeper's description a lockout and retard box don't belong on a street car but if there is something we don't know I'll gladly hear him out on it.

I admit to the extreme likely possibility that this thing will see the track both in quarter mile and either autocross/road course format.

Suggested this, because you, along with ever other friggin guy out there always goes to far with the build, there modded street car becomes race car. So skip the bulls**t and go right to it.
As you stated in your post above, your already inclined to go that route and the car aint even done yet!!! lol
:facepalm:

[BonzoHansen]

i see that logic. as usual, the owner needs to be honest with himself over the real intended usage. that is the true fail on most builds. Is that at the track 20 times a year or maybe twice? Intended use is as important as budget before you buy 1 part.

If it is 99% street and maybe twice a year at the track I'll still take KISS for the block!

If it's 50% track, well, go all out - strip out all the useless junk, get that 3rd gen under 3000 lbs, get a cage and rock it.


"both in quarter mile and either autocross/road course format." - fairly different suspension requirements.

[L695speed]

Bnozo and Sleeper. Both of you have valid points. I originally was going to take it too far and realized what I initially had was not street practical. If you want the chances in percentage of the car's usage, it would be probably indeed be 99% street time and 1% track time. Its not an all out race car as I am not stripping the interior or anything. And what I meant by both formats of racing was I will likely hit an autocrooss as well as the occasional friday night grudge night at the local strip. The suspension has already been built with Koni Yellows, UMI A arms, LCAs, Panhard blah blah blah. Bushings have been done and so on. Even got a 36mm sway up front.

What I meant when I said take it to the track was, yes it will see the track at a grudge night or an HPDE event at NJMP, but its not a race car. Just a fast street car. So KISS is the way I'm going. I didn't mean to start anything, just wanted clarification on the start retard and lockout dizzy. So please treat this as a street car.

[L695speed]

If you guys both want to know the car's usage, a friend of mine from school had his car put in HPP. Similar build but I'm not gunning for the 10 second quarter mile. He was. I'd be happy with a 12 flat on a perfect run. Heres the article. Only difference is while he changed the car's appearance drastically and ran an automatic with a 406. I'm keeping mine a manual trans with the T56 and a eventual 383, and keeping the car's appearance nearly stock. I'll likely run less power than he did too.

http://www.highperformancepontiac.com/features/hppp_0703_1982_pontiac_trans_am/viewall.html


Another guy I know from school had the CETA that was featured a month or two back in HPP. BOTH of them are street cars. Mine will also be so. While I'll eventually stroke the 350 out and build it up, I want to drop in the 350 and run it as it is til I have the parts put together to build the stroker. Hence my asking what the intake and carb should be so I can just swap it on. The intake seems to have been settled. Carb and distributor are up in the air.

[L695speed]

Ok, what if I did this, if the motor I pick up is in reasonable shape get the following:

RPM Performer Intake
Holley 750 DP carb Electric choke, mechanical secondaries (car is a manual trans)
and this distributor
http://www.summitracing.com/parts/MSD-8362/

then drop the motor in and run it til I am ready to squeeze more power out of it. The 750 carb is more than enough to run on a 350 and 383 running to around 6500 RPMs.

KISS to the bare essentials.

[The_Bishop]

don't buy an accel hei.

^ This.

I have a crooked knuckle on my right hand thanks to an accel HEI. Long story.

About your choices:

I don't like Holley carbs on drivers. Crappy, leak-prone design that doesn't do part throttle (90% of street driving!) well, always tends to run rich leading to stinky exhaust, fouled plugs and poor mileage unless you spend far, far too much time dicking with it. And when the weather changes it's out of sorts again. For a car that spends a majority of it's time at WOT they're pretty damn good, though.

Do this one instead:
http://www.summitracing.com/parts/CMB-03-0056/

It's a far better and cleaner carb for street use and doesn't have fuel slosh issues like the holley ones do. Also comes with the calibration kit. No leak issues.

[L695speed]

^ This.

I have a crooked knuckle on my right hand thanks to an accel HEI. Long story.

About your choices:

I don't like Holley carbs on drivers. Crappy, leak-prone design that doesn't do part throttle (90% of street driving!) well, always tends to run rich leading to stinky exhaust, fouled plugs and poor mileage unless you spend far, far too much time dicking with it. And when the weather changes it's out of sorts again. For a car that spends a majority of it's time at WOT they're pretty damn good, though.

Do this one instead:
http://www.summitracing.com/parts/CMB-03-0056/

It's a far better and cleaner carb for street use and doesn't have fuel slosh issues like the holley ones do. Also comes with the calibration kit. No leak issues.

A friend of mine told me the Holley gave him literally hell on his street driven pick up truck. Told me to get an eldobrock 750 for the Vortec 350, since that would work on the 350 and 383. And if I so chose to upgrade I could use a Quick Fuel Tech 750 carb. In fact its matched to the RPM Performer intake from what I gathered on the instruction sheet I found online. The distributor seems to be a lil trickier. Seems the census on the Holleys is they suck on the street even for a 12 second street car. I will still take input on the Eldobrock 750 carb. I would prefer an electric choke as opposed to a manual one.

I believe my friend with the 82 in the link provided above has a factory GM HEI distributor. Run through a 6AL MSD box. At least according to the story. I will have to ask him what else he did. Even if the peak power is made between 5-6000 I'd prefer to have a rev limit of somewhere above 6000. All the cars I've driven including the TA which had an L69 initially revved above 6000 RPMS The few I've driven that redlined below that I couldn't stand.

I still have the factory HEI distributor somewhere. I rebuilt it during the initial swap. But I don't think I can use that one if I'm ditching the computer. I have a build thread on the projects forum. Those who have seen it know I have a rolling chassis that just needs a motor and hard lines. So the car is pretty much built.

[S.J.SLEEPER]

^ This.

I have a crooked knuckle on my right hand thanks to an accel HEI. Long story.

About your choices:

I don't like Holley carbs on drivers. Crappy, leak-prone design that doesn't do part throttle (90% of street driving!) well, always tends to run rich leading to stinky exhaust, fouled plugs and poor mileage unless you spend far, far too much time dicking with it. And when the weather changes it's out of sorts again. For a car that spends a majority of it's time at WOT they're pretty damn good, though.


The new holleys don't have these problems. I do agree with you if your talking about the older models, weather tempermental...blown power valves etc...

I just put on a new holley 750 on a maverick which had the eldebrock performer, ford 302 crate motor. was deadon perfect besides having to adjust idle right outta the box.

Edelbrock carbs are very good though...not knocking them, just making things clear on the holleys.

[BonzoHansen]

My holley works good.

[L695speed]

The new holleys don't have these problems. I do agree with you if your talking about the older models, weather tempermental...blown power valves etc...

I just put on a new holley 750 on a maverick which had the eldebrock performer, ford 302 crate motor. was deadon perfect besides having to adjust idle right outta the box.

Edelbrock carbs are very good though...not knocking them, just making things clear on the holleys.

So its possible the Holley my friend had on his pickup was an older model then. He spoke of having to constantly keep it in tune. If its truly almost a toss up because of the street car nature of the build, I guess I'll go on price and worry about the intricate details when I am ready to squeeze the power out of it. I'd like to get it running and enjoy it for a bit despite the shape off the body. Especially the way the chassis is setup.

[BonzoHansen]

So its possible the Holley my friend had on his pickup was an older model then. He spoke of having to constantly keep it in tune. If its truly almost a toss up because of the street car nature of the build, I guess I'll go on price and worry about the intricate details when I am ready to squeeze the power out of it. I'd like to get it running and enjoy it for a bit despite the shape off the body. Especially the way the chassis is setup.

or perhaps he doesn't know how to tune a carb?

[WildBillyT]

So its possible the Holley my friend had on his pickup was an older model then. He spoke of having to constantly keep it in tune. If its truly almost a toss up because of the street car nature of the build, I guess I'll go on price and worry about the intricate details when I am ready to squeeze the power out of it. I'd like to get it running and enjoy it for a bit despite the shape off the body. Especially the way the chassis is setup.

My holley works great too. Some guys blame timing issues on their carb.

[S.J.SLEEPER]

My holley works great too. Some guys blame timing issues on their carb.

:stupid:

[The_Bishop]

I didn't have timing issues after I threw out the POS accel HEI I had. Went to a completely adjustable MSD billet distributor (Not the HEI version) and 6AL box with a nice short curve that started around 14 degrees and ended around 34-36, all in by 3000 or so. (It's been *years* so I might be fuzzy on specifics.)

I had a box-stock 750 vacuum secondary. It was a POS. Hard to get the balance right on the secondaries opening; they were either too damn fast causing a bog or not open fully. Swapped that one out for a 650 double pumper. No bog on WOT, but fun, fun, fun with pig-rich idle and part throttle operation that took a lot of screwing with to get close to right. Got tired of fouling out plugs with that disaster and moved to an Edelbrock 750. Had zero issues. It was almost perfect out of the box.

Holley's don't (or didn't; I haven't messed with a carburetor in a *long* time) handle part throttle transitions well. The power valve is a sledgehammer fix to part throttle transitions; it's on or off and not linear. It was designed as a 'race' carburetor, so part throttle operation was secondary to WOT mixing.

Meanwhile, the Edelbrock is a lot like a Carter AFB, which was an OEM street car carburetor. It was designed with part throttle driveability and economy in mind. It uses a linear needle for low vacuum enrichment, not an on/off valve. By picking the correct needle and spring setup, you can control how fast and how much enrichment you're getting.

Believe me, I used to be able to tune carbs and distributors. I was the go-to guy for it amongst my friends. I have since discovered fuel injection and can now tune without getting my hands dirty, so I'm out of touch with the latest in 'barely controlled leak' design in carburetors these days, and ignition can be controlled in a vastly superior way that doesn't involve vacuum pull offs, weights and springs.

[The_Bishop]

Also, no matter what you're tuning, get a damned wideband. Otherwise you're shooting in the dark. Reading plugs is witchcraft unless you cut the engine off just right and you've seen hundreds of plugs to get an eye for what you should be looking for other than "it's black, so it must be rich" or "it's white so it must be lean."

[L695speed]

Ok guys I get it, either one will do. If it really doesn't matter these days, I'll run with whatever carb fits my budget. I won't run a start retard box because this is a street car, but digging around and your input seems to say to use a 6A or up box with a vac advance distributor. Question is if I should use a stock GM vac advance HEI or use an MSD setup or skip the HEI all together. I will state again, this is no race car, I just want a fast street car. 450 horses is my final target, if I exceed that great. I WILL NOT use an Accel dizzy. Believe me, if I was in the mood to rewire half the car I would have went with the fuel injection, likely LSx. But I will save that swap for another car.

[Slow Z]

I ran a 750 Speed Demon and RPM intake on my old Vortec 350. I run the same carb on my current motor but since I no longer use Vortec heads I run a Professional Products hurricane.

I'm also a huge fan of locking out the timing on just about any car with an aftermarket cam. In my experience it always makes the car idle better, run smoother, and go faster at the track. I have a 10.8:1 SCR motor with a CVR mini-starter and crappy walmart battery and it starts just fine without any sort of start delay even on the hottest of days.

[Paul Huryk]

Holleys offer a lot more adjustability thana Q-jet or edelbrock, but are not for the impatient.

I absolutely despise the 6AL box - had 2 and they both crapped out as did probably 8 of my friends, this was a while ago and hopefully the issues were fixed.

If you want to run 12.0 with your car, it is going to need a power to weight ratio of 8.5 or better to run the 115mph typical of such a run. In a 3500lb car, that is 411hp, in a 3250lb one, 382hp, in a 3000lb one, 353hp. I had run 12.5 at 113mph with the transplanted 350 in my 3500lb third gen, making about 400hp with a 700R4, peak power about 5500rpm. 450hp would push the car easily into the 11's with traction.