I rebuilt my 350 a while back and I can't get it to jump off the line. Here is some info on it:

Comp cam 270* adv. duration, .470" lift Hydraulic
GM cast 14096242 Intake
750 Holley 71 main 75 secondary
GM 2.02 76cc, stainless valves
My rough calculations put my compression around 8.885:1, but I guessed on gasket thickness and deck clearance.
Everything else is pretty much standard, i.e. distributor, pistons, push rods, rockers, etc.

It currently has a 10-bolt open 2.73 ratio. I am willing to bet that may be part of the problem and I have a posi 12bolt with 3.73 gears lined up to put in it if that is the consensus.
The transmission is a 350 but is about to kick the can. It slips and the pump is really weak... overhaul planned soon.

If I am sitting still at idle, in gear, and tromp the gas, my engine sputters and tries to die. If I don't let off the throttle, it WILL die. At higher RPM it does really well but I have to be moving a good speed before I can open it up. When I first put the thing together I had carb problems (black smoke, rough idle, and would die with any throttle depression). I know the carburetor is too big for a 350, but I am not going to mess with until I get my rear end in. Maybe jet it down? I didn’t adjust the carburetor or timing, I had the mechanic do that so I don’t know the specifics off hand. I am really wondering what I should do next. I was thinking of putting the rear end in and seeing how that works, then adjusting the carburetor some more. What does everyone think? Any tips or suggestions are welcome. Thanks.

always start with the distributor, you need at least 12 degrees initial and 34 to 36 total all in by 3000 or sooner depending on torque converter, rear gear, weight and gas used.
once the distributor is set up right work with the accelerator pump on the carb. jets have nothing to do with off idle exceleration

I agree with mechanic427. I also think you should go for the 3.73 gears and maybe a small stall converter after you rebuild the tranny. maybe like a 2500 or so, nothing to big. would help acceleration. if I remember right, Comp claims the 270 is the biggest cam you can run with a stock converter but I think with that cam, a 2500 stall would be pretty good.

Thanks for the info. I'll work on the distributor this weekend. What exactly should I do with the acc pump? (carburetors aren't my strong point)
sscheveelfan, your right, that’s the biggest recommended cam for a stock converter. Any specific converter you can recommend or are they all about the same? I looked into them a while back and noticed the prices varied greatly, but I couldn't see why. Will a 2500 stall have any effect on the drivability of my car on the street? It's really only a street car with the occasional drag race so it can't be too radical.

where do i start? sounds like you are new to our sport and it's hard to tell you what to do till you have the dist fixxed and can decribe exactly what the car is doing once the dist is done.
but hang in there, we will help you but it's best to ask for advice befor buying stuff because we've all been there and you can learn from our mistakes and save a lot of money.
once the car launches correctly the tranny won't last long in it's condition. and don't rebuid it so it barks the tire going into second or you will be rebuilding it real soon again.

It's only 1-wheel drive so it barks 2nd and 3rd gear, even though it takes a while for it to shift smile.gif I understand most of the things I've done to the car, but carburetors aren't something I'm very keen with. Something I just thought of: I live on a gravel road (about 2 miles of rock) so wouldn't a stall converter be a bad idea?

The first thing I notice is that you have jets in the secondary of your carb. That leads me to believe that you have a 750 double pumper carb (tho not necessarily).

A double pumper carb, automatic tranny, stock converter, highway gears and an unknown timing curve is a recipe for very soft performance.

The very first thing I would do would be to get the timing curve set. A cheap and easy way to get this done would be to buy a ProForm balancer cover with the etched timing marks. I just picked one up for about $28 to my door. I've installed it, but haven't gotten around to doing anything else. With the etched cover and a timing light, you should be able to plot the curve out.

I agree that 12* initial would be a good start. Disconnect and plug the vacuum advance to do this. Try to get about 24* of mechanical advance in at about 2800-3000 rpms. This gives you 36* of total timing.

See if you can swap on a 650-750cfm vacuum secondary carb. Go from there. Those would be the easiest and cheapest things to do. Oh yeah, might want to start saving up for a tranny rebuild.

It's not a double pumper (it's vacuum secondary), but it does have a secondary metering block. I messed with the timing today and it might run a little better, but I will definately check out that cover you are talking about. Money isn't a problem for building the transmission, just don't have much time to do it! Thanks.

TCI and B&M both sell good converters. I had a 3,500 stall in my last chevelle and it was my only car at the time. a 2,500 won`t be to noticable on the street untill you nail the throttle. I would`nt go more than that, you just don`t have enough motor to need it.

Anybody have any ideas on how to set mechanical advance w/o a tach? I have a feeling the answer is "Get a tach" smile.gif
Looked at stall converters today. I found a B&M for $150 with 2300-2500 stall. Sounds good to me, sound like a winner to you?
Also got my moser axles and should have my rear in within a week, maybe two if I can't find the time. So, I'll see what effect that has with the lower gears.

Excellent. You have a vacuum secondary carb. That helps the situation out a bit. I have a 750 Holley 3310 vacuum secondary on my 355cid and it's mint. There are pleeenty of guys on here with carbs that big on 350's, so you just need to get everything tuned out.

You could get a cheap Equis tach (or equivalent) at a parts store. I got one for about $30 or so a few years ago. It will suffice. If you would like one a little nicer, an Autogauge (the economy line of Auto Meter) wouldn't cost an arm or a leg. But, yes, it would be very nice if you were to get something along those lines.

What did you set the initial timing at? Please tell me you aren't doing this by ear. smile.gif tongue.gif The cheapest things I would pick up to get the engine lined out would be...

ProForm etched balancer cover
Crane distributor kit (adjustable vacuum advance canister, plus it comes with varying weights and springs for the mechanical advance)

Holley Rebuilding and Modifying Manual (invaluable book...trust me on this one)

Holley Quick Change Secondary Pod
Holley Secondary Spring kit
Holley pump cam assortment kit
cheap vacuum gauge
I'd hold off on any nozzle squirters for the carb, until you can verify what you are using now.

Fresh tune-up...if you haven't done it lately. Plugs, wires, ignition coil (MSD would be nice here), cap and rotor. Oh yeah, an air and fuel filter, plus a PCV valve.

Now, you also need to make sure that you don't have a blown power valve or any vacuum leaks. You'll have to pull the front bowl and primary metering block off of the carb to check the power valve. You could replace it with a new one, as they are cheap, but I think you can also suck on it to see if it will open (never tried that myself, tho). There should be some #'s stamped on it which will help you verify what size it is. My guess is you have a 6.5, but you never know.

For a vacuum leak...well, that could be harder. You can spray some WD-40 around the base of the carb or the intake manifold. If the idle speeds up...you've found one. Or heck, you may not have one at all. You do have some symptoms of a possible leak, tho.

Also, you need to check your float settings. This could cause it to load up and run rich at an idle. I told you that you needed that Holley manual, right? ;)

There's a lot of stuff...but that's what we're here for. If you can get what I've provided on that list, we can take it from there. I say get the tach, vacuum gauge and Holley manual, first and foremost. (plus a timing light if you don't already have one...NECESSITY) We can guide you from there.

Oh yeah, it's good to hear that you are going to go with the 3.73's. That should pep things up a bit, but we need to get that engine running smoothly.

Please keep us posted.

Yeah I agree with getting a different converter and a tach. I went to O'reillys and found an autogauge one for 35 bucks. Btw, I think I have seen your car driving around in Shen acouple times. You will have to look for me in spring, I'll be up at the Rolling Thunder drag strip with my chevelle :D .Good luck.

-Dan

Thanks for the helpful jump start. I went looking for a distributor kit and found something that comes with vacuum canister, adjustable diaphragm, advanced weight springs, and instructions. Is that fine or do I need something with weights?
As far as the carb leaking, I can't say it's not, but I doubt it. If it's messed up already (after 1 year and less than 10,000 miles) I don't think I'll buy Holley again. I had my dad's friend put my carburetor on and tune it so I think he would have caught any obvious problems out of the box. The only thing I have messed with on that carb is the floats and mixtures, the rest is a puzzle to me smile.gif What sounds legitimate to me is adjusting the accelerator pump, so I will definately look into that. The same guy who tuned my carb has a tach, he wants $50 for it so I'm going to check that out. After I get tht timing set I will move to the carburetor and attemt to fix it!

Dan, if your takling about the track near Pacific Junction, I live like 5 minutes away from it. When it first opend I took my dads turck on the track, it doesn't handle curves well at high speeds.

Some things I may need to mention:
Since day 1, the engine has continued to run after the igniton switch was turned off. Tuning the carburetor since it was built has not cured it. I usually leave the car in gear when I turn it off to prevent that.
Today I drove my car and paid more attention to it. I noticed that while depressing the pedal very quickly, with the trans in nuteral, the engine was at first slow to pick up rpm, but the higher the rpm, the faster the rpms accelerated. Not too sure if thats normal for my setup or not...

Engine run-on can be caused by a few different things.

1. Engine running hot.

2. Idle speed too fast.

3. Accelerator pump out of adjustment. This allows gas to steadily drip out of the nozzle squirters. Makes the car want to keep running.

That timing kit you found would be fine. Changing weights probably won't net you much right now, I'd concentrate on other things. Once I had that kit, I'd probably put the heavier springs in it for a bit, then use a timing light to verify that your mechanical advance isn't coming in at idle and throwing you off.

Holleys are EXCELLENT carburetors. However, it takes either someone showing you the ropes on one...or getting a manual ;) . There is waaaay more to it besides setting the floats, air/fuel mixture and curb idle speed. You have the primary and secondary transfer slots, primary and secondary jetting, accelerator pump, nozzle squirters, electric choke, power valve....

....and that's the easy stuff. If you upgrade to a Holley HP carb or something like that you would get into adjustable air bleeds power valve channel restricters (PVCR's)...etc.

But, I digress. Get a Holley manual, tach and vacuum gauge. Don't give up. You're just starting.

Not sure about the rpms in neutral thing. One of those "have to be there" kinda deals.

Please hang in there. We've all been there once. smile.gif

Talked to the guy who is setting up my gears. He told me to wait until I get the lower gears in to mess with the timing because he thinks I'll be pleased with the way it runs with only new gears. I might be getting a different carb, if so, he said he would buy mine for is 454. He said different distributors need different degrees of initial and mechanical advance (or something along those lines). What’s the deal with that? He also said a TH350 wont hold up long with a stall converter and my setup, and the dead spot at low rpm was 'normal' for that cam since my carburetor is a little on the large side. Forgot to ask him about preignition though, maybe next time. Second opinion or explanations anyone? I feel like I'm going in circles.

It sounds like the primary throttle blades may be open to much allowing the transfer slot to be mostly exposed which would cause an off idle hesitation and contribute to the run on situation after the ignition is turned off. Get the timing curve figured out and then work on tuning the carb, it may be necessary to open up the secondary blades slightly so you can close the primaries down a bit. Do a search here on Holley carb tuning and you'll probably be amazed at how much info is available. Different distributors shouldn't need different advance curves, your combo, fuel and air quality are the only things that should dictate what spark curve is right for you.

If it has a dead spot that tries to kill the car the problem is not the gears.

I have 3.08 gears in my car and it didn't pull very hard till 2,000 rpm but it was enough to squeel the tires if you floored it from a stop.

My combo is just a decent 350 with a 650 spreadbore Holley. You have problems somewhere besides gearing.