Technical 383 sbc stall in gear & hesitant

Hey all, sorry if i'm asking an all-too common question, but I'd like to see if I can get some advice on this.
I've got a 383 in a 64 gmc step side. It's got a brand new comp 292H-10 cam, single profile. New hyd lifters that go along with it. It's ran well on this exact cam setup for my granddad for the past 25 or so years, but we put a new one on just a few months ago. It has an edelbrock 650 (may be a 750, can't confirm as it's in storage and roads are icy but I'm almost certain it's a 650)
The carb has been freshly cleaned and had a new kit put in, new edelbrock victor mech. Fuel pump, running through a holley regulator. HEI distributor, 6AL ignition, blaster coil. No vacuum advance, both vacuum ports on carb are plugged. 3400 Stall also, with th400 tranny.

The problem: once started and warmed up, it idles perfectly fine- I had it set to idle about 850rpm. As soon as I put it in gear, it would drop drastically. It won't stall out right away, but if left like this (such as a stoplight) then I have to give some throttle to keep it going. Changing idle speed had very little effect on this issue, if any. Also, when accelerating, it hesitates just a bit, such as coming from a stoplight. At mid-higher speeds and WOT, the engine runs perfectly fine. My granddad recently handed it down to me, and beforehand he had his mechanic put the new cam, freshen the carb up, etc for me. I'm pretty sure the pressure regulator should be turned down to 5.5 (currently at 6) And since it's been driven a little since being worked on and having new gaskets installed, I'm betting that things could be tightened up a bit. When better weather comes, I'll go do that, as well as check the timing.
So, what's your advice? When I go to play with it, what should I be looking for?

 

With a 3400 convertor that should idle at 850 really easy .I would go thru and check the basics, Timing , check for vacumn leaks,pvc if its got one, and work on carb adjustment . My guess its a tune up type problem.

 

This should keep you busy for a while.
https://www.edelbrock.com/faq

 

I'm thinking your main problem is carburetor related. Are the idle transfer slots partially uncovered at idle?
Pete

 

When freshening the Carburetor the accelerator pump may have been changed from a big squirt to a small squirt.

Edelbrock has a good video on this setting titled Hesitation & Stumbling.

 

I thought of this too, but the accelerator pump is actually on the top pin, suprisingly.

 

Update: the carb *IS* an Edelbrock 750, #1407.

 

How did it run before all these changes?
Get a vacuum gauge on it and report back.

 

You may need to change your power valve springs or metering rods.

 

I don't believe edelbrocks have power valves

 

I would start by looking for a vac leak. The simplest repair and the cheapest. Then go onto the hard shit.

 

Why no vac advance?

 

Not like a Holley, but there is a power enrichment system. The metering rod springs can be changed to tune for low manifold vacuum which requires a lighter spring. Before diving into the carb try running more initial advance, idle quality, manifold vacuum and throttle response with the 292 cam in my 440 was vastly better after setting timing at 20 BTDC. Then tune the power valve so the metering rods are pulled all of the way down @ idle. If adjusting the mixture screws doesn’t have any effect then the throttle blades are probably open too far and it’s drawing fuel off the transitional fuel circuits. If that’s the case, you can drill a small hole in each primary throttle plate or tweak the secondaries to open slightly more at idle to allow more air into the engine without cranking the curb idle screw in so far. Carb tuning can be time consuming because you want to sneak up on the proper settings. Make one small change at a time...

 

Spend some quality time with the air/fuel adjustment & idle screws.

 

Shouldn't effect idle quality.

 

Have fun with the Edelbrock tunning !!
There is a lot of steps and involvement to tuneing a carburetor .
Get your self a good quality wide band o2 gauge.
327or383 ?
What intake ?
With a 3,400 stalll , set idling around 1,000-1,200 Rpms . 3,400 stall that little big but I do not know what yr goal is .
Then blade angle ( relationship to idle circuit / transfer slot ?))
Are the heads stet up for the cam change ( valve spring pressure )
No mention of what your initial timing is at idle ,
If mine I would start around 15 degs or higher (what ever motor likes) but more then factory's settings .
Total around 34-40 degs .
Compression ratio what fuel you're running ?
Plug wires ,the plug manufacture and heat range ?plug gap ?

 

Does it have power brakes ? If so block that port on the carb and see how it acts. If no power brakes and has a pcv hooked to that port, then block it off and see how it acts still.

 

What jets, needles and springs in it now? I think you will have to make some adjustments on the fuel curve. A 292 cam doesn't have much vacuum at idle...

 

I agree, but he wrote that when accelerating it hesitates just a bit.

 

A few issues come to mind . 1st is vacuum advance , why is it not working and hooked up ? 2nd , I’m sure idle slots are not working , need to drill a super small hole in the throttle plates . Drill too big carb is a flower pot . Get yourself a good timing light with advance on it and determine how much and when adavance is coming in . I’m sure you will see vacuum advance is needed as well as recurve in dist .

 

Hello guys, spoke to granddad today. I myself am new to this, so sorry if I'm being ridiculous!
Anyways, he suggested I adjust the idle mix screws. He also mentioned that he chose to leave the vac advance off as it wasn't especially useful for the engine build and he noticed no difference with it - That being said, it's ran great for the better part of 25 years on this exact set up, up until recently, so we're looking at what the shop could have tuned wrong. Apart from a fuel pressure that should probably be turned down (could this contribute?) I noticed they had placed a mark at 8 degrees advanced on the timing marks. Correct me if I'm wrong, but shouldn't a setup like this call for much more? Granddad says they tried more, but it wouldn't work. He also always thought it used more advance. Could this have been because they also incorrectly set the carb/fuel pressure, thus skewing them from setting the timing right?

 

Might also add he seemed to agree with the idea of a vacuum leak, too.

 

I ran that exact cam in the past, understand the lack of vacuum. When you get it running I would test the vac advance, I ran without one.

 

Was your torque converter rebuilt? I just solved a problem that sounds a lot like yours. The TQ had only 250 miles
on it and had a broken sprag. Put it in gear and it would kill the engine but out on the road it was okay.
Had to put in neutral at stop signs. I went through all the above suggestions to no avail because I assumed a new
TQ would not be the problem.

 

8° of initial timing is not enough !!!
Was the Cam installed correctly ?
We need more information like I ask at beginning of this thread .
Op , you Look to be you're young guy NEW to Hot Rod ""cars "", it's gonna take a little bit time .don't get discourage but the ones on here are Sharing good advice & knowledge , Hot Rodders , race cars & land speed Racing & engineers

 

Seems that nobody has asked why the cam was replaced by Granddad's mechanic with the same exact one it had, so I will.

I realize you are a "youngin", and trying to learn and that's good, Granddad is probably an old timer, with not so great memory anymore, not so good.

What was wrong with the first cam? People just don't replace cams with another of the same, just to freshen it up, so some more clarification is needed.

What was actually done to the engine by Granddad's mechanic, other than the cam, freshen up the carb, fuel pump etc. as stated?

Was more done like different heads, intake etc?

That's a pretty lumpy cam and needs higher compression than 8.5-Was it degreed the same as the first cam? Probably don't know.

We need as much background info on the engine and the repairs etc., as possible to help you with your issue.

 

This place is something , 25 posts , numerous suggestions , no useful info from the
OP , it COULD be almost anything , hard to determine from nothing ...LOL !!

 

Heads are 215cc Dart Iron eagle heads,polished & ported. Hooker super comp headers. 5.7in stock rods. Intake is an Edelbrock victor Jr - Single plane, 3500-8000 RPM range. Part # for intake is 2975.
The mechanic replaced old fuel lines, cleaned the carburetor (which was full of crud from old fuel line), put a new set of springs in there, put new brake lines in, bled all brake lines and set them up, set timing, adjusted idle/idle mix screws, installed new intake, head gasket, header gasket, and carburetor seat gaskets, new HEI distributor cap, new spark plugs, wires, and installed a new fuel pump & filter. Coolant/Radiator was also flushed. Cam WAS broken in with cam lube and ran for approx. 45 minutes at constant RPM (I beleive to be 3200, but it began at a lower RPM.) during the break in. I do NOT know about it having been degreed at this time, as I did not ask if it was done. However, I will ask the mechanic. The truck drove well the day I took it from the shop, however since it has been like this. I will also ask about the timing and why they claimed they "couldn't get it running right at 12 degrees BTDC", and will update here with their response. In addition, I will include pictures of spark plugs. When payday comes, I will get a vacuum guage and do the vacuum test as others mentioned.
Again, forgive me for my long-winded, seemingly uneducated response, but I really respect the guys here and I welcome all the feedback I've been getting. I wasn't expecting this much response!

The cam was replaced because the #6 exhaust lobe was wiped, also bent the corresponding pushrod.
At this time, the truck had been sitting for some time, being driven by my granddad once or twice a month for a few years, and not long after I "began" taking it out, the cam wiped. A slow oil leak developed quite a while ago, but he (granddad) was very diligent in keeping the oil level perfect. I've always tried to check oil every time before taking it out, but in my young & uneducated negligence, I may have slipped up on this once and not noticed. I do *not* know for sure, but I am very sure this was the cause of the last cam being wiped, as it had never been problematic as long as that engine was in the truck. BEFORE the cam was wiped, I know *for sure* that there exists a correct tuning here (duh? lol.), as the truck ran phenomenally before. Crisp throttle response, perfect idle, everything. Held strong all the way up to 7,000RPM.

Speaking of which - Some posters noted a lack of adequate info posted, and I apologize. I'm giving as much as I know, haha.

Repair/Background on engine: Has been through 3 carbs, starting with a 650CFM Edelbrock, then a 670 Holley avenger, and now in currently, the 750CFM Edelbrock performer. The original 650 was a good performer, but he was gifted the holley, to which he told me "it wasn't a bad carb, but it didn't give the throttle response or idle like the edelbrocks did. At that point, he had put the 1st carb on another project of his. Therefore, he bought another edelbrock, this one being the 750 on there now. He was much more satisfied with this one, and said it ran much better with the engine. I do not know of the signifigance of this, but the 2 idle mixture screws are notably unevenly set, with the right being screwed in more. Accellerator pump shot is currently set on the TOP dot of 3.
The only other noteworthy event in the engine's history, is the heads. One head (drivers side) developed a crack about 7-8 years ago, to which it was welded. Since, he's had no issue with the head, and we also recently ran a compression test to make sure. All cylinders were equal and held the right amount. (at this point, I do not know the number, however the cylinder heads themselves were indeed in fine shape. The turbo 400 transmission also has a shift kit, of which I have no more info on. Was put on to shift faster and harder.
Apart from that, NO parts have been changed, replaced or broken since being put together in about ~1995-8 unless otherwise noted above.
He stated that he had built the engine for his drag racing days, but also wanted to be able to drive it around town and drive to shows. Never had problems with either. He did say that while he never intended to use vacuum advance, that I may find some use in it, corresponding with some posts above.

At the moment, it has no vacuum accessories such as vacuum brakes, advance, etc. Both vacuum ports are capped on the Carb.

**It should also be noted that the Stall converter is 3200, not 3400 as I previously stated**
**Another note: the engine must not have high compression, as he has always ran regular 87 octane gas in the truck with no detonation issue. Unless he was racing (113 octane then, whatever was available at the track) But, he prefers to put higher octane without ethanol in it if he can. I follow this, as I only put the highest grade with no ethanol I can find. Here, that's 91.**

Lastly, the engine does not instantly die out. Rather, it goes to a much lower RPM when put in gear (tends to drop to 500-450), and at that RPM it is rough and has a fair chance (though not 100%) that it will eventually stall if the low RPM is not counteracted by even just a wee bit of throttle.

I hope this clears a few things up, so let me know if I can provide anything else!

 

Thanks for the input - Did you experience similar things as I am before hooking the vac advance up?

 

In addition to all of the above, keep a close eye on your fuel filter, especially if the fuel system had problems.