70 ctls

Hi Guys,
I've changed too many things to back track and pinpoint the problem. Thought someone might have a handle on what's going on with my 350. Ok, so it has an edelbrock dual plane intake and rpm camshaft and was running with a #1406 600 cfm edelbrock carb. Gave carb to my son and rebuilt and put back the matching 750 QJet. Ran good but not like a runner more like a cruiser. Started to mess with timing curve/ and vacuum canister. Put on another Edelbrock 600 cfm that I had lying around and rebuilt and inspected it. She idles good but wants to stall when put in gear. I've reset timing, changed vacuum canister, changed metering rods and springs, and nothing works. Wondering if I have a vacuum leak at the rear edge of the intake manifold and block? Would rather not have to pull the intake off if it doesnt leak. Anyone got any ideas?
Thanks,
70 ctls

texasred

Take some carb cleaner spray and spray it around the carb-to-intake mating surface, the carb gasket "seams" and around where the linkage goes into the carb body. If you have a vacuum leak, the rpms will increase ase the fluid "plugs" the leak.

C.J.

70 ctls

Thanks, Thought of that. I also wonder if there might be a vac leak at rear of intake manifold what with edelbrock saying not to use the front and rear rubber gaskets but rather rtv only.
70 ctls
www.oldsmobilesforever.com

texasred

Blow/leak oil, yes. Vacuum leak, no. Did you just change the intake? Are all your vacuum hoses to carb/distributor hooked up or plugged? Is your distributor asembled correctly?

C.J.

70 ctls

C.J.
You're making me think know. No I did'nt recently change the intake
manifold and I you are obviously right about the seal to the block having nothing to do with vacuum. What I did change was the spot where I pulled vacuum for the power brake booster. Remember I originally had an edelbrock and pulled the brake from the rear of the carb. When I switched to the QJet I had to pull vacuum from a plug on the front of the manifold instead. Now I'm back to an edelbrock but plucked the back of the carb instead of returning the brake hose to it. Perhaps under load vacuum is reduced to a point where there is not enough for the vacuum advance? what's your take?
Thanks for thinking with me. John

Oldsguy

John,
I think the vacuum would be the same even if you draw from a different physical location. Total manifold vacuum is the same at the bottom of the carb, the front runner of the manifold, or the rear runner of a manifold. When moving the location where you take vacuum for the brake booster you might have overlooked a leak when you plugged the spot you previously took it from. You could check for that for sure. You might look at the throttle bushing on the carburetor as suspect. If the bushings are worn you could get a vacuum leak. I think it might be a good time for you to buy yourself a vacuum gauge. Hook it up to the manifold and monitor what happens to it when you put the car in gear. You should have about 15 pounds of vacuum in park at idle with that rpm camshaft. I think they advertise close to stock vacuum with it don't they? Just a couple of thoughts anyway.....

texasred

I was actually thinking more of an open vacuum port on the carb that shoulda been capped.

C.J.

70 ctls

Attachment 439
Well ...... Thanks for all the thoughts. Tried them all and nothing changed. So I took off the Edelbrock and put back the Rochester QJ. Walla!! She idles much smoother and when put in gear she is fine. Thanks Guys. I guess the engineers at GM during those earlier years really did know what they were doing.
p.s. The 70's 350 is in the 37. The 70 has a fresh 455, and the 32 is all original

Oldsmobiles Forever !

John

texasred

When I bought my Cutlass, it had an Ebrock 1406. After wasting way too much time and money rejetting and dinking with it, I had the original QJet rebuilt by the local pro (70Wcars on this board, actually) and have had a great time since.

C.J.

71rocket

I'm having the same dang problem with my '71 350. My mechanic is down to the point where the problem HAS to be with my 1406 carb. I dropped off a used quad-jet yesterday and he should know something this afternoon, I hope.