My 70' 455 4bbl does not respond as expected. It hesitate upon hard acceleration, (and I can't even get the wheels spinning :confused: . The car is a 68 Riv).
Engine is good, compresion within limits, new distr, (and tuned according to the spec's).
I have overhauled the carb, and have only been waiting for a new "air valve" for the sec. butt.fly. Got it today smile.gif , no much difference, still boging. Where do I go from here? Idle and normal running is smooooooooooth, but I also have a feeling that it get's too much fuel during "secondary" operation.

Buicks don't really mind running rich, especially at WOT.

I would first go after the accelerator pump- if you can get it to pump more fuel in, that will probably reduce the bog when you hit the gas.

Also, if you have too little timing (too retarded), that could cause it to be sluggish- do you know what your timing is?

-Bob Cunningham
bobc@gnttype.org

I had a q-jet on my 69 chevy pu. There is a secondary air valve spring? that controls the opening on the secondary air valve. Try tightening it up a half turn and see if it makes a difference. It is located on the top "butterfly's" for the secondaries near the shaft.

Hope that this helps

Thanks for your answers.

I have set the timing to 8 BTD. Will try with 10, or should I go higher?
Will also try to tighting the butterfly, but they are set according to the book.

The coluor in the exhaust pipe outlet is black, to me that indicate fare to rich mix. Also, it's not only boging, it's mis-fire before picking up.

A black exhaust does indicate "rich" in that the fuel is not being burned efficiently. You may have a timing problem. Advancing the timing is also a way to solve the black pipe. Check out the Buicks.net shop for an article on timing. smile.gif

is the new distributor an HEI unit, or is it still points and condener? if it is an HEI unit, you need to get a +12V wire from your fuse box in order to get the full amount of voltage that it needs.

It's a new distr. with point set . Tried with 10 dergee, but no change.
Am convinced that it is the carb's secondary. It run just perfect at normal driving, only missing the "kick" an engine of this size should give.

Will open the carb and have a look as soon as I get time.

Per

If you are sure it is the secondaries, wire them shut to prove yourself correct. The car should then run well, but lack power.

Checked the secondaries out last week-end. The hanger, ("F" marked), was badly bent, and gave too much fuel.
Compared it with an other and straightened it out as best as I could. Hooked up the "CD" rods and went for a drive.
Goes like a shot, just some fine adjustments left.

Thanks for your help.