So, someone had removed the AIR pumps from the Nose before I got it, I would have taken them off if they had not already been gone.

I have been curious for a bit, about the carburetor jetting, with those pumps gone, could I change to a smaller Jet? My tail pipes are a bit black on both sides, I have been told that is a sign of running rich. I really do not have any idea how to get a proper adjustment to the jet, I suppose exhaust Gas temperature is best, but I can not run fast enough to measure it at speed.

I need to put in a new accelerator pump, so while in there I could put in a jet. Even saving a half mile a gallon is worth the effort.

Any thoughts???

quote:

Quatra-jet

read these?

http://www.digitalcorvettes.co...owthread.php?t=88376

http://www.corvettefaq.com/c3/QJetTuningPaper.doc

Here's a quick response from our son Walker, he went to the Virginia Racing College in Martinsville, VA.

"Have you recently rebuilt your quadrajet or is it still original? A quadrajet needing a rebuild will create a rich mixture, I would not begin tuning mixture without rebuilding it first and confirming that all functions are operating correctly before adjusting it. If you get everything to a solid stage 0 and still want to adjust the mixture read on. Quadrajet's differ from Holley style carbs in that they use a stepped rod that has 2 or 3 diameters that slides in and out of a jet based on vacuum and load."

Walker would be happy to talk your ear off about carbs if you need help.

Bill

[quote]Walker would be happy to talk your ear off about carbs if you need help.[/quote!!!

Mine is probably in its original state. 60k on the engine. I did pull the top off last summer, looked pretty clean inside. So I should do a rebuild fist...ok!!

It does stutter a bit when stopped to get going, I suspect a new accelerator pump what else? I saw those needles that go into the jets, yes it is different you have taught me already..

I will need help so Walker thanks in advance...

Thanks Doug good stuff too

Ordered the rebuild kit, will take a week or so, gives me lots of time to remove clean up the Rochester.

I understand there are some adjustable needle valves behind some closed off access points, Shall I remove them so I can adjust the idle later?

I'll send Walker's cell # in a message.

Didn't you mean to say you ordered 2 rebuild kits? Mine can be there by xmas. :P

quote:

Originally posted by benebob:
Didn't you mean to say you ordered 2 rebuild kits? Mine can be there by xmas. :P

Hey how did your spring replacement finish up, is all well???

Rebuild kit, not here yet must be the Christmas package rush...I have not removed the carb yet either, must be the Christmas laziness. lol

quote:

Originally posted by Duane88:

quote:

Originally posted by benebob:
Didn't you mean to say you ordered 2 rebuild kits? Mine can be there by xmas. :P

Hey how did your spring replacement finish up, is all well???

Well I only got one side on before I was done for the year and no it didn't fix a thing. Still at the same ride height on that side and the tires rub the frame around turns (and there is zero weight in the back with empty tanks and no motorcycle on the hitch). Last GM product I will ever buy. I can't deal with such horrible engineering.

I have watched about 1000 u-tube rebuilds of the Quatrajet, really it is a pretty neat fuel delivery system. Got the rebuild kit and have the carb in the house.

Because mine was hooked to an AIR system I have to break out the idle mixture adjustment screws that factory set.

I was making adjustments to the idle screw, without really understanding how the high idle (cold engine) worked, there are 2 adjustments screws one each..

So far I have not needed to call Walker, I have 72 Primary jets I am still thinking I might get some a bit smaller, maybe 68 because the exhaust pipes are a bit black. I should call him and see what he thinks. Maybe the mixture adjustment might correct this problem.

The filter bowls were a bit dirty, one of the air tubes had fallen out of its seat, and the accelerator pump looked pretty worn, so these may be my problem.

I maybe all wet, the only reason I would be interested in changing jets or rods is because the AIR pumps have been removed and I think I can get better gas mileage if I lean it out a bit. I guess I should call Walker ...

Did a little further investigation, found one of the Vacuum motors defined as the "rear lock out" is defective. will not pull in, bad diaphragm.

So I guess I never had use of the 4 barrel part of the carb. Hope I can find a replacement motor.

I decided to take Walkers' advice and just get this working correctly put it back in and see what the heck I am dealing with.

The float adjustment was way to low, hardly any fuel was allowed to accumulate in the filler bowl. I suspect someone was in there before me.

SO...float, atomizer rod, bad vacuum motor and worn accelerator pump. I am surprised it worked as well as it did.

No adjustments to the idle mixture screws or the primary rod location. I may need to adjust the idle speed on both cold engine and normal run.

I guess I really never knew how this or any carburetor worked, more complex than I thought.

Got it all back together as far as I can tell everything works. I do have to wait until Tuesday to get the vacuum motor I need, NAPA had it only one ,but can not get it here till Tuesday.

I did find a guy with a 350 engine, converted to a test stand. $20 for the test, I think well worth it. Hot rod guys still love the Rochester.

I got my Vacuum Motor from NAPA early, waiting on a reply from the hot rod guy to test the Rochester.

NAPA must think the vacuum motor is made of gold $60 bucks, When I worked at Eaton Controls the factory cost was like a buck. lol Early 80's and this is old stock the box is faded to yellow no bar code either.

quote:

Originally posted by Duane88:
I got my Vacuum Motor from NAPA early, waiting on a reply from the hot rod guy to test the Rochester.

NAPA must think the vacuum motor is made of gold $60 bucks, When I worked at Eaton Controls the factory cost was like a buck. lol Early 80's and this is old stock the box is faded to yellow no bar code either.

Still can't believe I got a complete carb for the VW, with electric choke and gasket, postpaid, for $68! Gotta love those 3rd world prices...