Quadrajet Problem Solving > Dialing in your rebuilt Quadrajet carburetor

Slight burble and light cruise

(1/3) > >>

Daniel828:
I have a 1971 Oldsmobile 455. It was rebuilt this winter, the cam is 228 @ .050 .504 lift   Performer intake and headers into 2.5 exhaust with H pipe.  The carb is a 7040240 Buick 455 carb with 69 jets and 42B rods and DA secondary rods. The engine idles perfectly and has great response  up and thru WOT. The problem is, at light steady cruise there is slight burble thru the exhaust. I'm also using the original points dist with pertronix unit, and I got it back from bubbas hot rod ignition.  He found some advance problems and replaced a defective vac advance can. But the burble is still present. I have an HP kit and a APT kit installed. Any suggestions would be greatly appreciated
Thank you
Dan

Daniel828:
I've tried a few different things. I changed the jets from 69 to 71 and still has a slight burble in the exhaust note. I put the 69 jets back in, it just seems to idles cleaner. I also screwed the APT screw in and it seems to be very far in. I don't have a base line on this carb. I got it off of eBay and rebuilt it. Is it ok to use a Buick carb on an olds? I know it seems like a silly question.
I also went thru the valve train again. It's an hydraulic flat tappet with adjustable roller tip rockers. I'm not using the olds rockers with aluminum bridges. And the last thing I tried was adjusting the Aconcagua air door.  First tighter, then looser but it didn't do anything.  And I quicken up the choke vac pot. That was originally over 2 seconds, now it's about 1.5 seconds .
But the burble is still there
I'll try taking a vid and see if it will pick up the audio
Thanks
Dan

77cruiser:
How much timing do you have at that RPM?

Daniel828:
I started at 10 at idle, about 650 rpm and bumped it up to 12. Now it's at 15 initial and don't know where it is at total. When it was at 10 initial it was all in at 2600 34-36 degrees.  I sent the distributor to Jim at bubbas hot rod ignition. He recurred it. I'm thinking it may be the pertronix unit

Daniel828:
And I've tried ported and manifold vacuum. Doesn't make a difference. And I even tried with the vac advance disconnected.  Still burbles in the exhaust note.  I had the exhaust completely welded front to back except the header collector, that's bolted on. 

Navigation

[0] Message Index

[#] Next page