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 1959-1979 Big Pontiac Tech
 '64 Bonneville 389 carb issue
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DannyG
Tribal Scout

USA
6 Posts

Posted - 30 Sep 2013 :  10:36:11 PM  Show Profile  Reply with Quote
First off if like to say hello to everybody, I've been poking around this site a little bit and just joined for some guidance. My grandfather bought this '64 bonneville convertible a little over ten years ago as a project. He rebuilt the engine and had the automatic transmission rebuilt also. It sat for a few years with old gas left in it and what a mess we had. We sent the Holley carb to get rebuilt but it hadn't been right since, so we finally decided we'd just buy a new edelbrock carb from summit. Their tech assured my grandfather that all we needed was a edelbrock 1406 which is a 600cfm carb. After finally getting it put on the car just has pretty much no power at all. Just looking for some input on where we should go from here. I have for the most part all of the slips for everything that has been out into the motor. Any input would be appreciated. Thanks in advance!!

cortcomp
Coyote

USA
5338 Posts

Posted - 30 Sep 2013 :  10:37:59 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Never listen to anything summit techs say. ever.

however, should run OK with e-carb, just WOT bog, etc. Did you do any compression tests?
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DannyG
Tribal Scout

USA
6 Posts

Posted - 30 Sep 2013 :  10:44:48 PM  Show Profile  Reply with Quote
Don't get me wrong the car does run good it just has nowhere near the power that it had with the old Holley carb. And no we haven't done any compression tests. I'm no real mechanic lol. This car is only driven maybe a few times a week between June and October. We are lucky if we go through more than two tanks if fuel so fuel economy really isn't an issue for us
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cortcomp
Coyote

USA
5338 Posts

Posted - 30 Sep 2013 :  10:50:15 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Well, i'd try to drive it as much as possible (i drove my '66 389 2 bbl catalina as a daily driver for about 6 months, these cars like it) Also, advance timing until it pings under load and then back it off until it doesn't. 2-3 degrees timing made a HUGE driveability difference in my 389. As far as power goes for most carbs on a stock motor (even a 2 bbl vs a 4bbl, let alone a 4bbl vs another 4bbl) they should all have decent power except when running hard out in WOT. Most of the carb just isn't used cruising around and taking off from stop lights normally. (Not stop light drags, you'd notice it there.) Unless it's really rich or lean, it should feel OK with the new carb. 600CFM should be good for that, if it's the AVS carb they are jetted richer than the regular E-Carbs.
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DannyG
Tribal Scout

USA
6 Posts

Posted - 30 Sep 2013 :  11:04:55 PM  Show Profile  Reply with Quote
Well it's not a stock motor. It's bored .030 over
Edelbrock performer 2156 intake manifold
Carter m6907 fuel pump
Mallory electronic ignition
As well as a comp cam and exhaust.
When he built this car up it was meant to be a fun weekend driver that could get up and go. But since we put that new carb on we noticed a significant drop in power. And when I searched online I found that this was a somewhat common problem for that carb on the 389
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cortcomp
Coyote

USA
5338 Posts

Posted - 30 Sep 2013 :  11:21:45 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
do you have access to another carb to borrow or try? i had the 750 cfm on my 428 and it ran great except for when you dropped the hammer and got that trademark e-carb bog then WOT jerk that you couldn't tune out.
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DannyG
Tribal Scout

USA
6 Posts

Posted - 30 Sep 2013 :  11:28:12 PM  Show Profile  Reply with Quote
The only other carb we have access to is the old Holley which I believe was a 750cfm but we had trouble with it cutting out but it definitely worked a lot better than the edelbrock performance wise
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cortcomp
Coyote

USA
5338 Posts

Posted - 30 Sep 2013 :  11:55:32 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
Have you rebuilt the holley with newer parts (especially the acc pump)? Every single old carb i've had in the last 5 years has, after running normal gas on a regular basis, needed an accel pump rebuild. even one that ran fine when i bought it on the way home, month later, needed a carb rebuild. every one has ran great afterwards. I'm not a carb guy, i have them rebuilt for me so that i don't have to mess with it.

All that being said, you still have to do all the regular stuff like make sure no rusty gas tank, clean lines, etc, etc.

What comp cam?
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DannyG
Tribal Scout

USA
6 Posts

Posted - 01 Oct 2013 :  07:28:29 AM  Show Profile  Reply with Quote
We paid to have the Holley rebuilt. Yes they replaced the accel pump. I'm not sure what cam it is now, my grandfather would know. I can't find a receipt or anything.
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cortcomp
Coyote

USA
5338 Posts

Posted - 01 Oct 2013 :  09:49:07 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
It's not big deal about the cam, was just curious. Honestly, unless it's a big cam upgrade (and i doubt it because it'd be super choppy) that E-carb should be in the ballpark, and get you around town cruising no problem. If it were me, i would try the holley again (should be quick to swap over) and see if the e-carb issues go away and the holley issues come back. What do you mean by "cutting out" on the holley?

If you have the manifold i think you do, it will accept square bore and spread bore carbs without an adapter or anything, so you can swap a qjet on there or about anything you can find to test with to be sure it's a carb issue.

If the e-carb and the holley are close in cfm and both setup properly, you really shouldn't notice any seat of the pants different on a mild motor except on those WOT bursts, where that e-carb seems to stumble before taking off full bore.
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bnorris_74
Crazy Horse

USA
1442 Posts

Posted - 01 Oct 2013 :  4:24:46 PM  Show Profile  Reply with Quote
Do you have the vacuum advance connected on the distributor?

The reason I ask is I think I read that the Edelbrock carb has a couple timed vacuum ports. Depending on your vacuum source on the Holley you might have been running full vacuum with it and possibly ported (timed) vacuum advance with the Edelbrock.

The other thing to do is check the carb to make sure the gas pedal at w WOT is making the carb open up all the way.
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mike389
Big Trees

USA
568 Posts

Posted - 04 Oct 2013 :  01:21:45 AM  Show Profile  Reply with Quote
danny
i to had a 1406 which was a good running carb but no bottom or top end power on my 64 bonn./66 389 ! was told also by edel. tech it was big enough for a 389+30! finally sent my 800 cfm q-jet to Cliff and what a difference top end is very good i ran out of nerve @ about 120 but still had a lot more throttle left so i will never know top speed but if it is anything like my 68 lemans many years ago (140+) it would not surprise me! i highly recommend Cliff and q-jet set up, you would not regret it!! one of the best moves i made power wise! never had much use for holly or the clones but that my opinion!!!
mike
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cortcomp
Coyote

USA
5338 Posts

Posted - 04 Oct 2013 :  09:54:29 AM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
I think bnorris might be on to something there, the symptoms he describe don't immediately scream carb to me, but i know if i don't give my 66 the timing it wants, it does kill the drivability for sure. Does it still run well? sure, but if you give it a couple more degrees timing, it will roast the tires, and it's the 2 bbl small valve heads. that 2-4 degrees i don't let it have because of ping and running 87 octane make a big difference. It is more of a DD setup though, i didn't care to tune it for power.
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BVR421
Sitting Bull

Bahamas
245 Posts

Posted - 08 Jan 2014 :  6:26:14 PM  Show Profile  Reply with Quote
Here's my tuneup preachin LOL
99% of all suspected carburetor problems usually turn out to be problems in the ignition system, either wrong or improper parts or not properly adjusted.
The ignition system and timing must be 100% before you even think of other problems. Many ignition problems can mascarade as a "carb" problem.
100% accurate timing does not come from "timing by ear', ie: 'advance til it pings', or other shadetree fumbles. We've all done that with varying success but we all know its no substitute for timing lights, dwell meters and manuals.
Start with factory specs, including the whole advance curve not just the inital lead. Get it running as well as it did off the truck then evaluate carb setup.
-----------------------
Also dont overlook the relationship of the carb to distributor. Specifically the vacuum advance line. Make sure its connected correctly and no leaks. Make sure the dist advance diaphragm is not leaking, make sure the dist centrifugal advance weight retraction springs are stock and not that Moroso hotrod crap. Also isnt there two vacuum ports on the front of the afb clones? one is full manifold vacuum and the other is timed (ported) source? That can be a big change in total timing right there and cause a power responce problem at certain rpm ranges as well as exacerbate pinging. With a stock DelcoRemy dist Id always run what the factory did with all pre smog ignitions, full manifold advance.
Thats not set in stone. It can be changed and modified in specific ways for specific purposes, but if you have to ask, you dont know enough yet to effectively bend the rules.
Your 4sp hydro trans needs accurate carb to trans linkage adjustment for satisfactory driveability. Use a 1/4" dia phillips head screwdriver in the key hole to adjust the length of the linkage arms. Its all in the manual.

Edited by - BVR421 on 08 Jan 2014 7:13:19 PM
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cortcomp
Coyote

USA
5338 Posts

Posted - 08 Jan 2014 :  7:05:44 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
One pet peeve of mine is people that just swap gaskets and clean a carb up and call it a rebuild or pay no attention to the carb at all. Every time i go look at buying an old car that supposedly "runs like new!" It ALWAYS needs the choke fixed or adjusted or replaced, and the accelerator pump is usually gone in it because the new gas ate it up.

When i first looked at my 66 cat (389, 2bbl from above) he said he always had to let it warm up until you saw smoke out of both exhaust pipes (the thermostatic valve at the one exhaust manifold opened). It stumbled like crazy on take off, you had to pump and feather it. I knew right then he wasn't into touching carbs at all. He was like "it runs great when warm, but hey that's how cars were back then right?"

No. People went out, shoveled snow off them, started it at 5 below and instantly put in gear and went to work. They hit the gas at stop lights and it went.

A carb rebuild later and that car does run like new. $200 would have added so much value to that car.

I don't have a morale of the story or anything. I guess fix the little things, they make all the difference?!
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