Hello all, Got a BBC dyno at 525hp with dual 650 edelbrock carbs in progressive set up. timing is at 37 degrees of total advance. In my 48 coupe with a turbo 400 and 325 rear gears. This thing runs very strong and I love it. One BIG issue. Cannot do a burnout!!! Standing start smash the throttle it sounds like it is stumbling then goes. If I step on it fast but gradual it goes like hell and turnes the tires as it moves. Kick into passing it flies. Standing start full smash throttle is the only issue. too much fuel? Acc pump? Give me some ideas. Gary
those rear gears, plus the high first gear ratio of the th400 arent going to help much with the take off. does it have a stall converter?
Sounds like an accelerator pump problem in the carb. I don't have any multi-carb experience but I've had the same problem with both Holley and Quadrajet carbs and both times it has turned out to be the accelerator pump. Once the linkage was in the wrong place and the other the accelerator pump piston was leaking
Sounds like it may not be getting enough fuel for a burnout. If the accel. pump linkage is in the center hole, try moving them to the top and reset the carbs. That should give it a better initial shot. Also with a big block it may need a slightly longer step up spring unless they already have the longer ones in them.
just put a 6-71 between the carbs and the motor, it'll be fine (it's not a problem of too much fuel, it's a problem of too much air, which moves too slowly for the carbs to draw fuel to mix with the air...playing with the accelerator pumps and getting more initial timing might help)
Roots would be great but not yet. Forgot to mention it is a roller motor with about 8 hg of vacuum at idle. IMO radical cam, only .550 lift but rad. idle.
I will try the timing first and move to the pumps if too much fuel is not the issue. So the stumble, almost sounds like a rev limiter, is in your opinion too much air if not timing?
what ignition?[sounds like rev limiter]>>>not enough spark at hit of throttle or lean...also look at possible that running progressive carbs[why/]the carb that is not working is loosing 'prime' in the accel&other circuits causing lean out from that carb
I ran dual quads on my 468", however, my linkage was running one to one. It seems the front cylinders run lean with progressive. My buddy switched from progressive to one to one when he saw my set up. His temp dropped 15 degrees. With the Edelbrock manifold, he just installed carb spacers and it really woke the bbc up. Now, he lights em up at will.
I have an MSD/no rev limiter.8.5 mm pro wires with an MSD coil... So no one likes progressive. This is what Edelbrock recommended, but I can play with. I can change that. Timimg did nothing. I will change either the pumps or the linkage tomorrow. One at a time.The rear tire is 28.5 " dia.
I know mines a totally differant animal with a sbc, 4:10 rear and a M-22 trans with a 29 in tire but I have to agree. Even with the small block , setting it up progressive really doesn't work that well. Running them together will give you instant response so even with the automatic and taller gears it should fry the tires.
Move that pump linkage up to the top hole like RR said, it'll give it more of a shot on the hit and I'm also running one to one on my setup.
Are you talking Edelbrock/Carter AVS Carbs? They have an air valve secondary set up. Can't you adjust the Air Valve so it opens slower and not cause the bog. Just like QJET,s Air Valve.
The air valve in those things is just a piece of metal in the secondaries, it's not an AVS with a plate on top like the old Carters that Mopars used in the early 70s. When I suggested messing with the timing, I meant to change the distributor timing curve so it starts out with more timing and has it all in by 2500. What does the timing curve look like? Did you do the basics like set the float levels on the carbs? and watch the squirters to make sure they're working right? is the idle set rich enough? Progressive linkage should not affect how it works when you mash the throttle down, both carbs should open right away. The situation where it's not working right is about the only one where it doesn't matter if it's progressive linkage or not!
+1 on that. I run 2x4's on my 302 in my car and even when it had 2.79 gears, it would light the tires from a stop. I converted it to progressive in an attempt to get better mileage and it was hard to start, wouldn't idle and was a dog. I siwtched back and all was good again.
Like a lot of guys have said, more squirter. Sounds like a lean bog to me. PS You should be able to adjust your carbs for a bigger shot from the accelerator pump. Let us know if you figure out a solution, it might help the next guy.
Up in smoke baby!!!! I love it!! Moved the acc pump to get more fuel as suggested and I am burnin those T/A Radials like godd hot rodder should. Runs on the road much better also when hitting it. Only thought I was good before. Now I will be trying the one to one on the linkage. Thanks all for the support. Ahhhhh the smell of rubber Gary
Thank you very much for posting your solution. I find it very frustrating when everyone offers advise here and we never hear if it helped or not. Glad to hear you're boiling the hides now. Most bogs I've found (I'm the carb guy among my Friends, not an expert just better at it than them), are lean bogs. Guys get all scared when their new carb bogs their motor and instantly they think it's getting too much gas. Now how about a picture of the motor?????
Great to hear you got it figured out. Sadly,,most guys that go with dual carbs on a Ram can't hardly get it right and they give up,,or even worse,,they think it is right and it is actually a dog. When the engine is working correctly with a tunnel ram,,it might just scare the hell out of you. By the way,,mine is on a Mopar! Tommy I just noticed,,you didn't mention what intake,,I just assumed a tunnel ram,,,sorry.
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