I've read as many archived messages as possible and I give up. I had a holley 600 and have now switched to an Edelbrock 500. There are several reasons why I did this . One is that I live at around 5500 feet and I thought I was over carbed. The Holley always smelled of gas and was a dog off the line. I've tried several timing positions, jetted it down, you name it. Now the edelbrock is in and running. It launches great but is lame after that. This is out of the box and minor tuning. It pulls nice with part throttle but, sucks at WOT. I just don't know if it's air or fuel that it sucking that makes it suck...too rich too lean. I was set to tune it for altitude but now I think it might need to be richened up??? Any thoughts would be appreciated. I did something bad and changed two things at once by adding a 1" 4 hole plastic spacer. Do you think this is all I needed on with the holley? Here is what I know about my motor... It is an 89 302 gt40 heads and a supposed cam. My initial timing is 19 degrees so that might mean there is some kind of cam. Headman headers, 2 1/4" exhaust, MSD 6al, and duraspark II distributor. Any way, The edelbrock makes it seem like a normal car but after the first 25 feet forget about mentionable acceleration. I'm going to try the holley on the 1" spacer too but in the mean time will take whatever insight someone might have from experience or otherwise. Thank, JC
At 5500 feet You need to run smaller jets than at sea level. I would suggest a Holley jetted for your elevation. You can coll Holley and ask which jets you should run. You can also ask if the 600 cfm carb is too big - my bet is that it isn't.
That's what I'm thinking The Holley had been jetted from 64 to 60 on the primary. The stock specs were 64 but actually there were 65's in it when I opened it. The point is the holly was always slow on the launch no matter what jets it had and it stinks of gas. The Edelbrock doesn’t and it is snappy off the line, but doesn't set you back in your seat from part to full throttle... it's as if I'm adding allot more air and fuel or just air for a small amount of acceleration. Is that because it's lean? At 90 ish MPH it was still pulling and didn't sputter out... maybe the 500 Edelbrock needs jetted to altitude first? Why is the Edelbrock so much faster off the line even though I stay out of the secondaries? Because it's a smaller air horn and better signal. So, should I richen up the Edelbrock or lean it first? or just go back to the Holley but now with a one inch spacer? And a larger accelerator pump nozzle? Or 600 Edelbrock jetted down? Who else has made a similar switch, tell your story please? Thanks so far...
Sounds like your holley wasnt set up properly.Faulty power valve or incorrect.The PV operates off a vacuum reference.Floats set too high causing carb to be over rich all the time.Also due to the higher altitude. the vaporization point of the fuel drops from say 78 deg at sea level to say 60 deg at 5500 ft above sea level.So once the engine heats up it cooks the fuel off in the float bowls easier.Perhaps the source of the gas odor.As for the edelbrock carb it sounds like the enrichment circuit is not tuned properly.you have to change the rods in the carb.Its supposed to be very simple.the last time I worked with a carter afb style carb was when I had my 69 super bee many moons ago so I cant tell you much abpout them specifically.But the problems you describe corrolate to what I have told you.Hope it helps you.Good luck.
Thanks I already needlessly changed the power valve 6.5 I've tuned it every which way and didn't just jump into the 60 sized jets. Floats adjusted and I've tried every pump cam too. As for the Edelbrock, given my situation, would you go rich or lean on the rods? Originally I was going to tune it per the manual, but in light of the lack of power I thought richer might be the choice route? My other issue is I don't know what’s in my motor. 19 degrees advance and 15 on the vacuum gauge. Non-stock cam or some other problem? Another symptom of the Edelbrock is it idles too high... no more adjustment,is it too lean? Keep it coming Thanks, JC
Sounds like you may be to rich on the secondary and lean on the primary. Edelbrock has a tech line and a tune-up kit for the carb. I forget the guy's name on the tech line, but he is a long time bracket racer and can help you out. The smaller carb increases the vacuum your engine is pulling at idle. I've played with jetting and sometimes in the situation you have, the opposite we think is true.. I'm running a 600 Holley on my hotrod (305 engine) and just hate it. Good throttle response, but no MPG and it's burning clean. I ran a Q-Jet before at it was great on MPG, but stumbled an excel. I'm gonna try a AFB next or the Edelbrock Q-jet.
Its possible your holley carb has a warped metering block.Its also possible that it has a warped throttle base plate.Have you checked for any vacuum leaks???I know too late you allready swapped it out.You can check the carb base with a straight edge and see if its warped.3 Biggest mistakes poeple make with holley carbs. #1. Cranking down the hold down nuts/bolts.Warpes the base plate. #2.Running the thick base gasket instead of the thin one.(Warpes base plates) #3.Mixing gaskets.If you run a spacer with your holley,dont use a thick gasket and a thin one,use 2 thin ones.)one between the carb and spacer and one at the intake/spacer.Mixing them will cause warpage.Especially if you crank the hold down nuts down tight. The thick gasket has alot of give to it and causes people to crank down the nuts till that mushy feeling in the wrench is gone.Hence the warpage.If you do use the thick gaskets just calibrate your hand before you overtighten the nuts.Good luck.
I’ll call the tech line. As for the Holley, it appears to be warped. It was only bolted to a ¼” gasket no spacer… so if I put a spacer on it now, it would probably have a serious vacuum leak. I put a straight edge parallel and it looked square but from bolt to bolt diagonal it has gaps. Thanks. JC P.S. So why does a vacum leak make it smell rich instead of burning lean? Is it because less air is going where it needs to go?
Yes to question 1.Most likely reason is that it was warped and so out of whack(lean) tune wise becuase of the warp(mixture adustments and so on)that it allways stunk of gas. Yes to question 2.It can be tricky though,talk to a good machinest.and see what it will cost you.You may be able to replace the base plate for the same money.Good Luck.
This might be useless info to you, but are you sure your ignition system is 100% straight? Good cap, rotor, wires, plugs... Timing is right, distributor isn't sloppy? When I got my Mav, it ran terribly rich. I had a hell of a time getting it home, flooded it out, had to stop several times. Couldn't go over 55 mph and my trip up I-55 that should have been 3 hours took 6. I was told when I got the keys that the carb needed to be rebuilt. It has an Edelbrook 600 which I'm very familiar with so it didn't intimidate me. But it intimidated the previous owner and he was clearly sick of messing with it. I did rebuild the carb and it certainly needed it, but that didn't fix it. I changed the jets, rods, springs several times chasing carb ghosts and never quite got it. The best I could do was get it to run half-decently at 3/4 throttle up to almost 5,000 before the black smoke and the choking. I adjusted the timing up and down to no avail, and finally started looking for a buildable carb on Ebay when I decided to change the distributor. Once I did that, the difference was astounding. You'd think I had installed a blower rather than a distributor. Anyway, the point of this characteristically long-ass post of mine: Make sure your ignition system is ok before you spend too much more time and money on your carb, 'cause I swear my problem looked every bit like a carb issue until I changed the ignition system.
You might be able to straighten it without machining it. A good machine shop could do that too. It would have the advantage of aligning the throttle bores.
I took a file to my base plate and with figure 8's a planed the thing flat again. Now it's back on the car. It seems that with the edelbrock I can punch the gas and let off no problem but when I do that with the holley it dies. And when I walk in the garage I can tell the holley is back because I smell gas (no leaks)? Any way, I'll probably fatten up the edelbrock and keep it.
Just go down to the post office and get one of those pre-paid mailer boxes and mail that Holley to me. I have a Maverick that needs a good carb. I think the cost of the boxes and postage is $8 or $9. I will pay you for the postage. Rev. Paul Stephens 6522 51 Ave. S Seattle, WA. 98118
There is a potential trade on craigs list for a 750 double pumper.I'll have a daily driver carb and a drag carb. I'll cut my losses and try something completely different. Either way I have two carbs... I'm so stingy. Thanks for offering
