I'm thinking I've got too much carburetor. It's a Holley 650DP, sitting atop an Edelbrock Performer, on a fresh 302 with a Comp Cams 270H. I also have BlackJack headers, a 2100 rpm converter, and 3.55 gears/limited slip (I'm still fighting with the rear, btw). I put a kit in the carb and it seems to be working well- plugs are dinner roll brown in color, and the engine runs good, but I have no power at the get-go. I can't remember which power valve or squirters I put in. I was following the instructions in the trick kit, and guidelines I'd downloaded from a great carb site that was posted here a couple of years ago. First question: is the 650 too big?

Next question is: what should I replace it with? I read the archived thread about this and am leaning toward the Autolite 4100. There are a few on ebay- would any 4100 from any year work (or be modified to work)? I am also looking at Holley 4150s. Same deal: lots of different models to choose from and I'm a little bewildered. I'm thinking vacuum secondaries and an electric choke if I can find one so equipped. Do I want another double pumper?

Last thing: what questions should I ask before buying a used carb?

Thanks for the reply.

------------------
mike r
racing is real
everything else is just a game.
81 capri-7.51 @89mph 1/8
1.54 60 ft.

http://www.angelfire.com/ny5/billswebsite/pg06.html

quote:

---

Originally posted by project66:
3.55 gears/limited slip (I'm still fighting with the rear, btw).

---

Those were Richmond gears that are real noisy, right?

For your carb, I don't think it's too big either. I think you just need to work on adjusting your accelerator pump. Are you totally sure there are no vacuum leaks? Nothing kills response like a vacuum leak.

If you do look at used carbs, take a close look at the throttle shaft/throttle shaft bore fit. Once this gets sloppy you'll never have a good running carb.

I like the 4100 series too, and I've been thinking of buying one to experiment with, myself. You can make a 2100 run beautifully, and I'm sure the 4100 is the same.

I'll do some fidgeting with the accelerator pumps and go back and figure out what squirters I put in. I'm assuming that I should start with the primary pump? Other thing I know about my set up is that I get a lot of advance and I get it fast. Don't remember specifics- besides starting it every weekend, I haven't played with the car in over a year. Will have some questions about distributor curves soon. I've got a Duraspark with a MSD box, btw.

I'm really not sure whether I have a vacuum leak. Had a big one initially that was a real pain to find. After replacing the intake gasket three times (got real good at it), I found that one of the threaded holes at the back of the intake went all the way through. It was a mounting hole for the carb's return spring that I was no longer using. Doh! I stuck a bolt in it and the car would actually go.

The rear- you're memory amazes me, Steve. I had the Richmonds replaced with new, US gears and got the exact same noise (big growl at speed when I lift off the accelerator). This was about the time that the car began its long sit. Gonna see how much money I have left after Christmas and either take the chunk to "the rear end guy" ($$$) in town, or go to the junk yard and pull one with 2.79s.

Looks to be a nice weekend here. Hope to be back under the hood and working some of this out. Thanks again for the suggestions.

As to which carb you would replace yours with the choice is up to you, both af the carbs you are thinknig about are good, it's just what do you want. I do agree with the 4150 Holley over teh 4160, I have had issues with the 4160 series in the past and will not use them.

If you cannot get your current carb to work out and would like to try another carb before you purchase one to ensure that is the problem my engine is apart right now and my 750 Edel is sitting on the shelf, I can rejet it and we could put it on you car one weekend and see if it solves the problem, I know the 750 is a little big for your 302, but it is a vacuum secondary carb and would work for a test.

Thanks for the shout. The car actually goes pretty good unless I get deep into the peddle. It will not spin the tires though. It needs to be able to do that Thank you for offering the carb- might take you up on it if I can't adjust this out. Can I adjust in the driveway or does it need to be tested under a load?

Didn't get anything done on it this weekend: too much football on Saturday and yesterday was just too nice.

How long have you had the Mach 1? I know where there is another 69 that has been sitting on 4 flats for as long as I can remember.

Have you had any experience with Zimmer? Seems like a real grouch but he's the guy that 9 out of 10 recommend for gears. The other guy is on your side of the river and was the one who took two shots at mine.

Thanks again for the reply. Missed you guys and plan to hang out around here again for a while.

The carb really needs to be tested under load, just a quick hit from idle will tell you if the bog is gone, I usually do it in front of the house just smoking the tires a little. Since it only bogs when you go WOT I would play with the rear pump and see what happens. If you don't have any luck maybe we can get together one weekend and see if we can get it straight.

We have had our mach1 for about 7 years, might have to get you to tell me, or show me where the one is setting on 4 flats.

Earl Zimmer is "The Man" in tne Baton Rouge area for gear work, and yes he can be a grouch. He is the type of fellow that you tell him what you want and then leave it to him. I have not talked to him in about 25 years, so i cannot realy say that I know him. I have talked to his son in the last year or so, and he will tell you that his dad would rather be in the back working on gears than dealing with people, too many try to tell him how to do his job.