carb question

Do you have big valve heads? Dual exhaust (big size)? Headers?

The 600 would be my first choice... But the AVS has a neat feature in that you can adjust the secondary air valve and you could slow it up and probably do quite well with it... Jeff

"N8N" wrote...

no, sort of (stock, but '55 had an unusually large exhaust) and maybe (possible future plan...)

nate

Jeff Rice wrote:

Nate, you will like the AVS. I am replacing the almost new 500 on my Daytona with an AVS when I install the 4.10. I had an AVS from a 340 Mopar on it for a while but it was a tad too big and there are very few rods and jets available for it. They are different than the modern version. Seamless transition into the secondaries and like Jeff said, extremely easy to adjust to your liking. Studebaker George

600 which I believe is still over carbing the engine...

JT

N8N wrote:

I'd normally agree, but I'm not necessarily going to leave this stock forever and would like some room to grow (and it is an R1...) and the reason I am considering the AVS is I have been told by more than one MoPar guy that it's near impossible to go too big with an AVS, and that they adjust well to engines that are theoretically too small for the carb size, but would just like some confirmation that someone has used them on a Stude...

nate

Grumpy AuC> 600 which I believe is still over carbing the engine...

I'd stick with a 500. Properly tuned the transition from primary to secondary should be very smooth on any of the Edelbrocks. I run 600's on two engines beside the R2 Avanti, a stock 318 Mopar and a 350 Chevy. The 600's had to be leaned out considerably on both those engines for proper performance. Because the air valve won't allow the engine to take in any more air than it can use, and I don't think you would use all of the 600, the 500 might give better performance. If the engine can't draw enough to open the air valve all the way or demand is such that the opening only occurs at the top of the rpm range the smaller the better. The primaries would really affect your driveability at part throttle and cruise if the primaries are the same size, which I think the 500 and 600 are, either carb would perform the same at part throttle assuming proper jetting.

As a point of reference I believe the 302 Z28 Camaros used a 525 CFM Holley, my 69 GP 400 CID with a dialed-in 750 runs 14.20's and on an experiment with a 600 it ran 14.5 and I just threw the carb on with no tuning at all. Later I found out that same carb had a rod stuck in the down position which means it was running leaner than it should at WOT.

I'd be willing to swap the 600 off the 318 Duster for your 500 if you would like to experiment.

Ernie R

N8N wrote:

Well, I was talking with Dave Thibeault re: carb selection and he seemed to think that there was a slight but noticeable advantage to a

600 AFB when really wound out. Plus the 600s are cheaper than the 500s, and this is not going to be a daily driver. The whole reason I am asking the question, to be perfectly honest, is I have a chance to buy a reman 650 AVS for less than the price of a new 600 AFB, and it's got me scratching my head... I've always wanted to try an AVS on a Stude but don't want to end up with yet another paperweight carb... I've got several of those already.

nate

Big E wrote:

You could probably get your money back on ebay if the 650 wasn't to your liking. Standing offer on the 1406 Electric choke for 500 carb swap. Less than 2,000 miles on the carb a little oxidized on the outside because the car does more sitting than driving.

I say buy the AVS no matter what.

Ernie R N8N wrote:

1406 swap is tempting, but I don't actually have one in my possession. I do have an older 9000 series carter (625 I think?) on the engine now but I can't get it to idle right and it's jetted all wrong... I would just rejet it but the fact that I can't get it to lean out at idle makes me just want to buy a new carb and be done with it. I have to admit, I'm not used to working on these oldfangled carbs, I'm much more comfortable messing with Bosch CIS or similar :) (I bet that's a sentence that's not often seen in this newsgroup!)

nate

Big E wrote:

if I have done my research correctly, I believe if you have a parts AFB laying around just use the springs, hangers, cover plates etc. off an AFB and you can replace the 3-step rods of the AVS with the 2-step AFB rods which are still available. I believe that is what Edelbrock is doing with the new "Thunder Series." you'd have to download the new book off the edelbrock web site though as the part numbers have all changed. I think Jeff R. posted a link to a scan of an old Carter book if you still have a Carter strip kit, and I should have it saved on my hard drive somewhere as well.

nate

ooops, just realized that there are no hangers on an AFB, only pistons, springs, and rods. was thinking of a WCFB there for a second. rest of comment still stands.

nate

Nate... You obsess way WAY too much... You car will like either... (Especially with your Stone Clone 'prepped & tweaked' intake manifold)... I have bought and swapped carbs for Stude's just for the fun of it...and here you are worrying about one carb! Just buy the AVS and try it.. If it doesn't work out for you, clean it up and sell it for a profit and go with the 600... And to all those that follow the carb cfm rule to a "T"... Rules are generalities. You can make your combination work any number of different ways. I am running too big a carb (750AFB) on my yellow truck since 2001. 17mpg, beating the piss out of it, and it only hiccups when I floor it stone cold. Once it is warmed up it works just fine... Yeah, I had to put jets in it (and metering rods), but shoot... I would have done that with ANY engine I put together. That's the difference between making my engine perform to the max, and just bolting on parts. Reading plugs is getting to be a lost art (and HEI is hastening that, too). Jeff

Do you mean there is no change when the mixture screws are turned in? If so, you probably have a vacuum leak. These carbs are real simple. The problem I've seen most often is not the carb but the static timing is too low resulting in low idle. Then the idle is increased at the carburetor opening to compensate which opens the plates enough to make the carb think your cruising. And, if you hit it just right the distributor starts kicking in centrifugal advance and then the idle is all over the place.

Easy thing to check is that the rods are moving freely. Sometimes they get bent when the last person to have the carb apart tightens the top down without making sure the rods are centered in the jets.

Also make sure the sec> 1406 swap is tempting, but I don't actually have one in my possession.

Anyone who wants this AFB book (pdf) can e-mail me and I'll send it to them as a big attachment. It is THE bible for AFB carbs (Except R2 stuff) Jeff

screw the carb.. helping a guy put TBI on a 289 today.. were doing the electronic adjustments.. already heard it running once...

screwdriver to adjust, and that box is UNDER the front seat --Shiva--

exactly, one idle screw just barely starts going lean, the other one you can actually screw it all the way in without affecting the idle

probably but if so it is within the carb, because it's exhibited the same behavior on three different engines in two different cars.

I am just sick of messing with it... I did "kit" the carb recently and nothing jumped out at me as being amiss, and it's still acting exactly the same...

nate

Send it to me, and I'll post it as a downloadable file on NCSDC.com

Ray

Jeff Rice wrote:

Anyone who wants this AFB book (pdf) can e-mail me and I'll send it to them as a big attachment. It is THE bible for AFB carbs (Except R2 stuff) Jeff if I have done my research correctly, I believe if you have a parts AFB laying around just use the springs, hangers, cover plates etc. off an AFB and you can replace the 3-step rods of the AVS with the 2-step AFB rods which are still available. I believe that is what Edelbrock is doing with the new "Thunder Series." you'd have to download the new book off the edelbrock web site though as the part numbers have all changed. I think Jeff R. posted a link to a scan of an old Carter book if you still have a Carter strip kit, and I should have it saved on my hard drive somewhere as well.

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There's a point where "kit-ing" a carb is a waste of time and should be sent to a professional rebuilder such as National. The carb will come back and perform as to original specs with a guarantee...

JT