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Karl
01-28-2007, 10:31 PM
Does any one know what the stock metering rods and jet were on tne R2 carbs. Think I saw a thread on it . But did not write them down[:I].Looking for a base line. My two apear to have .098 jets in them. The AFR is out of site.(rich) at WOT.Changed the metering rods and got the part throttle cruise in line.13.5 - 13.7 afr.Thanks in advance.:D

63 Twin Supercharged Avanti
64 Avanti R3w/NOS
88LSC Avanti 350 Supercharged w/NOS

Karl
01-29-2007, 01:26 AM
got one of my carb tags out. 3726S

63 Twin Supercharged Avanti
64 Avanti R3w/NOS
88LSC Avanti 350 Supercharged w/NOS

Mike
01-29-2007, 05:56 AM
A "3725S" AFB carb is listed for "64V" R2's in the Jet Thrust parts book supplement. It's sometimes refered to as the "late R2 carb". A '63 R2 used 3588S. Avanti R2's used 3507S, 3588S (mine), or 3725S. The # is on a tag screwed to the top rear of the carb, (or lost!) ; and should also be stamped on the right front mounting ear.

A year or so ago, I researched jet and rod sizes for my 3588S; with an eye to leaning the primarys. These are notes I saved. If you have a 3725S, it's different. I'll look for stock sizes for it. There is some good information at VS57.com, under "Tech Ref". There's also a chart of jet and rod sizes for the old style part #'s, in "Avanti Magazine" Fall/Winter 2003, issue 124.

The standard R2 primary jets from Stude, for 3507S and 3588S were .1015, with .076 X .049 rods. First step lean was the same jet with .077 X .0515 rods. Secondary jets were .089 .

The original primary jets and rods, from Stude, were larger than are
available now. You can subtract rod cross sectional areas from jet area; and find combinations of currently available jets and rods that give similar totals, richer, or leaner. A programmable calculator would save time. As far as I know, the new jets fit. The top of the rods may be different and require modification to the lever they hang from. Summit Racing has handy charts of available jets and rods, and their sizes.

Jets:
http://store.summitracing.com/egnsearch.asp?N=4294925239+4294839063+4294920710+400065+115&Ne=110905&NeXID=110905 .

Metering Rods:
http://store.summitracing.com/egnsearch.asp?N=4294925239+4294839063+4294814878+4294865278+115&Ne=105315&NeXID=105315 .


For one step leaner than stock, on my R2, I figured EDL-1426, .095 jets;
with EDL-1449, .070 X .037 rods.

For two steps leaner, same jets, with EDL-1455, .073 X .042 rods. Rods can
be changed on the car, without removing the airhorn.

Five bowl/airhorn gaskets are EDL-1499.

Step up spring assortment is EDL-1464.

Marine accelerator pump, with seal for R2, is EDL- 1471; $22.69.

Inlet needle and seat, .110 size, is EDL-1466.

Mike M.

Mike
01-29-2007, 12:25 PM
3725S AFB
Primary Jets: Carter #120-224, .0995". Rods: 16-287, .078/.045"; with 16-289 and 16-290U for one and two steps leaner. Secondary Jets: 120-166, .0935".

Thanks to "PaceRacer50" for correcting the rod part#, (my typo); and providing the actual rod size.

Mike M.

Last edited by Mike M on Wed Jan 31, 2007 3:30 am; edited 1 time in total

Karl
01-31-2007, 06:14 AM
THANKS GUYS:D

63 Twin Supercharged Avanti
64 Avanti R3w/NOS
88LSC Avanti 350 Supercharged w/NOS

Karl
01-31-2007, 04:51 PM
All this info on the R2 carb was great. What about the R4 set up??From what I am seeing in my own set up . Is the stock R2 set up is rich. But when you times it by two . it's out of site rich. I've leaned this thing down by .015 in both carbs.And its still rich. But getting there.gone from 10.9 to 12.2 afr at WOT..099 to .086 main jets. Thank again .

63 Twin Supercharged Avanti
64 Avanti R3w/NOS
88LSC Avanti 350 Supercharged w/NOS

Mike
02-01-2007, 06:54 AM
Something is wrong. If my figures are right, and your carb is a 3725S, the .089 jets with .073/.052 rods that you tried would be very, (dangerously?), lean. It could be a high float level and flooding is giving you a rich mixture. What is your fuel pressure?
Using the method I mentioned above, I come up with a .098 primary jet, with a .075/.042 rod as close to original.
I would buy .095 jets and .073/.037 rods, for a little leaner; and .075/.047 rods, for leaner still.
I would stick with the .0935 secondary jets, if I had them. Summit has .092 and .095 available.
Mike M.

Mike
02-03-2007, 06:02 AM
I didn't pick up on the dual, pressurised, carbs! Maybe the R4 jetting would be of some use. It's available on Bob Johnstone's "Tech Tips" at:
http://www.potomacsdc.org/ . Look under "R3/R4 Data", "Pics/Data Sheets". Page 8 is a nice list of R3 & R4 rod and jet part#'s and sizes.
Consider how float level is set; and how one or two gaskets affect fuel level in the bowl. Do you have the sealed version of the 3725S?
It's important that fuel pressure track with SC boost, (not the same as manifold pressure). Too high fuel pressure at low boost levels will flood the carb; especially with the big float valves.
Paradise Wheels has inexpensive 0 to 15 lb gauges, $10 each. The vac pressure gauge at: http://www.actron.com/product_detail.php?pid=16176 , is available under "Parts and Acc." for under $10 - much less than the whole Sears test kit. It's safer to mount them in a bracket outside the car for testing; especially the fuel pressure gauge! Paxton McCulloch test procedures are outlined at VS57.com.
Mike M.

Karl
02-03-2007, 06:42 PM
The fuel pressure does track the s/c 1 lb of boost at 1000rpm - 10lbs boost at 6000rpm. less than 1/2 pound diffenence above and below carbs. fuel press is always 5-6 pounds more.Fuel pressure boost come from my left s/c which feeds ths rear carb. I use it as the primary unit the front comes in about 4000 rpm.
Thanks for the tip at Bob Johnstones site.:D

63 Twin Supercharged Avanti
64 Avanti R3w/NOS
88LSC Avanti 350 Supercharged w/NOS

Karl
02-09-2007, 05:11 PM
Hi guys:Got a set of .077 main jets. AFR is now up to 12.6.:DPower is up notably.:DGoing to try a set of metering rods One step leaner.About .004. No testing today as its raining.:(

63 Twin Supercharged Avanti
64 Avanti R3w/NOS
88LSC Avanti 350 Supercharged w/NOS

ivorydan
02-10-2007, 08:49 AM
Five months ago I was talking with Ron Hewitt of Daytona Parts. Ron said that after Avanti Parts bought out SASCO, they gave him copies of all the final Studebaker revised Carter rod and jet applications. He also had similar final factory change information from Carter. He said Bob Palma had asked him to do an article for Turning Wheels about it but he hadn't yet had the time to do so.

I told Ron I was interested in leaning out the R1 Hawk 3589s to get better gas mileage. Ron said don't do it. He said the gasoline we're putting in these engines today is much different from the gas they were designed to use. He said modern gas is equivalent to leaning out the engine one or two steps already.

Consequently, I kept the stock 120-159 (.089") jets and 16-99 (.069"/.058") rods.

Karl
02-10-2007, 06:52 PM
With out having a AFR meter . You just dont know.I driven this car for thirty years. I didn't beleve how far off my car was.It was ok at idle and cruise but nuts rich at WOT.I went down .021 / .098 to .077 on the main jets to bring them inline. But I am working with two carbs not one. I

63 Twin Supercharged Avanti
64 Avanti R3w/NOS
88LSC Avanti 350 Supercharged w/NOS

Karl
02-11-2007, 09:56 PM
No rain today.:DTried out some different metering rods .070 / .056
Cruise AFR went to 13.6 down from 14:)
WOT went to 12.9 up from 12.6 :DThen it went to 10.7. Lost a blower belt on the 3-4 shift at 6500.[:I]


63 Twin Supercharged Avanti
64 Avanti R3w/NOS
88LSC Avanti 350 Supercharged w/NOS