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View Full Version : 500 or 600 cfm Edelbrock



blackhawk
08-21-2005, 03:46 AM
I bought a 600 cfm Edelbrock 1406 carb with electric choke (NAPA #735-3556) to replace the orginal Carter AFB on my '63 R1 GT Hawk. I got the 600 cfm model based on Jim Pepper's advice to Roger Bawdon in the January 2005 Studebaker Co-Operator column. Roger has a '64 Daytona with R1 engine and 4-spd, which is the same setup as I have in my hawk. I haven't installed the new carb yet and can still take it back if need be. This Edelbrock seems bigger than my stock Carter AFB. So, I am seeking other opinions. Which size is best for the R1, the 600 cfm or the 500 cfm?

The original air cleaner housing will not fit on the Edelbrock; the base is too small in diameter to fit the top of the new carb. All the local NAPA store had that fit it was a Mr. Gasket 14 inch air cleaner (# 735-4703). It has a knockout on the underside that theoretically will work for attaching the vent hose from the oil pan, with a bit of jerry-rigging. This new air cleaner is also unused and can be returned. Is this one okay? What are the rest of you using when you change over to a new Edelbrock carb?

Are there some differences that will involve a workaround, such as throttle rod hookup? How about the electric choke... is this any good?

Any advice will be greatly appreciated!

Dale

N8N
08-21-2005, 06:43 AM
Electric choke is fine, hook it to the OD wire in your wiring harness (with a fuse of course)

Throttle hookup will involve using some carefully selected washers and/or machining a little piece to fill the big hole in the linkage, because that's the one you want to use. There's a small hole that looks like it will work but it will be closer to the throttle shaft than stock making the gas pedal "touchy" (and Studes already have less pedal travel than most modern cars)

For the air cleaner, why not just buy a cheap aftermarket air cleaner with the right base, and retain the stock R1 lid and element? Any new AFB, Performer, etc. is going to have the larger opening and old filter housings will not fit, sorry. I think I know what air cleaner you're talking about (in fact I am running one on my '55 coupe right now) but if you have a correct R1 lid in good condition a) it's a fairly valuable piece and b) it'll be somewhat quieter than an open element when you stomp on it. I guess what it comes down to is do you like a refined, quiet ride or are you a fan of the "giant sucking sound?" <G>

good luck,

nate

--
55 Commander Starlight
62 Daytona hardtop
http://home.comcast.net/~njnagel

Dan White
08-21-2005, 07:51 AM
I have been running a new style 625 cfm Carter AFB w/ electric choke (Same as Edelbrock) on my R1 Hawk for several years now (replacing a Holley the previous owner had installed) and it runs just fine and has plenty of spunk if I want to get on it. Some say this may be too big but it seems to work without any problems. I did adjust it when I got it but have never messed with changing the stock rods etc that it came with. I am using an aftermarket air cleaner, since you are correct the old ones do not fit. There are plenty of styles to choose from or as Nate said just use the base off a new one and your original top.

Dan White
64 R1 GT
64 R2 GT

N8N
08-21-2005, 07:59 AM
I forgot to mention, you will want about a 1/2" spacer or else cut off the bottom of the throttle linkage to clear the manifold. There's extra stuff down there for a GM tranny throttle pressure linkage. Personally I'd run the spacer unless you have a hood clearance problem. Jeff R. has recommended a Mr. Gasket part that's basically a stack of gaskets alternating with thin metal plates, seems like a good idea (gives a little heat insulation as well as sealing and spacing)

good luck

nate

--
55 Commander Starlight
62 Daytona hardtop
http://home.comcast.net/~njnagel

blackhawk
08-21-2005, 01:42 PM
quote:Originally posted by Dan White

I have been running a new style 625 cfm Carter AFB w/ electric choke (Same as Edelbrock) on my R1 Hawk for several years now (replacing a Holley the previous owner had installed) and it runs just fine and has plenty of spunk if I want to get on it. Some say this may be too big but it seems to work without any problems. I did adjust it when I got it but have never messed with changing the stock rods etc that it came with. I am using an aftermarket air cleaner, since you are correct the old ones do not fit. There are plenty of styles to choose from or as Nate said just use the base off a new one and your original top.

Dan White
64 R1 GT
64 R2 GT


Thanks Dan. The reason I ask (in addition to the Edelbrock being larger than my original AFB) is that it sounds like other threads have leaned toward using the 500 cfm. Take for example the following post by Casey with reply by Mike Van Veghten:

Casey
Posted - 08/17/2005 : 4:05:14 PM
I put a new 500 cfm Edlebrock on a rebuilt (stock) 289. Works
great. This engine resides in my Lark type.
My Hawk and Champ truck both have 289s with oversize pistons
(.040 & .080 respectively), way oversize valves (R3 basically)
and R3 headers. I've struggled with old AFBs on both these
vehicles and now I just want to buy new and get it over with.
Should I go with the 600 cfm or 500 cfm Edlebrock? -- thanks

Mike Van Veghten
Posted - 08/17/2005 : 5:15:39 PM
Casey,
The 500 CFM.
Unless your combination has about 150% volumetric efficincy
and revs to 7000rpm, the 500 will give the best of everything.

It sounds like Casey's engine is a stock 289 and not an R1. The displacement is the same; do the differences in the R1 over the stock 289 warrant using the 600 cfm over the 500 cfm model? Your successful installation of a 625 cfm seems to indicate this is the case.

Dale

N8N
08-21-2005, 01:45 PM
The extra RPM capability of the R1 may warrant using a larger carb. The stock 289 cam completely runs out of beans somewhere around 5200 RPM so the extra airflow capability is totally wasted.

nate

--
55 Commander Starlight
62 Daytona hardtop
http://home.comcast.net/~njnagel

blackhawk
08-21-2005, 01:54 PM
quote:Originally posted by N8N

Electric choke is fine, hook it to the OD wire in your wiring harness (with a fuse of course)

Throttle hookup will involve using some carefully selected washers and/or machining a little piece to fill the big hole in the linkage, because that's the one you want to use. There's a small hole that looks like it will work but it will be closer to the throttle shaft than stock making the gas pedal "touchy" (and Studes already have less pedal travel than most modern cars)

For the air cleaner, why not just buy a cheap aftermarket air cleaner with the right base, and retain the stock R1 lid and element? Any new AFB, Performer, etc. is going to have the larger opening and old filter housings will not fit, sorry. I think I know what air cleaner you're talking about (in fact I am running one on my '55 coupe right now) but if you have a correct R1 lid in good condition a) it's a fairly valuable piece and b) it'll be somewhat quieter than an open element when you stomp on it. I guess what it comes down to is do you like a refined, quiet ride or are you a fan of the "giant sucking sound?" <G>

good luck,

nate

--
55 Commander Starlight
62 Daytona hardtop
http://home.comcast.net/~njnagel
Thanks Nate. sometimes I overlook the obvious. I do have the stock lid (I didn't know it was "a fairly valuable piece") and it certainly is heavier construction and nicer looking than the tinny Mr. Gasket one. I really do not want the giant sucking sound, so the partially enclosed filter option is the best for me and, besides, I would like to retain the look of the original. Thanks too for the tips on the throttle linkage. That will save me some time. I'll check hood clearance for a spacer, although I probably will just grind off the part of the arm that hits the manifold. I live in a cold climate (interior Alaska) and have always tried to keep the spacers to a minimum on purpose to get some heat to the carb. I don't run my Hawk during the winter cold so this is not a big deal for this car, but even our summers temps are not so high that too much carb heat will be a problem.

Dale

Dan White
08-21-2005, 01:57 PM
Nate is right you will need the spacer. I forgot about that. I got one from Summit Racing. The throttle linkage though is pure stock, bolted right up. I only wished I had done it before instead of putting up with the Holley all that time.

Dan White
64 R1 GT
64 R2 GT

blackhawk
08-21-2005, 02:03 PM
quote:Originally posted by N8N

The extra RPM capability of the R1 may warrant using a larger carb. The stock 289 cam completely runs out of beans somewhere around 5200 RPM so the extra airflow capability is totally wasted.

nate

--
55 Commander Starlight
62 Daytona hardtop
http://home.comcast.net/~njnagel
Well, I never wrap mine over 5200 rpm. It is willing but I see no point in subjecting it to the extra wear of the high revs. I don't think I have ever run it over 4,500 rpm and usually don't wrap it that high. I remember reading somewhere long ago that engine wear goes up exponentially with the rpms. Anyway, if high revs is the only reason for choosing a 600 cfm over a 500 cfm Edelbrock, I probably should opt for the 500. It probably will get better gas mileage. This is sort of a non-consideration with this car; it is not set up for economy (obviously). But with it needing hi-test gas and the price of gas being what it is, cost IS starting to be a consideration.

Dale

blackhawk
08-21-2005, 02:05 PM
I have to go to work. Thanks for the advice guys. I will check again when I get home this evening.

Dale