conventional wisdom for a 2.8 conversion calls for a 390 CFM Holley. I have buddies who swear by Edelbrock carbs and claim things like "If they don't work right out of the box, you can send them back" etc. I see that there is a 500 cfm (the smallest) 4 barrel Edelbrock that has a lot of interesting features and a manual choke. Does anyone have a comment or advice concerning the suitability of this carb for a 2.8 conversion
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Carburation
- Thread starter Thor 1211
- Start date
A comment on the carb design, but I have no idea of its suitability. Way back when, I bought a 390 to bolt onto my AMC 6, don't remember if it was a 232 or 258. Regardless, the 390 was a mess. One flat spot after another. The speedshop owner said it was jetted for small Chevy V8's. He took it back and gave me a Carter 410. Worked beautifully out of the box. A few years later, the 410 was bolted onto an AMC 360. Once again, absolutely no problems. It is a good design and is very flexible, but I would hesitate to say it is that flexible.
I do think a Carter 410 would work better than the 390. Finding one in good condition might be a problem.
Bill
Thanks Bill.
The only reason I make the inquiry is because Sven Pruitt in his book recommends the 390 with the aftermarket dual plane manifold and V6 Jose recommends it as the only way to go. I am assuming that the barrel set up and bolt down configurations are the same on the Edelbrock, but maybe the fitment requires further study. Also, I have a concern that a 500 cfm might be over-carburation with a 2.8 in pretty well stock state of tune otherwise.
The only reason I make the inquiry is because Sven Pruitt in his book recommends the 390 with the aftermarket dual plane manifold and V6 Jose recommends it as the only way to go. I am assuming that the barrel set up and bolt down configurations are the same on the Edelbrock, but maybe the fitment requires further study. Also, I have a concern that a 500 cfm might be over-carburation with a 2.8 in pretty well stock state of tune otherwise.
DanR
Diamond Level Sponsor
Thor, You refereed to Sven's Book.... His section of the Carburation is an excellent one.
Since obtaining His Book I refer to it reguarly. Helped me on the 390.
After installing and testing three (New) out of the box 390 Holley 4 bbl's on my Commodore Blue V6, I have come to the conclusion there is nothing wrong with the Carb's...
Timing was and is my major problem with the idle.... Lots of help comes for the Guys on this Forum... I might get it straight yet
DanR
P.S. The 500 I believe from all I've read is too much!
Since obtaining His Book I refer to it reguarly. Helped me on the 390.
After installing and testing three (New) out of the box 390 Holley 4 bbl's on my Commodore Blue V6, I have come to the conclusion there is nothing wrong with the Carb's...
Timing was and is my major problem with the idle.... Lots of help comes for the Guys on this Forum... I might get it straight yet
DanR
P.S. The 500 I believe from all I've read is too much!
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The brutal truth is that if you are looking for over 125 hp carburetion, the 390 is the only game in town. Maybe a pair of Holley-Webers. Fun fun fun. Does one of these buddies have an Edelbrock 500 laying around you could test?
EFI would be best (always is) but getting there would be a trip!
Bill
RootesRacer
Donation Time
I have seen DCOE to small bore 4bbl adapters, both in the single and twin configuration.
If the height is not too great, a single 45 DCOE will flow up to 400 CFM per carb with the right chokes.
Apples and oranges with regards to what CFM means on a 2bbl versus a 4bbl plus the differences in the suction pressure specifications but I am absolutely sure a pair of 45 DCOEs will out flow a 4160 and have a great deal more dimensions in tuneablity.
If the height is not too great, a single 45 DCOE will flow up to 400 CFM per carb with the right chokes.
Apples and oranges with regards to what CFM means on a 2bbl versus a 4bbl plus the differences in the suction pressure specifications but I am absolutely sure a pair of 45 DCOEs will out flow a 4160 and have a great deal more dimensions in tuneablity.
Could you put all that into the context of the original question? i.e. if 800 cfm of DCOE's would be fine, does that mean a 500 Edelbrock would not be too large?
Bill
MikeH
Diamond Level Sponsor
If 500 is too much, has anyone tried an Autolite 4100 4V with the 1.08 bore? This would put it at 480 CFM. The Autolite 4100 is probably one of the most reliable carbs ever built. There was a 1.06 bore made with 450 CFM, but they are probably hard to find. Info can be found at http://mustangtek.com.
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DanR
Diamond Level Sponsor
Thanks Mike for and excellent site.... Here is something I also found on their site that is interesting:
RPM and MPH Transmission Gear Ratio Calculator
Find out your RPM at cruising speed with or how much RPM the engine turns at any given speed.
Try it out - Mustangtek transmission ratio and shift point calculator
Simple way to get answers to all your questions
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RPM and MPH Transmission Gear Ratio Calculator
Find out your RPM at cruising speed with or how much RPM the engine turns at any given speed.
Try it out - Mustangtek transmission ratio and shift point calculator
Simple way to get answers to all your questions
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RootesRacer
Donation Time
Bill, you modify the effective CFMs on DCOEs by changing the chokes (venturies).
A single 45 DCOE would then have a range of about 175 or so to 400+ CFMs.
A pair would therefore be from around 350 to 800 CFMs.
When you talk about 4 1.08" chokes making 480CFMs, thats more or less the same as running 2X45 DCOEs with 29mm chokes (29mm chokes are considered tiny even for 40s).
If the 4150/60, 4100 or the Edelbrock had replaceable chokes with a range for 26 to 40mm, then they would be equally adaptable for 250 to 800CFM.
Personally, 500 CFM seems way too much for a 7000 RPM 171 CID engine. 390 CFM even sounds a bit much to me...
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Barry
Diamond Level Sponsor
Jarrid hit an important nail on the head.
An old (and accurate) rule of thumb for 4-barrel carburetors on naturally aspirated street engines is 2 CFM per HP.
A more or less stock Ford 2.8 V6 might make 125 HP = 250 CFM.
A moderately modified Ford 2.8 V6 might make 150 HP = 300 CFM.
A highly modified Ford 2.8 V6 might make 175 HP = 350 CFM.
Anything less than a full race (not street) Ford 2.8 V6 simply does not need 400 CFM.
A carburetor that is too big does NOT make more power, but it does reduce throttle response / driveability and make tuning the carburetor more difficult.
Despite being too big, the Holley 390 is the only readily available game in town, so .....
Just my opinion, YMMV.
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crs
Gold Level Sponsor
Barry quoted "Jarrid hit an important nail on the head." +1
Best readily available option.
The ONLY issue that I have had with my 390 cfm Holley is that the installing mechanic did not properly adjust the slow speed idle (but then he was a track drag race guy and liked a very fast idle to avoid bogging down off the line).
By following the Holley instructions, I was able to get the slow idle down where it is tractable and the high lift cam lope is tolerable.
Best readily available option.
The ONLY issue that I have had with my 390 cfm Holley is that the installing mechanic did not properly adjust the slow speed idle (but then he was a track drag race guy and liked a very fast idle to avoid bogging down off the line).
By following the Holley instructions, I was able to get the slow idle down where it is tractable and the high lift cam lope is tolerable.
Fordtootsie
Donation Time
carb size
I get a kick out of reading all the carb info.
I just through I would throw in by 2 cents. So here it is!!!
Assume perfect cam, no friction looses, 100 % eff no turbo or ram effect and 100% eff on everything....
a 171 cu in engine will ingest 247 cu ft per min at 5000 rev per min if I did the math correct.
John in Colorado
I get a kick out of reading all the carb info.
I just through I would throw in by 2 cents. So here it is!!!
Assume perfect cam, no friction looses, 100 % eff no turbo or ram effect and 100% eff on everything....
a 171 cu in engine will ingest 247 cu ft per min at 5000 rev per min if I did the math correct.
John in Colorado
crs
Gold Level Sponsor
Link to Holley Installation doc for 390 cfm carb, from Holley web site:
Carb overview:
https://www.holley.com/products/fuel_systems/carburetors/classic_holley/parts/0-8007
REPLACEMENT CARBURETOR - MODEL 4160
P/N 0-8007
Installation and adjustment Instructions:
http://documents.holley.com/199r8108-2rev4.pdf
My engine drove OK, but I was not satisfied with either the fast or slow idle, so I printed this doc and followed the tuning instructions for fast and slow idle and all was well. This was 3-4 years ago and it has worked well since.
I am not a mechanic and the above is all that I know about the M4160.
Carb overview:
https://www.holley.com/products/fuel_systems/carburetors/classic_holley/parts/0-8007
REPLACEMENT CARBURETOR - MODEL 4160
P/N 0-8007
Installation and adjustment Instructions:
http://documents.holley.com/199r8108-2rev4.pdf
My engine drove OK, but I was not satisfied with either the fast or slow idle, so I printed this doc and followed the tuning instructions for fast and slow idle and all was well. This was 3-4 years ago and it has worked well since.
I am not a mechanic and the above is all that I know about the M4160.
Barry
Diamond Level Sponsor
John,
Absolutely correct @ 100% volumetric efficiency, but a good "performance" street engine probably has a VE of no more than 90% which changes the 247 CFM to 222 CFM.
Just my opinion, YMMV.
Fordtootsie
Donation Time
Yep !!
Makes a Holley 390 cfm a little big.
John in Colorado
Makes a Holley 390 cfm a little big.
John in Colorado
Barry
Diamond Level Sponsor
Definitely too big, but the only readily available 4-barrel that is even close to the right size.
A 410 Carter in good condition would probably be a better choice, but good luck finding one.
FWIW, the 200 gross HP (probably about 175 net HP) 289 in the Mk-II Tiger used a 500 CFM Holley 2-barrel that worked very well. The 500 CFM rating is misleading; when tested the same way as a 4-barrel, the 500 CFM 2-barrel only flows about 350 CFM. The "mucho macho hot rod" factor would be missing, but it would probably work well for a "street performance" Ford 2.8 V6.
Just my opinion, YMMV.
A 410 Carter in good condition would probably be a better choice, but good luck finding one.
FWIW, the 200 gross HP (probably about 175 net HP) 289 in the Mk-II Tiger used a 500 CFM Holley 2-barrel that worked very well. The 500 CFM rating is misleading; when tested the same way as a 4-barrel, the 500 CFM 2-barrel only flows about 350 CFM. The "mucho macho hot rod" factor would be missing, but it would probably work well for a "street performance" Ford 2.8 V6.
Just my opinion, YMMV.
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todd reid
Gold Level Sponsor
I have read somewhere (maybe here) that across the pond in England, the popular carb upgrade is to replace the stock two barrel (where the barrels open in progression) with one where the barrels open simultaneously. If the Holley is oversized, maybe they are on to something - especially for a basically stock engine.
TR
TR