|
Sponsored Links (Register now to hide all advertisements) |
|
|
Thread Tools | Display Modes |
06-09-2018, 12:36 PM | #1 |
Senior Member
Join Date: May 2010
Location: Snohomish,WA
Posts: 1,030
|
8BA or 8CM and Holley 390 cfm vs other combinations
After reading the recent loadamatic distributor threads concerning the Holley 390 cfm and the other thread on the 2gc carb info I would like some input on experience with the Holley 390 and various other distributor options. I have a 52 Mercury flathead with EAC on the heads that I plan on installing in a 36. I have the single and dual carb intakes , all 3 bolt , and a Edelbrock 4 barrel intake too. I am leaning towards the 4 barrel with a 390 cfm Holley. If I do this I would use an aftermarket distributor such as a Mallory or Chevrolet conversion from Bubba. What about vacuum vs mechanical advance ? What are the thoughts on doing this as opposed to the 94 , 97 , or 2gc ? Thanks in advance for any input offered. Also , I do have tube and Fenton headers and aluminum heads available to use if needed.
|
06-09-2018, 01:17 PM | #2 |
Senior Member
Join Date: May 2010
Location: Oshkosh, Wi
Posts: 4,527
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
Go with the Chev conversion with mechanical and vacuum advance. Multiple carbs have the cool factor, but you can't beat the reliability and simplicity of the 4 barrel. I've been running mine for 20 plus years without touching it.
|
Sponsored Links (Register now to hide all advertisements) |
|
06-09-2018, 02:32 PM | #3 |
Senior Member
Join Date: May 2010
Location: Coral Springs FL
Posts: 10,943
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
I have a 239 8BA with a Holley 4 bbl and it runs fine. Double check and make sure your Edelbrock intake has the generator mount in the center so the fan pulley lines up with the crank. The OFFY intake is 1 7/8 in. offset. Not good. I am running a Mallory UniLite mechanical advance distributor. Folks say that Chevy dist. is a great conversion so you might want to try that. You have to install the 390 carb backwards so the throttle linkage will work. Also using FENTON headers. Heads are early style with 1 inch spacer.
Last edited by 19Fordy; 06-10-2018 at 10:08 AM. |
06-09-2018, 04:29 PM | #4 |
Senior Member
Join Date: May 2010
Location: Oshkosh, Wi
Posts: 4,527
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
What's the problem with the offset?
|
06-09-2018, 05:56 PM | #5 |
Senior Member
Join Date: May 2010
Location: East Hartford, Ct
Posts: 5,898
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
There really isn't any problem with the offset, just be aware that it is offset
7/8" (.875") to the drivers side, not "1 7/8 in." Just check for any interference.
__________________
DON'T RECALL DOING SOMETHING FOR MYSELF BASED ON SOMEONE ELSE'S LIKES OR DISLIKES Last edited by 51 MERC-CT; 06-09-2018 at 06:02 PM. |
06-09-2018, 07:30 PM | #6 |
Senior Member
Join Date: Feb 2013
Location: Pittsford NY. USA
Posts: 1,096
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
Sponsored Links (Register now to hide all advertisements)
|
06-09-2018, 10:23 PM | #7 |
Senior Member
Join Date: May 2010
Location: Snohomish,WA
Posts: 1,030
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
Thanks for the input everyone. I do have another question. While I have no experience with the 2GC 4 bolt carb nor do I have one, would finding one of those and matching intake be a better choice than the 390 Holley ? Thanks again
|
06-09-2018, 10:41 PM | #8 |
Senior Member
Join Date: May 2010
Location: Chester Vt
Posts: 8,860
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
I go with Flatjack, the 390 is a great carb and coupled with the Chevy dist will give good performance as well as economy/ Had one on a 296 with L-100 and it got 20 mpg in cruise. Unfortunately the C4 wasn't so lucky in town
|
06-10-2018, 04:01 AM | #9 | |
Senior Member
Join Date: Dec 2013
Location: Minnesota, Florida Keys
Posts: 10,317
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
Quote:
I have a 2GC on a bored out aluminum Canadian Merc manifold on the 255 ci '51 Mercury I have in my current '51 Ford club coupe. As I have said before, mount it backwards, and everything falls right into place except for the manual choke. However, the automatic choke ports on the Mercury manifold hooks up to the choke mechanism on the carburetor just by shortening the choke stove tube a little. I don't usually like automatic chokes in old cars, but once I had this one dialed in, it was "set it and forget it". I am completely satisfied with the performance of this setup. Its trouble free and really steps out compared to the tired 239 8BA it replaced. While I am quite happy with this combination, to be frank, my performance expectations for this car were a bit lower than I had for the '36. Overall, for a relatively heavy car with a hood, I would go with the 2G hands down because of fitment and cost. I am also currently building a "Hot Rod" (open wheels and engine compartment). Of course, that will get dual carbs on an aftermarket manifold; a four barrel just wouldn't be right on that type of car. As a side note, I am very interested in flathead 4 BBL setups. I have Fenton, Sharp, and Edmunds four barrel manifolds and have rebuilt a Carter WCFB and a couple of Rochester 4G's. At the present time, I am experimenting with running a Quadrajet (yes, that's right; one of those 750 cfm monsters) on a flathead. With their small primaries and "on demand" secondaries, they would seem to be the ideal 4 BBL carb for these cars. Plus, they are easy to find and cheap to buy. Just try to find and/or buy an older square bore carburetor core these days; they are getting very scarce. Last edited by tubman; 06-10-2018 at 04:07 AM. |
|
06-10-2018, 08:20 AM | #10 |
Senior Member
Join Date: May 2010
Location: Chester Vt
Posts: 8,860
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
When switching to a different intake system. One of the first thing you have to check is the AF ratio, especially with the Holley, they come rich out of the box. For an interesting read on carburetors, try JWL's book "Flathead facts'" He covers most of these swaps.
|
06-10-2018, 10:09 AM | #11 | |
Senior Member
Join Date: May 2010
Location: Coral Springs FL
Posts: 10,943
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
Quote:
I do recall seeing some postings about ways to correct the offset by modifying or making a new fan carrier bracket. Last edited by 19Fordy; 06-10-2018 at 10:16 AM. |
|
06-10-2018, 09:10 PM | #12 |
Senior Member
Join Date: May 2010
Location: Oshkosh, Wi
Posts: 4,527
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
Again, why would you worry about this offset or spend the time to change it?
|
06-11-2018, 12:17 AM | #13 | |
Senior Member
Join Date: May 2010
Location: East Hartford, Ct
Posts: 5,898
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
Quote:
After installing the manifold it was found that the fan hit the shroud. Therefore a new fan mount was fabricated to bring it back to center. The alternator is still off set.
__________________
DON'T RECALL DOING SOMETHING FOR MYSELF BASED ON SOMEONE ELSE'S LIKES OR DISLIKES |
|
06-11-2018, 07:54 AM | #14 |
Senior Member
Join Date: May 2010
Location: Oshkosh, Wi
Posts: 4,527
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
Yep, that can be a problem.
|
06-11-2018, 08:37 AM | #15 |
Senior Member
Join Date: May 2010
Location: Coral Springs FL
Posts: 10,943
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
51Merc-CT fan carrier bracket with built in offset is a
great solution. Well done. You can also make a modification where the pulley can swivel to compensate for the offset and also be adjustable up and down for fan shroud centering.. Last edited by 19Fordy; 06-11-2018 at 09:03 AM. |
06-11-2018, 09:24 AM | #16 |
Senior Member
Join Date: May 2010
Location: SPEEDWAY INDIANA
Posts: 4,148
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
Another vote for the 390 Holley , pretty foolproof......
|
06-11-2018, 01:35 PM | #17 |
Member
Join Date: Dec 2012
Location: michigan
Posts: 74
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
I have a holley 390 with a davis unified distributor and it runs great. holley 390 can be hard to find and $ if you do find one..
|
06-11-2018, 03:12 PM | #18 |
Senior Member
Join Date: Jun 2010
Location: Lomita, California
Posts: 104
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
If I can ask, has anyone had problems with the Holley 390 4 barrel ? I've always used Holley's on my cars (1960's C****'S and Ford's) over the years with excellent results. Recently, I put a new Holley 390 cfm 4 barrel on my slightly modified flathead (Edelbrock heads, offenhauser intake maniflold, with fenton headers). The car is a 40 Coupe. The previous owner did say it also has a Mercury crankshaft. The problem I am having is a stumble under light acceleration. So far, I have had the crab distributor rebuilt by a reputable Early V8 Member. The distributor was correctly setup on his distributor machine. The dwell, total advance, and timing is all within spec. After installing the rebuilt distributor, the car still stumbled under load. The only improvement was, the engine responded better when revving in neutral and it also idled better. Moving on, I checked the carburetor float level, checked the accelerator pump adjustment, adjusted the idle mixture (using a vacuum gauge). This yielded no improvement. Also, checked for vacuum leaks and found none.
I then increased the nozzle size, from.025 to a .031 nozzle. Some improvement, however still stumbles when accelerating. I also moved the stock accelerator Cam (orange) from the factory position (no. 2) to the no. 1 position on the throttle linkage arm and readjusted the accelerator pump. Slight improvement, however the stumble is still present. Has anybody else running this carburetor had the same or similar issues? if so, what did you do to eliminate the problem? Thank you in advance, Scott |
06-11-2018, 05:11 PM | #19 |
Senior Member
Join Date: May 2010
Location: Coral Springs FL
Posts: 10,943
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
Modelacoupe3: I found that properly adjusting the secondary's on a 390 really makes a big difference in a smooth idle and throttle response. In the video below I replaced the factory screw with a hex socket head cap screw that permits adjustment of secondaries without having to remove carb from engine. Maybe this will help you also. Also, I used a power valve that is about 1/2 the number of the highest vacuum reading instead of the one that came with the carb. Stock jets are 51. Number stamped on air horn is 8007.
https://www.google.com/search?q=how+...hrome&ie=UTF-8 Last edited by 19Fordy; 06-12-2018 at 07:43 AM. |
06-11-2018, 06:46 PM | #20 |
Senior Member
Join Date: May 2010
Location: Chester Vt
Posts: 8,860
|
Re: 8BA or 8CM and Holley 390 cfm vs other combinations
I have 2 390 Holley carbs, however, one has a larger secondary venturi. I called Holley, but they have no answers. One person suggested it might be a 450, but that has a different list number.
???????? |
|
|
Sponsored Links (Register now to hide all advertisements) |
|