Offy 4BBL intake

My son inlaw has a 600 Holley I can have. Do you guys think that is to big for my engine. It's real stemmy engine, 276, 400jr cam, Offy 375 heads, pistons pop up over the block, I had to use copper gaskets with a .020 copper shim to get .040 piston clearance. I'll play with jets and power valves but you cain't go to small with jets if you getting to much air. Thanks Walt
 
Walt I have a holley 390cfm on my Merc. powered highboy,works great.I think 600 CFM is a bit much. Phil
 
Here are the 2 Holley 4bbl carbs that I have on my 32. They work pretty good
 

Attachments

  • chassis engine 001.jpg
    chassis engine 001.jpg
    122.9 KB · Views: 70
Walt, keep in mind that the generator mount on an OFFY 4 bbl. intake is offset 7/8 inch. towards the driver's side of the car. This affects fan belt alignment.
 
19Fordy said:
Walt, keep in mind that the generator mount on an OFFY 4 bbl. intake is offset 7/8 inch. towards the driver's side of the car. This affects fan belt alignment.
Click to expand...

What am I missing here 19Fordy? I don't remember my 4 barrel Offy being offset but if it is there has been no issue.

John L
 
trainguy said:
Walt I have a holley 390cfm on my Merc. powered highboy,works great.I think 600 CFM is a bit much. Phil
Click to expand...
Well think about this, I have four 97's running straight linkage on my 40 with a 276 and it runs perfect, 18mpg on secondary roads, I've had been running this setup for 2 yesrs, I really haven't done turn pike trip with it. Of course I have a T-5 with a 9in. rear with 3:50 gears. at 60mph I'm only turning 2000rpm in OD. NOW, with four 97's I beleive that over 600cfm. SO, with the 600 4bbl that's 600cfm with all 4bbls open. Most of the time your only running on 2 bbl. I think I'll try this 600 Holley. Walt
 
Have been running a Holley 390 for many years. Really like it. One thing I like about it is the vacuum secondaries. Only open when needed. The older carbs have mechanical secondaries and are not nearly as smooth. I made my own adapter plate.
 
19Fordy said:
Walt, keep in mind that the generator mount on an OFFY 4 bbl. intake is offset 7/8 inch. towards the driver's side of the car. This affects fan belt alignment.
Click to expand...

I've had mine for nine years and the slight offset has never been a problem. Just sayin'.
 
40grit said:
What am I missing here 19Fordy? I don't remember my 4 barrel Offy being offset but if it is there has been no issue.

John L
Click to expand...

John, When I installed my OFFENHAUSER 4 bbl. intake the generator would was no longer "centered" and neither was the fan pulley. It turns out that the OFFY generator support flange is cast 7/8 in. off center to the driver side of the engine. I do believe that this is because the OFFy manifold was to be used with the offset generator bracket that bolts to the driver side head. Perhaps all OFFY 4 barrel intakes don't have this "offset" but I have not yet seen one. I never realized this was a problem until I experienced it. Edelbrock intakes are centered. See here:
http://www.speedwaymotors.com/Offenhauser-1949-1953-Flathead-4-Barrel-Intake,8150.html
 
Last edited:
19Fordy said:
Walt, keep in mind that the generator mount on an OFFY 4 bbl. intake is offset 7/8 inch. towards the driver's side of the car. This affects fan belt alignment.
Click to expand...

40grit said:
What am I missing here 19Fordy? I don't remember my 4 barrel Offy being offset but if it is there has been no issue.

John L
Click to expand...

4dFord/SC said:
I've had mine for nine years and the slight offset has never been a problem. Just sayin'.
Click to expand...

19Fordy said:
John, When I installed my OFFENHAUSER 4 bbl. intake the generator would was no longer "centered" and neither was the fan pulley. It turns out that the OFFY generator support flange is cast 7/8 in. off center to the driver side of the engine. I do believe that this is because the OFFy manifold was to be used with the offset generator bracket that bolts to the driver side head. Perhaps all OFFY 4 barrel intakes don't have this "offset" but I have not yet seen one. I never realized this was a problem until I experienced it. Edelbrock intakes are centered.l
Click to expand...
Mine only became a problem when I re-installed my fan shroud and found out that the fan hit the shroud. To solve the problem I fabricated a new fan/pulley mount (offset 7/8" )
 

Attachments

  • fan.jpg
    fan.jpg
    51.4 KB · Views: 43
Last edited:
Walt this is the adapter that I modified for the Edelbrock 500cfm carb similar to the one Richard used in his 276. Runs great and gets good mileage
 

Attachments

  • IMG_20121224_152934.jpg
    IMG_20121224_152934.jpg
    57.3 KB · Views: 93
The adapter I built looks just like Ron's except I used 5/16 flathead screws to bolt it to the manifold. Used a countersink to set them level with the adapter. My engine is only 245 cu in so the 390 works great. Tried a 600 and it was way to much. Would think a 500 Edelbrock would be good for 276".
 
19Fordy said:
John, When I installed my OFFENHAUSER 4 bbl. intake the generator would was no longer "centered" and neither was the fan pulley. It turns out that the OFFY generator support flange is cast 7/8 in. off center to the driver side of the engine. I do believe that this is because the OFFy manifold was to be used with the offset generator bracket that bolts to the driver side head. Perhaps all OFFY 4 barrel intakes don't have this "offset" but I have not yet seen one. I never realized this was a problem until I experienced it. Edelbrock intakes are centered. See here:
http://www.speedwaymotors.com/Offenhauser-1949-1953-Flathead-4-Barrel-Intake,8150.html
Click to expand...

Bingo. :) I am running a Cooling Components shroud and electric fan. That explains why I never noticed the offset. Thanks for the feed back.

John L
 
Walt this was a commercial adapter I bought. But the bores were very small and mis aligned with the carburetor. I installed the Edelbrock gasket and bored the adapter and manifold to align the carb bores. Then using a die grinder smoothed of all the rough edges. Yes most of the late carbs have vacuum operated secondaries and thei makes then preform very well on the street. But their biggest advantage is the ability to tune then for better fuel economy, which Richard had done quite well.
I have a Holley 4180 for the 280, this was Holley's attempt to improve milage with their carbs. We'll see how it compares to the Edelbrock.
 
Ron I think a sore point with the 4180 might be the lack of idle mixture screws. Holley's usually have the screws on the primary metering block, but the 4180 was engineered for smog-motor 460's and 302's and as a result there are no screws, the mixture was fixed at the factory. You should be able to change the primary block to one with the mixture screws from another carb.
On the plus side the venturi boosters are annular discharge; instead of a discharge from one central point in the booster the 4180 will give a better atomization of the fuel. Finer droplets of fuel will help provide better fuel mileage and seat of the pants road feel.
 
I have a 4bbl Holley with manual chock,( List no. 1850 - 4 ) can anybody tell me what the CFM is. It's practaly a brand new carb, I've had it on a shelf in my storage barn for about 20yr's. Thanks Walt
 
You must log in or register to reply here.
Back
Top