Log head mod question

[Anonymous]

To those who have milled the log for a 2 barrel carb. Did you keep the angle of the carb as it was or mill it to the same plane as the head to block matting surface? I may have time this weekend to use the mill at work.
Thanks
Steve

 

[drag-200stang]

jrx,

Side to side the top of the log should be parallel to the head. Lengthwise I would shim the head as necessary to keep the log parallel to your mill in the area that you're maching for the adapter, not the raised up area the carb sits on. That way you'll get the largest surface area to seal your adapter to and the thickest material to tap for your mounting bolts. May have to JB weld some low spots. If you're concerned about the carb being level, you might be able to mill the adapter on an angle. Only you know the rake of your car and how level the carb will be to earth. I wouldn't worry about it too much. Acceleration and deceleration has a greater effect on fuel in the bowl. Hope this makes sense. Ask if it's not clear.

 

[Crosley]

I checked the angle of the OEM carb surface first. Then i milled the log intake flat to remove minimum material from it.

Then I milled the aluminum adapter to the angle of the original carb base

 

[66 Bronco]

In regards to my post yesterday and this whole log mod deal..

Am I misunderstanding that you guys are some how adding material (metal) to the log before you mill it for the adapter?

Hjörleifur.

 

[drag-200stang]

66 Bronco,

Yes, I believe that you are mistaken. Depending on the cylinder head that you are dealing with and the adapter that you are bolting to the log, sometimes JB Weld (a 2-part epoxy), a machinable plastic, is used to take care of slight low spots so your gasket will seal. It doesn't take a wide area for the gasket to seal on if done right. I had .080 in one small area on my tripower adapters. Never leaked. Used the aviation permatex brown goo (forgot what number). There is no need to braise or weld for this application. It will only cause problems.

 

['68falconohio]

I didn't add any addl. material to my D7 head. I also didn't shim the cylinder head up on the mill table. I did, smooth the transition from the newly machined carb plate surface to the original casting surface. I wanted to eliminate the stress riser of a 90* angle.

As you can see, it was hard to locate a 'slot' in the head that matches a holley 2V adapter plate and leave mating surface on each side. As drag-200stang said, you don't need a whole lot of sealing surface.(EDIT: If the two mating surfaces are true)

There was no way to get the four holes that already came in my adapter plate on the log head, so I had to put a 1/4-20 in between them.