All Small Six Big log carb bolt spacing [SOLVED]

[Kritas]

I've been looking at Clifford's Weber carb conversions. The choices he gives aren't "big log vs. small log" they are "3 5/8 stud centers vs. 2 3/4 stud centers". I'd assume that 3 5/8 is the big log measurement, and my head is from a 250 with the larger 1 3/4" bore. However, a PO drilled out the carb mount on my head as pictured below. Using a caliper to measure, the holes have 2.6" centers, and the studs have 3 3/8" centers.

Just to be clear, I'm measuring from the center of the holes and the center of the studs to the center on the opposite number. I realize that someone drilled a couple of new holes for a god-only-knows-what carburetor, but I expected that one of the measurements would match Clifford's site. I don't want to end up with a new carb that's cattywampus and I'd prefer not to drill new holes in this head. Any thoughts?




The scuffed areas are from prepping the engine for paint. That valve cover needs work.

 

[bubba22349]

In your above picture the studs are currently in the right holes, so yes measure them center to center for the correct Bolt spacing. On those two extra Holes drilled and threaded if they go into the Logs Intake Opening then use a set screw and some good sealer like Permatex Aviation Cement to close them up. This Carb adapter would work for a Weber Carb on a Large Log Head. Good luck https://www.vintageinlines.com/product-page/weber-1v-2v-adaptor-large-log

 

[Kritas]

In your above picture the studs are currently in the right holes, so yes measure them center to center for the correct Bolt spacing. On those two extra Holes drilled and threaded if they go into the Logs Intake Opening then use a set screw and some good sealer like Permatex Aviation Cement to close them up. This Carb adapter would work for a Weber Carb on a Large Log Head. Good luck https://www.vintageinlines.com/product-page/weber-1v-2v-adaptor-large-log

I've seen the VI adapter. I was trying to order the entire kit with linkage from Clifford's. The holes in the base don't go through to the intake plenum. I'm just confused by the difference in measurements. I may just buy the carb and accessories from VI instead.

 

[Invectivus]

Yeah, I'm surprised about the difference between Clifford's 3 5/8ths vs your 3 3/8ths, but I've honestly never looked at the actual measurements. I'll try to peek at my large log at home tonight.

 

[chad]

log refers to that big red lumpa in ur pic.
"Large" refers to the volume of it not bolt spacing, chamber volume, or other.

 

[Invectivus]

Oddly, mine measured ~3.3 inches, so a bit less than you’re 3 3/8ths. Pretty approx though. I was measuring holes not studs.

Ha! I notice on Clifford’s site the large throat adapter is for stud distance ’more than 3 1/4“ apart’. Maybe there’s just that much variance in the ford spec.

 

[chad]

℄ is measured on center of hole or center of 'stud'.

 

[Kritas]

log refers to that big red lumpa in ur pic.
"Large" refers to the volume of it not bolt spacing, chamber volume, or other.

I understand. I'm just discussing the characteristics of the manifold relevant to mounting a carb.

I went ahead and placed my order with Vintage Inlines.

 

[78_200_C4]

There are a couple reasons to change the stud spacing.
If you put a large log head on a small log head Ford you may want to run the small log carb. adapter.
This allows you to run the stock throttle linkage and a load'o'matic Autolite 1100.
To stop a vacuum leak under the small log carb. adapter a 1/8" steel plate can be drilled for the carb studs.
A hole saw will cut the throttle bore hole.

 

[Kritas]

There are a couple reasons to change the stud spacing.
If you put a large log head on a small log head Ford you may want to run the small log carb. adapter.
This allows you to run the stock throttle linkage and a load'o'matic Autolite 1100.
To stop a vacuum leak under the small log carb. adapter a 1/8" steel plate can be drilled for the carb studs.
A hole saw will cut the throttle bore hole.

The car came to me with the large log head, a '66 carb spacer with coolant running through it, and an Autolite 1100. The PO "couldn't get it to run right". This is what I found after I figured out what engine and head the car actually had in it (thanks to everyone here who got me started, the PO evidently thought it was the stock 200 with a small log head). I have the issue sorted now after installing a VI spacer of the proper size.