Holley "G" differences

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration
Model T Ford Forum: Forum 2018: Holley "G" differences
Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham, Blackfoot, Idaho on Saturday, August 04, 2018 - 04:46 pm:

Delving into three "G" carbs, I have one with a replacement aluminum venturi, one with an original "pewter" venturi which measures the same as the new aluminum one, and a third, original venturi the opening of which tapers from 1" at the top to .7121" at the bottom. The other two measure .840"

What would be the result of reducing the throat diameter of the venturi by .1279" (as well as the angle of the taper) ?? Am I correct to assume the Venturi effect would be increased velocity ? How would this affect performance ? FWIW, the "necked down" part came from a brass-bowl carb which I presume to be an earlier version.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Curt Brainard on Saturday, August 04, 2018 - 08:12 pm:

I have machined and tried several different size venturies. Quite honestly I found no noticible differences. I will try to find my notes on the sizing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Corey Walker, Brownsboro TX on Saturday, August 04, 2018 - 08:45 pm:

I found one without the bulge at the bottom. It's just like a straight pipe with a flange at the top.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham, Blackfoot, Idaho on Sunday, August 05, 2018 - 02:05 pm:

Corey, thanks for that ! Adds a third variation to the venturi question. No taper in that one ? Here's my apparatus for setting float height - more about floats anon . . .


Top of pagePrevious messageNext messageBottom of page Link to this message  By Steve Jelf, Parkerfield KS on Sunday, August 05, 2018 - 03:06 pm:

Yes, the brass bowl would be the earliest. I assume it's on a bronze body. Next would be a steel bowl on a bronze body, then a steel bowl on a cast iron body. In its few years of production the G went through several changes, and some of them seem to be simultaneous. Some have a ridge around the intake like an NH, and some don't, like the one in the picture, and I think both kinds may have been made at the same time. I'll leave it for somebody smarter than me to figure all that out.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Corey Walker, Brownsboro TX on Sunday, August 05, 2018 - 04:06 pm:

There were 2 different Pats Pending tops, one with larger letters and one without a period after Pats. Then other variations in the brass and cast iron tops.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham, Blackfoot, Idaho on Thursday, August 09, 2018 - 02:56 pm:

Comparing the original cork float (left) with the reproduction float now available (right) and a new float cut down to original size. (bottom) The new material weighs the same as cork, which is a good thing.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham, Blackfoot, Idaho on Thursday, August 09, 2018 - 03:08 pm:

More differences - earlier carbs have a slender all-brass mixture needle. The needle on the top has a steel point tapered to a slightly shallower angle and swaged into the threaded brass shaft. It came out of a carb with a steel bowl.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham, Blackfoot, Idaho on Thursday, August 09, 2018 - 03:18 pm:

I'm not a good scientist. Having changed the new type oversized float for original cork, the new replacement aluminum venturi for the original with a tighter throat, and the steel tipped mixture needle for the earlier all brass item, on the basis of a single four-mile test drive, I find the car performs better all around. Idle is smoother, and it seems to have better response to the throttle and more power at low speeds. ?!? With three variables in play I'll never know if only one change made the difference or if it's due to all three in play. ?!?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Duey_C west central, MN on Friday, August 10, 2018 - 01:53 am:

"the new replacement aluminum venturi for the original with a tighter throat,"
No wonder one of the posters here had said if you open up the venturi, It'll run like a scalded cat.
How the heck did you reshape the float? :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham, Blackfoot, Idaho on Friday, August 10, 2018 - 10:03 am:

Duey, you're confusing me. In effect I closed down the venturi - the old original is 1/8" smaller in diameter at the bottom. ?!?
The new replacement material for the float works very easily. I just sanded one side with 100 grit paper until it was 3/8" thick, matching the old cork float, then rounded the edges to match the profile.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Corey Walker, Brownsboro TX on Saturday, August 11, 2018 - 03:49 pm:

Here is another difference. Most only have one small hole in the body that goes from inside the bowl to inside where the jet screws in. Some have 6 small holes drilled around that area. Both of these 2 are brass and had Pats Pending tops.


.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Chillingworth on Saturday, August 11, 2018 - 06:38 pm:

You will also find that the Gs that have the single hole inside the body that Corey shows also have a single small hole drilled through the air inlet to the interior. This applies to both the bronze and the iron bodied G's.



The bronze ones with the 6 holes inside the body do not have this hole drilled in the air inlet. All of this type that I have seen seem to be 1914s meaning they have the disc topped mixture adjusting screw, Pats. Pend. cover plate, and brass bowl. Any other, or differing, ideas?

Rich C.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Rich Bingham, Blackfoot, Idaho on Saturday, August 11, 2018 - 07:53 pm:

Thanks fellows for adding to the G carb's anatomy. Very interesting . . . to me, at least.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Duey_C west central, MN on Monday, August 13, 2018 - 02:00 am:

Sorry for the confusion I raised Rich B. Wasn't intended at all.
I am also liking the info shown here.
:-)


Add a Message


This is a private posting area. Only registered users and moderators may post messages here.
Username:  
Password:

Topics Last Day Last Week Tree View    Getting Started Formatting Troubleshooting Program Credits    New Messages Keyword Search Contact Moderators Edit Profile Administration