Gapp & Roush drag Holley
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Gapp & Roush drag Holley
I was sorting through my junk earlier and came across an old Gapp & Roush centre squirter dated 1977 .... number on it is GR031
I'd always it assumed it was a 660 4224, but a closer look shows the venturis and throttle plates look on the larger side
I know they put the 850 (?) baseplate on the 660 but other than that ...... drilled butterflies and venturies
I'll post up some pics & dims tomorrow
TIA
I'd always it assumed it was a 660 4224, but a closer look shows the venturis and throttle plates look on the larger side
I know they put the 850 (?) baseplate on the 660 but other than that ...... drilled butterflies and venturies
I'll post up some pics & dims tomorrow
TIA
Re: Gapp & Roush drag Holley
Throttle bores 1.750", venturis approx 1.500"
50cc pump (I think)
Any first hand comments welcome
50cc pump (I think)
Any first hand comments welcome
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Re: Gapp & Roush drag Holley
That carb has some interesting mods.... I would post these pics here
https://www.tapatalk.com/groups/racingfuelsystems/
There are some folks there who might be able to give a little insight
https://www.tapatalk.com/groups/racingfuelsystems/
There are some folks there who might be able to give a little insight
My Dyno is 1320 ft long. Romans 12:2
Re: Gapp & Roush drag Holley
There was a #4223 Centre pump model, 850 cfm 1 9/16" pri & sec venturiis, 1 3/4" t/bores, 50 cc pump.
Re: Gapp & Roush drag Holley
frnkeore I'll flip the blades open and take another pic
The baseplate looks 'matched' to the body, not 'chamfered' or blended such as when a larger baseplate is attached to a smaller body ...... on cursory inspection anyway
The baseplate looks 'stock' to the carb, I'll measure the venturi dia again but I'm pretty sure it's 1 1/2"
Carb was only ever used on a 351c drag engine singly, to the best of my knowledge
The baseplate looks 'matched' to the body, not 'chamfered' or blended such as when a larger baseplate is attached to a smaller body ...... on cursory inspection anyway
Ok, I didn't know that, thanks ....... I think you could be onto something there .......Geoff2 wrote:There was a #4223 Centre pump model, 850 cfm 1 9/16" pri & sec venturiis, 1 3/4" t/bores, 50 cc pump.
The baseplate looks 'stock' to the carb, I'll measure the venturi dia again but I'm pretty sure it's 1 1/2"
Carb was only ever used on a 351c drag engine singly, to the best of my knowledge
Re: Gapp & Roush drag Holley
Geoff2
Thanks you were spot on ...... gauged a rule over the venturi initially but vernier now shows it's 1.562" ish
Metering blocks are 5800 / 5802, 50cc pump, downlegs, ...... so it's a 4223 850cfm
Just goes to show what happens when you assume things, only had it nearly a quarter of a century, lol
I'm guessing the drilled TPs & venturis are extra idle air bleeds to keep the butterflies out of the T - Slot when setting the idle
Thanks you were spot on ...... gauged a rule over the venturi initially but vernier now shows it's 1.562" ish
Metering blocks are 5800 / 5802, 50cc pump, downlegs, ...... so it's a 4223 850cfm
Just goes to show what happens when you assume things, only had it nearly a quarter of a century, lol
I'm guessing the drilled TPs & venturis are extra idle air bleeds to keep the butterflies out of the T - Slot when setting the idle
Re: Gapp & Roush drag Holley
The drilled throttle plates will help with the idle richness but the holes at the bottom of the venturi taper are above the throttle plates and will be active when the throttle is open. In theory they should lean the transition and the main circuit. They might have been utilized for a very specific engine combination as there are other ways to do that. Yours is the first time I've seen that practice. Interesting piece for sure.
Re: Gapp & Roush drag Holley
As it's piqued a bit interest some more pics :
1 : 1 linkage
Did a bit of digging and there are references to Chevy 427 & Edelbrock Hi perf ..... I guess it's just an over the counter one, modded by G&R, but no choke horn so no number
Only made for a couple of years, apparently
1 : 1 linkage
Did a bit of digging and there are references to Chevy 427 & Edelbrock Hi perf ..... I guess it's just an over the counter one, modded by G&R, but no choke horn so no number
Only made for a couple of years, apparently
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Re: Gapp & Roush drag Holley
Here is some pictures of a Stock R-4223 850 center squirter carb I have It has the Venturi holes but not the throttle plate holes. Also the cam type secondary opening has not been ground to delay the secondary opening like the G&R has. Don't know why the pictures turned ?
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You are only limited by your machinery and your imagination!
Re: Gapp & Roush drag Holley
Thanks, nice to see the venturi holes are factory .......
If you post them on a site where you can't re-orientate the pics, you must remember to to hold the phone horizontal (on it's side) as if taking a landscape pic, with the shutter 'button' to the right side of the screen ...... apparently
You most likely took them vertical, as in a portrait pic ....... and the default flips them 90 degs when posted
Even a couple of mine came out wrong, because I held the phone too 'flat' in the planar horizontal looking down ......
It's to do with the default settings within the phoneDon't know why the pictures turned ?
If you post them on a site where you can't re-orientate the pics, you must remember to to hold the phone horizontal (on it's side) as if taking a landscape pic, with the shutter 'button' to the right side of the screen ...... apparently
You most likely took them vertical, as in a portrait pic ....... and the default flips them 90 degs when posted
Even a couple of mine came out wrong, because I held the phone too 'flat' in the planar horizontal looking down ......
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Re: Gapp & Roush drag Holley
4223 - 850 CFM center squirter . Production , over the counter. Throttle blades drilled for idle. Their "special" carburetors were done by the late Harold Droste and had hand stamped serial numbers.
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Re: Gapp & Roush drag Holley
The holes in the side of the venturi were put there to introduce a blast of air going over the throttle shaft to keep gasoline from leaking out through the shaft.
Almost any brand carburetor had something like that before 1972 when the EPA started measuring engine compartment hydrocarbons. Any air leakage points in carburetors were discontinued and carbon canisters became the newest thing.
Almost any brand carburetor had something like that before 1972 when the EPA started measuring engine compartment hydrocarbons. Any air leakage points in carburetors were discontinued and carbon canisters became the newest thing.
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Re: Gapp & Roush drag Holley
From an old Holley Spec book
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Re: Gapp & Roush drag Holley
Thanks for the replies, all info helpful
It's likely been allocated a use, at long last
It's likely been allocated a use, at long last