Carb question

goinbroke2 · 09-12-2011, 07:07 AM

Looking at most carb spec's online it says 2v, part number or 1.563/108.0 or whatever.
This is all chev and dodge and older fords (pre 78 or so)

The question is, the later fords (81 for example) have 2700/all or 7200/all.
Is there more in depth numbers somewhere?
I'm looking at a 81 302 fairmont with a 302 and it has a 2150 (regular 2bbl carb 1.08 venturi) from the factory but the only thing listed is 2700/all. As far as I know, the 2700 and 7200 carbs are variable venturi carbs.

So;
1) do I get a VV carb to be legal or can I run the one that came with the car from the factory?
2) If I have to get a VV and it says "all" can I pick any VV carb? I'm guessing the VV off a 351 2bbl would flow pretty good!

Billy Nees · 09-12-2011, 09:45 AM

Welllll, the right way to do it is find a carb with the correct #s on it and start with that. There are some combos running that have no dimensions listed running big carbs but remember that somewhere the correct #s exsist and you wouldn't want to get "blindsided" somewhere down the road.
I've actually played with a couple of VV carbs and would like to compare one to a regular carb on a bench. I think they might flow better.

Rory McNeil · 09-12-2011, 10:55 AM

I didn`t look in the classifacation guide today, but a 302 was not available in a 81 Fairmont, only the 78&79 Fairmont had 302`s, 80&81 only came as a 255 for a V8 option. All the V8`s were 2 barrel only.Visually the only differance between the 78 & the 79-81 Fairmonts was that 78`s had clear front park/signal lens, 79& later were amber. I know that Ford used the variable venturi carbs on 302s in Thunderbirds and the big cars for a while in the early 80`s, but I`m not sure how they would work in a low vacuum enviroment in a race application.

goinbroke2 · 09-12-2011, 09:40 PM

Thanks guys...glad I didn't jump too quick on it. It doesn't have the funny "open" intake of a 255 so I'm thinking it's not the original engine even though the guy says it is. I saw a 302 then looked it up and thought, heyyyyy....oh well

Looking at the class guide a little closer answers all the questions, DUH! I guess hindsight IS 20/20! LOL

Now to find a 2 door ltd with a 302 VV......

09-12-2011, 07:07 AM	#1
goinbroke2 Senior Member Join Date: Mar 2002 Location: NS CANADA Posts: 892 Likes: 1,624 Liked 393 Times in 153 Posts	Carb question Looking at most carb spec's online it says 2v, part number or 1.563/108.0 or whatever. This is all chev and dodge and older fords (pre 78 or so) The question is, the later fords (81 for example) have 2700/all or 7200/all. Is there more in depth numbers somewhere? I'm looking at a 81 302 fairmont with a 302 and it has a 2150 (regular 2bbl carb 1.08 venturi) from the factory but the only thing listed is 2700/all. As far as I know, the 2700 and 7200 carbs are variable venturi carbs. So; 1) do I get a VV carb to be legal or can I run the one that came with the car from the factory? 2) If I have to get a VV and it says "all" can I pick any VV carb? I'm guessing the VV off a 351 2bbl would flow pretty good!

09-12-2011, 09:45 AM	#2
Billy Nees VIP Member Join Date: Oct 2002 Location: On a hilltop in Pa. Posts: 4,494 Likes: 3,597 Liked 7,734 Times in 1,739 Posts	Re: Carb question Welllll, the right way to do it is find a carb with the correct #s on it and start with that. There are some combos running that have no dimensions listed running big carbs but remember that somewhere the correct #s exsist and you wouldn't want to get "blindsided" somewhere down the road. I've actually played with a couple of VV carbs and would like to compare one to a regular carb on a bench. I think they might flow better. __________________ Billy Nees 1188 STK, SS I'm not spending 100K to win 2K

09-12-2011, 10:55 AM	#3
Rory McNeil VIP Member Join Date: Jun 2007 Location: from Vancouver BC Canada, now in Nova Scotia Posts: 1,311 Likes: 317 Liked 1,104 Times in 302 Posts	Re: Carb question I didn`t look in the classifacation guide today, but a 302 was not available in a 81 Fairmont, only the 78&79 Fairmont had 302`s, 80&81 only came as a 255 for a V8 option. All the V8`s were 2 barrel only.Visually the only differance between the 78 & the 79-81 Fairmonts was that 78`s had clear front park/signal lens, 79& later were amber. I know that Ford used the variable venturi carbs on 302s in Thunderbirds and the big cars for a while in the early 80`s, but I`m not sure how they would work in a low vacuum enviroment in a race application. __________________ NHRA 6390 STK M/S 85 Mustang

09-12-2011, 09:40 PM	#4
goinbroke2 Senior Member Join Date: Mar 2002 Location: NS CANADA Posts: 892 Likes: 1,624 Liked 393 Times in 153 Posts	Re: Carb question Thanks guys...glad I didn't jump too quick on it. It doesn't have the funny "open" intake of a 255 so I'm thinking it's not the original engine even though the guy says it is. I saw a 302 then looked it up and thought, heyyyyy....oh well Looking at the class guide a little closer answers all the questions, DUH! I guess hindsight IS 20/20! LOL Now to find a 2 door ltd with a 302 VV......