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1968 Mustang Coupe, 351w, 4 spd, acapulco blue CS/GT clone (in progress)
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Discussion Starter · #1 ·
So I'm at the point where I really need to pick and choose a carb for my engine build. Its a 69' 351w bored .030 over with a comp cams thumper (gross valve lift: int .490, exh .475), comp cams roller tip rockers 1.6 ratio, Weiand 8023 stealth intake. Overall, a nearly stock rebuild. I've heard that a 650 cfm should be plenty for street use but I just don't know. I know I want a Holley in Dichromate finish to resemble the stock appearance. What about double pumpers vs single? More or less cfm's? I'll be running a stock mechanical fuel pump. Any help would be greatly appreciated.
Hood Automotive tire Tire Motor vehicle Wheel
 

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With a Thumpr, that isn't going to act very stock. And if you want a Holley, well, get a Holley. Not sure what you are trying to achieve here, but hope it acts like you want it to.
 

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1968 Mustang Coupe, 351w, 4 spd, acapulco blue CS/GT clone (in progress)
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Discussion Starter · #4 ·

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1968 Mustang Coupe, 351w, 4 spd, acapulco blue CS/GT clone (in progress)
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Discussion Starter · #5 ·
With a Thumpr, that isn't going to act very stock. And if you want a Holley, well, get a Holley. Not sure what you are trying to achieve here, but hope it acts like you want it to.
Yes, it'll have some "thump" to it but with mild exhaust I don't think it'll be very noticeable. Holley is my preference but there are so many options. I'm looking for suggestions based on experience as to what worked best for others. That's all.
 

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Not to put too fine a point on it, but engines work best when the parts match. That cam's a poor match for the rest of your engine. It will have reduced torque through most, if not all, of its powerband, and it will have worse mileage. The Thumpr cams are all about sound, primarily. I would choose a carb around 600 CFM for that engine.
 

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So I'm at the point where I really need to pick and choose a carb for my engine build. Its a 69' 351w bored .030 over with a comp cams thumper (gross valve lift: int .490, exh .475), comp cams roller tip rockers 1.6 ratio, Weiand 8023 stealth intake. Overall, a nearly stock rebuild. I've heard that a 650 cfm should be plenty for street use but I just don't know. I know I want a Holley in Dichromate finish to resemble the stock appearance. What about double pumpers vs single? More or less cfm's? I'll be running a stock mechanical fuel pump. Any help would be greatly appreciated.
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Could run a Holley 670 Street Avenger, or any 600-650cfm with vacuum secondary's like the Holley 4150. I would not run double pumper on that setup.
 

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Carb....Autolite 4100 1.12 with a possible jet change, Edelbrock 1405 or a 1406 with 1405 baseline as a beginning tune, or something in the family of an 1850 for a Holley if ya just gotta have one.
 

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Holly sniper 😁. OK I know that's not a carb but it's easy to use. I personally like the holley 4160 they are stout produce a lot of power and if you know how to tune them they are amazing. The downside of the holley is you will constantly be fiddling with it. I found running lucas fuel injecation cleaner once a year lubes the needle and seat and since i have never had a stuck one. The edelbrock is kind of like the ron popeel of carbs you set it forget it.
 

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Not to put too fine a point on it, but engines work best when the parts match. That cam's a poor match for the rest of your engine. It will have reduced torque through most, if not all, of its powerband, and it will have worse mileage. The Thumpr cams are all about sound, primarily. I would choose a carb around 600 CFM for that engine.
That is a good point. The Thumpr cams are designed to sound snotty at idle so you can be cool cruising into the Dairy Queen. Do they make power? Yeah, sure. But where?

My take is annular boosters are a very good idea for a street car. If you want a Holley style carb, I think you would have to go with a "Super Holley", like something from Quick Fuel to get annular boosters. Or you could go with a Summit carburetor. Those are a Holley version of the Autolite 4100 and they have annular boosters.
 

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AFAIK, without custom work, the 750 is the cheapest Holley that has boosters you can change out (and put annulars in).
 

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Another "which carburetor should I buy" thread that's going to have as many opinions as the day is long... With being a stock or close to stock 351w, I personally wouldn't go over 600 cfm as you're not going to need it. You could run a double pumper or mechanical secondaries since you've got a manual transmission but again, it's a pretty close to stock motor so it's really up to you. I'd give Holley a call, tell them what you've got and see what they'd recommend, of which you'll probably get a couple different options. If it was me and I wanted vacuum secondaries then I'd probably run a Holley 570 cfm Street Avenger carburetor. If I wanted mechanical secondaries then I'd say a Brawler 600 cfm or a Quick Fuel 600 cfm carburetor.



 

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1965 Mustang GT. 11.898 @ 113.646, all motor, three pedals
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I've never seen such an animal. Is it custom, or am I just missing something?
I could do without the choke, but that’s resolved easy enough

 

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1965 Mustang GT. 11.898 @ 113.646, all motor, three pedals
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Without the choke
edit: blow thru carb, so it’ll need some tinkering for n/a

 

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I have a FB friend that has a pretty cool 63 Fairlane built as a road race car. I believe he runs in a class that requires a 2V carb. His build is a 302, Edelbrock heads, Thumper cam 500 2V Holley on 80’s Ford aluminum 2V intake. Made 350 hp on the engine dyno. Anyway on the dyno is one thing and driving it is another. It was running like a dog. To fix it he locked the timing out, no mechanical advance. What ever initial timing is, is full advance. Starts up with a twist of the keg without pumping the gas. So the take away is that you may have to do something with your timing to get it to run halfway decent.

As said everyone is going to have their own. I agree a 600 will be sufficient. While I am a fan of Edelbrock I think a Edelbrock just might be well suited. Here’s my reasoning. With that cam you’re not going to have much manifold vacuum. I’m all for vacuum secondary carbs for most applications. The Edelbrock has manual secondary plates. However it uses a air flow valve that responds to air flow for secondary operation and not manifold vacuum to operate. I’m thinking it will be easier to tune.
 

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I could do without the choke, but that’s resolved easy enough

Yes, that's a Quick Fuel which is a "Super Holley". I've never seen a Holley 650 with annular boosters.
 
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