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I would try the 670 first. There is more to carb selection than weight and trans. Among the other factors are compound gear ratio and driving type. A 750 DP would run well, especially to get that last ounce of power at max rpm. As weight, trans type, launch rpm or lack of one, stall (if auto), style of shifting, compound ratio, and other factors play-in, the compromise of a DP to cover low-speed fuel dropout becomes a handicap. It's easy to pick a carb for a simple, light, deeply-geared, high-launch rpm drag car. It's when you load it slower or vary throttle extensively that it can become an issue. Compromise is then toward flow velocities in the low and mid-ranges, part-throttle shift recovery, and avoiding power losses due to fuel wall wetting and puddling from the DP - issues that do not affect a drag-only car the same. If chosen well, the result is no loss of max rpm power, but as much regulated velocity as possible for more efficient and greater average power.

Considering a warm 351W can make 440 hp on the venerable 600 cfm 4100, a 670 should be about perfect for more rounded performance without top-end sacrifices. Additional benefit to the better responsiveness would be much-improved city mileage. It all depends on how you're using it and where you want your performance.

David
 

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Martin,

I love your car! Really nice, but I can see why you're doing an engine swap. That thing needs a nice rumbly Ford V8! With the car being black that leaves your color choices wide open.

As I recall the hood (bonnet) is narrow so you aren't going to see much either. I agree that the blue would be on my short list but I have to wonder what it would look like in gold. My '65 Falcon came from the factory with a black block with all gold parts like the valve covers and air cleaner but I have no idea what Shelby did. If you really want to know the "correct" color try looking at one of the Shelby forums or websites.

Blue is always good! Let's see some more photos of that car. You can upload them here on their "Garage" section like I did.

John
 

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Discussion Starter #23
Martin,

I love your car! Really nice, but I can see why you're doing an engine swap. That thing needs a nice rumbly Ford V8! With the car being black that leaves your color choices wide open.

As I recall the hood (bonnet) is narrow so you aren't going to see much either. I agree that the blue would be on my short list but I have to wonder what it would look like in gold. My '65 Falcon came from the factory with a black block with all gold parts like the valve covers and air cleaner but I have no idea what Shelby did. If you really want to know the "correct" color try looking at one of the Shelby forums or websites.

Blue is always good! Let's see some more photos of that car. You can upload them here on their "Garage" section like I did.

John
I've put a couple more pictures in the Garage section but its not letting me add any more..................Computers eh!!??

Martin
 

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Considering a warm 351W can make 440 hp on the venerable 600 cfm 4100, a 670 should be about perfect for more rounded performance without top-end sacrifices. Additional benefit to the better responsiveness would be much-improved city mileage. It all depends on how you're using it and where you want your performance.

David
Yes and what would be the power of the 351W with a 750 CFM..,

Of course i am talking about modern carburetors, with annular boosters(i.e. QF 750 SS-AN).
With "old" technology, i am agree,a smaller one will be better for low rev throttle response...
 

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I've put a couple more pictures in the Garage section but its not letting me add any more..................Computers eh!!??

Martin
Martin,

I know you said it currently has a Rover V8 but looking at the photo(s) in here it sure looks like a SBF to me. It has Cobra valve covers on what looks like the same bolt pattern, distributer in front, intake looks right, etc. Are you sure about that?

John
 

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Discussion Starter #26
Martin,

I know you said it currently has a Rover V8 but looking at the photo(s) in here it sure looks like a SBF to me. It has Cobra valve covers on what looks like the same bolt pattern, distributer in front, intake looks right, etc. Are you sure about that?

John
Definately a Rover John!! Look at my website here martins-cobra.co.uk
The valve covers are Ford. I had to get some coverter plates to fit on the heads so the valve covers would fit. Real nightmare to stop them leaking!! The Rover Distributor was always at the front, but is angles at about 45 degrees as opposed to the Ford which is straight up. also the Rover is about 200bhp less than a decent Ford!!!

Martin
 

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Definately a Rover John!! Look at my website here martins-cobra.co.uk
The valve covers are Ford. I had to get some coverter plates to fit on the heads so the valve covers would fit. Real nightmare to stop them leaking!! The Rover Distributor was always at the front, but is angles at about 45 degrees as opposed to the Ford which is straight up. also the Rover is about 200bhp less than a decent Ford!!!

Martin
That explains it. I noticed later that the header bolts are top/bottom rather than side by side. When it's all done you're going to be one happy guy!
 

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Yes and what would be the power of the 351W with a 750 CFM..,
The same at peak, give or take a couple HP. The gains are the average HP when the low and mid-range are included. While a drag car launched at 5000 and redlining at 7000+ doesn't care as much about average usable HP and is happy with a 750; a light road car with a 2500-6000 rpm range (like his) will be faster with the smallest carb that will feed it fully at peak HP. A 347 at 6000 (yes, only 6000) will have no lack of air from a 670. Tuning and fuel distribution are completely separate issues that affect final average and peak HP.
Of course i am talking about modern carburetors, with annular boosters(i.e. QF 750 SS-AN).
With "old" technology, i am agree,a smaller one will be better for low rev throttle response...
That's why I compared using the 4100 - it started the whole annular booster thing, and is a good comparison to what you would buy in a 'modern' shelf carb. Unlike EFI, using more carb than the engine can use creates a compromise, even with current retail carb designs. My suggestion is he can have better overall performance for his purposes, and a higher average HP, using a smaller (yet large enough) carb for the job. While a 750 may make him perfectly happy as it does you, he already has the 670. May as well try it.
200 BHP is better than a stock 302 4V with 220 SAE HP ;)
Just to keep the record straight - SAE net is the underrated one, and is often regarded as the one "1/2 way between BHP and WHP". Uncorrected BHP is optimistically high and carries no additional real-life cripplers, like accessories, mufflers and air filters. So, 220 SAE net HP is roughly 250 to nearly 300 BHP, depending on application and SAE factors used.

David
 

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Discussion Starter #30
The same at peak, give or take a couple HP. The gains are the average HP when the low and mid-range are included. While a drag car launched at 5000 and redlining at 7000+ doesn't care as much about average usable HP and is happy with a 750; a light road car with a 2500-6000 rpm range (like his) will be faster with the smallest carb that will feed it fully at peak HP. A 347 at 6000 (yes, only 6000) will have no lack of air from a 670. Tuning and fuel distribution are completely separate issues that affect final average and peak HP.
That's why I compared using the 4100 - it started the whole annular booster thing, and is a good comparison to what you would buy in a 'modern' shelf carb. Unlike EFI, using more carb than the engine can use creates a compromise, even with current retail carb designs. My suggestion is he can have better overall performance for his purposes, and a higher average HP, using a smaller (yet large enough) carb for the job. While a 750 may make him perfectly happy as it does you, he already has the 670. May as well try it.
Just to keep the record straight - SAE net is the underrated one, and is often regarded as the one "1/2 way between BHP and WHP". Uncorrected BHP is optimistically high and carries no additional real-life cripplers, like accessories, mufflers and air filters. So, 220 SAE net HP is roughly 250 to nearly 300 BHP, depending on application and SAE factors used.

David
Hell!!! Thats all a bit confusing. I'm just a simple Petrol Head trying to build an engine that will get my heart racing a bit!!!
Thanks guys!

Martin
 
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