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Discussion Starter · #1 ·
Hey guys. I bought a new Ford Racing X302 small block (306 ci), and dropped it in the car a few weeks ago. I then bought and installed an Edelbrock Performer RPM Airgap manifold. Next question was which carb. Ford Racing's website has specs for the engine at 340 HP "with a Holley 650". However, the data sheet that came with the engine simply said "Holley 600", but no other details or guidance.

Holley's online configurator recommends a 600 if the engine is "mildly modified" or a 650 if the engine is "highly modified", the main difference being whether it's got aftermarket heads or not. Although they're only 170's, it does, so I'm leaning towards a 650. Also, based on the recommendation of the configurator, I decided on a double-pumper rather than vacuum, since the car is light and i like quick throttle response.

The sales guy said either would do, but I'd be almost at the limit of what a 600 could support, so I'd be better off with a 650 in case of future upgrades. I also read bunch of blogs and stuff, and folks seem to be split about 50/50, but they are usually talking about much heavier cars.

Although this will be predominantly a weekend car for the street, I hope to get some track days in occasionally. Also, not sure if it matters, but I live at 4,000 ft.

I'd like to get your feedback and/or experience on this.
 

· Pro FFR Builder and Moderator
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Holley pro series 650 or quickfuel 650 would work really well.
 

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Holley...

650DP or 750 vac sec...personally given the low weight of these cars, vac sec is not necessary so I would lean towards a 650 double pumper.

:rolingtire:let the good Times Roll
 

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I will offer the following:
1) Go with a db carb and stay away from vac secondaries since you have a dual plane manifold and a light car.
2) You might take a look at a Holley dp 600 cfm carb (JEGS has them) I have one on my old auto-x corvette with a 355 motor and it works fine.
3) The Holley HP pro series carb, 650 CFM is a race carb that comes with a milled choke horn and works great for an auto-x or track car. I have one on my 402-Roush motor after removing 760 street avenger that came with the motor. It is cold natured and tends to foul plugs but that may be the cam. I think you will be happier with a the 600 dp that has a choke on it due to your location. The neat thing about Holley carbs is you can change jets fairly easily if the altitude is a problem.
This has been my experience over the years:
HTH
CB
 

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Quick Fuel SS-650 on my 306. It starts and runs perfectly. Not cheap but a very high quality product. You would not be disappointed with how it works.

I've posted this many times before. I suggest you use a double pumper. My experience with vacuum secondaries on these cars was not good.
 

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I'm with Gordon. A 306 cannot handle more than 650 unless you're going to crank this thing, even then?
With a dual plane, do the DP and a 650. You could jet up a couple sizes (1 or 2) if needed but no need to get radical.
My 2 cents, just have some fun.
Jeff
 

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Discussion Starter · #8 ·
Thanks for all the advice guys. I bought a Holley 4150 - 650, DP.
 
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