i have a quick question regarding a 2x4 setup on a basically stock 348. what size carbs would be best for a driver car? i'm putting a 348 with a 2x4 setup and th400 in my 54 chevy 2 door sedan. not a race car, just a driver. any help would be great.
i wouldnt go bigger than 500 cfm carbs for a daily driver and with no other mods to the engine that is still going to be too much.thats just my opinion.
joeb, I used a pair of 450 cfm holley on my jet boat engine when I wanted fuel economy. 660 center squirts when I wanted more than gas savings(610 dyno'ed 468 BBC 2-4's on a tunnel ram). Your engine running at 100% efficency can only pump X amount of air. A total of 650 cfm is about correct (I didn't bother doing the math) anyway two four's closest to 650 or 700 should work fine. To some degree smaller carbs will perform much better in your application, remember, you said basically STOCK........JMO............ruggs
I couldn't help myself, I did the math for ya, Giving you a red line of 5500 rpm at 100% VE your 348 can only pump in the area of 553 cfm TOTAL. Two baby fours is all you need.......Just my opinion.......ruggs (P.S......Build it or blow it and these numbers change)
I'd agree to the 390 holleys. I've done many 351 Cl;eveland 2v engines with tunnel rams and used 390- holleys when tuning them for street use - These turn out to be a great choice as at this size you still have enough air velocity to make the power valves and jets work. You have to remember that on a carburettor it is air speed going down the throat that sends the signals to the carby as to what it needs to do - go too large in cfm and you kill air speed and the signals are not right and the tuner then has to use other means to compensate for the lack of "signal" - like fatten up or reducing jets and then you find they are running too rich or too lean. Its another case of bigger is not necessarily better. Sure there are instances when a larger pair of carby's will work well however on a stock engine with mild camming you only get so much "****" per intake stroke and the air speed created needs to be used wisely to keep the engine running as it should. The one thing I have always borne in mind is that you cannot change the laws of physics when mucking around with engines
Merf and 35Desoto made the best choice, another option is to use a pair of larger carbs but disable the secondarys. It would work but the 390's are the better choice...Just another of my opinions.............ruggs
Another vote for mini-Holleys, I've got a pair of 390 cfm Holleys on a mild 306 ci Ford and they work quite well.
I agree on the 390. Most of us "T" bucket guys around here are way over carbed. I run a 600 Edlebrock only because I got a deal on it. The darn 500 was more expensive.
One thing nobody mentioned yet is throttle response. On a mostly stock street driven motor, it seldom sees more then 2800 RPM's. Bottom end response is much better with a smaller carb.
Will the Holleys fit on the manifold inline, or will they need to be sideways? I would suggest a pair of 400 CFM Carter AFB's. Either part number 9400s or the superceding 9410s would work. These may be mixed or matched. The Carters can definately be installed inline. Jon.
I am using dual 465 Holley Vac Sec's on my 460. Price Motorsport Engineering (PME) has them already set up with with Vac Sec Links installed. If not, use the 390's or a set of 500's from Edelbrock w/ progressive linkage. No Double Pumpers!
I always love these posts and responses because my car must be the acception to the rules. I've got a 355 sbc, small 490 lift cam with 9-1 compression and run two 600 cfm Carters on a low profile Offenhauser intake. I've been driving it for a few years now and it idles to 6200 just fine with those "two big" carbs on there. I don't think there's a carb out there that you're just majicly bolt on and run, they all will need tuned. Don't be afraid of a bigger carb if you come across a pair for a good price.
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