Ford 300 inline carb question

I am putting a 300 six in my 64 Ford pickup daily driver and have bought a 4 bbl. intake from of the board. My question is if the little 390 CFM Holley would be a good carb choice.I mess around with flatheads and some use the 390.My thinking is that if I get the little 4 bbl. that I might have a carb that can be used on a lot of apps. The 300 is a stock motor with duel exaust and a stock ignition.Thanks!

 

I googled carburetor calculator and 391 cfm is just right.

 

The last couple years that motor was built, it had a neat cast dual exhaust header.

 

stock EFI headers (with a Walker downpipe for single exhaust byp***ing cat conv).

Holley 390 is a good carb for your 300. The edelbrock 500 can be too, but I think you'll be happy with the 390.

 

If you are buying new, those are expensive carbs.

I have a 600 holley, 4160?, one on a 283 and one on a 304AMC. Both run really nice and they are not a high priced carb.

I had a 300 in a bronco. dual exhaust, and an Offy 4 bbl manifold but I ran a 2GC Rochester on that. The engine really woke up with better exhaust and intake.

 

Yup! They seem to be a little high-does anybody have one for sale-hint?

 

I had a 300 CID six in our shop van. Replaced the 3 on the tree with a 4-speed, and changed to an Offy intake with Carter 400 CFM (part number 9400s) AFB. When I junked it after the body rusted out the third time due to salt and cinders (thanks Missouri road departments) the engine had almost 450K miles, and the head had never been removed.

Jon.

 

The 390 on a stock, or near stock 300 will be just dandy. If more heavily modded a 500 cfm would be better. 300's are silly cheap to work on while being very likeable engines. If you have a carbed head with stud mounted rockers, buy & install a set of Chevy 250 inline six rockers. The Chevy rockers have a higher ratio at 1.7:1 versus the stock Ford rockers at 1.6. Gives a performance increase, (small) easier & less expensive than a cam change.

I see you have dual exhaust. If it was / is a fuel injection motor than you will have pedestal style rockers. The above mentioned upgrade won't work. Fuel injection, (and cast dual exhaust manifolds) were on all 300's from 1986, (85?) to last year 1996.

Fantastic motors. 7 main bearings, forged rods & gear driven cam right from the factory. Also about 60lbs lighter than the legendary 327 Chevy. Weakest link in the 300's were cheap cast 300 pistons prone to skirt failures. Next would be head gasket issues if the compression is turned up much over 10:1. Better head gasket, (Felpro 1024) & ARP studs allow 11:1 without trouble, maybe more.

Have fun,
Worken2nuch

 

If you are using a six cylinder and you are the popular fomulas do not work right and you will wind up undercarbed. This is because a 6 cylinder does not know it is a 6 cylinder . In your case you have a cylinder of 50 cu inches . Whether that cylinder is in a 6 or an eight (or a 12 cylnder engine for that matter) it still takes the exact same amount of time to fill it at any RPM. I was a long tme figuring this out and in my younger year undercarbed probably all my 6 cylinder projects. What I do and it may not be perfect but it works is when doing CFM for a 6 is first make it an eight cylinder So your 300 ford 6 becomes a 400 for caculation purposes. Using my formula (aka Don's Law ) you simply double the cubes to get CFM and go to the nearest available carb size . Going to the nearest Up for race and the nearest Down for street. This will give you a 750 for street use and a 800 for race. Will it run with a 390 cfm carb ? Sure but the original carb was probably not far off that and a pair of them would certainly exceed that CFM. Even using conventoanl methods and ignoring the real lfe situation I get above 500 cfm and even using Dons law would have a minmum size of 550 cfm on it disregarding the piston volume make it a v8 thing. This is not "I think" technology. This is from the dirt been there done it many times. Some people will be able to understand what I have said , (cylinder of that size has only a certain amount of time to fill) others wont. it is however regradless so . So you say your saying a 300 ford six cylinder can use a bigger carb than a 302 V8? YES I am. Having been involved in many six cyl projects both mild and wild I will also say I think it would be very difficult to overcarb a 300 ford six. It is a very good engine and probably one of the best Ford motors ever built. Long stroke, big bore decent head. Would eat most Ford V8s of similar size for breakfast given equal tuning. Do i put my money where m ymouth is? YesI am currently running a 246 cube 6 cylinder with a hydraulic cam that never sees over 6000 RPM (about 5800 max) on 650 cfm carb with an automatic.
BTW I have "built few 300s for customers as well. Both budget builds and $$$ builds.
Don

 

I have a Holley 4160 on my GM V6 262 CI, it runs pretty good but I thought I was over carbed and was going to look for a smaller carb this weekend... glad I stumbled on Don's post, guess I'll leave it alone.

 

Wow! Thanks for all of this info.This sort of stuff has saved me more time and money than I can remember. This is why this board rules!

 

Don knows his stuff. We couldn't get a 300 I built to run right with a 390 on it, replaced it with a 650 off the 400 we replaced with it and presto. Ran great and pulled hard.

 

Don brings up a good point, and if at all possible mess with some carbs you may have laying around before spending the money on a new Holley 390. Anything that fits, is still better than the stock 1bbl, IMO (especially the early 80's spaghetti mess), and now you have the intake to use. I thought you already had a Holley 390 from your original question. I put one in my '79 Bronco plow, after it came out of a construction truck, and has near 300,000 miles on it, and the head has never been removed on it either. They are perhaps the best engine Ford ever built. I've done research on this engine for the time I decide to rebuild, and I've read the Holley 390 works better if the power valve is swapped to a brown one, IIRC. Also the Edelbrock 500, and even the Ford Motorcraft 2bbl perform better and get better mileage than the stock 1bbl. Some neat builds are done by Frenchtown Flyer and Colonel Flashman, putting out over 300hp. You won't be disappointed with this engine no matter what, IMO.

 

My 300 with Comp 270H Cam, Headers, and Offenhauser Intake runs great on a 600 Holley. Good Mileage and excellent power, plus it starts and idles well.