I think it's time I jump on board and go for the offenhauser intake and holley 390. I'm also going to the junkyard this weekend and I'm going I try and find a set of the efi exhaust manifolds. My question is, seeing that I want to get it all done as quickly as possible but at the same time I'll have to save up for the upgrades. Where would be the best place to look for a used offenhauser or a 390 carb?

 

Craig's list or eBay.

 

Yup, you can generally find them on both.
If you're looking for new, though, there's always summitracing.com

 

Ok, I'll keep looking on both. I was just looking on summit and it seems they have a c series and a dual port. What is the difference?

 

The C series is fully open and can accommodate any carb from a 1 to a 4bbl.

The DP (dual plane) ONLY works with a 4bbl, and has individual internal runners for the primaries and secondaries. The design is supposed to boost throttle response and gas mileage, but is only really recommended for stock to mild builds.

I have both, and personally, I'd go with the C. The DP is nice, but it's pros aren't really noticeable.

 

Awesome, thanks for the info! That's exactly what I needed to hear. Is there anything I should know before trying to install this? I'd like to have everything in some what order before I start.

 

The new ones aren't too expensive. Make sure to get the C-series and not the DP.

 

Best to fab/install the heat plate for the bottom of the intake before it's installed on the engine.

https://www.ford-trucks.com/forums/1...ing-plate.html

 

I need to add one bit of information and one correction. The correction is that the DP is a dual port, not a dual plane manifold. The info bit is that another good source for parts are auto swap meets.

When dealing with ebay and Craig's list, keep in mind that the cost of a new manifold includes a warranty.

 

maybe you can answer a question for me since you have a 300 with a offy 4bbl manifold.
i was looking at the manifold that jegs has for sale and they said it will not fit a fuel injected 300. i have a 300 that was an efi engine and it currently has a factory 1bbl carb manifold on it. so if the factory 1bbl fits the efi head then why would the offy 4bbl not fit the efi head? im putting the 300 in a 74 crew cab and was planning on efi exuast manifolds and the 4bbl intake. i bought the exaust manifolds and walker pipe already and then gegs told me the manifold wont fit. are they as wrong as i think they are?

 

If you are working on a budget don't over look running a 2V carb on an Offy C-series intake. You can pick up a 2V carb cheaper then a 4V one and it's also a little easier to tune.

If you do go with a 4V the Holley 390 isn't my first choice. It can be a little finicky to get tuned right on a 300. The Edelbrock performer 500cfm is a simpler carb to tune.







The only real exterior difference on the efi head is a couple additional manifold bolt holes. The Offenhauser intake will fit the EFI head fine.

You may need to do a little grinding here or there where the manifolds meet each other. But other then that you should have no problems using that intake on the EFI head.

 

thats what i thought too. the guys at jegs dont know what they are talking about. i have been thinking of the c series manifold and running a 2bbl autolite carb that i already have . i drove a 300 once that a customer had in the shop with a 2bbl on it and it ran really strong.

 

If the two barrel was good, image how it would get up and go with a 4 barrel. Or, another way to say it, is a two barrel is a four barrel with a governor.

A two barrel is a four barrel without the rear barrels. With a 4v you drive with the front two 98% of the time, then only use the secondaries when you're passing or getting on the freeway.