So, currently rebuilding my 300. Turns out it's a '75 block and a '72 head in a 1985 1/2 ton truck. Truck has had complete ECM delete and is using a blue grommet Duraspark II ignition system.

The engine is bored .040 over and will be using stock pistons. I will be installing the EFI exhaust manifolds. I'm thinking I'd like to also obtain an Offenhauser intake and 350cfm Motorcraft 2150 2bbl carb.

This won't be a race machine and I rarely tow. It is however a work truck and I do quite often carry extremely heavy loads. I'd like to get a little extra oomph out of it, because it was somewhat of a pig before even after having installed a rebuilt engine some many years ago. I would like to get somewhat decent gas mileage and it's rarely if ever driven over 65mph.

I have the NP 435 manual 4 speed (w/granny 1st gear) transmission and 373 rear end gears. 255/70r15 tires that are almost identical height to the stock 235/75r15's that it came with.

I guess my real questions are:

1. Do the Offenhauser intake and 2bbl carb actually give me anything beyond the stock intake and 1bbl carb without also changing the camshaft profile to something more aggressive like an RV or Stage 1 cam?

2. If not, what camshafts should I be looking at that will offer mildly better performance but still offer pretty decent mileage. I don't mind a slightly lopey idle, in fact, if I can get something that doesn't worsen the already terrible mileage it was getting (Which might have been at least partially due to the engine condition) too much, I'd prefer it, but it's certainly not essential.

Low and midrange power along with fuel mileage are probably most important to me, but I can stand a small loss of mileage if the quality of performance gain is worth it. I don't expect to be running any quarter miles and again, I don't much drive it over 65, but in between 0-65 I'd like to see just a little more overall and general performance out of it than it was stock. I'm not totally against going stock though if I'll still see some improvements over the factory log intake and 1bbl carburetor even without stepping up the cam.

Also, I'm planning to go with a master rebuild kit from Northern auto parts. If anybody knows of any reason why I SHOULDN'T go with a kit from them, please explain why. Looks like their kits are made up of mostly Federal Mogul, Perfect circle, Melling and Victor parts, so I don't really see any issues there, but maybe somebody has an insight into why a person might have a bad experience dealing with Northern. Thanks.

 

Yes, the intake and EFI exhausts will help extend the useable RPM range of your engine even without a cam change.
Even with a better cam the loss in low end performance would be nil-to-none.
I would expect to see the fuel consumption rate be commensurate with the amount of power you are using; i.e., if you use the additional power you have obtained expect the fuel consumption to increase accordingly.

 

Howdy Flyer. So, any recommendations regarding the camshaft profile? I'm looking at the profile of the camshaft they include in their kit, which is a Melling #SYB38, and it seems to me the specs are somewhat diminished from the factory camshaft profile so I may not actually want to use that camshaft.

Since this kit is for 67-83 engines, it's certainly not supposed to be a computer or California emmisions compliant unit, but it seems as though that's what they're including. I might be wrong on that but that's my suspicion based on product descriptions from several online vendors.

Just wondering if you have some measure of experience with the 300 and if so, perhaps you have some other observations or recommendations to offer. I have a good deal of automotive experience having worked in this field for a fairly long time, however, when it comes to some of the finer points of engine rebuilding I have to confess that I am limited in that regard since almost all of my experience has been limited to strictly mainstream stuff. Primarily chassis, driveability and non-performance applications.

Currently I'm loosely considering the Melling MTF-6 stage 1 camshaft, but only loosely as I'm looking at other alternatives as well. Aside from OEM equivalent stuff, I have little experience knowing who are the preferred but still budget friendly camshaft manufacturers. I am of course familiar with most the names in the industry like Crower, Comp, etc., but simply because a name is well known doesn't necessarily mean that's who you want to go with. I know Melling is pretty solid, or at least they have been in the past for mostly stock applications.

 

https://fordsix.com/viewtopic.php?f=2&t=62982

Take a look at that...