Once again I’m swapping over from a 351m to a 300 on this 77 4x4. The ‘79 300 motor I got didn’t have an exhaust or intake manifolds. Locally I found wrapped headers for a 300. I’m not sure if it’s worth it or not and how it all fits up with being a 4x4.

With the V8 exhaust manifolds they dump past the motor perches while the I6 headers seem to split around the motor perch unless I’m miss understanding it wrong?

 

Headers just make the horrible sound of a 6 cylinder a little louder and any increase in performance would have to be measured with a micrometer.

Find a stock manifold and skip the leaks and heat problems.

 

The stock manifolds from the EFI 300’s are what you want to get. They are cast iron and don’t trap your starter either. They should still be plentiful in junkyards.

 

Look for EFI exh manifolds... unless the headers are for a 4x, you'll just aggravate yourself trying to fit them in. On my 79 4x w/300 I used the EFI ones Y into 1 - 2.5" pipe, short (12") glass pack as close to engine as I could and then out behind rear tire, sounds nice at idle and has a nice cackle, if you like that. Had headers on 2 of my 2wd trucks, really only noticed it with the one with the more aggressive cam. The EFI ones are easiier to work with and keep the exh away from the starter more, AND if you have to change the starter you don't have to fight with the headers...

 

First, never ask a v8 guy anything about a 300. If you go on Fordsix.com, in the 240/300 forum, you find links to dyno test vids. One of them shows that a long tube header adds 10 hp. As far as leaks go, get the type with ball and socket collectors and you'll never have a leak. I have run headers for 10+ years w/o a leak.
However, the Hedman long tube header does make your engine compartment an oven, and the carb sits right on top of that, so there may be some vapor lock issues, unless you use the old style, non aluminum Holley. They are immune to the heat. Having said that, you can get the best of both worlds by installing a set of EFI era exhaust manifolds. Those 3 into 1 manifolds, with a nice flowing exhaust, and you'll be happy. No heat and better performance.

Here is a set: https://www.ebay.com/itm/29682465430...Bk9SR4iZyOD4ZA

 

yeah after I posted about the headers double looked at my truck I realized I don’t want to deal with it. I’ll do there efi style manifolds or an old school exhaust manifolds. Right now I’m trying to go the least of path of resistance. I could change things out later

 

Agreed. Unless you’re doing supporting mods the choke point is mostly still in the head via the lazy cam. I doubt you’ll notice 10HP and it’s not worth the hassle. Go with the EFI manifolds.

I personally think inline 6s sound pretty good. V6s… that’s another story.

 

IF in your travels you find a HD 300 out of a medium truck, those log manifolds are a bit better than the stockers in pickups. Not sure about fitment as they exit differently, but I think you can see if they would fit in your truck just by looking should you come across one.

FWIW. This thread also has good pics of the EFI manifold setup.

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

 

On that 10 hp gain I want to know if just header or header & intake / carb? Guess it was header / intake / carb as I cant see just a header doing that.

As for leaks it is not at the collector but the head / flange that warps and blows out the gasket.
I have run a non-Ford header and not had a leak at the head but the header was not cheap either.

Sound with headers on a 6 be it straight or v6 will never sound like a v8. Heck ever hear a flat head v8 it also dose not sound like a modern v8.
Most straight 6 headers are 3 ports to 1 outlet so you have 2 outlets, just like the EFI cast manifolds.
Now how you go from there is up to you. My header truck had a shop made Y pipe to single to a small turbo muffler and tail pipe behind the rear tire.
It had a nice sound at idle and when on power it barked some but not really that bad.
My 81 F100 I run EFI manifolds to a factory replacement Y pipe and 94 F150 system bake to tail pipe. No cat and run a Thrush welded muffler.
Nice rumble at idle and would say at speed too but I am never outside when it drives by
I am still running the factory log intake / carb and air filter as I was looking for better MPG and have it look factory under the hood and get parts at any parts store.

I also konw of a 85 F150 w/300 running EFI manifolds & Y pipe, offy intake and Snipper 2300 EFI with an adapter.
Has a glass pack muffler and tail pipe behind tire, no cat and it is really too quite for him & me. He dose have a welded muffler like I have that he want to install so we will see.

To me on any motor a lot has to do with the muffler(s) and where they are placed.
But there is no way a 6 will ever sound like everyone of the v8's that are out there
Dave ----