I have a 4 barrel intake C5AE9425C of a 65-67ish FE motor. I would like to put it on my 68 390 but the intake ports are larger than the one's on the heads C8ae-H. Will the intake still work?

 

Yes. As long as the gaskets seal on the heads and the intake. The Ford intake ports were always larger than the head ports. Your heads likely have a similar ports as the medium riser 427 engines and the intake probably is more like the earlier low risers but they should match up good enough to run. A closer port match would be better.

 

The C5 intake has large runners while your heads have small runners. It will work but it is not really the best way to go.

Oh and moto is wrong, the intake runners are always smaller than the heads. The only exception was the 427 industrial engines.

 

I believe you need to look at some unmolested heads and intakes as the step at the of the port going into the head is an engineering design, not a flaw. It is there to creat a tumbling effect which helps raw fuel get atomized and into the airstream. The design is not real pretty but it is effective at the lower rpm range of the engine. A normal street engine does not need matching or polished ports as they rarely go into the rpm range where it would be of benefit and as the fuel/air mixture transforms into a "wire draw" type of pattern at high rpm the mis-match is of little consequence to an engine that is not in the highest rpm range most of the time.

 

Now that's good news. I have a terrible port mismatch with my after-market intake. The top and bottom of the head ports stick up (or down) in the way of the airflow by quite a bit...maybe as much as 1/4 inch, but a bit less I think.

Oddly, the sides are the opposite with the head ports wider than the intake manifold ports.

Basically, tall narrow intake ports, short wide head ports.

It seems to work well, although I have no doubt I'd be better off with a dual plane manifold vs the one I have.

And of course, I have no way of knowing if it works better or not if the ports were more closely matched. I do tend to think it's more an issue at higher rpms though.

 

The factory almost never did this an never on a performance engine. It screws up the air flow. Simple physics tells you this. I said it would work, BUT it is NOT the correct way to do it. Either match the ports or the head should be bigger.

 

And you have an Engineering Degree specializing in Flow Dynamics to substantiate your statement?

I'm only relating information learned from a research paper written by Ford Engine Engineering and submitted to the Society of Automotive Engineers and from personal experience.

 

I have enough smarts to understand flow dynamics and reversion pulses and how to stop then and create them (they are bad things). Your way creates them, my way stops them.

 

It's not my way. It is an engineering principle that has been proven. I once believed the way you do but the SAE paper that I read taught me different and I had to revise my thinking on the subject. For race and high rpm uses the closest matched ports are the best. For normal street use, the way Ford built it is best. The newest engines, the modulars, have pretty good port matching as is but they also have fuel injectors in the ports, almost at the valves. There is no need for the tumble effect there.
The newest designs, possibly the Boss engines soon, are supposed to have direct injection into the combustion chambers.

 

 

If that's the best rebuttal you have, you ain't got nothin'

 

The best I have is:

"Never argue with an idiot.* He will drag you down to his level and beat you with experience."*

 

My thoughts exactly and you said it. Thank you.

 

well looks like we have a bit of

 

Its running...