berkleyjet

So my question is... can i use a rectangal port intake on oval port heads? the heads are larger than the oval port intake that came off, but not as large as the rectangular port intake i have. the ports measured on the oval intake 1 5/8" across, the heads were 2" across and the new rect. intake is 2 1/2" across.

gerry72

No. It will bolt up but it won't work very well. It is possible, but not advisable, to use an oval port intake on rectangular port heads since the flow path is going from a smaller manifold intake port to a larger cylinder head intake port.

berkleyjet

no you misunderstood me. i want to use a rectangular port intake on oval heads. so it would go from larger openings to smaller openings.

Mr D.

Yes it will work. I had this setup on my 66 427 and had no problems at all. Use the round intake gaskets.

gerry72

I didn't misunderstand you at all. I was simply explaining that it is functional to go from smaller to larger but not the other way around (you want to go from a large manifold port to a small head port). I pointed out that you can bolt a rectangular port intake onto oval port heads but, and you can visualize this, you're running the flow path into a dam and expecting things to be alright. The engine will run (if you use the right gasket) but it's a very poor performance choice. The only way I could see doing this is in dire circumstances (dead broke, got a free manifold, need to get the car running to get to work tomorrow). And depending on which oval port heads you have (the standard, early ports, or the peanut ports) it could be even more irregular.

fauxrs

:iagree:

Definitly not the plan if you are looking for any kind of real performance, out of your oval port head. There are reasons you could do the opposite, but there is no good argument for running a square port manifold on an oval port head.

If you cant presently afford an oval port manifold, ask around on the forum, someone here must have one they could let go for cheap, if you can...well then there isnt any reason why a edelbrock performer, or performer rpm shouldnt be purchased and installed instead of the rect port manifold.

berkleyjet

well heres the story... i currently have a edelbrock performer 2-0 oval intake on. but as we all know the stock hood wont work. i am replacing the stock hood on the car and i need to get a manifold that will work. i got a GM alum high perf. manifold that is rect. port.. when i removed the intake i discovered oval ports. :( thus my delema. :confused:

fauxrs

If you are replacing the hood I assume you mean so that you can have the needed clearance and if so then why put on a different manifold. Or is the new manifold an interim fix?

If this is just an interim fix until you can get a new hood installed an painted then I guess I might consider it. I would never consider it a solution to your problem - A permanent fix would be to resell (or if possibly return) your new manifold and opt for one that provides the needed hood clearance.

427Hotrod

Years ago, it was very common to install rectangular port intakes on oval heads. Mainly becasue no one made a decent oval port intake. Of course these days it's no big deal.

But to do it right, you HAVE to open the heads up to match. That takes a good bit of grinding and you need to go into the port almost 2" to make it taper without being to stupid. It is functional, and it will make more power, but it's a lot of work to make right. It can be done on the engine. You can tape off lifter valley REAL good and fill ports with shaving cream to catch metal debris. Then attack with grinder and use vacuum cleaner to suck out shaving cream with metal shavings inside. Not the best way to spend a weekend, but it will work!

Otherwise, if you aren't concerned with performance, you can just bolt it on and drive it, but know you are giving up LOTS of power!


JIM

gerry72

Question then: Do you need to complete the process because the car is your only transportation?

If "yes" then you may just be stuck for a while with an inadequate solution.

If "no" then take the time to get a manifold for your head type that will fit under the hood. By not caving into haste and doing it right you will come out far ahead in the situation. Oval port intakes that will work for you are not hard to come by. They are only slightly more rare than dirt.

I must say that your further input only makes things more confusing. You're replacing the stock hood...so what are you replacing it with? Sure, with the stock hood you are limited to low profile intakes but if you're replacing it with something like an L-88 hood then you can use just about any intake short of a tunnel ram.

berkleyjet

no the car has on a raised hood now. i want to put the stock big block hood back on, but i need to get rid of the edelbrock manifold that is on it now because the stock hood wont close. so that is why i am looking for a shorter manifold. i would like one that will give better performance than just a stock manifold.

berkleyjet

also i was confused when i removed the edelbrock oval intake last night. the oval ports on the head are larger than the ports on the intake. they are somewhere in between rectangular and oval ports. is it normal for the oval intake to be that much smaller than the head?


[Modified by berkleyjet, 4:08 PM 7/2/2003]

gerry72

For a Performer manifold smaller manifold than head ports are normal. The Performer is a lower rpm high velocity intake and uses a small runner cross section which consequently makes the ports smaller than the factory manifolds. It's just a different flow technology which is why in many cases a Performer performs not measureably better than a stocker other than saving some weight. The manifold also has to fit the much smaller peanut port heads so the manifold's ports are really quite tiny.

You really do need to get a low-rise factory or factory-type intake to make the situation satisfactory and, again, they are fairly common. Many folks say the Edelbrock Torker has a suitable height but it won't look stock and being an open plenum intake won't make as much grunt down low.