I'm sure it's been done but have any of you guys had it work out and actually run ok? I have a *****in tunnel ram I want to run but can't afford new heads Posted using the Full Custom H.A.M.B. App!
Yes. The rectangular port intake can be run on oval port heads, have not done the tunnel ram but have used other intakes with single four barrel. Just remember not to over carb...
I've done it running a rectangular port Dart intake on my oval port heads. The engine would RPM about 600 higher over a Holley Strip Dominator intake.
Have a friend who's using a rectangle port tunnel ram on oval port 454, and it doesn't run well. If it's a good buy, I'd get the tunnel ram and either resell for profit, or try to trade for an oval port tunnel ram. I'm running an oval port Weiand on Edelbrock oval port heads with twin 600 vac. sec. Holleys, and it works so nice!
I've seen it where guys make the oval heads into pseudo rectangles by port matching them to the rectangle gaskets. Then let them quickly transition back to the oval port. Then it doesn't have a big weird non matching stop as it p***es to the head.. Anyway that's one option. Posted using the Full Custom H.A.M.B. App!
Ran an L-88 square port intake on oval port heads for years,and never missed a beat,make sure you are using square port intake gaskets.
I talked to Jeff Smith at Car Craft about this a while back. They had done some testing and in the 600HP range it didn't make a lot of difference. You have to remember that when the column of air is moving through the manifold and ports, the outer edge is fairly calm while the center is where the velocity is. At higher RPM it could cause some issues but you will probably run out of port size before it is a problem.
Well there you go. Couldn't be that he cant tune worth a ****. Running a square port intake on oval port heads works well. Throw the square port intake on a flow bench, and map the port opening with the pitot tube, and the reason why will become clear.
I have some buddys that have done it with single 4 carb and clame to have been there best runnig street engins.
I ran a square port, single four intake on oval port heads on the BB 402 in my '57 Chevy. I just used what I had available at the time. It ran very well and would pull the front wheels off the ground running on the street...no tuning problems...
I don't think you can compare one intake with another. The differences in port shape on a hi rise, or lower intake, and the same differences on a tunnel ram with twin carbs are not equal. As well as a hi rise might work, tunnel rams don't seem to work as well with mismatched ports. Likewise for blower engines. Putting a square port blower intake on an oval port head will give all sorts of fits. I got my oval port heads this way. The original owner tried to put a square port blower intake on them, and never could get it to run right, nor could several good tuners. They finally swapped to rectangle port heads, and I bought the oval ports cheap.
With the amount of parts available these days, running mismatched intake / heads is a variable that could just well be eliminated. Everyone's combo is different, so someone else's setup could work fine but in no way indicates what would happen on your car with the parts you own. How about selling the rect. tunnel ram and picking up one that matches your heads? The Edelbrock Street tunnel ram I run is around $400 new and about 1/2 that on the used market. No, this doesn't address the OP question. But you could buy/sell/swap and end up with a matched combo for $200 or less.
Have had a sq. port tunnel ram on oval port heads for 13 years now on my model A pickup, many many miles ,works fine ! Chris
Just epoxy the runners in the intake and port match them to the heads, I don't know the epoxy's name but have run several sets of heads that were epoxied to maximize flow on a flowbench.
http://m.summitracing.com/parts/drt-70000003. Search epoxy at summitracing.com and many choices come up, a call to the tech line will verify if its correct for intake runners.
This... http://www.devcon.com/products/products.cfm?brand=Devcon&cat=Metal Repair But you are wasting your time re-shaping the port exit on a BB chevy sq-pt intake, the corners you are filling are virtually dead as far as air-flow anyway.
This has worked fine on my car for 29 yrs. Do you think I should change it now? I didn't know there was a problem till the experts chimed in!
Back in 1966 (late 1965 actually) a friend and I both bought '66 SS 396 Chevelles with 360 hp 396s (just prior to the release of the 375 hp version). For a very short period of time the Chevrolet parts book listed the 425 hp/427 rectangular port aluminum intake at the same price as the cast iron oval port intake. When we were informed about this oversight both of us ordered the rectangular intake...........cost us less than $40 each. Both cars initially used the single feed Holley that came on the 340 hp engines and both ran really good with a slight jetting change. I eventually put a 780 Holley (stock carb for the 375/425 HP 396/427) and it added 2-3 hundred rpm to the power peak. Frank
People have done it Give it a shot. Intake gaskets are cheap enough. I was gonna do it with a big block cross-ram I have, But i didn't have a second carb so i just sent with a regular single carb oval port intake. Mothballed the cross ram, One day!
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