Intake compatability
May 21st, 2020, 5:19 PM
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Intake compatability
I have 1976 stock (maybe mild cam) 454 with 366781 heads (oval port). I just got a factory aluminum high-rise intake number 19131359 (rectangle ports).
Will be test running the engine with a Holley 750 (10569)
Can anyone tell me if its a compatible setup to test run the engine?
Thanks
Will be test running the engine with a Holley 750 (10569)
Can anyone tell me if its a compatible setup to test run the engine?
Thanks
Last edited by Brian270; May 21st, 2020 at 5:44 PM.
May 21st, 2020, 11:13 PM
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May 22nd, 2020, 8:38 AM
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The difference between the oval and rectangular ports, I'm thinking that the bolt pattern is different and I'm not sure which gasket would work to provide a working seal between the two. Again this from old memory but I think the oval port heads were the desired heads but the down side to going to the also required an intake change to match them making it more expensive doing the swap.
May 22nd, 2020, 10:05 AM
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The difference between the oval and rectangular ports, I'm thinking that the bolt pattern is different and I'm not sure which gasket would work to provide a working seal between the two. Again this from old memory but I think the oval port heads were the desired heads but the down side to going to the also required an intake change to match them making it more expensive doing the swap.
I verified the bolt pattern is good before taking the intake so that's ok.
I spent a bit of time online last night and found that there was a lot of info regarding mismatched ports which I will share for the benefit of anyone else looking to do this. Many of the articles lean towards it not being an issue backed up by dyno runs by a few.
The rectangular gasket is used (larger than the oval ports) and the only restriction is a portion of the top of the oval port closing off some of the intake manifolds rectangular port.
Some have said they believe it causes more swirl to the mixture as a small benefit. Hmmm.
There was an article by a fluid mechanics engineer who believed that since the mixture is under suction it won't pile up on the sort of dam created and cause issues but will create more turbulent flow which could be beneficial to an extent.. Hmmm again.
If it was being pushed by a super charger would be a different story so he says.
I'm sure there are arguments both ways on the technicalities but we are not building a 600hp+ motor so based on my research think we should be good to go.
Thanks for the words of caution which prompted me to look further.
Cheers
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