Intake manifold options on stock sb350

[brassnut]

Good day,
My intake manifold has a stripped thread on one of the 4 mounting holes for the carb. I want to replace the intake manifold but have seen that intake manifolds offer different opening styles depending on the type of carb you have. I will be keeping the stock 4 barrel Qjet carb and cannot understand the different bore types on the intake manifold.

So, here are the basic questions I am hoping I can get a little help with when choosing a good replacement intake manifold:

1- Type of bore (square or spread)
2- Steel or Aluminum (advantages/disadvantages)
3- Plane style (single or dual)

Also, how will I know which intake manifolds are compatible with my heads?

Here are some of the specs on my setup:
81 K5
4 bolt main, stock sbc350/th350/208
hedman elite headers
stock hei distributor

If I forgot any important info, please let me know.

Thanks,
Austin

 

[Bowtie85]

Good day,
My intake manifold has a stripped thread on one of the 4 mounting holes for the carb. I want to replace the intake manifold but have seen that intake manifolds offer different opening styles depending on the type of carb you have. I will be keeping the stock 4 barrel Qjet carb and cannot understand the different bore types on the intake manifold.

So, here are the basic questions I am hoping I can get a little help with when choosing a good replacement intake manifold:

1- Type of bore (square or spread)
2- Steel or Aluminum (advantages/disadvantages)
3- Plane style (single or dual)

Also, how will I know which intake manifolds are compatible with my heads?

Here are some of the specs on my setup:
81 K5
4 bolt main, stock sbc350/th350/208
hedman elite headers
stock hei distributor

If I forgot any important info, please let me knoow.

Thanks,
Austin

Edelbrock performer RPM is a good choice, the only real different intake for a sbc is the 96 up vortec style fwiw. Anything pre 1986 is what your looking for.

Stick with a dual plane.

You will also need a different kick down cable bracket as well, I don't know the edelbrock part # off hand that I recently used.

 

[dyeager535]

Do you want to replace the intake, or is the stock one fine?

A variety of methods to repair those type of threads, certainly cheaper than replacing the intake if that is a concern.

 

[brassnut]

Well, i would like to replace the intake manifold gaskets as I suspect they are leaking. I figured I might as well do a new manifold to cure the stripped thread problem. Is there any benefit to a more modern manifold , like the one bowtie85 suggested?

Thanks

 

[919jackass]

shoot me a pm if your interested i have a new performer intake i would like to sell

 

[dyeager535]

I really can't answer if there will be a benefit. Generally stock heads suck for flow anyway, not sure an intake will pick up appreciable power without better heads and exhaust.

If anyone has dyno comparisons on a stock motor with standard heads and stock intake vs. aftermarket, I wouldn't mind seeing them. It does not seem like there is much data on the stock intakes in terms of flow.

The reason for recommending dual plane is port velocity, and going with a better flowing intake of any design, with heads as the bottleneck may very well cause a decrease in power. My suspicion is that if performance is better or worse, it's unlikely to be much. But until I see hard numbers (and not marketing numbers) that's not necessarily fact.

 

[Bowtie85]

Idk if there is a true gain with just a performer intake, internet searching differs quite a bit I found.


I've never upgraded a intake w/o a motor swap at the same time. So I can't speak on the differences/gains.