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Intake Runner Question

Posted By: Mr PotatoHead

Intake Runner Question - 11/05/21 08:51 PM

Im working over a smog 318 intake in hopes of putting it on my lil cheater 318 thats not a 318 and would like some input on what I might do further on the runners from the plenum area.

Also pictured for examples are box fresh intakes from the same time period (almost) first the TM5 and then the Weiand? X cell.....

So would I follow that thought process or is there a better way before I start cutting more out.

TIA.



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Posted By: B1MAXX

Re: Intake Runner Question - 11/06/21 12:53 PM

Just my first reaction, You should't use the other intakes as guides. Runners are larger, and plenum doesn't have those cast in bulges between pairs. So you have to look only at what you have for improvements.
I don't think you can remove the plenum reducers between the pairs of ports I think they are cast in, you could reduce them some. Thin up the dividers, and put a open spacer on it. If your 318 has 340-360 port heads on it that intake will never work. If it has 318 port size heads on it I really would't do much, I'd put a 1 or 2" spacer on it. and call it a day. Judging by the size of those runners I'd start my shift rpm about 4800. That's the main thing I'll say, imagine doing a full runner port/enlargement on every runner. Use the part as intended, for a nice little 2 bbl 318 upgrade. twocents
Depends on what your intentions are.
Years ago I had a 79 power wagon with a 318 bone stock, I put an sp2p and a holley 390 cfm double pumper (one of the early circle track carbs). There was nice, noticeable improvement over the stock 2bbl set up.
Posted By: Moparite

Re: Intake Runner Question - 11/06/21 01:58 PM

What are you objectives? Mid/upper rpm performance?
Posted By: Sniper

Re: Intake Runner Question - 11/06/21 02:33 PM

Originally Posted by Moparite
What are you objectives? Mid/upper rpm performance?


With a Streetmaster intake? Wrong application if so.

Best use of a Streetmaster intake is to sell it. Scrap if nothing else. It was a crap intake even back when it was new.

A regular Performer would have been a better choice for all around improvement. A stock 4bbl intake would have been a better choice as well.
Posted By: B1MAXX

Re: Intake Runner Question - 11/06/21 02:44 PM

Originally Posted by Sniper
Originally Posted by Moparite
What are you objectives? Mid/upper rpm performance?


With a Streetmaster intake? Wrong application if so.

Best use of a Streetmaster intake is to sell it. Scrap if nothing else. It was a crap intake even back when it was new.

A regular Performer would have been a better choice for all around improvement. A stock 4bbl intake would have been a better choice as well.

I disagree a little, a stock 340 intake on a 318 port head is a bad mismatch, that street master is better for a 318 port.
Posted By: Sniper

Re: Intake Runner Question - 11/06/21 03:03 PM

Having run a stock 2bbl, a 360 4bbl, a Streetmaster and a Performer intake all on the same 87 2bbl 318 base engine I stand by my comment. The Streetmaster is not worth the cost of the tootsie rolls to clean it up much less paying for one. Een the so called mismatch issue between the 360 intake and the 318 2bbl heads was an noticeable improvement over the Streetmaster.
Posted By: B1MAXX

Re: Intake Runner Question - 11/06/21 03:19 PM

I have not run a 340-360 port intake on a 318 port. But I do know what a head flows like with a large step in a runner. That's all I am going by, theory I guess. Even Chrysler put 360 heads on 318's with 4 bbls. shruggy
Posted By: Sniper

Re: Intake Runner Question - 11/06/21 03:57 PM

Originally Posted by B1MAXX
I have not run a 340-360 port intake on a 318 port. But I do know what a head flows like with a large step in a runner. That's all I am going by, theory I guess. Even Chrysler put 360 heads on 318's with 4 bbls. shruggy


Chrysler also put 360 heads on the factory 4bbl 318's. Just grabbed the entire top end from the 360, cheap and easy. Too bad they didn't put a decent cam in too and some compression. I'm not saying the bigger port intake on a smaller port head is optimal, I am just saying it's better than the Streetmaster.
Posted By: Mr PotatoHead

Re: Intake Runner Question - 11/06/21 05:47 PM

Lets not forget how this intake was cast and this is how many view it, in its org. form.


The TM5 was not the best but it was ok, and this in reality is nothing more then a smaller TM5.


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Posted By: B1MAXX

Re: Intake Runner Question - 11/06/21 09:12 PM

up don't make it anymore expensive than it already is. sawzall
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