How to port a front EM? - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 05-02-2007, 09:44 AM   #11
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You cannot achieve equal flow without welding. Take your manifold to a welding shop, Cody. Find out what they'd charge to build that material up for you. Make sure you have a REAR also off the car to compare port sizes to when you do it. You want them equal. This isn't just a matter of 'make 'em bigger'.
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Old 05-02-2007, 09:47 AM   #12
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You don't have to weld under the runners to port the front mani. People have been porting them on these engines for years without welding and they haven't been cracking.
I had an unwelded set from WPI for a while and they went on my buddies car. No cracking there.
There are definite gains to be had going from those terrible casting error riddled ports to a mild port job. You could go farther welding but I don't think it'* worth the extra work. (preheating etc.)
This weekend I'm working on the kid'* car who has those pems. I may be able to make a plug of a runner or somehow measure it to give a better idea of how far you should go. Interested?
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Old 05-02-2007, 09:52 AM   #13
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I saw a set of PEM'* at WCBF that weren't welded on the front. The port sizes were nowhere near equal from front to back. Your choice. Do you want a mismatch (similar issues to the Powerlog) or do you want to do it right. It'* not just a port size issue, either. It'* a direction/angle of flow issue.

Have it off? Do it RIGHT. You want all 6 ports, front and rear (ideally) to be identical. If you're going to do it, go all the way and do it right.
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Old 05-02-2007, 10:11 AM   #14
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So how much would it cost to have someone weld it correctly?
It'* not like they can have this done at the muffler shop. You have to preheat it.
For the cost and trouble to go farther I don't think it'* worth it.
A front mani that is ported correctly without welding is a MAJOR difference from stock size. Not to mention how much the ports vary from each other.
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Old 05-02-2007, 11:48 AM   #15
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Quote:
Originally Posted by 95naSTA
So how much would it cost to have someone weld it correctly?
It'* not like they can have this done at the muffler shop. You have to preheat it.
For the cost and trouble to go farther I don't think it'* worth it.
A front mani that is ported correctly without welding is a MAJOR difference from stock size. Not to mention how much the ports vary from each other.
I'm sure it could be done cheaper, but when I looked at getting Ed Morad to send a stock front mani to W-Body store, then they weld and port/polish, then send to me, it would have run me in total about $150 or so. I passed.

I'm maybe $30 into my "fake" PEM. If I find it to be worthless, I could probably sell it over at ClubGP for 50% profit
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Old 05-02-2007, 11:50 AM   #16
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I would guess most machine shops would charge you no more than $50 to do it. You're only ADDING material to be able to fully match the ports and get them flowing in the right direction so you can port properly. The shop will just add a 'blob' under the 'chin' of 3 ports.

This isn't rocket science. If you get a high quote, go to another shop.
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Old 05-02-2007, 12:21 PM   #17
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agrazela did you really test youre fake PEM like the rest of the thing you have change or its still very new on the car
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Old 05-02-2007, 12:23 PM   #18
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To clarify this,

Bill, you're saying that I need to add material under the front ports? Then port them so they match the rear? Is that correct?

I have a friend that runs a metal shop, I'm sure they'll do it for free.
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Old 05-02-2007, 12:56 PM   #19
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IF you want front and rear ports to match, yes, add material 'under the chin'. So you can grind through what used to be the lower inner wall to match the rear.
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Old 05-02-2007, 01:40 PM   #20
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Quote:
Originally Posted by firebuick
agrazela did you really test youre fake PEM like the rest of the thing you have change or its still very new on the car
If all goes as planned, I'll get test data via PowrTuner on it this weekend. Didn't test it last weekend because we've had a "cold snap" (mid-60'* F) and all my other testing has been at 70-75 F
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