UIM/LIM job, possible L67 TB swap? - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 03-09-2008, 02:42 PM   #1
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Default UIM/LIM job, possible L67 TB swap?

Well, as soon as the weather gets better i am planning on replacing the Upper Intake (the previous owner put one from a junkyard in... ???) and the LIM. I have no record of whether it was ever done. But my question is, is it worth it to port the LIM? i don't have a lot of dremel equipment, and i don't know how well i would be able to do the runners. would it benefit me enough just to clean up the ports to make it worth the trouble of borrowing some dremel equipment? is it feasible for someone who has never done this before? how long did it take those of you that did it the first time?

And willwren, hurry up with your secret Upper Intake mod
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Old 03-09-2008, 02:47 PM   #2
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you dont replace the LIM, you replace the LIM Gaskets, with the GM revised metal ones

from the 3-4 L36'* that i have seen there is nothing to port, the heads and the LIM runners are pretty close. you can smooth the runners for some improved flow and decreased heat
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Old 03-09-2008, 02:51 PM   #3
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i know you don't replace the LIM... but my question was whether it would be worth it to port it..
i have heard just the opposite, that the L36 LIM was horrible compared to the other Engines and would benefit a lot.. but maybe i was mistaken?

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Originally Posted by willwren
The ported LIM is the best bang for your buck for the L36, assuming you do the work yourself and only have to pay for gaskets. It'* far more effective than a gutted airbox or high-flow Cat, but really does go hand-in-hand with those mods. The difference is remarkable, but primarily because the factory port quality (casting) is so very poor to begin with on the L36.
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Old 03-09-2008, 08:10 PM   #4
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I ported mine just 3 days ago and noticed a difference. I didn't have a dremel either. I used a file, to smooth out the ports and sand paper for where my file couldn't reach. I did a fairly conservative port job on mine and had great results.
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Old 03-09-2008, 08:12 PM   #5
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Quote:
Originally Posted by 1993 SLE

from the 3-4 L36'* that i have seen there is nothing to port, the heads and the LIM runners are pretty close. you can smooth the runners for some improved flow and decreased heat
Are we on the same planet here? The L36 is the worst mis-match of any car I've ever seen. There'* a good 15-20% to be gained by slightly UNDER porting. Every single L36 manifold I've seen has made me sick to my stomach.

'Seeing' is one thing. Try measuring sometime.
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Old 03-09-2008, 08:42 PM   #6
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has anyone ever done a dyno, or any type of scan results of a before/after porting job?
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Old 03-09-2008, 10:31 PM   #7
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Agrazela did some detailed scans, jr's3800 did some MAF scans as well, after a combination of a LIM/shaved throttle shaft.

Both of them proved beyond a shadow of a doubt there were serious benefits (to back up the seat of the pants everyone has felt).

In terms of best factory match to worst:

1. Series 2 L67/L32
2. Series 1 L67
3. Series 2 L36 (distant third by a long shot)

I've ported all of these, and hands down, the L36 will benefit the most. Mass production has it'* drawbacks. In this case, it'* factory LIM casting quality.
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Old 03-10-2008, 04:11 PM   #8
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Ok, so i have been looking at agrazela'* VE charts, and between the Ported LIM and the L67 TB, there is a HUGE advantage over stock. would a mini-AFC be all i need to adjust for the increased flow of an L67 TB? would it be worth it?
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Old 03-10-2008, 04:14 PM   #9
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An AFC is a tuning aid. Not much more than a band-aid. You'll want a full-blown tuner to go the way he did.
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Old 03-10-2008, 04:16 PM   #10
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why is it only a bandaid? I don't doubt you, but i just don't see why you would need to do anything more than balance the increased air flow with increased fuel flow, and monitor the output via 02 sensor.
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