Urgent Questions About My 3.8

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Renthorin

Greasemonkey
Jan 5, 2006
107
0
0
Michigan
This is the one that comes to mind:

http://store.summitracing.com/partdetai ... toview=sku

But I think it has the Monte tail pipes that exit straight out the back and I prefer out the sides.

If you already have the muffs you might be better off going to a muffler shop and seeing what they will charge you to piece the system together.

You would only need the Y pipe and the two over the axle pipes. That kit from summit includes a test pipe in case your cat 'accidentally' falls off........

If you go with a 'cat back' system you will be screwed into buying muffs which I think you said you already have.
 

averagewhiteboy

Master Mechanic
Jun 7, 2006
370
1
0
Pittsburgh, PA
I already bought a Thrush Turbo muffler (still new), OR I can buy my friends lightly used pair of Dynomax Super-Turbos for real cheap. So I may stop over at the shop and see how much of a price variant I'll run into fabricating the single muffler (stock set-up), verses the Y pipe duals.

I know I've heard a few cool sounding GN's for sure, but I couldn't ever see my GP sounding cool until I get a V8. lol. And yes, I'd rather go for side exits... But I don't really care too much...
 

G_Body_Enthusiast

Royal Smart Person
Supporting Member
Feb 28, 2005
1,056
16
38
Louisville, kentucky
i have a 3.8 and i like the engine. sure its not a power house but the biggest flaw IMO is that POS dualjet they put on them. i had a 4.1 and it ran tons better and the biggest difference was the 4 barrel carbs. its been said the dualjet is the worse half of the qjet and i believe it. the qjet from a 4.1 wouldnt be any worse on your gas mileage than the dualjet as long as you lay off the secondaries, otherwise expectt the gas gauge needle to drop like a stone on a regular basis.

IF you switch to the 4.1 intake and qjet make sure you pull the cip out of the computer as well, i was advised to do this when i was talking about doing this conversion.

some things i have done to my engine was improve ignition, i put in a hotter coil for better spark, i still use stock plugs and it runs better than it did with the stock coil. i use bluemax wires, they work and they work well. moroso makes them and IMO they are worth it. i also switched out the cap and rotor for an accell cap and rotor. they use brass terminals and i think it makes a difference.

i also put on a muffler. i didnt bother going with a cat back, its just a 3.8 and doesnt need a catback unless i do something like stab a cam in it and put headers on it and if i put headers on it i'm redoing the whole exhaust to get the most out of it. but that's just me. i put on a hooker maximum flow muffler and it works great. sounds better and it did improve performance just a hair.

my engine doesnt like to be hot, it hates it so i dropped in a 160 degree thermostat then yanked the belt driven fan and radiator out for an electric fan and plastic tank, aluminum core radiator. the car now runs cool consistently and as a result performance is more consistent. not only that but taking the stock fan off improved performance by being one less thing the engine had to turn. so its been a win win all around.

even with all this my car was being tested and passed emissions every time, in fact it seemed to test better after i got done doing this stuff. the ignition upgrades helped a lot. of course a new cat will hide shortcomings in the emissions department...lol.

if you want to keep the 3.8 and want some performance out of it consider a rebuild, or look into something else like a 4.1 and build it up if you like V6's.
 
Sep 1, 2006
6,687
31
0
Tampa Bay Area
One interesting thing to point out is that the computer has nothing to do with the secondaries on an electronic Q-Jet. It only controls the primary side of it through the mixture control solenoid. These primitive computer systems go into an open loop mode when at WOT, because they lacked the computing power to control it. The O2 sensor is not referenced at this time, so it may be possible to run this setup on the stock computer if you use the setup from the 4.1 liter car. Be sure to use a Q-Jet air cleaner base too, as the 2 bbl one won't fit.
 

Uncletruck

Master Mechanic
Apr 22, 2007
442
0
0
Erie, PA
I have done a few swaps on '81-89 GM cars with the computerized carb (mixture control, TPS) to standard non computerized carbs. This swap is well worth it if you can do it. You do not have to change the distributor or do anything regarding the timing other than adjust it a bit after the swap. You still leave the computer in, and remove the check engine light bulb from the dash. (IMPORTANT: Don't do this swap unless you live in an area where don't have to worry about emissions tests!)

The only thing you have to change is the throttle kicker, if you want to use it for your A/C. With the computerized carbs, if they develop problems and you don't have to worry about emissions, you might as well just toss the carb in the trash, they are complete junk IMHO. I have recently swapped a non-computer Rochester quad in to an '85 Caprice that had the computer Quad, and also did the same on my own '81 Malibu wagon with 229 V6 and computerized Dualjet. Both cars run a million times better with the non computer carbs, (No more annoying part throttle flat spots, or wandering idle) and the cars get about the same MPG. I sometimes touch up the timing after doing this swap to be sure the engine does not detonate on hard acceleration. Other than that, it's that simple. If you swap in a close year GM carb (I put an '80 unit on my '81 Malibu) the vacuum outlets are nearly identical.

Computer Command Control isn't really a computer by today's standards, it is a feedback circuit board with no memory or any real processing capabilities. I'm no expert on it by any means, but I believe there were four systems to it that worked independently, fuel, timing, TC lockout, and EGR. The timing end uses the distributor and a detonation sensor. The fuel end uses the oxygen sensor, mixture control solenoid, and throttle position sensor. The EGR solenoid is activated by the engine temperature sensor. I'm not sure how the torque convertor lockout switch ties in to the thing, but on the cars where I disconnected the MCS and TPS for the carb swap, the TC lockout continued to operate at the proper vehicle speed. In performing these carb swaps, I found deactivating one system does not throw the other systems into a "loop" or anything that shuts them down. Others I talk to say the same thing- the timing end of CCC is great, the feedback carb system, forget it.
-Mark-
 

Uncletruck

Master Mechanic
Apr 22, 2007
442
0
0
Erie, PA
Non CCC Dualjet swapped on to 229 V6 that had CCC feedback carb.

http://gbodyforum.com/photos/albums/use ... 0_1020.JPG

THis car is my daily driver. Nothing to cheer about performace wise, but it runs, idles and accelerates very smoothly with the non-CCC Dualjet, and gets respectable MPG.
-Mark-
 
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