Smokes AFTER rebuild?! Nooo!!! - Team Camaro Tech
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post #1 of 14 (permalink) Old Mar 29th, 02, 01:14 PM Thread Starter
 
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Location: Estacada, OR
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Hey all, I swear camaros.net is the best troubleshooting source on the net. Here's the deal, I just rebuilt a TPI 305 for my 85 IROC. Now, the beaut runs like a damn top, and have about 400 miles on it so far. I have been breaking it in nicely, driving sane, changed the oil at 300 miles (looked great), and keeping the RPMs below 3000. However, at 3000 RPM (Typically where I shift at the latest) it will puff smoke between gears. I have stopped on a straightaway, and from idle to 3000 in 1st gear, at about 2/3 throttle, it just took off, NO SMOKE. I stopped the car, put it in park, and held the gas, no smoke up until about 3000 and up. Did I "fudge" up the ring install? Is there any hope? Do I need to perform rebuild #2? Everything is new if not rebuilt, it had valve guide problems before, but these are different symptoms, and they were replaced anyway. I'm hoping the rings just need to seat more completely and that I just need to take it easy. Thanks for the help, I hope for good news!

Ben - Chevy408
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post #2 of 14 (permalink) Old Mar 29th, 02, 01:33 PM
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what kind of tranny ?? if it is a auto the modulator valve could be bad , they will draw trans fluid up thru the vacum line ,
just a thought , earl

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post #3 of 14 (permalink) Old Mar 29th, 02, 05:04 PM Thread Starter
 
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It's a 700r4. I tried an exercise where you cruise at about 30mph/3000rpm and apply to brake and gas to load the engine for about 5 seconds, then cruise up to about 50mph, and yank it down a gear so it will buzz up to about 4000rpm. The 1st part is supposed to help force the seating of the top rings, and the 2nd part is for the 2nd rings, no real difference noticed. However, after more tests, the smoke has an almost gassy smell, as if the mixture were too rich. I tried disconnecting my cold start injector but no luck. I checked my plugs and they were picture perfect.
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post #4 of 14 (permalink) Old Mar 29th, 02, 05:46 PM
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Can you tell what color the smoke is? Does it idle dead smooth? Does it seem to run as well or better than before the rebuild? Was the engine bored? What kind of rings?
Sorry for all the questions
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post #5 of 14 (permalink) Old Mar 29th, 02, 06:01 PM Thread Starter
 
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It runs 10x better after the rebuild has a very smooth idle (aside from cam lump). However it has recently started some funky problem where at about 2500rpm it runs real choppy. I've tinkered with ignition timing, but no resolution, it seems like an induction problem of some kind. I suppose I should have mentioned that earlier but it just now comes to me that it could be related (perhaps directly). The smoke is the average dark puff, but not black, more of a charcoal haze, you can see through it. Above my rear bumper where the tips dump there is black soot, like you'd find on a rich mix/fouled plug.
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post #6 of 14 (permalink) Old Mar 29th, 02, 06:02 PM Thread Starter
 
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It was bored 30 over and has hypereutectic pistons with Speed Pro rings.
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post #7 of 14 (permalink) Old Mar 30th, 02, 09:56 AM
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just some thoughts:
Might be mixture or tuning related problem.
If it were oil you would see high oil consumption.
If the old engine was using a lot of oil there could be a lot of soot and oil residue in the exhaust system that is burning out when you get on it.

If just one of the little O rings slipped off during cyl head assembly it can cause it to drink a lot of oil. I messed one up and it drank a quart in half a tank of gas!
David


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post #8 of 14 (permalink) Old Mar 30th, 02, 02:47 PM
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Hmmm...you mentioned cam lumpiness. What size cam did you install? If you put in a big aftermarket cam in that thing then there are a lot of possabilities here.
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post #9 of 14 (permalink) Old Mar 30th, 02, 05:07 PM Thread Starter
 
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I put a 270H Comp Magnum Cam in (224вк int and 224вк exh - 0.470" int and 0.470 exh).
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post #10 of 14 (permalink) Old Mar 31st, 02, 04:07 AM
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I am not a fuel injection expert, so maybe someone else can chime in here, but that much cam in a computer controlled engine is going to freak your computer system out. FI engines require a certain amount of engine vaccuum to operate properly, and to keep everything working within the specified parameters burned into the chip. When you get outside the factory set vaccuum range, things get wierd. Hopefully someone else can elaborate on this.
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post #11 of 14 (permalink) Old Mar 31st, 02, 08:33 AM
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I'm no expert on these systems, but here's a fiew things I have heard.
You would need higher flow injectors, and a full recalibration of the injection to make it work.
Just the move from a 305 to 350 by GM required higher flow injectors. A hotter cam would have less vaccumn which would trigger the computer to add more fuel.

David

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post #12 of 14 (permalink) Old Mar 31st, 02, 01:40 PM Thread Starter
 
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I stepped the injectors up to 22lb/hr, and have an air:fuel ratio gauge with normal readings. Also a hypertech chip has been installed to allow for such modifications. As far as the cam, I was worried about that too, but it's given no problems (unless this is it), but I have installed Rhoads lifters to smooth the bottom end. The lifters are supposed to expand to full length when cruising down the road or when you've got your foot in it. Perhaps 3000rpm is when they fully expand resulting in too much lift. But the car runs good at 3000rpm or under a load, I think the cam is about the limit, but works fine.

[This message has been edited by Chevy408 (edited 03-31-2002).]
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post #13 of 14 (permalink) Old Apr 1st, 02, 05:04 PM
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Are you running the stock chip? If so check out thirdgen.org computer section. Someone on there might be able to burn a custom chip for you or you can do the research and burn your own. An option you might think about is to ditch the EFI manifold and run a carb with a non-computer HEI. Since you have an overdrive tranny you'll still get good MPG. Non-computer is just easier to run and adjust IMO. Plus once you break in the engine that intake might run outta juice on the top end for that cam.

You can still pass emisions as long as you get a CARB approved intake and you keep the cat. Just something to think about (that's what I'd do).
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post #14 of 14 (permalink) Old Apr 1st, 02, 05:44 PM Thread Starter
 
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I've got the Hypertech Thermo-master chip installed. I went through a lot of trouble to calibrate this TPI system (ported and polished + many aftermarket replacements) and feel it will turn out just right, afterall, it is a 305.
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