Chuck84TA

By the end of the month - Hopefully - my 355 build that I started a year ago will be up and running.

I have decided to gut it out with my E4ME Qjet. For no other reason than to see what happens, since I already have it and recently rebuilt it.

I did the following to the carb

Bushings for the Primary and Secondary throttle shafts
















Replaced the black cover -- cracked





The fuel filter installed was the wrong size!!! Go figure!! Could that be why I had idle issues with bogging sometimes or at WOT??





Then I had the throttle plate sanded down to alleviate any warping






Also adjusted the secondary stop so the secondaries can go the full 90*

But what happened during the rebuild might be classified as dumb luck....
I was trying to remove the idle air tubes but I broke a drill bit in the thing ..


I called Cliff Ruggles... He told me to send it to him, then I told him I was building this carb to work with a 226/234 cam, and he said.... Well you'll need larger tubes anyway, I'll be sure to get larger ones in.



So here we are... It also has a new MCS, TPS for good measure...

Chuck84TA

Cam profile-

Chuck84TA

So then, I called GMCOPO to help with burning a PROM to run on a later model ECM -- very much like the ZZ4 but with the following modifications

No EGR
No Charcoal Canister
No Smog
No EFE
No Thermac
More aggressive timing.

We shall see....

Chuck84TA

Ok, so far it idles better than expected....still needs a tps adjustment....showing 75 volts on the autoxray 6000. I'll check it again after the timing is set

Chuck84TA

Some key things that I noticed...

1-I don't think the Mixture control solenoid worked on my old carb....don't remember hearing that ticking sound before

2-Doing all that's necessary to stop vacuum leaks is absolutely mandatory -- bushings in throttle bores, sanding down plates, plugging potential leaks..etc.

3-replacing all electrical solenoids

Damon

Ah, so you got it up and running. .75V at idle isn't that bad. The ECM/programming in these things is pretty "stupid" when it comes to various things being a little out of adjustment. In all likelihood you are going to need more throttle opening to hold an idle with that cam anyway, so it will read higher. Make sure it still gets over 4V at WOT if you decide to back off the TPS adjustment to get the idle volts to read lower. You don't want to adjust it into range on one end of the scale just to put it out of range on the other.

Alternatively, you could also open up the idle air bypass ports (not the IAB- the OTHER idle air bypass system) a little to help you get the throttles closed a bit further.

Chuck84TA

Yeah, funny thing is.... I actually never have to hold down the gas pedal to keep at idle, even when the fans kick on. Its running much better than I expected, Ill try to get pics of vac readings and scanner readings later today.

Chuck84TA

But on a side note, took this out for "quick" spin..... I think Im going to need drag radials just to keep from fishtailing!!! lol

RamIt

Very curious how this turns out Chuck.
I have a Vortec crate sitting in my garage with a 218/228 112 Lunati cam.
I just ASSumed that the quad and computer would have a tough time driving in traffic.

Same setup in the Vega but it has a 650 Holley dp. Traction is a joke but it weighs a lot less.

Chuck84TA

It will be a little while .... Gotta put this new trans in first...
Hopefully get this thing running more consistently early next week

Chuck84TA

My guess is that if you get the later ECM, rebuild the carb,you should be good to go...I think yours will probably run smoother

Ozz1967

iTrader: (4)

Man I remember when my Qjet was that clean! Good looking build going on there!



I also have a 355 with a CC Qjet only I had Cliff Ruggles from www.cliffshighperformance build it for me. I love it and it runs very well. Going on 25K miles now.

I don't know all of what he did, but I know he moved my TPS voltage up to around 1.0 at idle. This helps keep it on the idle circuit due to the lower vaccum of my cam. Speaking of which... my cam card and dyno reading after initially putting the build together are in the attachment. Following a better tune on the carb I jumped all the way to 262hp and 281 ft-lb of torque at the wheels. I'll find the dyno sheet and post it if you want.

Overall the carb handles a moderate cam well and the car will pull and run all the way to the RPM drop off of the intake I'm using...around 5500rpm. With my new built trans and 2800rpm stall, the car really scoots!

----Edit----

Found my updated dyno day results.

Ozz1967

iTrader: (4)

I am curious to see this as well because I've been told that it wasn't worth trying to burn these old ECM's...

Ozz1967

iTrader: (4)

Basically what you described is what Cliff did for me...raised the voltage at idle to compensate for the lack of Vacuum I'm pulling. He also did some work on enlarging the idle circuits a bit. Should do good for this motor in his build as well.

Damon

Yeah, Cliff is almost as smart as I am.

Ozz1967

iTrader: (4)

Wish I were closer so you could show me how to properly tune this thing by myself. lol

Ozz1967

iTrader: (4)

Also, don't use the factory filter in the nose of the carb. Get an in-line filter that flows better and leave that little paper nose filter out completely. With 7PSi I still had issues keeping the bowl full when running the car hard.

Took it out, ran a separate filter and that fixed my issue.

Chuck84TA

And the results.....

Chuck84TA

Mixture control dropped ... I think that's supposed to be 30? It dropped down to 37 after adjusting it...quite sensitive though

Edit- I also noticed that this setting changes from different starts. Sometimes it's 78 sometimes 30 something

Chuck84TA

Vacuum pressure seemed steady between 11-14 inches.

Timing (base) was set at 20-25. BTDC. No knock sensor indications

Chuck84TA

Thanks Ozz!

Chuck84TA

Idle is most certainly choppy as youd expect. It idles at approx. 1000rpm. You need to "gas it" every now and then when you turn corners in idle, so it certainly isn't the best in terms of driveability

RamIt

Hmm.

Did the later model 3rd gens use a pressure switch in the power steering high pressure side? I am just thinking that you might to be able to incorporate that with the throttle kicker solenoid.

naf

iTrader: (7)

87 LG4 used a power steering low pressure switch that either engaged the kicker or disengaged the AC compressor. With AC it cut out the compressor under low pressure, the throttle kicker was already engaged with the compressor. Switches are different, one NO other NC. System couldn't do both.

With that cam and idle I'd assume you're getting some nozzle drip?

Chuck84TA

I didn't think of that --
I need to adjust the
Idle solenoid a bit-- that will probably take care of that issue

Damon

This is the point where you start thinking about a higher stall converter. With lockup function, no, they aren't cheap. But it'll help with your low speed drivability and idling-in-gear issues.

Chuck84TA

So, higher stall converter? I've got a TKO-600.

Damon

Whoops. Sorry. I even went looking for your specs in the first post and my eyes still went right past it.