Some Carb Rebuild Info

[Cream79L82]

Hey guys, got a couple of questions for ya. I want to rebuild my stock '79 rochester q-jet and I've got exploded views of it and some info, but I was wondering if anyone had compiled some info on a similar operation, or knows of a good web site. :confused
I recently replaced my bendix, that googly little gear that transfers power from your starter to your flywheel, and found out that, at least it looks like, my flywheel is not spinning perfectly true. It seems to be rubbing the flywheel cover housing at some point along its rotation.
I'm not super stressed out about it, as the sound it makes is not unlike a huge, awesome cam turning over, but I'm pretty sure it's a contributing factor in at least some of these areas: robbing some of my power, making it harder to get the engine started, causing the tranny to 'be confused' at high rpm's and not shifting, wasting gas, and being a general safety/maintenance hassle.
Do you think it might be affecting anything else? and is there any way of shimming or truing the flywheel up without dropping the tranny and buyin a new one? :eek
Lemme know what you think about any of that and thanks.

 

[Yoda]

I'll defer this to stingray6974 (Mike) Best Quadra-Jet man I know..

He should be along sometime shortly

BudD
i

 

[Cream79L82]

Thanks Rare.

I'll be awaiting his response while we watch 3 college football games at the same time tomorrow. :s

Anyone know what to think about that crazy flywheel??

 

[Jack]

Download these qjet tips from lars.

http://www.corvettefaq.com/c3/QJet_Tuning_Paper.doc

Also, randy has these qjet tips ... from a Pontiac perspective but still correct.

http://www.500cid.com/mts/tech/Quad.htm

If the flexplate on your TH350 is wobbling then you need to replace it ... could be cracked (launches at dragstrip right?). There's 3 bolts in large circle holding it to convertor & 6 more in small circle holding it to crank. Put in park, Drop the starter & inspection cover & loosen crank bolts first & convertor bolts next & push convertor back into trans a bit & pull out flexplate ... you should be able to remove/replace it with motor & trans in car.
JACK:gap

 

[Stingray6974]

I'm not quite sure how to answer this one. Having rebuilt hundreds of quadrajets I can now do them with my eyes closed. If you haven't ever been inside one or watched someone rebuild one I wouldn't recommend doing it yourself.
All flexplates have a little wobble in them. As for the symptoms you described, the flexplate won't cause any of them. What kind of noise do you have? Only when starting or after the motor is running? I would be more suspicous of a warped inspection cover.

Mike

 

[Cream79L82]

Thanks for the responses guys... sorry I haven't got back with you yet. My computer power supply went out and I had to fix that. Just not as fun working inside the computer case as the beast.
This past weekend I drove from Norman, OK to Stillwater to Bartlesville, OK on saturday and the same trip sunday. That's well over 300 miles, and she's still turning good, but I think the flex plate is probably the culprit for that annoying sound. To see if it was that inspection cover, I took it off and drove all the way back down here with it off. It was superfluous, as I can hear the noise as soon as I start it up and stick my head on the ground. How much should I pay for a flex plate?? Thanks for the links and the help thus far men. Probably be under her tomorrow.

 

[cntrhub]

You sure it's not the Bendix hanging up after starting? Sounds like you only hear it when first starting? You might need to... ever so slightly... loosen the start bolts, click the starter so the starter shifts a little. Tighten the starter bolts and see if the noise went away? Maybe the Bendix is not retracting? In that case, you might need to replace the starter. Since the shield is off, look at the flex plate teeth and see how ground down they are?

 

[Cream79L82]

Well the teeth are ground down some, but I think that could have been because the last bendix wasn't shimmed in there properly. I've got it dang near 1/8", and if I go any closer, the bendix does indeed not retract and gives me a terrible loud, annoying, scary sound. I'm pretty sure it's not that, and the sound is that as long as the motor is turning over, from idle to 100 :cool Trust me on that. Keep coming up with ideas though, all. Thanks.

 

[cntrhub]

If you have things "crunching" up in bell housing cavity, there sure will be telltale signs of metal chips. Take a flashlight and look up along the sides of the bell housing. See if there is any aluminum powder going on up there? It should have told you something when you dropped the shield cover. Move the flex plate all the way around, and see if there is any shinny spots? Usually it will be on the engine block side of the flex plate. The Trans side has quite a bit of clearance and i would suspect either a flex plate bolt is working it's way out, or the flex plate's outer edge "could be" hitting something on the engine block side?

 

[Jack]

How much should I pay for a flex plate??

Don't bother with a used one.

About $16 - $25 new, locally for an OEM replacement type.

If your flexplate is cracked (I still think that's a distinct possibility) and you're gonna continue dragstrip launches ... I suggest an SFI-approved type. They're a bit thicker (less prone to crack) and a bit heavier (helps improve launch). Jegs, Summit etc have them for under $60 ... probably no more than $75 locally. If you R&R flexplate, do use new convertor bolts & crank bolts ... not hardware store stuff.

 

[Cream79L82]

The teeth on the flex plate are quite shiny on the block side, and there were plenty of metal shavings in the inspection cover when I dropped it. I just thought those were from the old chewed up bendix, but there is obviously a lot of wear on the block side teeth of the flex plate. Right it looks like I should probably buy a new plate and all the bolts to match huh? Let me know if that gives you any other thoughts. Thanks all.

 

[Cream79L82]

Well I got under her and played around for a while and finally decided there was no way to get the flex plate/ drive gear/ flywheel bolts that connect it to the torque converter off without dropping the tranny. I really didn't want to do that.... but she'll have to spend the night without a starter, crossmember, tranny fluid, or an exhaust from the long tubes back. Come to think of it, when I get it all back together, I might accidentally forget to put the pipes back on.
Other than the whole process costing me a few bucks and cutting in hard to time that should have been spent on writing a report on Quintus Hortensius the Roman orator, I'm not too worried about finishing it up this weekend, except for one thing.
Do you think there is a possibility that the torque converter itself could be warped? It spins real easy in its axis and it doesn't appear to 'drift' back and forth... I just would hate to fix it all up and still have a problem.

Oh and cntrhub.... I do believe you were right when you said something about the flex plate hitting something. The teeth are really chawed in some places and one of the block to flexplate bolts I took off is pretty well shaved on one side. Time to read the Haynes.

 

[cntrhub]

The torque converter is very easy to spin. This is normal. The run-out of a converter is pretty rare. There is a little bit of float of the torque converter going in and out. Meaning, that you can move the torque converter away from, or back to the flex plate, for clearance and line-up. This too is normal. What you don't want to do, is pull the torque converter all the way off the input shaft!! This will soak the floor with Trans fluid and also, when you reinstall the converter, you have to spin the converter back on... to line up the pump and converter teeth. If you slide the converter on, it will slide on the input shaft and look ok, but when you go to put the Trans back in, the converter will hit the flex plate way before the bell housing meets the engine block. This is how you know you didn't line up the gears between the converter's inner fan and the pump in the Trans. By spinning the converter, and lighty pushing, it will engage the gears, then slide deep into the bell housing and make a big clunk, telling you it's home. I'm not trying to confuse you, but if the Trans was shifting ok when it came out, it should be all right going back in. You don't need to service the torque converter.
I would though, check the 3 threaded flex plate holes in the converter. If you can't screw the bolts in by hand without any one hole binding, then you might need to either tap and salvage the hole or replace the converter. If you need to replace the converter, then knowing the above information will help reinstall the converter correctly.
Replace the converter's seal, if you "do" need to change out the converter. Some converters come, with or without fluid in them. Remember to prime the converter with a number of quarts (4) of Trans fluid no matter what.

 

[Cream79L82]

Alright.. I think I'm going to leave the torque converter alone, because I don't think there is anyway to tell if it was malfunctioning since the flexplate was so bad. It previously was not shifting from 2nd into 3rd while floored, but after looking under there, it seems to me, for no explainable reason, that the flexplate's 'wabble' at really high rpm's could quite easily be "messing with" the torque converter enough that it wouldn't shift properly.
When I let off the gas, she'll shift immediately and I can peg it again, but of course, with the 3.36 rear-end, I'm so far down in revs it absolutely slaughters my 1/4.
Everything is disconnected from my tranny besides the cooling lines and this one stupid driveshaft bolt, and she's just resting on a board on a floor jack. I know this is a precarious position to be in, but I thought I could just lower it a little bit once off of the engine to where I could get that last driveshaft bolt that is on the top left, right out of workable reach. Is there anyway I can make the tranny tail spin the driveshaft manually???? I've already take off the flexplate to converter bolts of course, and it doesn't seem to want to rotate by hand or by torquing on a big screwdriver run up through driveshaft coupling.
:bash :bash :bash Oh yeah, and while tightening the LAST tranny pan bolt back on after draining it, I snapped the d@mn bolt head off :slap with the shaft of the bolt neatly threaded in the tranny case. Any special precautions here, other than don't screw up the tranny case??

I would greatly appreciate help and suggestions stemming from anyone's experience with similar problems. Thanks alot. orship

-Jon

 

[cntrhub]

Turn the crank at the front of the engine. Crank the engine clock wise. Looking at the front of the engine that is. This will move the bolt in a better position than reaching at the top for it.
If you have the enging cocked at an angle and the Trans is still in the way, you might be jamming the converter into the flex plate and that's where you're binding up, i.e. = hard to turn. Jack the engine up a little to clear the converter.
That shift problem sounds like the governor or modulator? Make sure you have a good vacuum hose on the modulator and is air tight between the intake manifold and modulator hose fitting.
Drop the Trans pan again. If you're lucky, you could take a small pointed punch and drive out that broken stud with light taps, moving in a circular motion. Try not to hit the aluminum case, or else you'll cave in the aluminum around the metal stud.

 

[Cream79L82]

Man this sucks. I've finally got the tranny sitting on the floor of my garage with only a few inconveniences... except for the big two. I didn't bother trying to rebolt things together to get the driveshaft to move... I just got on my bike and pedaled to the store to invest in one of those crazy Universal pivot socket things. Good investment. I've still got that old pan bolt shaft broken off in the cover, but I haven't tried the cold chisel method yet. I might just have to have some good ole fashion drilling fun. The worst news of all, however, is that flange for the bolt on the top left of the tranny case broke off somehow on the way down. I really don't know how it happened. I was just lowering away when I heard a piece of metal hit the ground and my heart just sank. My best guess is that I got hung up on the top of the flexplate over there some place and that aluminum just decided to give. I am suddenly very interested in finding a way to bond aluminum together very sturdily and inexpensively.... translated, is there any way I can fix this problem short of having to buy a new case??? :confused I know I read on the package of my JB Weld that some guy had used it to repair the engine block on a caterpillar. Does anyone think this might be able to work??? I know it's probably pretty important to keep the surfaces where the engine and tranny meet really smooth, but if there are 5 other bolts holding everything tight... couldn't a strong enough bonding agent do the trick since no one place will be under a massive amount of stress?? Spread the word to any of your friends who might have tried something like this. Thanks alot.
-Jon

 

[Jack]

Heli-Arc it

/JON ... I am suddenly very interested in finding a way to bond aluminum together very sturdily and inexpensively.... translated, is there any way I can fix this problem short of having to buy a new case??? I know I read on the package of my JB Weld

Jon:
Sorry to hear of these difficulties. Since you have the tranny out, I would haul it to a weld shop. Heck, that thing may've been cracked already ... were any tranny bolts loose when you began to remove?
JACK:gap

 

[cntrhub]

JB means: J-UST B-LEW up the rest of my Trans! What if that JB welded piece of aluminum fell into all that spinning mass of high RPM at the most inopportune time? Take the broken piece and Trans, and let a welder bring back the integrity to the Trans case. It's not worth the chance of emaciating the rest of the Trans case.

 

[Cream79L82]

None of the tranny bolts were loose when I began to remove them with my regular old crafstman combo wrench. They weren't very easy to move at all. I do think, however, that the case being cracked before I lowered it is a distinct possibility because I just can't see how it could crack on the way down. I mean, if that flange had got caught up on the top of the flexplate on the way down, I think I would've remembered a pop or a noise of some sort before I heard the piece hit the ground 8" from my head. I'm going to buy a fly wheel puller tomorrow so I can finish the swap and start putting her back together. I took a healthy chunk out of my right middle finger trying to do it the old fashioned way... looks like I'll be riding my bike to campus for a couple more days.
-Jon

 

[Cream79L82]

Well I got the tranny mounted back into my car. I got that broken off trans pan bolt by working it around with a cold chisel, then Dremeling a slot in the top of it so I could then screw it out with a little phillips. I'm goin to take those trans cooling lines to a specialty shop so I can hooked up with a new fitting. I'll let you know if everything else goes smoothly.
-Jon