questoins and more questions on a 74..

[wolf_walker]

Updated : questoins and more questions on a 74..

New guy here, who hasent gotten around to writing something for the introductions forum, so in the meantime..

Mission: Good daily driver for a woman in her late 30's that dosent want to have to replace things again.

Subject: One pretty blue 74 convertable automatic, matching numbers, base model 350, nothing really special. 100K or so on it, had been resting in a barn for a decade when I started work on it.

To date: VanSteel rear wheel bearings and matched rotors, re-welded GM's slopy crap on the T-arms, adjustable strut rods to replace the bent one's, KYB shocks all around, polyurathane everything front and rear, basicaly new everything that wears front and rear, stearing gear included(except gear box), F41 spec springs fron and rear, stock swaybar in front(for now), brakes are new from VetteBrakes except for the booster that seems fine, U-joints, lots of cleaning, tune up, compression check, more of a tune up, finally found a stupid vacume leak that had been playing havoc with the poor motor, hoses, belts, I'm sure there's more but that's all that comes to mind at the moment. It's been a long project done off and on when I had the time. The owner is a good friend obviously.

Problems:!
1. The vacume leak is from the headlights somewhere, they still work, just slowly(surprise surprise), does anyone make a kit for all the hoses and such or do I just piece one together. Are the actuators likely leaking internaly? Replace or rebuild?

2. The front and rear things that are called bumpers, since being driven finally in the last week or so have devoloped about 12 cracks between the two of them. I'm assuming patching is either not possible or not worth the effort. Anyone make especially good replacements? Any to avoid?

3. After takeing it out for it's first real drive yesterday I heard a vibration. Only on throttle, back off and it's gone, seems to continue no matter your speed or gear, it's upper middle pitched.
My first guess is ujoints, which are all new, and the thought of removeing again makes my head hurt, or the rear differential, which I havent bothered with. It was one of the things I cut corners on, figuring they dont often go out, least not on most cars. One odd note is that I would almost swear it didnt make this sound untill after I had it aligned at the GM dealer(those idiots are awhole different story).

4. This single point distributer has GOT to go, the motor is just begging for more spark. I would like to keep the original due to it haveing the mechinical tach drive(which needs a cable), I'm thinking either Mallory or Petronix conversion kit and a good hi output coil. Recomandations? Also are the stock grade wires and plugs up to the higher energy ignition? I know the HEI used different one's.

I think that's it for the moment. It's been a long and educational journey since I first saw this thing gathering dust in a barn, had sat for a decade, everything was shot. I'm still amazed to see it shining and moveing(and stoping) on it's own. I'll post more of how I got tangled up in this later...

Thanks...


Rex

 

[silver 80]

headlight kit.. yes there allot of companies that sell what you are looking for . just examples corvette central, mid america, paddock, zip, the last detail. there are more but this is just the tip of the berg. try and look at the portal site here it list some great companies to get what you need. headlight actuators have seal and that's most likely your problem with them coming up slow.
bumpers yep I like the flex fit but that's just me. You can get the stock bumpers , fiberglass, flex fit.
I think that ecklers is the best but then that's just me again.
tom

 

[JohnZ]

For the vibration, check the condition/presence of the rubber bushings where the front diff mount bracket attaches to the frame; when these deteriorate (or are stacked wrong when replaced), they allow the diff nose to move upward, and in some cases allow the rear universal to touch the underbody. Even if it doesn't touch, it can alter the operating angle of the rear "U"-joint under load such that it creates a vibration.

For the ignition, just swap out the points for a Pertronix unit and Pertronix "Flamethrower" coil - you'll feel the difference, and never touch points again. Follow the instructions - it needs a full 12 volts. Keep the existing distributor so you'll have a tach. I'd pull it and check it closely, re-shim the bottom drive gear to proper clearance (.002"-.007"), lubricate the upper bushing (hidden grease well under the breaker plate which never gets any attention, goes dry, and scores the shaft and upper bushing - the lower bushing gets engine oil, but the upper one doesn't). At the same time, you can inspect the tach drive gear and lubricate it; nobody ever does that either, and it ends up tearing up both the cross-gear and the mainshaft gear.

 

[wolf_walker]

Great, thanks guys.

JohnZ, that's an excelent idea on the diff bushing, I know I replaced it with one out of the poly kit, weather I put it back in right is a good question. I seem to recall the bushing and a few large washers on it, remember what order then go in or anything special about instaling them?

I was pretty proud of the suspension overall, this is my third full set of poly on a car and I havent had one squeak yet, people seem to complain about that alot.

 

[JohnZ]

Two other Corvette owners have posted with this same problem on other Boards recently, and in both cases they had replaced the diff bracket bushings with poly (same kit for both), and the bushings were the wrong thickness (too thin) compared to the OEM rubber bushings, and were missing sleeves and washers. Dump the incomplete poly kit with all wrong parts and get the correct OEM replacement bushings and install them exactly as shown in the Assembly Manual; all the resto parts houses have the correct kit with all the right parts.

 

[wolf_walker]

I'd almost bet money this is the same deal with mine. It's been over a year but I recall it being a differnent looking bushing. I forget where the kit came from, likely either Energy Suspension of the other big company that makes kits for older vehicles, I'd have to check. I'll look into it this weekend. So it's the pinion angle that's off with the incorrect size bushing?

 

[wolf_walker]

Any idea where I can get the demensions of the stock bushing? I'll replace it with a stock rubber one if I have to, but I'd like to try and make the poly one work if at all possible.

 

[wolf_walker]

update:

replaced bushing with stock, sound still there.

Comes in like clock work @45mph in any gear, only while on throttle, back off and it's gone. Has to be in the driveshaft's somewhere I figure. Could an out of balance shaft do this? Or should I look at the U-joints. There all new, but were a serious pain to install, especially the four on the half shaft's, the things would flex while trying to center up the joint so that the clips would fit in, idea's? And how harmfull is it really?