The Stovebolt Site Forums The Shop Area Engine Shop Tired 283

I just bought a very straight 1966 c-20 p/u with a tired 283 with powerglide. I drove it
on the freeway home and could not get past 60 mph. The oil pressure was very good,
did not waver and temperture stayed cool. So my question is, Do you think it just needs a valve job, (that's what Im thinking) or do I need to go through the whole engine. Also the 2 spd auto trans was not slipping but did not seem to operate the way
it was supposed to. Starting out, I had to manually put it to low on a couple of small hills since it would not drop in on its own. One other note, I was told the truck sat for quite some time and that may be a factor. Thanks for any help you can give. Steve

Mastkey, Glad to hear about you new acquisition. I would never advise rebuilding only the heads on an old engine, you will only be asking for problems later-ie, excessive wear on the rod and main bearings. Are you certain, since it has been sitting so long, that you don't just need to flush the tranny? I believe I would try that first, it may cure all ills. Oh, and change the old oil in the engine. And, you shouldn't really talk about how nice a truck it is, some fellows on here are the jealous type-LOL. At least take a picture so we can see it.-LOL

Steve,- I forgot-
Welcome to The Stovebolt Page- Enjoy

Thanks for the advice, I will try changing the tranny fluid first, then on to more expensive options. The engine oil has already been changed and new plug wires, cap and rotor. Ill try to get a picture and put in on the web as soon as I can.

Don't get ahead of yourself. Do a diagnostic of the engine and see whats going on.
Any smoke?
2 or 4 bbl?
What are the head #s? (under valvecover)
What is the block casting #? (driver's side of bellhousing behind cyl head.)
Do a compression test.

The engine may just be badly out of tune. You can also take that PG out and swap in a TH-350 very easily.

I did get a small amount of smoke when I first started up the truck. But once I took off and was driving down to freeway, I would check in the rearview mirror, let off the gas and see if I had any smoke, but it seemed clear, so that was good.
It is a 2 barrel and the other info Ill have to check on (head# and block casting #.
Im not sure what that info has to do with how this runs but Im sure you'll let me know.
:-). Just picked up the truck yesterday so haven't had a chance to do more than clean it up a bit.

A small amount of smoke after starting is normal due to the valve stem seals. They get hard with age. I will recommend a full diagnostic before tearing down the engine. Lots of things it could be that don't require major surgery. Check the points and plugs. Compression check will tell what the rings are like. A leakdown test on each cylinder will tell if the valves are seating. Hook up a vacuum gauge, it's a wonderful diagnostic tool. Vacuum gauge tuning

A little update on my tired 283. I discovered that
the rod that connects from the accelerator pedal to the carb. was too long and there was no more adjustment left. I got a shorter rod which gave me a lot more pedal and now I have a bit more power, as the carb. was only opening about 1/2 way
before the rod change! A simple thing with a big improvement. I drove it over the weekend on a 100 mi. jaunt ( found the correct wheels for it) and
was actually passing other cars!
I also changed the valve cover gaskets as I was getting quite a bit of oil thrown back on the undercarriage. That did not seem to help much.
When I got back from my trip, I still had a lot of oil blown back. Anyone have any thoughts on where it is coming from? Im thinking the rear main seal. But if there is anyplace else it could be, let me know.
One final note, The powerglide has been shifting from low to high almost immediately, way too fast, and I discoverd there is no tube going from the back of the engine to the transmission
modulator. I think that could be the problem, so I am going to go get the adaptor and line and see if that helps. Ok, that it for now. Steve

Mastkey,

If you want significant improvements on your top end, you need to do one (or a combination) of the following three things.

1. Increase your engine output. Bigger engine or rebuild the old one with higher output items.
2. Install an overdrive transmission.
3. Change the rear end to one of a lower final drive ratio.

Your oil "blow by" could be the rear main seal. If you have a spot leakage between the engine and tranny then it's either the rear main cap seal, the rear oil pan rubber seal or the front tranny seal. If you don't have a spot then it could be a simple oil pan gasket leak.

If you consider replacing the 283 a 350 would drop in place with no mods. So would a 292 inline 6. Your choice.

Powerglide without a working modulator shifts at 20 mph. You will need to run steel tubing for this, rubber hose will collapse on a run this long.

Tyler's right, sounds like a rear seal. Not that hard to change, jack up the engine and remove the crank pan.

Well, last night, I tried hooking up the vacume
hose from the intake manifold, with a fitting I had to go purchase, and by the way it was a 1/2 inch hole so I had to get a reducer and fit the smaller adaptor inside of it, probably not the most efficient method, but that was all they had at the parts store. Anyway, ran a hose to the trans modulator and took it for a drive. Did not change at all! So I either need to try some tubing and see if that works or I have some other transmission problem. Did check the fluid when hot and it seemed right where it was supposed to be.

I guess I may have to look at changing to a 350 or 400 trans. Would that fit without any mods or do I have to make some changes?

Did you check the modulator? If it was left open it could be full of gunk. Usually when the go bad they leak fluid through a hole in the diaphram. Only way I knew of was to suck on it, which is not recommended. Tranny fluid tastes terrible!

Modulator had about a 2 inch piece of black tubing
on it and thats all. How can I tell if the modulator is bad or do I just assume it is? Also Is there some kind of adjustment on the modulator I can make. It is kind of hard to get to plus it is massively greasy! I think I need to get the undercarriage steam cleaned.

Usually if the modulator is shot, you get a really harsh shift. Also, if I remember correctly, you should have a mechanical linkage from the throttle linkage to the transmission. This is known as the kickdown linkage and it enables you to downshift by tromping on the gas. If this linkage is not adjusted properly, it may affect your shift point (singular beacuse it is a powerglide), in other words it may cause it to upshift early.

I checked on that and there is no mechanical device that will kickdown the trans.
I was wondering why it didn't have the linkage
from the carb to the trans. but I was not sure if they all had them or what.

mastkey-dunno if this will help, but I'm almost certain that I remember some kind of mechanical kickdown linkage on the 327/powerglide in my father's dearly departed '68 Camaro ragtop (ahh...yet ANOTHER ONE that got away!) Take a look around along the sides of the tranny just above the oil pan rails, and see if anything is hanging out in mid-air looking like it should be connected to something. Best of luck.

Wannabe

P.S. My personal vote would be to swap in a TH 2004R auto overdrive....but that's just my $.02

Mastkey, That engine trans combo should have a mechanical kickdown lingage. it bolts to the two top bolts on the bellhousing and has an arm that connects to the carb. right below the gas peddle connection. I would speculate if that is missing and you have an oil leak that someone may have taken the intake manifold off and the rear seal on the manifold is squeezed out, a common problem , thus the oil leaks down the back of the motor on the trans. The kickdown linkage also connects to the trans where the shifter connects. Another place to look for an oil leak is the bolt in front of the motor that holds the fuel pump rod when you change the pump, if it is out it will leak.

Hey Guys,
Forgive me if I'm wrong, but I thought the vacuum line to the modulator came from the throttle body on the carb., not the manifold. I don't know, but there might be a different level of vacuum there.
There definately should be a mechanical kickdown. If you put the shift lever into low range and left it there, this would over-ride the trans. upshift and you could wind the 'Glide out to about 90 mph. in standard trim.
Bob

I don't think I saw this mentioned, so check the timing and make sure the mechanical and vacuum advance are working correctly. If either one of these are inop, it will run slugish. 283's are great engines, but they aren't rocket ships either.