Questions - Timing, Transmissions and Gear ratios
 

Hi guys, I know these questions get asked a lot, but I'm not finding answers specific to my issues/situation.

First and foremost, Timing. I've got a 283 with an Accel HEI distributor, A Quadrajet in need of a rebuild, and Camelback 192 heads. I unplugged the vacuum advance, and from what i'm reading, I'm sitting right at 14* advance while in gear (someone else was holding the truck in gear)

Does this sound right? With a stock cam, should I be sitting this high?

Second. My brother and I converted the truck from manual to auto. I've got a TH400 in there now, but while driving at highway speeds, It's screaming for another gear. I could go with a 700r4 or a 4l60e, but was wondering about going to a T5 or NV3500. I don't have the old clutch linkage or pedal anymore, however. Besides the pedal, do I need any of the rest of the stock linkage if I plan to run one of these manual transmissions? (I can easily find a clutch pedal.)

Third, What is the most common rear axle ratio provided in these trucks? I originally had an SM465 installed. I could remove the diff cover and get a real easy answer, but if someone knows what's pretty common, I would appreciate a quick answer.


thanks guys!

Re: Questions - Timing, Transmissions and Gear ratios
 

What you see in most of them is 3.73. A taller tire works to kill some of the gear. What the timing is at idle in gear is really close to what it is out of gear so don't work on it in gear. The curve of the distributor is what is needed to help you figure out what you need for timing at idle.
Jimmy

Re: Questions - Timing, Transmissions and Gear ratios
 

Both of my 64 1/2 tons had 3.73 gears when I got them. As for the timing, the way I was taught was to set it at full advance and not worry so much about idle, but that was working on race trucks. I usually do it that way.

Re: Questions - Timing, Transmissions and Gear ratios
 

I try to set about 12-14 initial.....but, as mentioned above ^, more focus on the total timing! call the "all in spot around 3000 rpms (2800-3200), depending on gears. I try to shoot for a total of around 34 degrees all in , with the vac can unhooked & plugged(street/heavy, & pump fuel). Cut (limit) the vac can to around 10 degrees @ the crankshaft(full manifold,@ idle), & you should be close to target ;) Remember, that the vac can , is a load sensing device, & will back totally out @WOT....its for cruise/economy & throttle response in the lower rpm ranges.........longhorn

Re: Questions - Timing, Transmissions and Gear ratios
 

That little 283 is working it's tail off to spin that TH400. The TH400 takes about 40 to 50 more HP to turn over a TH350 or a PG. It was designed to go behind BBC's. There were some installed behind 350's in 3/4 and 1 ton applications in later years.

Off chance it might have 4.10's back there.

Gary

Re: Questions - Timing, Transmissions and Gear ratios
 

Gary, You might be right. I know that if I'm doing 65, my Tach is reading close to 3100 rpm. If my math is right, I would have either a 4.10 or 4.11

If that be the case, then i'll have to look into going with a 3.73. I'm not looking for power, as most of what this truck does is light around-town cruising and light work. I will be eventually swapping a different transmission into this, and I'd like to consider all options before I commit.

That's where my question about going manual came in. If I could find a way to essentially go back to manual, I would seriously consider it. I can go with a T5, and keep the 283 in it, Or possibly a 350 with a 700R4/4L60E.

As far as timing goes, (and because I've never done it myself) I need to warm it up, rev it to about 3000 RPM, and adjust timing at that point, right? I'm looking at a total advance of around 34 degrees?

thanks for the responses guys!:metal:

Re: Questions - Timing, Transmissions and Gear ratios
 

I know it's a bit of a drive, but if you want to come by the house sometime, I can help get it dialed in and we can pull the 64 grill off one of the trucks if you're still looking for one.

Re: Questions - Timing, Transmissions and Gear ratios
 

akaupp, you know clint? are you the guy that came in to Jack-It? If so, yeah, i'd love to swing by.

Re: Questions - Timing, Transmissions and Gear ratios
 

I do know Clint and I am the guy.

Re: Questions - Timing, Transmissions and Gear ratios
 

cool, PM Sent!