Picked up a 1970 GMC C3500 dump truck that needs some TLC

[FairfaxStu]

I wonder how reliable this distibutor will be.

Well, anyway you cut it, it will still be more reliable than something that does not work at all. If you look out there, you can find "high performance racing distributors" for a bit above $100.
-Stu

 

[Stimw]

I bought a new Chevy Van in 1979, it had the HEI distributor in a 350 cuin. At 59,000 miles I really felt guilty because I had not changed the spark plugs! What the heck, it still ran great!
The old plugs didn't look much different that the new ones!!! And I was towing a 7000 lb boat with it!

 

[pclausen]

I wonder how reliable this distibutor will be.

Well, according to the text describing the unit, it comes with:

--- cut ---
LIFETIME WARRANTY, UNLIMITED MILEAGE!

THIS IS THE COMPLETE DISTRIBUTOR BODY, SHAFT, GEAR, 65K COIL, CAP, ROTOR BUTTON

THIS IS THE NEWEST VERSION ON THE MARKET. THIS UNIT HAS A PERFECTED MODULE SYSTEM VIRTUALLY ELIMINATING FAILURES, AS WELL AS THE NEW 50K COIL!! THIS COIL IS ESSENTIAL ON ANY MODIFIED ENGINE.
--- cut ---

I'll be hard pressed to put more than a few hundred miles on this dump truck each year, so I suspect it will do just fine.

 

[Harold_J]

I wonder how reliable this distibutor will be.

Wondering the same thing. Would they be as well built as original? Are they Chinese made? I have had bad luck with Chinese window motors, etc.

 

[pclausen]

New HEI distributor came in today. Looks really nice!

Put it on and got the engine to fire on starter fluid right away, but my timing is off. I barely got it to idle and in the pic below you can see where the timing mark is for cyl 1:

The current position of the distributor is the only one where I can keep the engine idling and get out and shot the timing pistol. As soon as I turn it either clockwise or counterclockwise, it stalls. I tried starting with it as far as it will go before the ignition coil hits the firewall, and it wont start, and as far as it will go before the vacuum advance hits the firewall.

Perhaps I'm off one cog on the gear, but when I try to correct that, the distributer won't seat all the way.

Basic question, which direction should I turn the distributer to get the timing closer to the timing tab from its current position?

 

[Harold_J]

It appears it's firing early, before it reaches the tab. To ****** the timing rotate the distrib in the same direction that the shaft rotates. Some HEI's can have firewall clearence probs on older non OEM vehicles. You do have the plug wires installed correct, right?

 

[pclausen]

Yep, the wires were all moved over one at a time into the same position. So being that the distributor shaft is on the left side of the shaft (standing in front of the engine), and the cam is turning clockwise, that would mean (I think) that the distributor is also turning clockwise, so I should turn it further clockwise. I'll give that a try in the morning. starting liquid.

 

[pclausen]

Yep, checking timing with vacuum hose disconnected.

Loosing ground when turning is a good possibility I think given the paper gasket I'm using . I suppose the new distro gear could be keyed differently relative to the oil pump drive and that explains why it won't go in in the position that the original one was in. It was getting late and dark, so I was kinda rushing a little too, which never helps.

 

[Gale Hawkins]

in the old days dad always did it by sound but I'm not sure how. the guy that set my 454 in the motorhome he did it by sound.

 

[ultrarunner]

If you can... double check the wires are in the right order.

I did a 400 and it had me baffled all morning and then I found the problem... plug wires were in the wrong sequence.

 

[Degolyerent]

You have to bring up #1 piston to Top Dead Center (TDC) on the compression stroke, note the position of the rotor button it should be positioned to the # 1 firing position in relation to the cap. Most likely you are 1 notch out. You have to take a long straight slot screwdriver and back up the dist. drive which is down in the hole where the dist. came out of, reinsert the dist. until the position is correct.( The relation of the rotor is correct with the relation of # 1 on the cap.)
John

 

[Harold_J]

The wires can be in the proper firing order sequence but if #1 is off position you may not be able to adjust without something hitting the firewall. If all else fails you might have to try rotating each of the wires sequentially on the cap maintaining the proper order and then readjust.

As Degolyerent said, the rotor should be on #1 when the marks line up; you might have to rotate the engine one turn to move from exhaust to compression stroke. Since the truck didn't come with HEI you may have to fiddle with it a little to clear the firewall and still be in time.

 

[Harold_J]

in the old days dad always did it by sound but I'm not sure how. the guy that set my 454 in the motorhome he did it by sound.

In the "old" days they would often keep advancing a little at a time until it started to ping/knock, and then back off some; so depending on the gas you were using might get a little more power out of it on high octane.

 

[Degolyerent]

I have timed them by ear most of my life, start the truck and with the bolt slightly loose rotate the distributor until it reaches it's peak idle then shut off the truck and restart, if it turns slow or binds turn the timing back slightly until it starts properly, it may take a couple of attempts but when done it should have peak power. If you notice the temp. Gauge running to warm drop the timing back slightly more. If you leave the distributor bolt snug but not tight until you get it right it may save you some aggregation.
John

 

[pclausen]

I got her running good again. I think my main issue was a vacuum leak. Once I plugged that (and the one going to the distributor), I was able to get it to idle after keeping at 2500 rpm for a few minutes and upping the idle speed to about 1200 rpm.

I was then finally able to turn the distributor and observing the change in idle speed. Peak idle occurred around 14 BTDC. I then backed it down to 10 BTDC and reduced idle screw to get about 600 rpm. At this point it would hesitate when hitting the throttle, but once I connected the vacuum back up, that went away. Running real good now!

Here's original:

And the new $39 one:

 

[Degolyerent]

Great!!!

 

[ultrarunner]

Great accomplishment to see a problem though and thanks for the update...

I've got a starter Gremlin in my 1991 Silverado with a 350.

Original starter just wore out... it was the brushes... bought AC/Delco OEM exchange and have had intermittent starter to ring gear clash ever since... pulled and inspected/shimmed and just when I think all is good after 20 good starts I get two grinding ones...

I'm really starting to think it's the new starter because new a gear clash in 22 years...

 

[FairfaxStu]

Good job Peter. What is next? Paint? Rebuild that 350 you have?

 

[RobertN]

You have a Gremlin and a Silverado? You have some collectors, but has the market for Gremlins started to improve? Now if you had a Gremlin AND a Pacer to tow behind you Silverado, you might be on to something

I've got a starter Gremlin in my 1991 Silverado with a 350.

 

[ultrarunner]

I actually drove a Pacer for awhile and after that a Hornet with overdrive...

My Silverado has started 15 times without starter/flywheel clash... I've started to keep a log!