"Interesting" Problem...

[Vanlande]

Hi!

I'm new here, just picked up a '66 C10 SWB Stepside, good lookin' truck. Pretty much the only 60's era tuck I like, as i'm more of a car guy.
Brief history of me so you know where I'm coming from with the problem I'm having... Worked on Classics since I was in high school (got a 77 Pontiac Grand Prix when I was 16) so I have 8 or 9 years experience. Always had cars, some GM, some MOPAR, even a Ford and an AMC (67 Ambassador).

My new Chevy has (I think) a 77 or 78 Caddy 425ci bolted to a TH400. Guy i bought it from told me 500ci, but that ain't right. Here's how I found out...

Bought the truck running, hesitated on cranking but then fired and ran ok, pings when you stomp it, but if you go easy had some get up n' go. Then, about a week after I get it, that hesitation turned into grinding, got 1 last start out of it then drove it home. Looked under it, only to find a broken nose cone Then I look for a replacement for a 500ci starter, and it's a completely different thing! Turns out it's either a 472 or a 425. Got a new starter, bolted it on, appears to be too close to the flywheel. Shimmed it, as well as adjusted the timing. Started great for about 2 dozen times, now back to the horrid grinding sounds.

Gonna crawl back under her and see if the bolts came loose in the morning, and make sure I didn't break another nose cone. Any suggestions on what this could be, other than what I've covered? I would greatly appreciate it.

[Rooster's 67]

Dont know for sure, but i Know the big block Chevy had a bracket that was on the motor end of the starter and gave it stability. It mounted to one of the starter motor can thru bolts, and the block, decreasing the likelyhood that the starter would "twist" and change the starter tooth engagement at the other end of the starter.

these brackets may be on the caddy motors also, and may be missing on yours. But like I said I may be completely wrong as my caddy recall is fuzzy.

[Vanlande]

Originally Posted by Rooster's 67

Dont know for sure, but i Know the big block Chevy had a bracket that was on the motor end of the starter and gave it stability. It mounted to one of the starter motor can thru bolts, and the block, decreasing the likelyhood that the starter would "twist" and change the starter tooth engagement at the other end of the starter.

these brackets may be on the caddy motors also, and may be missing on yours. But like I said I may be completely wrong as my caddy recall is fuzzy.

The first one I pulled off DID have a rear bracket, and the guy at the parts store told me it wasn't necessary... Jeeze, now I gotta find one.

[markeb01]

I don't know the answer to your problem, but welcome to the forum. Sounds like a very fun truck once the bugs are worked out.

[T Smith]

Those big Caddy engines are torque monsters, should really get that old iron moving and be surprisingly efficient doing it. Good luck with your starter quest!

[66farmer]

If the nose cone on your starter broke you better take a look at the teeth on the flex plate. I had a big bloock chevy that did that and I had to replace the flex plate.
Good Luck

[Vanlande]

Got under it again today, guess what? another broken starter. Teeth on the flex plate are ok, bolts are tight, and there's no wobble. Odd thing is, the better the timing was, the more hesitation I seemed to get... (whum...whum...whum...VROOM)
Perhaps my shimming was incorrect? The bolts were solid, and the flex plate showed I was getting about 3/5 bite on the teeth. Maybe 3/4. Shouldn't be missing enough to break an aluminum nose cone. Ugh, what a nightmare.

[awbrown]

first off you have too much advance on the engine , get a timing light and take 5-10 degrees out of it and see if it startes without binding ... or just loosen the distributor and if I remember right the dist. shaft turns clockwise ( better pull the cap off the dist. and tap the key to be sure ) meaning to retard it you need to turn the dist. clockwise to retard it ,loosen it and push it back a 1/4 inch and try to start it (with a new starter on it of course) keep backing it up til it starts without binding ... I normally replace flywheels and starters together just to make sure the flywheel doesnt eat the drive gears , but it sounds like you have a timing issue......

[Vanlande]

Well, the timing seemed to be the culprit. Retarded it a bit and got her to turn over pretty good. Though the crappy electric fuel pump is out now, so it'll be a bit before I know how well she runs for sure.

[powerdriver 1958]

If those big engines (Big block chevy or Big caddy) ever "kick back" on the starter , It's over with . I dug around and found a cast iron nose cone . Not sure that's an option for the caddy .

[77chris03]

[oldgoalie]

Had a big block chey do that, found out that the advance weigths in the dist where sticking in the advanved posistion. Busted a couple starters before I found it.

[MARTYZ]

I agree with all the above , sounds like timing is the root of your issue, You should have a good look at your flywheel(flex plate) make sure it hasn't cracked any where after smashing the starter a couple times.

[markeb01]

You might also want to check the condition of the timing chain, it could be adding to your timing problems. I don’t know for sure but assume if it’s original it probably both very tired and came with the nylon tooth "silent" cam gear which can shed teeth when they wear out.

Easy tests would be to gently increase and quickly drop the engine speed to idle while listening for rattling near the front of the engine. With a timing light attached, do the same exercise and see if the timing marks dance around when the throttle is closed. If the chain is tight, the timing should move smoothly. If it bounces all over it could indicate a worn chain, because torque is being removed from the tight side of the chain allowing the cam gear to move around under the slack in the chain.

For a more precise way to check it mechanically, the information on this thread should be helpful:

http://www.misterfixit.com/chanslop.htm

[Vanlande]

I may have to look into those advance wights sticking, hmmm... Flex platel is great, a bit scuffed in a spot or two but no big deal. No cracks or anything, and I actually went through and counted every tooth, and inspected the whole thing. That being said, it's definitely electrical and not mechanical, since, if you take the distributor cap off and turn it over, it literally NEVER hangs up. I'm ordering the fuel pump tomorrow, so we'll see how she act when that's back on.

[Vanlande]

Originally Posted by 77chris03

What would i take pics of?

[64shortbox]

What markeb01 said,
Check the timing gear NOW! I have a 71 Caddy (hearse) it too would ping climbing a slight grade and if I did anything more than ease into the throttle. I pulled the timing cover and sure enough there was no nylon teeth left on the timing gear. I have no idea how the motor ran at all. These Caddy 425, 472 & 500's are interference fit motors. In other words if you loose the timing chain while driving you'll bend every valve at the very least. I wish I took pictures at the time but I didn't own a digital camera back then. I finally bought our 64 fleetside and no longer have to use the Caddy to tow the boat cause the truck now gets that duty. If you look through the windshield of the truck in the last picture you can see the roof & landau bars of the hearse. The bad news, both vehicles only seat 3 and both get a lousy 10 MPG. WTF is with that?

[64shortbox]

vanlande,
Here's a link on how to check GM starters for proper shimming. Hope it helps.

http://marinemechanic.com/site/page169.html

[Vanlande]

Thanks for the heads-up shortbox, I'll have a look at the timing chain ASAP!!! I'd love to have an old hearse like that, maybe put third row seating in it for the kids, lol!