Jumped Timing..??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

frankdatank01 · 08-28-2007, 04:44 PM

Well, Well, Well,

I was looking to rebuilding the 455 buick in my 70 C10 this winter. It leaks in a couple spots, I dont know the age or miles, and I just figured I'd finally rebuild one for the first time. I was planning for these in the Dec/Jan timeframe. However.......

Today, I was getting a little

agressive and opening the carb up a bit going down the parkway. As I turned the corner to go into work, the ole truck dead and backfired at me.....I figured it lost fuel flow or a piece of dirt or something easy...but I was unable to get it started again.

After the insurance towed it home (thank goodness I added that extra 2.00 a month on the policy), I determine that fuel is getting to the carb (has electic fuel pump and I can see it) and I pulled the number 1 spark plug and I am getting spark (has HEI distributor).

When I try to start it sounds like it wants to start, spits and sputters but cannot get itself running. It might limp along for a couple seconds and die again. Giving it gas tries to make it better but it cant hang in there. There are no major bangs, knocks, or crashes...

Is it possible I jumped the timing chain??

Whats the best next step? I am tinkering with determining the compression stroke and finding TDC for #1 cylinder, then lifting the cap to see where the rotor sits but I dont have all the tools or prior experience...just operating on my own analysis...

Any tips or secrets of the trade??

Oh yeah, I just bought the truck 4 months ago.....

but I bought it to drive to work and work on it so I am actually not too upset if I can still get it rebuilt.

Thanks for any advice....Tank

71tahoe · 08-28-2007, 04:49 PM

I'd say it either jumped time or the distributor worked loose and moved.

frankdatank01 · 08-28-2007, 04:51 PM

Oh yeah, I looked at distributor hold down and it looks to be in the same spot. You can see the groove and marks from where it sits. Tank

LUV2XCLR8 · 08-28-2007, 04:52 PM

Quote:

Originally Posted by frankdatank01

After the insurance towed it home (thank goodness I added that extra 2.00 a month on the policy)

State Farm? (Reason I asked is that is what they charge me and it's Priceless)

I'm no expert, but there are plenty on here, someone will help you out w/ this

bryanw1968 · 08-28-2007, 05:05 PM

Where is your timing currently?
Does it drag at all when you try to start it?
Jumping a tooth is rare but possible.

71tahoe · 08-28-2007, 05:16 PM

I've had one jump time and while trying to adjust the dizzy to get it drivable, it jumped again as soon as it got enough combustion on the power stroke. I had to get a new timing set. If you can get it running better by guestimating with the dizzy (the balancer mark won't be close), it won't be long before it jumps again.

08-28-2007, 04:49 PM	#2
71tahoe Registered User Join Date: May 2006 Location: Jonesboro, AR Posts: 916	Re: Jumped Timing..??? I'd say it either jumped time or the distributor worked loose and moved.

08-28-2007, 04:51 PM	#3
frankdatank01 Registered User Join Date: Jun 2007 Location: Dayton, Ohio Posts: 95	Re: Jumped Timing..??? Oh yeah, I looked at distributor hold down and it looks to be in the same spot. You can see the groove and marks from where it sits. Tank

08-28-2007, 05:05 PM	#5
bryanw1968 Senior Member Join Date: Jul 2006 Location: Leander, Texas Posts: 850	Re: Jumped Timing..??? Where is your timing currently? Does it drag at all when you try to start it? Jumping a tooth is rare but possible.

08-28-2007, 05:16 PM	#6
71tahoe Registered User Join Date: May 2006 Location: Jonesboro, AR Posts: 916	Re: Jumped Timing..??? I've had one jump time and while trying to adjust the dizzy to get it drivable, it jumped again as soon as it got enough combustion on the power stroke. I had to get a new timing set. If you can get it running better by guestimating with the dizzy (the balancer mark won't be close), it won't be long before it jumps again.

08-28-2007, 04:44 PM	#1
frankdatank01 Registered User Join Date: Jun 2007 Location: Dayton, Ohio Posts: 95	Jumped Timing..??? Well, Well, Well, I was looking to rebuilding the 455 buick in my 70 C10 this winter. It leaks in a couple spots, I dont know the age or miles, and I just figured I'd finally rebuild one for the first time. I was planning for these in the Dec/Jan timeframe. However....... Today, I was getting a little agressive and opening the carb up a bit going down the parkway. As I turned the corner to go into work, the ole truck dead and backfired at me.....I figured it lost fuel flow or a piece of dirt or something easy...but I was unable to get it started again. After the insurance towed it home (thank goodness I added that extra 2.00 a month on the policy), I determine that fuel is getting to the carb (has electic fuel pump and I can see it) and I pulled the number 1 spark plug and I am getting spark (has HEI distributor). When I try to start it sounds like it wants to start, spits and sputters but cannot get itself running. It might limp along for a couple seconds and die again. Giving it gas tries to make it better but it cant hang in there. There are no major bangs, knocks, or crashes... Is it possible I jumped the timing chain?? Whats the best next step? I am tinkering with determining the compression stroke and finding TDC for #1 cylinder, then lifting the cap to see where the rotor sits but I dont have all the tools or prior experience...just operating on my own analysis... Any tips or secrets of the trade?? Oh yeah, I just bought the truck 4 months ago..... but I bought it to drive to work and work on it so I am actually not too upset if I can still get it rebuilt. Thanks for any advice....Tank



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