New distributor

sailormedic

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Howdy Y'all,
I have a 99 Tahoe 4x2 LT 4 door. I put the last 4K miles, of 226,000 since buying it in June of 2014. Since I bought it it had this little hesitation that has gotten progressively worse until it wouldn't start at all. Got a P1345 but no engine light so figured it wan't that bad. Finally decided to replace the distributor. I've been researching the procedure for doing this and thought I had it understood. As I was removing the old one it turned out the hold down bolt wasn't securely holding the dist in place and it moved out of timing. Since I already bought the new one I decided to replace the old one anyway. Took me quite a while since I'm old and not very limber anymore. Anyhow I finally for the new one in and it has a hard time starting and still bucks and farts. I figure i must off a tooth. I'm not sure I found TDC on the install. Since I'm working on this by myself I'm not sure if I actually founds TDC. I pulled the #1 plug and hand cranked the crankshaft, from underneath the truck. When i look at the dampener from the top i can the timing mark but I can't see the thingamabob on the timing chain cover to align it with because of all the other parts attached to the front of the engine. i tried using mirrors but that didn't help. So i figure i got to reinstall but want to make sure Im at TDC. Any advise before I smoke a .45?
Thnx
 

MO Viet Vet

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When you have someone "tap" the engine with the ignition key, quick crank and release of key, with your finger over the #1 spark plug hole, you will get a pressure feel at your finger when the piston is at top dead center on the compression stroke. Your timing mark on the damper should be just before or just after the pointer on the cover. You have to align the mark with the pointer. Even with all the stock pieces on the front of the engine you should be able to see it. Then drop the distributor so that the rotor points at #1 on the cap. Run the wires in the correct firing order 1-8-4-3-6-5-7-2 and then when you set timing make sure you snug the retainer down.
 

sailormedic

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Thanx raiderron, unfortunately i'm working by myself so i don't have anyone to bump the starter. But i think i got it installed correctly. Just took it for a test drive and it' still hesitating, especially uphill. will it still run if my install is off by a tooth.
 

MO Viet Vet

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You can remove the spark plug and then rethread it back in the hole about 1-2 threads and simulate the finger blocking the hole but you have to listen for the compression spitting by the loose plug to hear the compression stroke. Yes it can run when is 1 tooth off. The hesitation could be a dirty throttle body or dirty MAF
 

lesterl

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I agree with it running 1 tooth off, You can turn the crank with a ratchet to determine TDC Compression, or you could use an air compressor with a rubber ended blow gun to see if it will pass air out the manifold (wrong stroke).....
 

MO Viet Vet

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At this point you need to get some MAF cleaner at the parts store and follow directions and clean the MAF and get some carb cleaner and a clean rag and clean the throttle bore at the throttle plate. That may fix the hesitation unless your timing is still off.
 

franklin

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You have a code R Vortec 350 correct? If so, here's what I have learned about this dist setup;

You cannot change or vary the timing of this engine. The timing is determined by the crankshaft sensor which is not adjustable.

But, you do need to get the rotor pointed to the correct post in the dist when that cylinder is at TDC. Unlike the older distributors which had the timing wheel inside the dist, on the same shaft as the rotor, this engine has the timing wheel on the crank and the rotor still in the dist. So they need to be sync'ed together. There is a sensor inside the dist on the rotor. Here's the procedure for setting this up manually and getting it in the ballpark. After this, it still needs to be checked with a scanner that has the ability to give you the correct parameter(not all do). You then tweak it in exactly.

Here's the link to how to install the dist. http://www.gmtruckcentral.com/articles/distributor.html
 

jpaul505

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I know this is an old post but thanks. Going to try this tomorrow. Thanks for the website link to that info. Changed the cam sensor two days ago and have not been able to get it to crank since and have been unable to find anything that would fix my problem.
 
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