PLANT PROTECTION

iTrader: (6)

I have a little history with this problem, the thread can be seen here.
https://www.thirdgen.org/forums/tech...ear-teeth.html
I thought the problem was an incorrect distributor gear size, but that doesn't seem to be the case, unless the General screwed up like I did. I bought a brand new, late model GM distributor and bolted it in and it is showing signs of the exact same type of wear. This gear has about 5k miles on it so the problem seems to have lessened from before. Any new theroys on why this is happening?

SpitotRs305

what type of cam are you running? hyd roller, flat tappet?

Guest

Have the block, heads, or intake been machined? May need to space the distributor up a bit.

PLANT PROTECTION

iTrader: (6)

The block and heads have been machined. My block was 'lightly' decked, pistons are .018 in the hole. Heads are AFRs with stock 72cc chambers machined down to 64cc and AFR said the intake surface was corrected. Intake is stock. The cam is a hydraulic roller, happened with both my hotcam and LPE219. Madmax, sounds like a good theroy, but how can I check to verify it and know how much to shim?

Guest

Go by feel?
How much was the block 'lightly' decked? Like .005 or something to clean it up probably?
IIRC its .006/cc on the AFR's so they were probably cut about .050... enough to mess things up. I'd shim up the distributor by about .030 and see how it does then. Might need more, I came up with .038 not taking the intake milling into account (hard to say where its actually at).

I had a similar problem myself, shimmed up the distributor to account for the milling and so far... so good.

PLANT PROTECTION

iTrader: (6)

I have an update on the problem. I installed a .100 nylon housing shim with a new gear and in 100 miles it is showing the exact same high wear pattern, but now the upper most portion of the tooth isn't worn most likely due to not being engauged fully into the cam gear. It definately looks like that wasn't the problem.

PLANT PROTECTION

iTrader: (6)

Still fighting the problem. Doing as much reading as I can on the issue, lots of guys will make note that their distributor installs easily, mine does NOT drop in easily. I typically have to make sure the oil pump shaft is properly lined up then jam it down with quite a bit of force to get it past whatever it is catching on, other times it drops in most of the way and it just takes a jiggle at the base of the shaft for it to fully seat. What could cause this symptom? I bought the bare block from a machine shop, so I do not know its history. I am running a ARP oil pump driveshaft, it has a pinned metal sleave that keeps it engaged on the oil pump. Compared to the stock style nylon sleeve, it seems a little sloppy, could this be an issue? Only other thing to note is the oil pump spins easily with a screwdriver. Any new input would be helpful, thanks.

PLANT PROTECTION

iTrader: (6)

ttt one last time before I yank the motor to further investigate the problem.

Guest

Thats weird. I wonder if the timing side of the block was machined at some point, though thats really a stretch.

PLANT PROTECTION

iTrader: (6)

It's something to look at. I plan on pulling the oil pump driveshaft and seeing if the distrib installs any easier, if not removing the cam gear and cam retainer plate and moving the cam both in and out to see if it drops in any easier. Other than core shift, I don't know what else it could be.

PLANT PROTECTION

iTrader: (6)

Pulled the motor out last weekend. Upon investigation, I measured ZERO camshaft endplay. I was running a Dynagear double roller timing chain and the cam gear was rubbing on the cam retainer plate for the roller cam. If I am thinking correctly, this would be forcing the cam toward the front of the block. Also, the crank gear and cam gear wern't exactly lined up, the crank gear was out roughly .035 further, possibly causing even more of a pull on the cam gear. Although I am very curious to see if some cam endplay and lined up timing gears would correct the problem, I also found a seemingly faulty main bearing, a trashed thrust bearing, and crank thrust surface causing .041 crankshaft endplay, so I have decided to replace the motor. As far as the distributor being difficult to install, that was an issue with my ARP oil pump driveshaft. The ARP shaft has a very shallow sleeve allowing for quite a bit of misalignment. I installed a Melling driveshaft also with a pinned steel sleeve but deeper engagement and the distributor dropped right in after that, so I was able to solve something.

player 88

iTrader: (2)

make sure you have the correct timing chain set for a factory roller cam block, it is different then a non roller block timing chain. Also it is not uncommon to have to grind the blcok a bit to clear a roller chain. I had to on mine.

I am running a mid 90's 4 bolt truck block and it was deck at some point, the pistons are approx .013-.015 in the hole. I used both a GM dist and a MSD pro billet and they both sit high of the manifold, i put shims between the manifold an d ths distributor. you don't want the dist to be bottomed out in the oil pump drive when the hold down is tight. there should be just a bit of play, vertically. I

good luck