I have 85 RAM B150 with slant 6. At 217,000 miles I had the engine rebuilt. Installed the engine in, wanted to set basic timing, but the timing mark was jumping 10 degrees. Took the pulleys out, timing chain cover out, chain and sprockets were new, but chain had big slack. Bought new set at NAPA made by Cloyes. Installed, but chain has slack still, less then before but no good. I am now hunting for OEM set for the 85 year but cannot get one anywhere. What could be the problem? I cannot imagine that the rebuild would change the distance between the crank and the cam shafts.

I can chime in a bit. I have one of the basic cloyes silent chain sets I used on the slipping chain problem in my valiant, I also recently got a new Melling timing set (these used to be fairly good quality)... both of them have crank gears with the same 'cloyes' part number stamp on them, the cam gears are different construction, and the chains look to be exactly the same). I'm thinking some if not all of the parts are now made by some outsourced parts house and just thrown into a brand box and shipped to the supplier. One think that was interesting was a buddy and I compared the cloyes setup, the melling setup and an old nylon gear setup out of an OEM slant, and the way each set was stamped for 'connecting' the dots was different (the new melling set was not good, we estimated it was machined to be retarded about 11 degrees if you played connect the dots...compared to the others...).

There should not be that much play in your setup, I guess a quality roller chain set would be a much better improvement (and last longer).

-D.Idiot

Probably painted with lead paint too...

I am thinking of getting the Rollmaster chain, but what stopped me in tracks is the fact that the engine rebuilders put -a crap- new chain in, slack. Then I go and put another new chain in, slack. So I started to thing may be there was a design change in the late slant 6 engines so that the shafts are closer together. The safest -I thought- would be OEM. I would mind to try Rollmaster event with $150 (with shipping) price, but I am tire of taking the radiator, pulleys, ballancer off. Putting all back so that there are not leaks.
I would love to do somethng different for change.

Could the block have been align-bored? It's possible that some machine work can reduce the distance from the cam to the crank centerline.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

There was no design change that moved the shafts closer together, so that's not it.

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A good answer. There was no design change. Since I had two new chains installed I assume that the shafts are closer whatever is the reason.
What is the correct distance so I can measure it. But! What can be done now? I guess a timing belt conversion of some sort.
Anyway, you guys are giving me some hope. Thanks.

I had a block with the cam and crank bores too close together. Slack chain no matter what. I threw out the block. If you can't do that you might consider a tensioner similar to the Magnum small block and 3.9 V6.

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Joshua

In Australia the slant came out with a silent chain of 1/2" pitch if memory serves me correct.I tried to replace my chain six months ago with an old original equip one but none were available.The only ones available were rollerchains with a 3/8" pitch.I found exactly the same as what has been discussed on the forum - a slack new chain.I believe if you do the maths there will be some slack in the chain because of the pitch difference and the fact that the centre distance must remain the same.
ie centre distance remains same
pitch dia for crank sprocket=
pitch dia for cam sprocket=
The car seems to run ok but from an engineering point of view it doesn't seem right.

Alan