Been busy with 3.3 sd4. Having problems with load on thrust plate. Since I can't find a straight cut timing gear set, I thought about going to a chain drive cam. Has anybody done this ? Any problems with gear drive for distributor and oil pump. Can you get a true double roller timing set for a sd4. Give me your thoughts, pros, cons. This could be another year set back. Takes bullet about 6 months to make a cam. Any ideas.
Thanks. Rick

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85 GT 3.4
14.9 @ 90 1.9 60' Old TH125/3.06
Unknown New 4T60/3.42

Does your gear setup have an idler gear in the mix?
If not then going from a 2 gear setup to a chain setup will reverse the rotation of the camshaft - which would change the valve opening and closing events among other things.

No idler gear . New cam would be reverse rotation specific. I've got 17 cams and one is reverse rotation, must have been for a boat with twin motors. Haven't found a true double roller timing gear set yet. Just single and they're only good for 6500 rpm.

I don't know if you need a source, but Rockauto has a bunch of timing sets listed.
None seem to be high performance, though.
https://www.rockauto.com/en...&+component+kit,5756

Edit - Summit shows Cloyes and Melling, aftermarket for ~$38. Or Mahle "original" for ~$59.
https://www.summitracing.co...cending&fr=part-type

[This message has been edited by Raydar (edited 03-28-2024).]

Radar, looked at all of them. Melling says it's gear set not good for over 6500 rpm. The cloyes HD might be better. I sent them a question about the rpm rating. A spur cut gear set would save me alot of time and money. Oh well good old capitalism.

What kind of valve train do you have? The timing chain life expectancy is not RPM dependent. They give you an RPM number as a guideline. If you use those stock "6500 RPM" chains with your engine that probably has very high valve spring pressure, aggressive cam profile and probably heavier springs and valves, that "6500" limit would become "4500" and the chain itself would be immediately stretch making way for a future chain failure. You have 2 options to solve this problem.

1- Get 3 sets of stock chain/gear sets and get them Cryo threated and nitrated. This approach will increase the strength, wear and life expectancy by 70-85%. I've been using cryo treatment for more than 15 years in all my projects.

2-Get a set of stock chain/gear and use them as is, but you'll have to replace all your valves for titanium units to reduce valvetrain mass and by doing so you now can use more modern single and lighter springs with slightly less pressure.