Billet timing set

No, I think all the I6's and the 150ci I4 (AMC 2.46L) will all share timing parts, lifters, and such.

But why? We've got people tearing OEM engines down with 400kmiles on them - and no (or nearly no) timing slop. So, why bother?

If the OEM chain is good enough, it's useful enough to replace "like with like." You want an upgrade? Go with Cloyes roller chain and sprockets, or find a gear drive set (double idler, and less than $250, please.)

5-90
 
Panama XJ said:
What do you think about this timing set, look pretty neat and price is OK
http://www.fastengineparts.com/products_view.php?id=467
Click to expand...

Yeah, that's a sweet piece of kit but unless your timing set needs replacing, why bother? The stock timing set usually lasts well beyond 200k miles and rarely needs to be replaced. My old 4.0 had 174k miles on it and when I stripped it down, the original timing chain still had only 3/8" of deflection (well within the 1/2" limit).
 
I guess if your going to replace it anyways like on a stroker it would be good--it's a double roller, right? How much do they cost from other sources?
 
OK - it's a double roller (I didn't take a good look last time. I guess I got turned off by the magic word "billet.")

I've nothing against a roller timing set, but we've got such longevity with regular "silent" chains that they're really a non-issue - and I've got more faith in Cloyes if I were going to replace the set anyhow - I've got more experience with them.

Still, if I were going to go with some sort of high-output engine, I'd take the very slight additional parasitic drag that would be offered by the gear drive, and I'm a picky SOB on balancing the reciprocating assembly, which my machinist understands (I'm not my machinist - yet. One of the things I'm going to school for...)

I guess it's just the whole "billet" thing that makes me look the other way - it's tossed around so much that it's really meaningless anymore. All "billet" means is that it's made from a "billet" of steel or aluminum, and machined - and a "billet" is little more than standard "wrought" stock that you'd get from a mill or a supplier (look it up.) So, we've got "billet" thrown around like it's everything - but really nothing - and everyone jumps on the wagon anyhow.

I guess I'm just cranky, but I'm not about to be taken in by marketing hype or the misuse of the English language that is proliferating in schools and in marketing. Gimme the specs, and I'll sort the rest out for myself. Yep, I'm just cranky...

5-90
 
The engine family shares crank to cam centerlines as well as a lot of other stuff...a double roller set is a good idea for performance applications where you are increasing valvespring pressure and/or planning to rev the engine above base design.

The Mopar Performance kit is made by Cloyes. It has 3 keyways cut in the crank gear...stock, advance 3? degrees and retarded 3? degrees. It is a great mod for the 2.5 which uses a whimpy single row design with a spring loaded tensioner.
 
Gear drives are not the best choice for this application. They use up power to operate, and transmits unnecessary harmonics to the valve train. Stick with a quality timing set with a chain.
 
The power loss for a gear drive is, as I recall, negligible. As far as the crank harmonics, as long as you're balanced well in the reciprocating assembly, there won't be harmonics worth transferring.

I have found that gear drives reward careful engine builders. I'd not recommend them for just anyone - but if an engine builder knows what he's about, they're not a problem.

Crankshaft harmonics are part of the reason that you can get belt drives (like Jesel) for Small Block Chevvy - but I'd still see that as a refuge of an incautious builder. If you want to eliminate harmonics, eliminate them at their source - the reciprocating assembly. Although, I've never really liked belt drives - from a longevity point of view...

I've known quality double roller sets to last a good half-million miles, and "silent chains" (the typical "laminated link" chain we all have) can last anywhere from 200kmiles to 500kmiles and upwards. In some cases, I've seen "silent chain" systems last upwards of 500kmiles - which I count as only "slightly fluky" - it's possible, but unlikely.

Did you ever say why you were considering replacing your timing set? It may not be necessary - in fact, it's unlikely that you do need to do so, unless you are having a number of other problems as well...

5-90
 
I'm building a street strocker for my XJ 95 Auto, with 9.6 CR, Hyper Pistons, Mopar HP valve springs, Crane or Erson cam. I already have all basic mods in my 4.0 (Banks headers with thermotech insulation, Banks down tube, MagnaFlow cat, Borla cat-back, Jet Stage 2 chip, performance distribuitors coil and cables, AFE cold air intake with thermothec heat barrier, 62mm TB, 62 mm TB spacer) and I want a good timing set to keep all running smoot for a long time.
 
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