Timing Gear Drive

[elwood blues]

Kind of a random thought, because I'm making a list of items to replace when I finally get around to rebuilding the head on my AMC 258 i6 / 4.2l , I thought about timing gear drive sets.

The thought was a mild cam with upgraded lifters (non-flat tappet) and either double roller timing chain and gears or a gear drive set. I've done a little bit of internet digging but really haven't come up with much. Anyone know anything?

 

[CJim7]

I ran a 262 duration Comp cam for several years in my AMC 258 i6 / 4.2l and absolutely loved it. When I did my 4.0 head conversion, that same cam complimented the freer-flowing head design perfectly. The 262 has a wider range then I first thought when I installed it...originally going for low end without (much) compromise to the top end. I was very surprised when I jumped up to the new head and a 500cfm 4bbl Edelbrock and found I had enough cam to support it.

I went with a double roller and left the lifters stock.

 

[73CJ]

Now's time if it's got the original.

Gears, probably not worth it for a mild AMC 258 i6 / 4.2l .

If the lifters a clicking, pull the head a drop some new ones in. Noting wrong with getting intimate with a AMC 258 i6 / 4.2l .

 

[elwood blues]

I ran a 262 duration Comp cam for several years in my AMC 258 i6 / 4.2l and absolutely loved it. ~ ~
I went with a double roller and left the lifters stock.

Stock lifters, double roller timing chain and gears and a 262 Comp cam, did it have good low end? Why did you stick with stock lifters?

 

[elwood blues]

Now's time time if it's got the original.

Did you add one to many time's in there? Because I'm completely confused if you didn't.


Oh yeah, everything internal to the engine is original. I've had a valve tick for, well as long as I can remember. Originally a buddy and I just wrote it off as an exhaust leak, but last year I actually got a stethascope on it and you can hear the tick coming from #1 cylinder.

 

[CJim7]

Stock lifters, double roller timing chain and gears and a 262 Comp cam, did it have good low end? Why did you stick with stock lifters?

It had excellent low end, even with the stock head...but I also went with high compression pistons that brought up the compression too...forgot to mention that, it's been a while since I had that motor

I guess I just didnt feel the need to change from stock lifters...I did install valve springs matched for the cam per Competitions' recommendations. The rest of the valvetrain remained stock.

At the time, I also went with a TFI ignition which is, in my opinion, one of the best upgrades out there. After all, it all starts (or ends) with the spark.

 

[elwood blues]

I have no intentions of ripping in to the lower half of the engine. It doesn't leak, make funny noises or burn oil. If (IF) the odometer is correct, it's only got 52,xxx miles on it. There's no reason the bottom half should need to be rebuilt. That's why I'm sticking with rebuilding the top half. All good info Jim, thanks

 

[BusaDave9]

Replacing the timing chain for a timing gear set is popular with the high performance / hot rod crowd. You don't have to worry about the chain slack and stretch. The gears hold the cam in the exact position that you set with your timing.
The cons are that they eat up horse power and are noisy. They add a whine to the engine noise. The hot rod crowd says that the horsepower you gain by having the cam exactly where you want it will outweigh the HP loss. But I say that a Jeep needs a wide bandwidth. You rock crawl and you need to pass on the freeway. The very small amount of chain slop won't trow off your cam timing.
Now on a HP engine or car you would drag race you would want to stay at a specific RPM range (near red-line) then a cam gear set would keep the cam timing accurate.
IMO I would stick with a chain. They actually hold up better with high mileage unless you really get a high end gear set.

 

[fzsk4p]

Stock lifters, double roller timing chain and gears and a 262 Comp cam, did it have good low end? Why did you stick with stock lifters?

Other then some very costly roller lifters from 505 performance I am not aware of anyone having rollers available.

We did a lot of work over on jeepstrokers.com and it was very cost prohibitive. The cam needs to ground differently for the rollers. Plus the design of the 4.x engines does not lend itself to the roller tie bars. Yes it can be done but the cost to benefit ratio is just not there.

Roller rocker arms are a different story. High lift cams and stock rocker arms do not get alone as well as one would like. Wiping of the valve stem. Galling of the rockerballs, high lifter loads and heavy side loads from stiffer springs raise hell.

Rollers give you a much better platform to work with. Plus you can set lifter pre-load. I am running a 480 lift cam with Mopar rollers. Valve train geometry works well.

Beware of the low buck import lifters. There has been cheap imports that have not had proper heat treating. Buy from a well know company to make sure you are getting good parts.

Another consideration is your engine oil. Our beloved Jeep engines were designed around oils that had relatively high levels of ZDDP anti scuff agents. Today`s oils have greatly reduced ZDDP.

 

[elwood blues]

The whining noise I knew about, the other stuff I ddin't. Good info Dave

I've been doing a lot of internet digging since my first post and I've found that Mopar used to carry a timing gear set for the 4.0/AMC 258 i6 / 4.2l at a cost of $600!!! But, they discontinued it a couple of years ago because of low demand. Just about everywhere else that ever made them also has stopped long ago because of really low demand. From what I've read about the only reason to really use one is on a 4.6 up to 4.8L stroker with the AMC 258 i6 / 4.2l block and the 4.0L head. The only place I've found that still makes them is a place called 505 performance, but they want $420 for them, and that's a lot more than I'm willing to pay.

Double roller timing chain it is :

 

[elwood blues]

Wow, more good stuff fzxk4p thank you. I really didn't know that about the roller lifters. I was just blind assuming.

As for the oil, I have heard that before about the flat tappet lifters. That today's oil doesn't have the same "stuff" that it had previously and can cause premature wear in flat tappet lifters.

 

[fzsk4p]

Welcome!

Joe Gibbs Driven - Racing Oil and High Performance Products

These two companies are "blue chip" when it comes to oils with all the good stuff in them. They may cost a few more bucks on an oil change. But I sleep happy at night knowing that my engine(s) is being feed the oils it was designed around.

5w-30 is all you need. 10W-30 in the warmer temps if it makes you feel better. 10-40 is proven to cause deposits ion the piston ring lands over time. 2

 

[CJim7]

Roller rocker arms are a different story. High lift cams and stock rocker arms do not get alone as well as one would like. Wiping of the valve stem. Galling of the rockerballs, high lifter loads and heavy side loads from stiffer springs raise hell.

Agreed. Once you get into into 272 and up cam with greater advertised lift and duration, it's relatively mandatory to run roller rockers. A gentleman by the name of Gabe from the old Jeepboard long ago pioneered his build around this. He also re-worked his head for chevy valves but that is another story...

 

[CJim7]

Welcome!

Joe Gibbs Driven - Racing Oil and High Performance Products

This is what I will be running full time in my 401 when I get it back together. (Thanks John)

 

[fzsk4p]

Welcome!

Joe Gibbs Driven - Racing Oil and High Performance Products

These two companies are "blue chip" when it comes to oils with all the good stuff in them. They may cost a few more bucks on an oil change. But I sleep happy at night knowing that my engine(s) is being feed the oils it was designed around.

5w-30 is all you need. 10W-30 in the warmer temps if it makes you feel better. 10w-40 is proven to cause deposits in the piston ring lands over time. 20w-50 is simply to thick to pass there the oiling system without undue stress on the timing chain, dist gear, and oil pump drive shaft. Chewed up cam drive gears and stripped dist gears are more common then you might think.

Maybe it your engine has lotsa miles and bearing clearance that you could drive a truck through....20w-50 might give you a few more miles of life. Other then that. Leave it on the shelf.


I type slow !!

 

[elwood blues]

I know all about BRAD PENN oil. I grew up in a little town called Pittsfield, PA. It's about an hour over the Allegheny Mountains to Bradford. I still remember Kendall oil, and I remember when BRAD PENN was first introduced. It was all we carried at the garage I worked at. The only gas station/garage in Pittsfield. I used to drive right by the refinery every time I went home when I lived in Connecticut. Small world I guess

 

[fzsk4p]

Penn took over Kendall. The old GT-1 stuff was pretty good.

Now Penn sells the good stuff do those who care.

 

[CJim7]

Have you considered a 4.0 head swap? Easy to keep your carb with a Clifford manifold. The power gains are amazing. Best bang for the buck IMHO

 

[elwood blues]

Yeah, I remember the old Kendall GT-1 oil. Everywhere back home carries BRAD PENN, I'll have to remember to pick up a couple of cases next time I get home. To heck with having oil shipped

 

[CJim7]

Penn took over Kendall. The old GT-1 stuff was pretty good.

Now Penn sells the good stuff do those who care.

Pen...penzoil...any relationship or just a coincidence?