Advice Needed Regarding 304

I have a 1977 CJ7 that is all original except for a new Edelbrock manifold and 4 barrel Holley carb that I put on it around 1980. I also put dual exhausts on it in 1990. It has about 40 k miles on it and runs great except for a leak in the heater core and a bad fuel sender that I'll fix later this winter.

I'd like to change the distributor from the Prestolite to the Motorcraft. I bought what was to be an OEM remanufactured distributor from Autozone, but I got a new Cardone select distributor in a box marked remanufactured. I bought a second one from Rock Auto and got a remanufactured Motorcraft that I plan to use. I trust the fit of the Motorcraft more than the new Chinese distributor. So my plan is to change the gear from the Prestolite to the Motorcraft so that the cam and distributor gears are matched (pitch, wear, hardness). Is this a good approach and how likely is it that I'll have gear problems?

That was all I planned to do, but then thought about the old cam gear with Nylon on the teeth. I changed my timing gears and chain in my Firebird 400 back in 1972 when it was only three years old and the Nylon could be peeled off the cam gear by hand. So I'm sure the Nylon on the 40 year old OE AMC cam gear is ready to fall off. I plan to use the Bulltear timing gears and chain, but it would seem that now there's even more of a chance that I'll have a gear problem since I'll have removed and reinstalled the timing cover.

Back in the 60s I never worried about changing distributors, timing gears or chains on GM engines and everything worked. The AMC V8, however, seems like it's more prone to distributor/cam gear problems, so I'm wondering if it's worth the risk of creating problems when everything is now working? I'd welcome any comments or suggestion on what you'd do. Should I just change the distributor? Should I also change the timing gears and chain?

Thanks.

Welcome to Bulltear.

It probably wouldn't hurt to change the timing gear if it is plastic. You can shine a light down the hole once the distributor is out and check. Some AMC truck engines were made with steel gears from the factory (plastic was used in cars because it's quieter). My 77 Jeep had a plastic gear, but I've seen some that didn't. That said, if you do replace it, be very careful to compare the factory top gear to the replacement. Pay attention to the position and depth of the oiling holes and slots. The oil flows from the front cam bearing out thru the upper cam gear and fuel pump eccentric to oil the distributor gear. Any blockage will shorten the life of the dizzy gear.

You're correct in swapping the gear to the new distributor, and it shouldn't be a problem. I hated the Prestolite. It failed on my Jeep several times. I carried an extra ECU in the glove box before I finally changed to a Mallory Unilite and never looked back.

I bought my 77 CJ7 in 1978. Finally sold it in 2010 just because I got out of the 4-wheeling scene. Mine had almost 160K on it, and it was converted into a serious rock crawler.

Bob
tufcj

Thanks Bob. It would be good if I had a steel cam gear so I could leave it. Glad to find out that the distributor gear swap will work.

Fred