Rebuilt Engine Question...

I am not far from completing my rewire, which means it is almost time to really get a chance to drive my new toy for the first time, but I have a few questions before I do. The PO rebuilt the engine 3 years ago, since then, it has only gotten a max of 75 miles put onto it. From what I can tell, its the FHead 134. When I first went and looked at the jeep, the PO asked if I would be able to trailer it home or if I wanted him to deliver it to me. Not knowing too much about rebuilt engines, I opted to have him deliver it to me, which he did at no extra cost, even though it was about a 3 hour trip. I have been told not to drive it too fast, which is not much of a problem since max speed limit round here is 60MPH, but I was curious as to why this is. One friend of mine said I might want to do an oil change around 500 miles or so, but nobody can give me a reason why I shouldnt be able to drive this thing like its new. Can anyone shed some light on this for me? I really need this to be my daily driver, well, weekend driver, since I only work weekends, but it has to be able to survive a 50 mile round trip each day I drive to work, all interstate/highway travel.

 

If you have the original engine, it is the F134.

Most rebuilders (and car companies) recommend some kind of break-in regime. This usually includes not driving at very high speed, and intentionally varying the engine speed, ie not driving at the same speed for a long time. This break-in period covers the first 500 miles or so.

If it were mine, I'd both keep the speed down and vary the speed for the next few hundred miles. I'd also change the oil now, and again at 500 miles. Outside the can, three years is old for motor oil.

 

Tim, thank you very much...I had plans to change the oil before getting it out of the garage, just because it sat for 3 years with only startups every month or so, but it would still break down.

So I should be able to drive it back and forth to work, so long as I dont drive it too fast? 60mph is fairly fast, so I had already planned on keeping it down in the 50-55 range, should I go lower than that and just take it to the city streets when I can? Max speed limit there is in the 25-45 range.

 

Taking the city streets will provide the varying engine speed Timgr is talking about. Plus you get to know the little quirks of your particular fun machine.

Just leave early enough that you aren't rushed going to work.

 

here's the list my shop sends out the door with a customer who we just built a motor for:

Initial Startup:
- Hold engine RPM at or around 2000 for 10 minutes. This allows for proper break-in
of the camshaft and builds up initial oil pressure.
- To help with seating of the piston rings, drive the motor up a long incline, gradually
accelerating under load.

After 100 Miles:
- Change the oil. We initially prep every motor with Non-Detergent oil. So drain the
oil and change the filter. This is when you switch over to conventional motor oil.

After this, start with a 2500-3000 mile oil and filter change. You can drive the new motor
as hard or easy as you like--it won't care one way or the other!

hope that helps,
- evan

 

With 33" tires (~10% overdrive), 50-55 mph should be no prob. With my 31's, I feel pretty comfortable at 53 mph at 3500 rpm, sustained. In these hills, I shift at 4K rpm. Drive it. See what you think.