New engine?

[gungfudan]

I got my new engine in and running I need to know how many miles till it is broken in. And I also need to know why the truck has a slight buck to it when I am at a constant speed? It is timed right and the carb seems to be adjusted right because the engine sounds great?

 

[Mark_88]

I guess it depends on the school of thought...I've heard that when breaking in an engine the first 100 miles are the first critical point and you should change your oil right around that point...the next one is 3,000 miles where you should change the oil again (including filters on both changes)...

Some recommend to remove the valve cover at the 3,000 mile mark and tighten the head bolts down to the last spec (85-90 ft/lbs) but I didn't do that with either of my head replacements and didn't have a problem with the head gasket leaking.

But I'd make sure you change the oil and filter at least once after a brief break-in period (say 100 miles) because if there are any filings that are going to let fly from fresh metal (if you bored or even honed the cylinders) it should come out in that first change...

 

[zekew64]

+1 on the first 100 miles; however, you should also change the oil at 500 miles and then again at 1000 miles. Also, from 100 miles to 1000 miles, don't be hard on it, but don't baby it either. After the 1K mark, consider the engine broken in.

 

[gungfudan]

Well I changed the oil after 95 miles and will again after 1000 miles I have been doing a lot of reading it seems to me that the pattern is 100 then 1000 miles and then again at 3000 miles. But after 1000 it is considered broken in

 

[Mark_88]

Sounds good...but I also agree with the babying of the engine till that 3,000 mile mark...just don't honk on it and start off nice and easy, shift around 2,000 to 2,500 RPMs till you pass the 3,000 miles...then gradually work your shifts up to higher levels or to what you normally would shift at.

I don't have a tach so I usually shift by speed and the recommended shift points are usually marked on the speedometer for best fuel economy...

 

[scotts90ranger]

I asked several people at work (that have been working on engines forever, one a performance engine builder) and they said running the engine for about half an hour just sitting and idling, blipping it a few times then do an oil change, next drive it, not babying it (not WOT or all high rpm) but not all out just normal driving for about 7-800 miles, then go to normal 3000 mile changes and do whatever you want...