Break-in on 91 Chevy 4.3

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  #1  
Old 03-03-04, 01:34 AM
Negoshe8n
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Break-in on 91 Chevy 4.3

I have about 1000 miles on my 91 S10 Blazer 4.3. Is it normal for it to use alittle oil during that time? Is it common for the valves to need to be re-adjusted after or during break-in? It has an upper valve tap at idle. Runs fine. Smokes just as I give it gas, but not during idle or when cruising. Is that normal during break in?
 
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Old 03-03-04, 03:30 AM
Desi501's Avatar
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You talk of breaking in a "91" vehicle but you don't mention what was do to the vehicle. A small amount of oils consumption during ring break in may be normal but it sounds like you have more than that. I believe the valves in that engine are hydraulic and shouldn't need any furhter adjusting. You may have some problems in the assembly of that engine if it has recently been rebuilt.
 
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Old 03-03-04, 05:15 AM
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agree with desi...

...was it just rebuilt or did you buy a reman from someone and have it installed???

a little oil consumption during break in is normal...

hydraulic valve lifters require no adjustment...and yes...that's what it is equipped with.

there shouldn't be ANY smoking...period

what color is the smoke? blue? white? black?
 
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Old 03-03-04, 02:10 PM
Negoshe8n
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I'm talking about breaking in a new motor for my 91 Blazer. The motor has been bored .30 over, TRW flat tops and lightened rods. I bought it from a guy that never started it. The cylinders were nice and shiney with the re-boring patterns on the walls. The pistons looked brand new looking through the spark plug holes. Maybe I worded this wrong. The rockers are what I am talking about that may need re-adjusting. Is that normal for them to tap? It has a tap from the top after it's warm. The smoke is either blue or white, maybe a greyish. Kinda hard to tell when I'm driving.
 
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Old 03-04-04, 04:47 AM
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rebuilt engine

i understand what you meant about the adjustment of the valve train. it doesn't need to be adjusted...provided it was done correctly when it was put together. when adjusting those rockers, the engine is put on TDC on the balancer, firing #1 cylinder. next, you would loosen the rocker nut until you feel lash and then tighten it back up just until the lash goes away, then turn the rocker nut an additional 1 full turn. this procedure will center the lifter plunger in it's bore. now...with the engine in that position (firing #1 TDC) you can adjust the following rockers. exhaust 1,5,6/intake 1,2,3.

now...you turn the engine over one full revolution back to TDC on the balancer...now you would be firing cylinder #4 and you can adjust the remaining rockers using the same procedure.

this should eliminate any valve train issues related to adjustment. keep in mind that altho the cylinders were bored and the pistons are new...valve train parts may have been used over and could be worn (rockers, valve stems, push rods) and may contribute to noise.

about your smoke...the color matters so figure out a way to see it. blue smoke is oil...black smoke is unburned fuel. white is usually coolant but in cool damp weather, it's more like a cloud you can't see thru. grayish vapor looking "smoke" is water vapor and that's a by product of combustion and catalyst action and goes away when the exhaust system heats up...don't be concerned
 
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