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Unread 03-13-2010, 08:30 PM   #1
jallglass
Registered User
 
Join Date: Mar 2010
Location: Louisiana
Posts: 1
break in period

Recently purchased an 86 cj7 with a fresh rebuild on a 258, (300 miles). The rear hole on the valve cover was blocked off and the front pcv was hooked to the vac on the offy intake. i was getting tons of pressure in the top end and plenty blow by with oil in the tail pies. i unplugged the rear hole and replaced with a breather and the condition got better, however i still have some blow by. Next step was to replace the break in oil with non detergent 30W, "IF" im heading down the right track; how long before i should expect rings to seal or some results? BTW 175 compression on all cyl.

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Unread 03-14-2010, 04:12 AM   #2
jeepmaster03
Member
1982 CJ7 
 
Join Date: Dec 2008
Location: Rayne, LA
Posts: 277
You need to continue to run an additive package in your oil to keep your cam and lifters alive. I too like straight 30 wt but add a break in additive that contains ZDDP which reduces friction between cam lobes and lifter bottoms. It should in no way affect the sealing ability of your rings.

Did you do the rebuild or sure it was properly done? The rings must be properly gapped and orientated. There are a host of issues that can contribute this problem.

My point is it might not necessarily be the oil.
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Unread 03-14-2010, 09:14 AM   #3
JeepHammer
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1973 CJ5 
 
Join Date: Aug 2007
Location: South West Indiana
Posts: 9,954
Actually,
Your camshaft is broken in after about 20-30 minutes.
Bearings are about the same.

What usually kills camshafts is people starting/stopping the engines because they didn't have things hooked up ready to run the engine for 30 continuous minutes and having to shut it down for more coolant, transmission fluid, ect.

Bearings will clearance in about 1 minute.
Some additional wear will result if you didn't Assembly lube the crap out of everything and/or Pre-Oil before you started the engine.

Cam lifter/lobe wear break in will take about 15-20 minutes unless you are using some super slick 'Synthetic' oil to break in with, and that's NEVER a good idea.

Usually, the best way to determine if your camshaft/lifer wear pattern went fine is to take a look at the pushrods while the engine is running.

The cam lobe is ground at a slight angle to the back of the engine, that rotates the lifter in the bore as it rides on the slope...
By putting a paint dot on the pushrod above the head,
You can usually see the pushrod rotating with the lifter.
That's ALWAYS a good sign when the lifter rotates correctly.

The second test is to use a dial indicator at the rocker to see if you are getting the correct lift.
If the lifer/cam lobe galled each other instead of breaking in, you won't get the correct lift.

If you have more than 100 Miles on the engine,
Then the camshaft is either broke in correctly (most do) or it's wiped out a lobe and will continue to gall the lobe until you don't get anywhere near the correct lift.

With 300 miles on the engine,
*IF* you correctly adjusted the rockers in the first place,
You should be able to roll the engine over until each set of valves for each cylinder are closed,
Then check for slack in the rockers.

Galling on the cam/lifters ALWAYS shows up as slack in the rockers, reduced lift at the rocker...

Generally, we broke the fresh engines in on the dyno,
Gave them about an hour of run time, readjusted everything,
Then went on with dyno trials to tune for best results.

Usually changed oil/filter after the first hour,
That's where the most metal will be shaved off during 'Break-In',
Then changed oil/filter again at about 500 miles.

You will want to change oil/filter at about 1,500 miles,
(1,000 miles on fresh oil)

Then wait the 3,000 mile interval for the next oil change.

I never used 'Break In Oil' and still don't.
I exclusively use Valvoline 10W40 for break in periods,
15W40 for extended run (full interval) oil changes with no issues what so ever.
It's worked for the past 30 years or so in all types of engines from screaming sprint car engines to garden tractor engines without problems.
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Unread 03-14-2010, 11:35 AM   #4
nshefbuch
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1982 CJ7 
 
Join Date: May 2009
Location: piqua, OHIO
Posts: 1,865
Quote:
Originally Posted by JeepHammer View Post
Actually,
Your camshaft is broken in after about 20-30 minutes.
Bearings are about the same.

What usually kills camshafts is people starting/stopping the engines because they didn't have things hooked up ready to run the engine for 30 continuous minutes and having to shut it down for more coolant, transmission fluid, ect.

Bearings will clearance in about 1 minute.
Some additional wear will result if you didn't Assembly lube the crap out of everything and/or Pre-Oil before you started the engine.

Cam lifter/lobe wear break in will take about 15-20 minutes unless you are using some super slick 'Synthetic' oil to break in with, and that's NEVER a good idea.

Usually, the best way to determine if your camshaft/lifer wear pattern went fine is to take a look at the pushrods while the engine is running.

The cam lobe is ground at a slight angle to the back of the engine, that rotates the lifter in the bore as it rides on the slope...
By putting a paint dot on the pushrod above the head,
You can usually see the pushrod rotating with the lifter.
That's ALWAYS a good sign when the lifter rotates correctly.

The second test is to use a dial indicator at the rocker to see if you are getting the correct lift.
If the lifer/cam lobe galled each other instead of breaking in, you won't get the correct lift.

If you have more than 100 Miles on the engine,
Then the camshaft is either broke in correctly (most do) or it's wiped out a lobe and will continue to gall the lobe until you don't get anywhere near the correct lift.

With 300 miles on the engine,
*IF* you correctly adjusted the rockers in the first place,
You should be able to roll the engine over until each set of valves for each cylinder are closed,
Then check for slack in the rockers.

Galling on the cam/lifters ALWAYS shows up as slack in the rockers, reduced lift at the rocker...

Generally, we broke the fresh engines in on the dyno,
Gave them about an hour of run time, readjusted everything,
Then went on with dyno trials to tune for best results.

Usually changed oil/filter after the first hour,
That's where the most metal will be shaved off during 'Break-In',
Then changed oil/filter again at about 500 miles.

You will want to change oil/filter at about 1,500 miles,
(1,000 miles on fresh oil)

Then wait the 3,000 mile interval for the next oil change.

I never used 'Break In Oil' and still don't.
I exclusively use Valvoline 10W40 for break in periods,
15W40 for extended run (full interval) oil changes with no issues what so ever.
It's worked for the past 30 years or so in all types of engines from screaming sprint car engines to garden tractor engines without problems.

just had my amc360 rebuilt and my mechanic says the exact same thing that you did jeephammer. i do remember him saying something like hydraulic lifters need a break in period but thats way over my head. i'd rather pay someone who knows what their doing on engine work. the smallest mess up can ruin everything.
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