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overheating and no coolant flow

overheating and no coolant flow
coldair said:
Do you have a dial indicator? Or do you have a scribe?
Click to expand...


I can borrow a dial indicator from work, yes I have a scribe set.
 
I will have to see if I can find my pictures so I can explain this better.
 
I just found the box in the garage for the pushrods, they are 9.650".
 
I know I'm learning something here thanks.
 
73CJ said:
Check this one out. Not sure why he was banned but good info.

http://www.jeep-cj.com/forums/f2/correct-push-rod-length-258-4-2-carefull-8362/
Click to expand...


I found that last night, and I found were MN copied it from jeepforum as well Different Length Pushrods ? - JeepForum.com.

The link you put up there from Crane Cams was also very informative.

So, I got my push rods from NAPA, which explains why the are 9.650" long. I also learned that my stock pushrods for a 1978 AMC 258 i6 / 4.2l should be 9.622" long.

Here's the questions I still have;

1. Do I need to replace the current pushrods that I currently have (9.650") with pushrods that are the correct length for a 1978 (9.622"), just to check lifter preload first? Or can I check the lifter preload the way I am now?

2. I don't completely understand the rocker arm shims, are they adding to or subtracting from the overall length of the pushrod? Let's just stick with the pushrods I'm running (9.650"), I add a .030" shim, does this take my pushrod length to 9.680" or 9.620"?


Thanks for all of the help :chug:
 
I would guess the shim raises the rocker so it should be shortening the relative length of the push rod.

I can't wait to see what the outcome of this is. Am I right in understanding that having slack in the rocker due to a short push rod will cause damage due to lack of constant and consistent contact with the cam?:cool:

where does this leave those with a 4.0 head? I think I used 4.0 push rods from a Jeep dealer.
 
IO, I hope you're not asking me to answer those questions, because I'm still trying to get a good grasp on all of this. I thought I had a pretty good understand of the AMC 258 i6 / 4.2l engine, this is proving that theory wrong :bang:
 
elwood blues said:
IO, I hope you're not asking me to answer those questions, because I'm still trying to get a good grasp on all of this. I thought I had a pretty good understand of the AMC 258 i6 / 4.2l engine, this is proving that theory wrong :bang:
Click to expand...
I'm with you there. :o
 
From my 1978 Technical Service Manual;

Cam Lobe Lift
AMC 232 i6 /AMC 258 i6 / 4.2l 1V .AMC 232 i6 inch



From the spec sheet of my new cam;

Lobe Lift
Intake .2890
Exhaust .3030



Now I'm even more confused :wtf: does this mean that I'm going to need 2 different lengthed push rods?

As soon as I get done typing this, I'm ordering a pushrod measurement tool.

This is turning in to a much bigger project than I ever imagined it would.
 
I would have to think that you could check "pre load" on the valve/cam/lifter with a feeler gauge, kind of like we did in the olden times.

The difference being that if you had too much slack, not enough pre load, you would have to remove some of the base of the rocker or the rocker boss on the head to hold some contact with the cam. like 78CJ did.

If you had no slack, full contact with the cam through the entire revolution, you could be failing to allow the valve to close all the way, especially at high RPMs. I think I could see that causing some problems maybe even hurting the engine.

Elwood: I suggest you buy a bag of oil dry, pull the cover and see if you have a rocker with too much slack in it at idle. Do it just before you were going to change oil anyway.:cool:

As far as the new cam causing a change in pre load, I guess maybe but I would think the base diameter of the cam lobe should be pretty close to stock to insure the cam closed all the way.

everything I have just said is purely speculation and as I just said, I can't wait to see how this turns out.:popcorn:
 
Rotate the engine by hand in the normal direction of engine rotation until
both the exhaust and intake valves have opened and closed completely. Allow a couple of minutes for the lifters to bleed down. You will have to do this to each cylinder for accuracy. Do not turn the motor over with the starter this will make the lifters pump up.
Using the valve cover gasket surface on the head as a reference point, place a mark on the pushrod. I used a razor blade to mark the push rods. The pushrod will be marked twice. It must be from the same reference point and angle for the measurement to be accurate.
Loosen rocker shaft bolts. Leaveing the rockers on the head so that they will support the pushrods. Be sure the pushrods are standing free in the lifters and do not have any pre-load. Using the same reference point, place a second mark on the pushrod. The distance between these two points will be the amount of lifter pre-load. If you want a more accurate way i will have to write up how to use an dial indicator. hope this helps:chug:​

 
I guess I have tyo go back to the beginning. Please define "pre load " for me as you understand it. I thought it was something different from what you have described. I would have called what you are measuring "lift".:cool:

coldair said:
Rotate the engine by hand in the normal direction of engine rotation until
both the exhaust and intake valves have opened and closed completely. Allow a couple of minutes for the lifters to bleed down. You will have to do this to each cylinder for accuracy. Do not turn the motor over with the starter this will make the lifters pump up.
Using the valve cover gasket surface on the head as a reference point, place a mark on the pushrod. I used a razor blade to mark the push rods. The pushrod will be marked twice. It must be from the same reference point and angle for the measurement to be accurate.
Loosen rocker shaft bolts. Leaveing the rockers on the head so that they will support the pushrods. Be sure the pushrods are standing free in the lifters and do not have any pre-load. Using the same reference point, place a second mark on the pushrod. The distance between these two points will be the amount of lifter pre-load. If you want a more accurate way i will have to write up how to use an dial indicator. hope this helps:chug:​
Click to expand...
 
IO all it is really how far the push rod sits in the lifter with the cam to where the lifter isnt hitting the lobes. Does that make sense?
 
mtnwhlr said:
The thermostat being installed backwards was the first thing I thought. And I always drill a small hole in mine when I change them it helps get rid of any air that is trapped.
Click to expand...


Most of the newer engines have t-stats with a small poppet vavle at 12
o'clock. It is helpful.
 
The Crane Cams "The shims will decrease lifter preload approximately .030”, .060”or .090”depending on the shims used. Maintain a recommended lifter preload of between .020”minimum and .060”maximum for proper lifter operation."

They explain it well. Just use a dial indicator with a magnetic base to measure. Measure where you are at right now and go from there. NAPAs are long so they can be shimmed. You have to measure every push rod.

Many things can cause the pre load to change - surfacing the head, doing a valve job ( the valve stem can be ground or the seat cut and the valve sits deeper) or putting in a new cam or lifters. The base circle can change as well.

I like to set mine at .040".

Too little preload - Noisy and lower power

Too much preload - excessive wear on the cam, possibly damage the lifters

So why did you put the cam in? To make more power! So take the time and do it right.

Let us know your progress.
 
mtnwhlr said:
http://www.cranecams.com/uploads/instructions/151g_.pdf
Have you look at this?
Click to expand...


73CJ said:
The Crane Cams "The shims will decrease lifter preload approximately .030”, .060”or .090”depending on the shims used. Maintain a recommended lifter preload of between .020”minimum and .060”maximum for proper lifter operation."

They explain it well. Just use a dial indicator with a magnetic base to measure. Measure where you are at right now and go from there. NAPAs are long so they can be shimmed. You have to measure every push rod.

Let us know your progress.
Click to expand...


Between the Crane Cams website and the info I found here on the Comp Cams site; COMP Cams® - Pushrods, I'm starting to understand it better.

I am waiting on FedEx to deliver my pushrod length measuring tool I ordered from Summit. COMP Cams: Magnum Checking Pushrod 8.500"-9.800", so until that shows up I'm on hold. Thanks you guys :notworthy:, I will definately keep you updated and will let you know if I have more questions.
 
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