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Just read your other post about the honing done on the block by your machinist. Pictures of your cylinder walls do not look good. Should have been bored out.
Has the block been bored out before? (I'll answer that, no, your the original owner correct?)
Did you measure bore and out of round yourself on each cylinder?
Do the pictures of the bad looking cylinders match cylinder #4 and #5 with the lowest compression?
I just did top end on my 351 that has over 300,000 kms, and my cylinders looked better than yours. After doing head gaskets compression is 170-175 across all cylinders.
Just read your other post about the honing done on the block by your machinist. Pictures of your cylinder walls do not look good. Should have been bored out.
Has the block been bored out before? (I'll answer that, no, your the original owner correct?)
Did you measure bore and out of round yourself on each cylinder?
Do the pictures of the bad looking cylinders match cylinder #4 and #5 with the lowest compression?
I just did top end on my 351 that has over 300,000 kms, and my cylinders looked better than yours. After doing head gaskets compression is 170-175 across all cylinders.
Block was from a '96 Explorer. Original cross hatch visible for the most part. I don't have the optimal tools to measure out of round. Using the ring gap method, I saw .003" as the worst taper.
Cylinders 5, 6 and 7 had the "spots". Five being the worst by far.
Conferred with my former neighbor, forty years in Ford service. No definitive answer but his hunch is the issue is mechanical. Looking like I'll need to pull a valve cover and degree the cam.
There are some "quick and dirty" ways without use of a degree wheel, at least for checking if the cam is installed in the ballpark, or way off out in the parking lot.
First thing to note is whether the TDC "0" mark on the balancer is known to accurate, i.e. that the damper ring hasn't slipped off axis. But every time the damper and pointer indicates TDC on a V8 the #1 and #6 cylinder valves will either be at overlap or fully closed, depending whether it's on the compression stroke or not.
Roll the engine over by hand carefully until the #1 cylinder intake and exhaust valves are exactly at overlap, can use a straight edge across the top of the valve springs to get close. Then, observe where the pointer falls relative to the TDC mark on the balancer - is it BTDC, or ATDC? A few degrees BTDC is probably what you hope to see. If it's way off the beam, then you know there is a problem with where the cam is installed.
There are some "quick and dirty" ways without use of a degree wheel, at least for checking if the cam is installed in the ballpark, or way off out in the parking lot.
First thing to note is whether the TDC "0" mark on the balancer is known to accurate, i.e. that the damper ring hasn't slipped off axis. But every time the damper and pointer indicates TDC on a V8 the #1 and #6 cylinder valves will either be at overlap or fully closed, depending whether it's on the compression stroke or not.
Roll the engine over by hand carefully until the #1 cylinder intake and exhaust valves are exactly at overlap, can use a straight edge across the top of the valve springs to get close. Then, observe where the pointer falls relative to the TDC mark on the balancer - is it BTDC, or ATDC? A few degrees BTDC is probably what you hope to see. If it's way off the beam, then you know there is a problem with where the cam is installed.
Easier in more ways than you describe. Observing #6 instead of #1 means that the upper intake can remain in place, only requiring driver's side valve cover to be removed. Thanks for the idea. And I am certain of the timing mark/TDC mark relationship. It's a brand new balancer.
I was about to say that 1-5/8 turns or .090" preload seemed a bit much. I was told 3/4 - 1 turn after first contact on a threaded stud or 0.030 - 0.045" of preload on a bolt-down.
Just checking... you have the complete roller valvetrain in there with roller lifters and the matching pushrods?
Try backing off the rockers a half turn and then recheck compression. If it comes up you need shorter pushrods.
Yes, complete roller valve train. Mustang F4ZE cam from a '94 Bronco, lifters, pushrods and hardware from a '88 Crown Vic. The lifters were all disassembled, cleaned and put back together.
Help me understand this. I'm getting 3/4-7/8 turn from zero lash on the four I have checked. My previous figures were possibly faulty memory. Instead of a half turn out for a compression check, I went to zero lash (finger tight with a half inch socket) then a further 1/4 turn. I got a bump, but just 10# or 110psi.
As a further check, I rigged up a dial indicator on the edge of the rocker, valve end and torqued the pedestal from zero lash. The oil filled lifters don't give and the valve end drops .090". At 1:7 (approx) that's .053" of pre-load on the lifter side. It takes about five minutes for the lifter to bleed off as the valve rises back into its seat.
More information. Used lifters, used block and new, standard duty Melling oil punp. New melling springs for '96 Explorer. 90# valve closed 210-220# open. Valve spring heights at stock settings. Give or take a .001" or two.
According to the F4ZE Mustang cam specs, the intake valve opens at 20° BTDC. Working with cylinder number six, the same as number one, I set up the dial indicator on the intake valve. When the cam just nudges the #6 intake valve, we're here. Yellow is TDC, white is ten before. Looks like about a 22° discrepancy. Or two and a half teeth on the cam sprocket. EDIT: This reading is probably erroneous due to partially collapsed lifter
First time ever trying to shade tree degree a cam. Tell me if I've totally missed something.
That particular method is way, way above my pay grade. Used a bent coathanger and an old pie plate, just wanted to make sure I didn't install the camshaft retarded, like I am, lol.
Was the lifter pumped up or bled down when you checked the opening timing? If they were pumped up and not compressing, then it's time to open it back up to the timing gear and check.
retarding or advancing the cam isnt going to lower compression on 2 cylinders id say one of 3 either leaking valves rings not sealing or valve adj to much pre load... did it have any windows on those low cylinders( shiny spots) ?
95 is low
The two low cylinders could just be they aren't seated in yet, or those cylinders may just be lower than the others. The main thing is all the cylinders are way low, and if checked correctly, the cam is way off on timing. Get the timing straightened out, and go from there. It may end up being six cylinders are 185 and two are 175. Those are livable numbers. The numbers may also even out after the engine is ran more. Moly rings don't seat as easy as the rings of old.
Getting of feel for how these hydraulic roller lifters (or any hydraulic lifter) act when loading and unloading them. I figured a sure way to actually measure the preload though. The measurements I got on five of the exposed eight rockers was from .053"-.065". Also, the lifters in their "not under oil pressure state" are not able to lift the valves to their full extent, in this case .444". Oil has been squeezed from the lifters by pressure from open valves and me generally jacking them around trying to find an issue. It cannot be replenished with just a dozen or so cranks with the starter. So the 20* late figure I came up with earlier is most likely due to the lifter being partially collapsed and just starting to push later.
Ordering shims, even though I doubt it will make much difference. Hope I'm wrong. .020" shims should bring all the that I checked into the .020"-.033" range. By my math, at a 1.6:1 ratio, a .020" shim will take out .032" preload.
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