1965 4.2L Engine rebuild project

Is that measured from crank journal centerline?

1 Like

That’s my understanding.

1 Like

Originally I was going to let the deck dimension guide gasket thickness but since I don’t really know how much the head has been cut over its life, I am planning to let compression ratio be the deciding factor for the correct head gasket thickness.

Does this make sense?

Rick

Don’t know how you’d do that. You’d have to scrap a few head gaskets before arriving at your desired comp ratio. Better to stall a piston fully assembled on the crank and see if there’s any space left before it tops out of the bore.

If he follows Ray Livingston’s canonical way to determine compression ratio, no need to scrap expensive gaskets.

One thing that will need attention paid, is how far the piston crown gets to or exceeds the deck height.

2 Likes

This guy explains it pretty well. Start at t=1:30

Rick

1 Like

XK combustion chambers are all pretty close to 100 cc in volume. If you cc the combustion chamber volume and it’s significantly less than that you’ll know it’s been milled. If you have the current combustion chamber diameter and depth and the current volume you can calculate how much it was milled.

1 Like

My 3.4 C head measured 104 cc on all chambers. I found a 13 year old post which suggests the uncut deck height is 11.48", FWIW…don’t remember seeing that spec in the manual, however.

Would only be approximate, many variables there, valve seat depth, valve head thickness, volume of the piston dome, bore size/oversize, compressed gasket thickness. Can only be calculated if measured accurately with burette & micrometer.

I’m glad you spotted that. I was going to suggest something similar.

1 Like

Agreed, that’s what I meant by ‘tops out of the bore’.

Crankshaft Damper Pulley C24366

Can anyone tell me if my original crankshaft damper pulley is usable? At $570-$700 for a new one I want to be sure.

Thanks
Rick

The one on my 3.8 was a little more perished than that and I changed it for new - I wouldn’t fit yours. They can also be reconditioned. These guys are on your side of the Equator.

Thanks. I will give them a call. I see a few other members have used them with no issues.

Rick

Hi Rick, yes, I have used DamperDoctor for my three cars. They are the best way to restore your damper.

Regards,
Allen

Update:
Block and crank are back from the machine shop. The shop felt a good polish would be sufficient, so that is what we went with. After polishing all journals, (mains and rods) are in spec. The deck only needed a .005 cut to sufficiently clean up the pits. The bores were honed out another .001" and now the piston to bore clearance is .0018" to .0025". I called AE (now DrivParts) and they said this is fine for cast hypereutectic pistons. Good news!

Main Bearings:
I bought a decent Mitutoyu (.0001") 2-3" micrometer and a Fowler dial bore gauge (.0005) to measure journals and main bearing clearances with new Mahle standard bearing shells installed and caps torqued. The clearance spec from Bentley is .0025" to .0042". I am getting .0020" to .0023" which is on the low side. For a second opinion I did a Plastigage test and it more or less confirms the low clearance, maybe even lower. Here are some typical shots:


I read this as somewhere between .0015" and .0020". So still on the low side. My question is: Is this clearance still OK or is it too tight? And if too tight, what can be done? I don’t think there are any undersize shells available. I have also mixed and matched the shells as much as possible to get the overall largest clearances.

Thanks for your help
Rick

For Street use, that bearing clearance is just perfect!

That’s what I was hoping to hear as I couldn’t imagine too many easy or cheap options to change it.

Thanks

Rick