Engine build question 52 Cranbrook 218

[Matt Wilson]

You might also consider buying a dial indicator and using it to see how much runout your crankshaft has.  My manuals say the runout at the "center journal" (it seems to me that there are actually two "center" journals - i.e., #2 and #3) is supposed to be no more tyan 0.003".  This seems large to me, but it's what the manuals say.  This is for new parts, while ised parts have a wear limit of 0.005" runout.

 

Anyway, if the runout is too large, that could be causing your crankshaft to bind in the bearings.

[DJK]

Talked to 89 yo George Ashe Jr. last week(who is currently building a flathead engine), he said as long as the crank measures std., go with std. bearings. Rod and mains ordered (sealed power), rod bearings arrived, checked with plastigauge as per George, a liitle less than .002" clearance. Waiting on the mains to show up. The way I see it, the engine had 40# of oil pressure with 68 yo bearings, the new bearings are approx. .001 thicker than the old ones, I should be golden!!!

[DJK]

Update: Mains arrived today, checked with plastigauge = just under .002" clearance, cleaned off plastigauge, apply prelube, torque main caps(w/o rope seal), crank spins very smoothly. Wed. AM my 80 yo friend, who worked on these vehicles back in the day, is coming to help install the rope seal. Life is good.

[DJK]

Update: engine is in and running like a top, 40 +/- 5# oil pressure, no noises and no leaks so far. I had adjusted the valves before installing engine @ .010 int. and .013 ex., I assume I should recheck them hot????? Thanks for all the help in getting this project ready. First cruise in is Fri.

[Dave72dt]

I have to ask.  What was the difference between the first set of standard bearings you thought were going to be too loose and the second set of standard brgs?  Yes, rest the valves hot and retorque the head.

[DJK]

9 hours ago, Dave72dt said:

I have to ask.  What was the difference between the first set of standard bearings you thought were going to be too loose and the second set of standard brgs?  Yes, rest the valves hot and retorque the head.

With .003 clearance, according to my manual, this is too much clearance. Went back to machine shop for remeasure, he suggested .002 bearings. Had .001 clearance with plastigauge, unfortunately crank would not turn, same with rods. Had already sent back the set of std. bearings, reordered new std. Sealed Power bearings from two different sources. Checked with George Ashe Jr. (who at 89 is still building flat heads) to verify the use of std. bearings. The crank journals were all well w/in specs. Just under .002 clearance w/ plastigauge and new std. bearings. Engine sounds great, 45# at fist start, 40# driving down the road, 35# at hot idle. I have done 3 heat cycles and retorqued head after complete cool down. Will perform hot valve adjustment. In regards to the bearings, the first set of mains were packed in shrink wrap and looked like new reproduction, the rod bearings had a piece of foam in the package that crumbled when touched not to mention they were rusty on the sides and crushed together with scratches on the bearing surface. 

[Dave72dt]

 

So, what you're suggesting is the first set of std bearings were out of spec and therefore defective?  Did you use the same stick of Plastigauge when measuring the second set of std brgs that you used for the first set?

[DJK]

On 5/5/2021 at 10:16 PM, Dave72dt said:

 

So, what you're suggesting is the first set of std bearings were out of spec and therefore defective?  Did you use the same stick of Plastigauge when measuring the second set of std brgs that you used for the first set?

I did use the same plastigauge. The new Sealed Power std bearings measured almost .001 thicker than the bearings that I originally took out of the engine. I figured if the engine ran 68 yrs. with std. bearings and the polished crank is within specs, it will run a few more yrs. for me.