194824 Gets a Checkup

[hanleyclifford]

Doing a partial disassembly contemplating another run south next winter. Compression figures were all within spec but end play was another matter. Crankshaft end play is .007" (spec max .003"). All 4 rods end play .018" (spec .008"). It is a testimony to the durability and flexibility of these engines that they can run so well, so loose, so long. All torque values on mains and rods were perfect (60 ft lbs and 25 ft lbs, respectively). I did not bother to check the bearings since I know they are near max but running well. I had one hot rodder tell me he ran his mains at .006". I would interested to hear end play measurements from others - wondering if I have the loosest goose on the marsh.

[lat 64]

I guess the end play is regulated by the condition of the thrust bearing, so if you got new main bearings, the end play would be restored.

.006" is a bit much for oil clearance. Sometimes I am confused between diameter and oil clearance. When you measure the crank, then the bearing insert, you divide the difference by 2 to get the oil clearance. There is oil clearance on both sides of the circle of the bearing. If your racer friend has .006" undersize crank diameter, then it could be that he has .003" oil clearance. Still a bit high, but maybe he runs heavy oil.
Do I have this right, Dave? Or, am I the one confused?

Russ


Happy t-bird day

[hanleyclifford]

Russ - In March of 08 I had .008" crank end play, had the crank ground .010" under and with new bearings the end play is now .007" after 1948 hours, so I gotta believe most of the wear is on the crank itself and I cannot correct it much with new bearings. I have not seen any issues with the exceptionally high end play so I've decided to live with it. The rods have gone out another .002" since 08 and I guess I am concerned about that; however, short of a new crank there isn't much I can do about that. After new cam bearings late in 09 I have zero oil pressure issues. Too bad they don't make main bearings with oversize thrust surfaces.

[Ball Racing]

Has the crank wore for the rod clearance or has the sides on the rods worn?
You can get some new rods right??

[hanleyclifford]

Has the crank wore for the rod clearance or has the sides on the rods worn?
You can get some new rods right??

Good question. I never thought of that. Do you know the out-of-the-box width for the rods so I could compare?

[Dave Neptune]

Yep

Been in the desert for a while and just returned. Russ you're spot on with the clearance. Yeh it is a bit much clearance, however not extreme. If things are "ROUND" it should be no problem running slow RPM's like the A-4 thicker oil and our "horse power to bearing area" is not near the low side!

It does seem the your end play wear is a bit high though, IE the .002 in the 1900+ hours. And as I recall you run your reduction A-4 at direct drive RPM's. A bit more spin (RPM's) will really reduce the end play and rod bearing wear though. The spinning keeps the "oil centered" better and reduces the stresses of bearing pressure over time~even end to end.

Dave Neptune

[hanleyclifford]

After all the talk about crankshaft flexing (and other scary thoughts) I couldn't resist looking at the mains since another trip is in the planning. How do these bearing shells look? (over 1900 hours, 2 trips)

[Loki9]

I can't really evaluate a bearing by looking at it. As long as the wear looks even, not scored, etc. it may be alright. Measurements are a must to determine if it is still in-spec.

[sastanley]

This talk is mostly over my head....but when I was rebuilding the Honda engine in my Civic, I used Plastigauge on a few things to check clearance. That was 10 years ago and apparently old-school even then as I had a little trouble getting all of the necessary materials..but, it gave me solid data on which bearings I needed.