rod journal remetalling clearances for 37T

Unknown

Ive had the crank ground and am sending the rods to Harkin machine for remetalling and boring.The crank journal diameters are 1.920,width 1.375.
What should the clearances be?
"motors"auto repair manual suggests .0003-.0006,but my machinist says this seems very tight.Any help greatly appreciated.

Geoff

Hudson Mechanical specs state .001", which when you consider is only 4 10,000th of an inch different from Motors Manual! The correct way to set them up is with shims, and have the connecting a very light drag on the journal with no oil. It should just hang at an angel, and then drop down with a very light nudge. Hudson original diamond bored all there cylinders and bearings which was very accurate. The most important is to get a good wide oil groove around the cap only, with a chamfer leading into both cap and rod surfaces of the bearing. These bearings need as much oil circulating through them as possible to keep them both lubricated and cooled. Good luck,
Geoff

Park_W

On the three engines whose bearings he's done for me, I've asked Mr. Harkin to finish for a (diametral) clearance of .001," and he's gotten them dead on.

Unknown

Just spoke to mr Harkin on the phone,he said that most Hudson owners go for .001 clearance,but my machinist thinks it might be better to allow an extra half a thou for a splasher motor,Any thoughts on that folks?

Park_W

Your machinist has worked on too many modern, full pressure engines. Stay with .001.

[Deleted User]

Best to go with .001.5 to .002. This is in the Hudson manual for splasher engines. With less clearance, driving on the highway you will burn a rod or main right out. No pressure here, so the rods have to splash oil to the mains and flow in through the top of the bearings, and the rods have to get oil all around the bearing and clearance is the answer. Walt.

Geoff

Sorry to have to disagree with Walt, but the 1937 specs are .001" clearance, and in the Step-down manual even less for the 8 cylinder splasher motors, .0003 to .0006" I have found that set up to .001 or less, and careful running in leads to longer life and quieter running. If you allow .002" clearance then by the time the high spots have worn off you have even more than that, and you will be able hear the bearings.

[Deleted User]

As long as he travels 35 mph or trailers it, that clearance will be fine. I'm talking about driving it on highways, 60-70 or 80, and that will burn the babbitt and flake it. I built 3 8 cylinder engines, and had the rods at .001.5 and the mains at .002 and that car has made trips 1500 miles one way. or 3,000 round trip and at 80 mph and runs like a dream, quiet and 19 MPG. The other 2 are trailer queens. Use 10-40 oil and you will never have bearing problems. This is not 1937 or even 1950 when these cars were driven 40 MPH. The higher the speed the more the clearance. Walt.

Unknown

Excellent and conflicting information,this is a bit like watching Superman and Batman duking it out!anyone else want to wade in?

Geoff

Simon, I can't imagine you wanting to break the law by driving at 80 m.p.h, particularly with your newly rebuilt motor!

[Deleted User]

When I rebabbit rods and mains, I set clearance at .001 to .0015. I feel oil lubricates of today have better viscosity and a slight more clearance is necessary.

Randy Maas

Unknown

Geoff C., N.Z. wrote:

Simon, I can't imagine you wanting to break the law by driving at 80 m.p.h, particularly with your newly rebuilt motor!

Simon is my meek and mild alter ego who goes to the monthly HET bingo meetings,sips tea and only drives his classic car on sunny days.Skip,however,likes to roar around the paddocks under a full moon at top speed
pretending he is a stockcar werewolf.
Simon will rebuild and run the motor in,then Skip will take over!:evil: :evil: :evil:

Park_W

I've always used about .001" diametral clearance, which is what you'd measure with plasti-gage on a dry bearing, but I note that the 1942-47 shop manual says .001 radial clearance, which translates to .002 diametral clearance. Hmmm.

[Deleted User]

Now Walt will say his piece. We are not in the 30's or the 40's anymore, we are in the 2000 and when you buy a new car, does it say you have to break it in by driving under 50 MPH for 500 or 1000 miles? With todays oil, get in and floor the pedal and that is why I say put the clearance in your motor and drive the wheels off it. Just like I do, 11 trips across this country, have hit 100 at times, so far 134,000 miles and my motor is still going strong and has never be touched yet and the NOR-CAL chapter members can tell you so. Put that clearance in and drive it. Just make sure the babbitt is top quality, and not 40 per cent lead as that will melt if you try to dry on todays highways. Here lies the secret, good or bad babbitt. Walt.

[Deleted User]

Those numbers come from when you want to drive faster. An extra half thousand to allow for expansion. And todays driving is faster. Walt.

ivanz62

In my professional opinion as one whose business has been doing this kind of work for more than thirty years, everyone here is correct!

The differences are in the type of work being done. Many babbit jobs use less than OEM quality babbit material. Many machinist do a less than optimal job of their part.

You can do an adequate job the "old way" by being very careful to fit everything close,in "burning in" the bearings, taking down the sump and re-shimming as required after an initial run in. This is essentially what happened after one could not buy centrifugally cast and precision machined factory parts. Thousands of Fords are still kept running this way.

The job can also be done in a more expensive way with more costly babbit (more tin in the alloy; less lead), careful grooves and spreaders, as original, machined after pouring, and precision sizing to give clearance between .0015 to .002". Done this way, there is "no breaking in" of the bearings. They are done. This does not mean the piston rings do not need seating and that no engine break in is required. But the sump need not come down.

So be sure you and your shops you work with are on the same page. Modern oils are better. Road speeds are higher to avoid being a target for a wandering Toyota. But if there is oil in the dipper tray, the Hudson splasher can do a lot.

Geoff

The last word Hudson gave on splasher engines is in the 1952 Mechanical procedures manual, which was the final version of the 8 cylinder splash fed motor, and they specify .0003" to .0006" DIAMETRAL clearance. I rest my case.

[Deleted User]

In 1952 I had hair and was 5 years old and now i'm 63 and bald. I've taken a few of the splasher 6 & 8's apart and rebuilt them. The babbitt back then you could scrape with a butter knife and needed tigher clearances in order to not knock the babbitt (rod) out. Hot oil then poured like water. Now we have better material for babbitting and oils that will hold their viscosity. Now oil pressure. Imagine that slinger rotating 500 to 2000 rpm dipping into the tray and the force it creates when it hits that pool of oil. Now,that's real pressure to the rods. If was was using a period nos replacement rod, I would hold the tigher clearances up to .001. Whatever works for every one works. As Forrest Gump would say -"that's all I got to say about that".

Randy

Unknown

i can just see myself standing on the side of the road with my hood up yelling"run,Forest,run!!"B)