Ford 800 172 engine sleeves--Overbore or Std 3.9?

[fordcomanche]

I was able to get some measurements on the cylinder wear from my machinist friend so thought I'd share them. The wear isnt too bad for 40 years since rebuild
The book listed bore spec as 3.900" and we measured the following:

Cylinder	Bottom of Bore (Inline) with no wear	Bottom of skirt area 1/2 way down bore (crosswise)	Upper Bore Area with Max Wear (Inline)	Upper Bore Area with Max Wear (crosswise)	Near top of bore in ridge ream area (Inline)	Near top of bore in ridge ream area (Crosswise)
1	3.899"	3.901	3.905	3.903	3.900	3.901
2	3.899"	3.901	3.904	3.904	3.8995	3.900
3	3.900"	3.902	3.902	3.902	3.8990	3.8990
4	3.8987"	3.8999	3.906	3.902	3.8990	3.8990

I showed him the existing sleeve wall thickness and mentioned about the thin sleeves in the overbore kit and he thought it would still be best to just bore these sleeves to .020 over and put in new pistons/ring.

The crankshaft main journals were ground .020 under during the 1970 rebuild and were still close, with the rear journal showing the most wear:
Original STD Spec 2.4974-2.4988, (20 under spec 2.4774-2.4788)
Journals were measured at 2 positions, 90 deg apart and were measured at both ends of journal

Crank Bearing:	Horizontal Meas	Vertical Meas
Front Journal	2.4774/2.4775	2.4774/2.4775
Center Journal	2.4775/2.4775	2.4775/2.4775
Rear Journal	2.4772/2.4772	2.4772/2.4772

Rod bearings were previously ground .010 under and also were still within spec.
The crank journals are smooth but do have some staining in the center of journals, so considering getting it polished

The camshaft itself had quite a bit of rust on it and although the journals look good and within spec, some of the lobes have some small pitting from the rust. Likewise a few of the valve tappets had some of this pitting on the surface riding the cam.

Please let me know how this motor condition compares to others that have undergone rebuild.
Thanks

 

[jaxs]

I would reuse crank,sleeves and pistons without resizing. I'd defer to someone smarter than me about the cam. I know the owner of a Ferguson I rebuilt several years ago and the engine still run's great eventhough I went against convention. By industry standard the engine block,cam,crank,pistons,sleeves and valve train should have been replaced. Cams run in block with no bushings in those early Ferguson engines. Cam lobes and journals reground and Tuffrided. Cam bores in block bored oversize and bronze bushings pressed in. Crank welded, ground to stock size and Tuffrided. Good used rocker assembly and push rods. Cam contact surface on old lifters machined square and polished. Head obiousvly had been worked on since bottom end so valve guides were knurled,seats and faces cut. New pistons & sleeves. All the credit go's to the machinist and I saved the best for last. After picking everything up 60 miles away,I discovered oil pump badly scored and took it to a local engine rebuilder who wanted more than I thought it worth to smooth it out. I called origional machine shop and he began laughing when I told him how much I was quoted. He said no need to bring it in. Secure aluminum cover to bench and use a file to take most of scratches out. Rubber cement strips of 600,1k and 2k sandpaper to window glass,blue plate surface and sand until flat. Same for pump rotor face. Shim from rear and button it up. Point of this being that less than perfect is sometimes good enough. I wouldn't try this with an engine that saw 15/1 compression or 8k+ rpm.

 

[John0829]

Depending on how hard you are going to work the tractor I would say you could get away with honing the sleeves and putting back standard rings and bearings matched to your crank. Seriously doubt you or the engine will notice any difference between doing that or boring it. As for the cam and tappets I would try to find a good used or have your cam reground this is an area you really want nice and smooth. These old Fords are very forgiving engines, it is not necessary for everything to be "perfect"

 

[fordcomanche]

Good morning John, Jax,
I appreciate your comments on the measurements, your thoughts are along the same route as my machinist friend.
He and I were joking when he started measuring that his mics had to be off calibration (since the readings showed such little wear), but he wasnt too amused by that.. He is an industrial machinist but also has rebuilt a few vintage car and tractor motors over the years.
After he measured, he basically said the same as you, that I could probably get by with clean up the bores and put new rings in it, but that need to address or replace the cam.

Before the flood the tractor ran fine other than some carb issues now and then. It did not use any oil and always had plenty of power. I mainly use it with a 5 ft bushhog, 5 ft blade and rear dirt scoop for dirt work on home property. Although its just work around home, I do dig it in fairly hard when moving dirt or cutting small saplings with the bushhog.

Also I checked and this motor does not have cam bushings/bearings, it is just the motor bore itself.
Heres the bore readings vs the camshaft readings:

	Camshaft OD	Bore ID	calculated clearance
Front cam journal	1.9252	1.9278	.0026
Middle cam journal	1.9248	1.9280	.0032
Read cam journal	1.9253	1.9275	.0022

A while back I had bought a used cam and as part of box of other used parts. I pulled it out and looked at the lobes.
Although the lobes were mostly smooth and shiny, on the peak of the lobes, it looked like it had uneven wear, like it was slightly tapered/worn toward the edges of the lobe. So its probably not a good candidate. I havent been able to get it measured yet or determine amount of taper/wear.

We do have a trustworthy race engine shop nearby and I have used them a few times for car/truck heads, not sure if they do the cams there or sub them out.

I'll try to get some pics this evening.
Thanks

 

[John0829]

Clean up the cam and re-evaluate it, remember the lobes of the cam are slightly slanted so the tappets will turn and not put all the wear in one spot. I have yet to see a Ford block worn enough to worry about the cam clearances in the bore but I have heard of some that have had the block bored out to fit cam bearing in. Again with the specs you have posted, fresh rings, inserts and gaskets (of course cam) then make that tractor earn its keep.

 

[Boss 302]

I love a sleeved engine; you can pretty much make it new all over again and it certainly minimizes machine work.

 

[fordcomanche]

Thanks Guys! This is all sounding much better than my original concerns of boring oversize.
I texted my machinist about keeping it standard piston/rings. He said cleanup and crosshatch of cylinders might increase bore size maybe .0015" to .002" at the most .

When we measured everything, we were mainly focused on the bores and didnt spend much if any time checking piston OD reading (at that time, we were assuming we had to bore oversize and get new pistons.)
The service book doesn't list piston OD, it only shows testing the fit with a feeler gauge and pull scale to check clearance in bore. So I was curious to know what the standard piston actual OD is of a new piston for comparison?

Today I was able to get both cams out in the sun to closely compare lobes
The bottom cam in the pics is the original and the top cam is the used cam I had bought awhile back.

I didnt get to clean either one much due to rain. I was hoping it would turn out nice, but pics show the spots on these lobes on .

It was hard to get the camera to focus tightly to show spots..
These are the worst spots, other lobes look pretty normal on both cams.

The journals on the top "used" cam are a little over 1/2 thousandth larger than journals on the original cam, so it would've fit a little tighter in the block journals. I priced a couple new cams, looks like they would be about $150-$175.

Could either of these be ground or is it just time to look at new cam?
Thanks

 

[John0829]

My guess would be that a quality shop could build up the defects and re-grind the cam but for the cost of that it may be just as cost effective to purchase new. I for sure would not use that cam the way it is.

 

[fordcomanche]

Thanks John,
I'm following advice on going back with Std size pistons and rings and starting to get things together for that work.

I've been looking at cams online over the weekend and will be taking the original cam to shop for estimate this week.
In looking online, evidently there are a couple of cam versions.. Mine has a bolt for securing the camshaft gear but I see that most of the new ones say they are the "snap ring" version.
Some also list two different sizes for the hydraulic pump gear mounting bolts (1/4" vs 5/16")

So I'm gonna have to compare descriptions on these closely to make sure they match my gears.

Thanks

 

[jaxs]

Thanks John,
I'm following advice on going back with Std size pistons and rings and starting to get things together for that work.

I've been looking at cams online over the weekend and will be taking the original cam to shop for estimate this week.
In looking online, evidently there are a couple of cam versions.. Mine has a bolt for securing the camshaft gear but I see that most of the new ones say they are the "snap ring" version.
Some also list two different sizes for the hydraulic pump gear mounting bolts (1/4" vs 5/16")

So I'm gonna have to compare descriptions on these closely to make sure they match my gears.

Thanks

Atta boy