Low compression

[Malcolm Towrie]

There are 4 really bad exhaust valve seats in the block, corroded and pitted. My local machine shop agreed they should be replaced, but he couldn't do it because modern seat removal/replacement tooling is designed to hold cylinder heads, not a whole block.
I decided to use the welding technique to remove the bad seats because i could do that at home, and buy replacement seats, figuring i could make up the simple tooling required to install them. I hit some snags.

The seats came out no problem by fitting a slightly loose 1/8" thick washer inside the seat bore and MIG welding it to the seat. This shrinks the seat and loosens it in the block so I was able to tap the seat out using a brass punch on the underside of the washer. One photo below shows the block with the seats removed, and the other shows the removed seat.

The first snag was the seat counterbores in the block were 0.005" out of round, varying from 1.625 to 1.630". This seemed a bit much considering the press fit of the seat in the block is 0.005" interference. The other snag was the new seats were 0.010" over nominal size on the outside diameter, which I found out is normal. The supplier assumes you will be cutting the counterbores 0.010" oversize to clean them up. Another minor problem was the new seats are 1/4" thick, when nominal size is 7/32".

So now I need to find a machine shop who can bore out the counterbores in the block to 1.635" ID so that I get the right press fit for the 1.640" OD seats. Parry Automotive in Orillia may be able to do this.

Malcolm

DSC00596x.jpg

DSC00597x.jpg

[Frank v R]

which vehicle is this engine from?

[Malcolm Towrie]

Hi, Frank,
It's the Mk I Universal Carrier, formerly known as Al's Carrier.

[Malcolm Towrie]

A quick update on the Ford engine - the Orillia shop found a small crack in the block under one of the exhaust valve seats. They recommended United Welding Processes in Mississauga to repair this. So off I went. They repaired it using the Lock-N-Stitch process, which is a neat cast iron repair technique that's avoids welding. They also installed the 4 new seats I needed. But I found when I got it home, they had not machined the new seats.

My favourite local shop, Jim at Carquest on Bloor St, Oshawa, still had the tooling to grind the seats on these engines because he's old school and never gets rid of anything. He also found that the chuck on his valve grinding machine would open up enough to accommodate the large diameter mushroom tip on the flathead valves so he could grind the 45 degree face on the valves. I blued one seat when I got everything back from him and got perfect valve to seat contact.

Next hassle was getting valve clearances in spec, 0.010-0.012" for intake and 0.014-0.016" exhaust. There's no easy screwed adjustment like in more modern engines (unless you upgrade to adjustable lifters, which I wanted to avoid). The valve tip has to be ground. I spent most of the day today on this and got 12 valves done.

This has turned out to be a really interesting job.

Malcolm

[Malcolm Towrie]

The Carrier's back on the road.
I brazed the cracks in the two oil cooler bosses on the bell housing caused by someone ovetightening the tapered pipe fittings.

I thought piston rings were ok but a quick leak-down check with valves now tight showed a lot of leakage. So I installed new rings and honed bores. That gave me acceptable leak-down results. Bore is 0.015" oversize but rings that oversize are no longer available so I got 0.020" o/s and filed the ends.

I found the leak-down tests quite variable. If you test just before piston reaches TDC, you get better results than just after because rings are being pushed down onto lower groove face by friction and sealing better.

I found a Dremel with a thin cutting disk very good at trimming the rope packing of the front crank seal. A utility knife just chewed the rope up trying to saw through it.

I filled the pan with oil and hung the assembled engine nose-down from the hoist to check the front crank seal sealed. It didn't. I pulled the front pulley and smeared grease on the hub and reinstalled it to check the hub contact with the rope seal. There was a wide band around 6 o'clock with no contact, so that was where the oil was leaking through. I used a brass punch and tapped the groove in the sheet metal oil pan to squeeze out the rope more. That got contact all the way around and sealed the crank.

We installed the engine and took the Carrier for a quick run without the sheet metal on. It heated up too quickly and showed how important the dog house and rad shrouding is for directing max air flow through the rad and fan. With all sheet metal installed the engine ran much cooler. But it's tough to do an easy break-in run on a rebuilt Carrier engine- the weight of the vehicle and the brake steering put a pretty high load on it.

She's got much more power now and is back to being fun to drive.
Malcolm