Comp Cams XE250H Camshaft

I happened to find a Comp Cams XE250H camshaft on sale in FMOC forum and decided to buy it. It had been installed in an engine but had not been ran so it was basically new. According to Comp Cams webpage, it offers "very strong torque, excellent mileage, smooth idle". Sounds good so I compared the specs a bit.

Parameter	Original	XE250H
Intake duration	266	250
Exhaust duration	244	260
Intake duration @ 0.050"	198	206
Exhaust duration @ 0.050"	198	212
Intake valve lobe lift	0.2303"	0.289"
Exhaust valve lobe lift	0.2375"	0.296"

I found the original cam specs from an online discussion so I'm not sure how accurate they are.

The XE250H seems to have more lift and duration when compared to the original but it is still a really tame camshaft that will probably run out of steam at about 5000 RPM. Oh well, my engine probably will not see those RPMs often so it should be fine. Especially with original intake, heads and exhaust. We'll see when the engine runs next time...

Block And Head Inspection

I drove to a machine shop in Mäntsälä with my block and heads to have them checked. They took a quick measurement of the cylinders and said that they had as much as 0.016 to 0.018 inches of wear. Way too much to be fixed by just honing. The block must be bored and I'll have to get new pistons.

My heads were a bit better. The machinist said that the valve guides were not too worn yet and the heads did not need a complete rebuild. I'll have to decide if I'll use them or the other, already rebuild heads I have.

Now I would have to get the pistons before the block could be bored. The machine shop did not have time to work with my parts before January anyway so I had a few weeks to buy them. After a few calls I was suggested to order Sealed Power hypereutectic pistons and moly rings as I was not building an engine with high power level. They were 0.030 inches oversized and should easily be strong enough.

One bad thing with them was the large valve reliefs. They would drop the compression ratio a bit. Maybe about half point from the original 9.8:1. I'll know the final ratio when the bottom end is back together.

Disassembling The Engine Part 4

My engine disassembly is finally finished. I removed everything from the block while it was still in the car. Including pistons. They came out quite easily by wiggling them a bit. The steps in the cylinder walls were so small that the piston rings came over them without problems. Finally I bolted some chains to the block and my friend came over and we lifted it out.

I'll take the block and heads to a machine shop next week. We also removed two valves to see how they looked. They wiggled slightly in the guide but I'm not experienced enough to say if that was too much. I'll have to ask what the machinist thinks. While waiting to get my parts back, I think I'll have enough to do with the engine bay. I'll clean and paint it before putting the engine back in.

Rebuilding my Autolite 4100 carb also took a couple of nights. I cleaned it as much as possible and used a Hygrade kit to replace seals, needles, seats and accelerator pump parts. The carburetor was completely covered with black dirt so I used a lot of cleaner and tooth brushes on it. I did get most of the crud off and, while not like new, it is much better now.