Help, before I make a Mistake I regret screw removal

[Steven Rempel]

I have 75 JDX8 with the 440/22 and CDI option. I bought this sled for parts cuase that all its worth. It's been outside exposed no hood for way too long. I am trying to save the upper and lower halves of the engine. I have it tore down to the point where I need to remove the ring coil behind the flywheel. Its held on with 4 allen cap screws 4mm, that won't move. I am scared that I will strip the heads and then have to grind the cap screw head off. I have been spraying with penetrating oil already and letting soak. I am not sure the ring coil is good or bad but would rather talk off intaced and deal with it after I see what the inside of the block are like.

1 question, If I grind off the head of the cap screws will the coil ring slide off, Or do the treads go in both the ring coil and the block.

2 If I use a torch to heat the cap screw to help break the rust, can the ring coil take some heat. I would make a small heat shield to stop the flames from touching the ring coil

3 Is there a difference between the upper and lower halves from the 440/21 and the 440/22. I ask as I have a few 440/21 upper and lowers if they interchange.

4 also is the crank different between the 440/21 and the 440/22. I am working under the assumption that that the jugs and pistons are the parts that are different.

[Matt]

I believe there are differences in the ports on the /21 to /22 so they won't interchange. The crank itself is probably the same.

[lwb140]

The timing ring holes aren't threaded, I think they are slotted which provides for adjustment of ignition timing I wouldn't use heat on aluminum I've never had good results with that , I'd bet you could find someone to trade you /22 blocks for /21 blocks as the 21s has fairly low production numbers at least within the Deere line-up

[HoosierDeereMan]

Can you use a impact driver to help get the cap screws broke loose?

The difference between the /21 and /22 crankshafts are the wrist pin inside diameter of the connecting rods. /21's use a 16mm wrist pin. /22's use a 18mm wrist pin. Since the bore and stroke are the same between the two engines, it might be possible to run a /21 crank and pistons in a /22 engine. I have not seen the intake ports in a /21 engine cylinder to compare with a /22. My best guess would be that a /22 may have an extra boost port????

Troy

[Kurts]

/22 has more transfer ports than a /21

[jep_800]

I would keep hitting those with penetrating oil of some type. Are we also assuming that these are the screws that were originally loctited from the factory? I know mine were a little stubborn, however they were very clean and rust free. But, I did like the manual said, and I placed the screw driver on it then rapped them with a mallet in order to break the loctite. Under firm pressure they broke loose. I was worried too, cause if it doesn't work, you'll damage something which you don't want.

[HoosierDeereMan]

I tried to do a little research on the 440/21 vs the 440/22. The bore and stroke is identical between the two engines. So what are the differences?

I don't have a /21 to compare all the parts and pieces to a /22. So this is an assumption. If someone does have access to both engines and can verify for sure, I would be very curious what you find.

The engine gasket kits are different. Kurts confirmed the transfer ports are different. So based on this, the /21 upper case half will have less transfer port reliefs in it. So the upper case half will not interchange with a /22 nor will will the cylinders interchange. The lower case half might be the same as every other Kioritz reed valve 340 or 440. I can't access the part numbers to verify.

I confirmed through Brian that the /21 has short cooling fins and uses the short reach spark plug. /22's have taller fins and use long reach spark plugs. So the heads should be interchangeable but must be done as a matched set. This also means the /21 engine shroud is probably shorter and will not work with the tall finned /22 heads.

Both cranks use the same seals. However the wrist pins are different. The pistons are identical ( I have compared these ) with the exception of the wrist pin. /21 is 16mm, /22 is 18mm. The crankshafts should interchange as long as they are matched with their correct pistons. i.e. a 440/21 crank and piston assembly should run in a /22 and vise versa.

Troy

[Steven Rempel]

Update:
So I want to thank you guy for you help and tip and pointing out the differents. I did this evening get it all apart but with that said it was not easy. I ended up having to weld a bolt on to the head of two of the hex cap screws in order to get enough purchese to be able to unscrew them. I was pleased with being able to remove the cap screws intact and not snapping them off. I have fought hard on other motors getting 35 plus year old parts to come apart but this one I will remember.

I was told the trick from a old timer at work that the very fast heat shock of welding a nut on to the bolt that is rusted in place helps break the rust bond that has formed. well it worked just fine. Now to figure out what to do with the crank it need new outer and inner bearings. But I will test it for "ture" first and see how if any much run out there is.