Jockey Journal Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
138 Posts
Discussion Starter · #1 ·
I got a set of dual plugged heads for my Shovel. One was blown out, and the other had a valve guide that had done quite a dance in there. The hole was beat up and a regular guide would not fit anymore. So, to attack the blown head, I made this jig to hold the head in our big lathe. Every piece was machined to within .001" and welded together. Then, the jig was turned in the lathe and marks made to orient it to the jaw so that it would always be true no matter how many times it was used.







Then, the head was heated in the oven and the blown part welded back in. After it was allowed to cool, I mounted it in the jig and turned the head down flush. The other head had the same treatment done. Now they are both perfectly true.









Next, the bad guide hole was reamed back to round. Since I know of no guides out there this big, I had to build one. I started with a guide from a diesel Ford tractor motor and machined it to fit the new hole in the head, but have the same dimensions as a stock guide everywhere else. The new guide needs just a tiny bit of finish work and after being fit in the head, will be reamed to fit the valve.





These heads may have been thrown away by others, but Im glad to have the resources to be able to make them right again. My old ones had cracks around the guides and a few fins broken off. My bike has 11/1 compression and is kick only so the other hole will have a compression release, which will be a welcomed addition.

There are plenty of ways to do this, but this is the way I did it.
 

·
Registered
Joined
·
689 Posts
That's the type of mentality I like to see. Well done. Anything can be done if you come up with a plan and put your mind to it.
 

·
Registered
Joined
·
1,584 Posts
Damn, thats cool. Suppose it would be a piece of cake to open up those heads for big bore, using the same method. Nice Job!
 

·
Registered
Joined
·
138 Posts
Discussion Starter · #5 ·
Damn, thats cool. Suppose it would be a piece of cake to open up those heads for big bore, using the same method. Nice Job!
Yeah, after I have my Sportster up and running in a year or two, and this Shovel shows any sign of getting weak it will get punched out.
 

·
Registered
Joined
·
138 Posts
Discussion Starter · #9 ·
How much did you turn off the mating surface of the heads? Will that raise the compression ratio?
They were both pretty worn out and took right at .015" each to get true. My cylinders have been tuned down .100" also. I still maintain a .010" squish in the spigot so that's good. I am running 8.5/1 KB pistons and I figure with all the mods I'm at 11.1 compression now. The Andrews B grind REALLY likes compression. This is a fun little motor. It is also going to be balanced this winter I will do a thread on that too.
 

·
Registered
Joined
·
138 Posts
Discussion Starter · #16 ·
Nice work. We been doing that for years. Glad to see the guide trick. That could possible save time and some money. We always welded the hole closed and remachined back to stock. Again nice work.
These type of guides can be picked up at nearly any tractor service facility, or you could contact me and I will hook you up with some. Brand new they are less than $10. a little machine work and they fit the bill perfectly. Way better than going through all the work to weld and re-machine.
 
1 - 16 of 16 Posts
Top