Shovelhead Intake Chipped Head Question

[Akamm47]

Been working on cleaning up my 76 Shovel over the winter, I recently picked this bike up over the summer. Bike wasn't running great so I timed it according to the manual and that helped quite a bit but was still having some trouble staying running. Since it is down for the winter, I pulled the carb, dipped it, and rebuilt it with new seals and shit.

I went to pull the manifold while I was at it and it looks like the rear intake port on the head is chipped. I inspected the intake seal and it has some indentation appearing that it might be sealing but not 100% sure obviously. Also appears to be a lot of residue built up outside of the head/intake manifold, is this indicative of a leak (front cylinder doesn't have this)?What do you guys think?






Rear Cylinder


Front Cylinder

[Dragstews]

Looks like oil was getting into the burn ..??
Sure would be nice to have some leak-down numbers to eyeball ...

On the broken lip of the intake track, you can get some conversion rings to be able to use the 78-up band type clamps...

[JBinNC]

In general, I would not trust an oring to seal with that much of the lip missing. You can switch to the later bands and clamps to suit, and using a band type manifold is a big plus when making that change.
The grunge is from oil going down the valve guides, not unusual on shovels.

Jim

[Whoremonger]

The slightest intake leak will prevent you from ever getting that bike to run right And you run the risk of burning a hole in a piston due to the lean condition the intake leak is causing.You need to get a manifold adapter and constant supply of at least 12 psi of air for testing for intake leaks. In my opinion the intake leak is WAY more of a problem than the oil thats getting by that valve.

[flatman]

get it welded and file it down.

[Dragstews]

After years of fighting intake leaks on my Shovelhead, I figured there had to be a better way. The FNA Tite Seal Kit is it; this kit installs easily, seals better, and eliminates the need to adjust your heads to get the intake to seal. It uses two custom clamps and fuel proof silicon hose per port. Can be used on Big Twin or Sporty 48-84, O-ring or rubber band styles. Now after many thousands of leak free miles I am offering this kit to you to solve the leaking intake issues.

[Akamm47]

Alright, got the conversion kit and some bands. Will test the leak down numbers when I get some time.

[Whoremonger]

Alright, got the conversion kit and some bands. Will test the leak down numbers when I get some time.

A leak down test and an intake leak test are 2 different tests. One gives you an idea of motors condition i.e. Valves,rings the other ( intake leak test) points out intake leaks. Make sure you do the intake leak test now that you put new bands and seals on. Do not assume all is well. Good luck

[Akamm47]

Ended up pulling the head to get it fixed. While I have the head away, I figured I'd clean up the rocker boxes since the chrome is chipping pretty bad, going to strip and polish the aluminum. I disassembled the intake rocker arm and shaft per the manual - Remove rocker arm shaft screw and o-ring, remove the acorn nut and washer, tap rocker arm shaft from cover and remove rocker arm/spacer. No problem.

Then I moved onto the exhaust rocker arm and could not get the rocker arm shaft screw off for the life of me. I ended up removing the acorn nut and pushing the shaft through anyways to inspect further. Below are some picture I took of the parts, I'm not sure if this is normal wear or not, not much in the manual about this. Also, what is the best way to get this rocker arm shaft screw off?

TLDR: Can't get rocker arm shaft screw off the shaft for exhaust rocker arm.

[Akamm47]

[JBinNC]

Clamp the shaft in a GOOD vise between the journals and you can turn the plug out. You will not hurt the shaft if you stay away from the journals.

The fit of the rocker arm bushings to the shaft has a lot to do with the amount of oil that ends up in the rocker box. And in extreme wear cases, excess oil use at the rocker arms cuts down on the oil going to the rods. (The top end gets on demand oil pressure and flow first, and the left over, if any, goes to the rods.)

Because the rocker arm oscillates on the shaft rather than spinning around it, a somewhat loose fit is acceptable. And note that the bushings wear on the lower side only (the load side). I replace bushings in any rocker arm if the clearance is .004 or more.

Also note that the shafts wear in one direction and end up being out of round a little bit. Again, because the rocker arm is oscillating, this is not objectionable.

Jim

[Akamm47]

Good info, thanks. I noticed the manual says .0005 to .002 for the fit in bushing, why do use .004? Am I looking at the right tolerance here? Also, what is the best way to measure the clearance in the bushings?

[Dragstews]

If the pads are bad, you can get a few more miles out of them ...

[JBinNC]

Wear tolerances are greater than new assembly tolerances. I develop my own wear tolerances from years of experience. Your results may vary. The evo manuals do give wear tolerances for some fits.

Let's see what the book says. '95 - '96 Dyna Service Manual says, replace bushing if shaft fit in bushing exceeds .0035. Well, son of a gun, about what I use. (The evo bushing and the shovel bushing are the same.)

Jim

[JBinNC]

If the pads are bad, you can get a few more miles out of them ...

Yes! This is a must. You can dress the pads with bench stones and a little elbow grease. No special fixture needed. I have a similar set-up but many times just dress them by hand with stones.

Jim