B6 Camshaft Mechanical Fuel Pump Lobe Help

[drddan]

Good luck Dr. Dan, maybe we can race someday! lol

^^^ Hee Hee Hee! (in evil tone) :p


By drddan at 2012-05-29


By drddan at 2012-05-29

Screw puttin' it in a lathe. Too much work!

I will be using a mech. pump.

Took my air grinder and 1 inch fine sand drum, and polished it. Done in 15 minutes. The shape is there, it was just the cast surface needed removed.
After measuring around on it, the "eccentric" wasnt as big as on the B3 cam.
Turning on a lathe and 4 jaw chuck (good call Movin'!) was judged a waste of time. The B6 cam didnt have as much offset, on the eccentric, and would have wound up a slight bit smaller diameter, and therefore, less lift on the fuel pump arm.
Prolly not enough to notice, but decided on the polish job.
Left some of the "witness" marks from the casting, on the eccentric to hold oil.

[zoe60]

That looks pretty good!

[drddan]

Thanks Zoe!

The hydraulic B6 cam should measure .213" lift @ the lobe. Depending on wear, factory grinding tolerance and what you used to measure it, (dial indicator, micrometer, caliper, etc.) you can easily be off by a couple thousandths. The rockers are variable ratio due to the follower design, but at max lift they give ~1.75:1 ratio for a valve lift of ~.373".

That is good info, Thanks.

My mearsurement would be made using matched V-blocks and a digital indicator good to within .0002 or less
The ends are not in the best shape to hold between centers.

There are advantages to being a Toolmaker for 30+ years.

[Movin]

That is plenty good!
The fuel pump lobe just has to
go up and down, do not worry
about profile, lobe shape other than eccentric
and just run it!! Hardness on a fuel pump lobe
to valve lobe specs is not comparable, if it
gets oil on it it will be fine.

[BigElCat]

Rock On Dr D...

Movin's right about the surface hardness, the pump lobe doesn't need rehardening. Another big el brain fart

[drddan]

Camshafts are hardened after rough machining, then heat treated, then brought back for final grind, The hardening process, is mininum .030 deep, and is more likely .060 deep. The whole shaft is heat treated at the same time, therefore, the pump lobe is hard too. A little grinding on it, by hand, or machine, to just clean up the rough surface, wont affect the hardness of the exposed cleaned up metal.

[frogman]

Good info and fix for a problem. Someone down the line will be helped.