Cam Retaining Plate Bolts

topcatcustom · Post by **topcatcustom** » Mon Apr 20, 2009 2:55 pm

These are 5/16 unc whic seem impossible to find- especially with countersunk heads which I need to clear my timing gear! Is there any problem with running an M8 tap through the holes to use M8 c/s bolts which I have dozens of? They are very near anyway and not much pressure on the plate- plus some loctite should be ok yes???

TC

sidecar · Post by **sidecar** » Mon Apr 20, 2009 3:25 pm

topcatproduction wrote:These are 5/16 unc whic seem impossible to find- especially with countersunk heads which I need to clear my timing gear! Is there any problem with running an M8 tap through the holes to use M8 c/s bolts which I have dozens of? They are very near anyway and not much pressure on the plate- plus some loctite should be ok yes???

TC

I don't know about the tapping to M8 but I had the same issue with the bolt heads hitting my Piper vernier timing gear. In the end I ground down the back of the cap head bolts that lock up the timing gear so that they were flush with the back of the sprocket. I also ground down the heads of the bolts that hold the cam thrust plate in place, the heads ended up being about 1.5mm thick! I had to flattern off a socket so that it would grip the thin bolt heads properly! They are hardly under any load so I think that it was OK to do this.

I think RPI have the bolts and a counter sunk plate. (I tried counter sinking the plate but it's rock hard!

All good fun!

Pete

vaultsman · Post by **vaultsman** » Mon Apr 20, 2009 3:51 pm

I'd be wary of running an M8 tap down them. Standard M8 coarse is 1.25mm pitch = .049". 5/16"-18 comes out at .056".

Stig Fasteners (for instance) have UNC Countersunk in Phillips & Socket head in various lengths, e.g. 1"...

5/16" UNC x 1" C/S Phillips

5/16" UNC x 1" C/S Socket

Also this guy seems to do them.

Stan

topcatcustom · Post by **topcatcustom** » Mon Apr 20, 2009 8:28 pm

just went to fit the plate and the damned bolt holes dont line up! It had the horseshoe gems plate before, and I think when I got the plate I popped it on and it went on ok- however the holes are not quite central so it doesnt sit square around the cam. Whats worse is both holes are slightly out not just one- and there's not enough meat left on the block to drill 2 new ones!

Any ideas? Is the plate too hard to put 2 new holes and countersink them? Have not yet tried...

TC, disappointed!

topcatcustom · Post by **topcatcustom** » Tue Apr 21, 2009 6:50 pm

So maybe the holes do line up when you put the plate on the right way round.....

What a pen is.

Major clearance issues with the bolt heads and vernier cam gear though- too much to grind off I think so looks like will have to go with fixed sprockets

CastleMGBV8 · Post by **CastleMGBV8** » Tue Apr 21, 2009 7:25 pm

Tom,

Add that one to the list then

Is your cam plate not recessed for the bolts, how much clearance is there between the bolts on the cam wheel and the cam plate?

kevin.

topcatcustom · Post by **topcatcustom** » Tue Apr 21, 2009 8:45 pm

The captive nuts on the back of the sprocket nearly touch the plate, infact they may touch. I will ask Perry about the timing as he uses the same cam as me, and if he can pull an 11.2 quarter mile over and over I'm sure if he uses a fixed timing set that will do me!

There are recesses on the plate for the bolt heads, I could take them a bit deeper on the mill and the same with the nuts on the sprocket if need be but its more messing around!

TC

CastleMGBV8 · Post by **CastleMGBV8** » Tue Apr 21, 2009 11:08 pm

Tom,

It's always the case, change one thing and two others don't fit!

Those flush head 5/16 UNC phillips head bolts looked like they would do the job if you could bevel the holes in the plate. I don't think there would be that thrust from the cam and if you loctited the bolts they should be ok.

kevin.

sidecar · Post by **sidecar** » Wed Apr 22, 2009 5:01 am

CastleMGBV8 wrote:Tom,

It's always the case, change one thing and two others don't fit!

Those flush head 5/16 UNC phillips head bolts looked like they would do the job if you could bevel the holes in the plate. I don't think there would be that thrust from the cam and if you loctited the bolts they should be ok.

kevin.

You could always use an impact screwdriver and a dab of locite on them so that they won't come loose

vaultsman · Post by **vaultsman** » Wed Apr 22, 2009 3:49 pm

Had a scout round at work. Got a couple of socket head countersunks, 5/16" UNC x 3/4" long overall if you want them?

topcatcustom · Post by **topcatcustom** » Wed Apr 22, 2009 4:40 pm

Excellent! PM me how much you want and an email addy for paypal, I have ordered a fixed iming set but will still try and use the vernier set to time it in properly.

seight · Post by **seight** » Mon May 04, 2009 5:58 pm

Did you get this sorted?

I'm about to do the same thing. My cam needs timing to 108 so I need a vernier to get it right.

Alternative for me is to get the timing gear that has a multi keyway on the crank sprocket which should get me near enough. But I don't know yet if one of those gear sets fits under the intermediate timing cover.

As said, one step forward ......

Mike

Post by **Coops** » Mon May 04, 2009 6:38 pm

i have a vernier set underneath my intermediate cover,
but cant remember which make they are.

the engine originally came from RPI, if i remember correctly.

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