SBC Stepped Nose Cam in Early Block? - Page 2 - Chevelle Tech
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post #16 of 34 (permalink) Old Jul 26th, 16, 7:18 PM
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Re: SBC Stepped Nose Cam in Early Block?

I like the idea..Seems easy enough.. Some of those Roller cams with stepped nose have a fuel pump lobe .. and some do not.
You know it does not hold the cam side to side.. so if you were really good with a drill and had some skill you could duplicate the attachment without the drill press.
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post #17 of 34 (permalink) Old Jul 26th, 16, 8:45 PM
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Re: SBC Stepped Nose Cam in Early Block?

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Originally Posted by jeff swisher View Post
I like the idea..Seems easy enough.. Some of those Roller cams with stepped nose have a fuel pump lobe .. and some do not.
You know it does not hold the cam side to side.. so if you were really good with a drill and had some skill you could duplicate the attachment without the drill press.
I wouldn't attempt it freehand, but I could envision Gary selling a fixture that pilots off of the cam journal with drill bushings positioned to guide the bit with a hand drill. You could include an arm to index the fixture off of one of the oil galley holes.
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post #18 of 34 (permalink) Old Jul 26th, 16, 9:30 PM
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Re: SBC Stepped Nose Cam in Early Block?

If looking at it from the computer I see there is a little bit of distance between the cam and the retainer..say .015" on either side..It may be tighter or looser.

Say you get the measurement then shim the thing on 4 sides.. so secure the plate to the step in the nose of the cam that is in the block.

Now it is centered..If you already had your 2 holes drilled in the plate (not countersunk yet) you could place a centering punch into the hole and divot a spot in the block to drill and tap.

Now. remove the plate, counter sink the holes in the plate so those allen head threaded screws sit flush.

You could build a thicker drill fixture that indexed off the nose of an old cam also.

Not saying it is going to be dead nuts on ,, just feasible. Especially if there is distance between the retaining plate and cam.

I have not graduated to Roller cams yet. But I do have a blown up block to play with.
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post #19 of 34 (permalink) Old Jul 26th, 16, 10:06 PM
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Re: SBC Stepped Nose Cam in Early Block?

Thank you for sharing that Gary!

That idea is "slicker than cat $hit on linoleum"
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post #20 of 34 (permalink) Old Jul 27th, 16, 1:16 AM
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Re: SBC Stepped Nose Cam in Early Block?

and that's pretty slick.

Rob, in post #7 you mention having seen this with pics before. Got a link or any idea how to find the old post? this is a pretty brilliant solution to an old and tough problem. I've been on here since '98, seems like I'd have seen it.

Gary, did you think this up or find it somewhere?
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post #21 of 34 (permalink) Old Jul 27th, 16, 1:20 AM
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Re: SBC Stepped Nose Cam in Early Block?

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Originally Posted by Tom Mobley View Post
did you decide on 1/4" bolts? coarse thread?
Those holes look a lot smaller than 1/4-20.

-Dave

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post #22 of 34 (permalink) Old Jul 27th, 16, 7:12 AM Thread Starter
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Re: SBC Stepped Nose Cam in Early Block?

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Originally Posted by Tom Mobley View Post
and that's pretty slick.

Rob, in post #7 you mention having seen this with pics before. Got a link or any idea how to find the old post? this is a pretty brilliant solution to an old and tough problem. I've been on here since '98, seems like I'd have seen it.

Gary, did you think this up or find it somewhere?
Hi Tom, kind of figured it out, never saw anything like this done anywhere before. I had been thinking about it for a while now, ever since we did the first BBC (MkIV) a few months back with the stepped-nose cam. The BB's are much easier to setup with the bolt bosses being already present in the castings.

Quote:
Originally Posted by ChevelleFan70 View Post
Those holes look a lot smaller than 1/4-20.

-Dave
Hi Dave, you have a good eye, the holes in the fixture should have given it away?

Here's the layout of the "jig", it has 2 (opposite) holes drilled with a #25 drill, these 2 holes drill the thrust face for the correct tap size. We used 10-24 (coarse-thread) c'sunk screws to mount the plate. The other 2 holes are pre-tapped to help start the tapped holes in the block. You simply turn the tool 90* after drilling the first 2 holes and line up the tapped holes using the point of the tap as a locator. There's a clamping fixture that straddles the tool to put some slight pressure on it while drilling/tapping!

Thanks, Gary in N.Y.

P.S. Due to the limited area you have to work with on getting the tapped holes in the thrust surface the 1/4-20's would be too large to pull it off. Plus you don't have much working "depth" on the thrust face. There's really no load (thrust) that the 10-24 threads won't handle. I don't see the (small) bolt size posing any issues. I will add 1 more shot (to this post) of the block later today without the plate mounted!

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post #23 of 34 (permalink) Old Jul 27th, 16, 7:46 AM
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Re: SBC Stepped Nose Cam in Early Block?

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Originally Posted by novaderrik View Post
got a pic of it without the plate bolted down?

the factory roller blocks have a machined face there to locate the cam in the proper place fore/aft so that the lobes and the cam gear line up properly, how did you verify that it's in the right place and how much can one block vary from another block?
Derrik,
The machined surface on the roller blocks is even with the cam thrust surface. The blocks with the factory provision for the plate are used for both roller and non roller cams so this is not an issue.

Bill Koustenis
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post #24 of 34 (permalink) Old Jul 27th, 16, 7:48 AM
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Re: SBC Stepped Nose Cam in Early Block?

Gary,
That is pretty slick. My only concern would be the back of the timing gear running across the holes for the bolts. Not sure how that would affect the lubrication. They do make a roller chain set with a torrington bearing. That would eliminate that concern.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md


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post #25 of 34 (permalink) Old Jul 27th, 16, 9:59 AM Thread Starter
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Re: SBC Stepped Nose Cam in Early Block?

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Originally Posted by BillK View Post
Gary,
That is pretty slick. My only concern would be the back of the timing gear running across the holes for the bolts. Not sure how that would affect the lubrication. They do make a roller chain set with a torrington bearing. That would eliminate that concern.
Hi Bill, that Torrington-brg timing set is the one we use anyway on most builds. Besides that fact, I don't believe running a factory type chain/gear setup would have any negative effect with the thrust plate bolt heads "buried". There's also one other "positive" to this setup, I can get oil directly on the thrust plate by drilling a tiny hole directly through one of the c'sunk bolts. Just need to make the holes deep enough to "hit" the groove behind the cam brg. At this stage I believe it would be a "non-issue" however!

Below here is another shot showing the parts as we made the, the only item not pictured is the clamping strap to hold the jig firm. Just a strap across 2 of the timing cover bolt holes. If you need a shot of this I can do that later. It's not really an important piece of the equation?

Thanks, Gary in N.Y.

P.S. I've already "kicked" this around with a couple local builders just for opinion's sake, all are in agreement, looks like all will be fine! I most definitely would NOT attempt this procedure by "hand", you'll most likely ruin the casting. It takes a decent lathe, the Bridgeport, and a decent rotating table to make the tooling! Also necessary is a 10-24 "bottom" tap to get every last thread possible.

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post #26 of 34 (permalink) Old Jul 27th, 16, 10:42 AM
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Re: SBC Stepped Nose Cam in Early Block?

looks like a great solution!

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post #27 of 34 (permalink) Old Jul 30th, 16, 11:12 AM
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Re: SBC Stepped Nose Cam in Early Block?

AFAIC, Gary gets full credit for this solution. Nobody has come up with any "prior art."

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Last edited by Tom Mobley; Jul 30th, 16 at 12:05 PM.
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post #28 of 34 (permalink) Old Jul 30th, 16, 12:44 PM Thread Starter
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Re: SBC Stepped Nose Cam in Early Block?

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AFAIC, Gary gets full credit for this solution. Nobody has come up with any "prior art."
Hi Tom, thank's for your support also here!

The sole reason for us chasing this issue down comes right back to our door, after doing the first BBC a few months back, MkIV block/MkVI cam, I knew there had to be a resolution for the early SB's, just took some "out-of-the-box" thinking for a while.

When ANYONE comes up here with ANY "unconventional" idea to solve an issue, we pay close attention, trust me on that. Once the "seed" is planted it's just a matter of working out or changing some of the details.

For us now, doing any of these type builds here, it's simple to get it done, I'm thinking of a way to help others in this area where they don't have access to the "right" tools. Like I stated earlier above you don't want to try this by hand, especially on any matching-numbers castings. I'm doing this stuff a very long time and I wouldn't try it that way myself.

I do have an add'l part of the plan where we could help others in the field to get this done, it would still require a decent shop OR at least some decent tools. More likely to have the casting machined during all the regular machining, maybe at their own machine shops doing their work.

Here's my take on this from another perspective, if you do this without the type tooling we put together but are OK with the plate being somewhat "proprietary" for a specific casting, in other words it will ONLY fit that block, then it could be pulled-off. Building these units here we need it to be "universal" so to speak, any drilled plate will fit any drilled casting. Our jig does well on that issue.

Thanks, Gary in N.Y.

P.S. I will have more on this issue at a later time, need more thought on the subject. Just a for instance though, maybe use our "jig" to pre-drill some plates and get these out to the public. In turn they could be used as a template for others (shops) to set up the casting?

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post #29 of 34 (permalink) Old Jul 30th, 16, 8:27 PM
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Re: SBC Stepped Nose Cam in Early Block?

>> Once the "seed" is planted it's just a matter of working out or changing some of the details.

seems like most good ideas are like this. sometimes it's a long ways from thinking of something to actually making it happen, much less happen in a reliable, repeatable manner. Productionized, IOW.

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post #30 of 34 (permalink) Old Jul 30th, 16, 8:40 PM
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Re: SBC Stepped Nose Cam in Early Block?

Quote:
Originally Posted by Tom Mobley View Post
and that's pretty slick.

Rob, in post #7 you mention having seen this with pics before. Got a link or any idea how to find the old post? this is a pretty brilliant solution to an old and tough problem. I've been on here since '98, seems like I'd have seen it.

Gary, did you think this up or find it somewhere?

Tom, I'm certain that I've seen this set up before and it was most likely on this forum although I can't seem to find the thread I haven't looked very hard for it but I've definitely seen this done before somewhere.

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