[spectramitch]

I just purchased the 3 pcs Program Eng. 4 bolt splayed mains for a 400. Shops local to me either wont touch a Pontiac to add them or are 7 months out to do the job. I work at a machine shop building plastic injection molds so I have machines that I believe I can rig up to do the job, and a boss that seems excited for me to attempt this task. I have a bridge port manual mill and large cnc's. But my questions are...has anyone done this? and what is a good way to fixture for this operation? I was thinking about making a 'saddle' for the deck to sit on.

[25stevem]

There’s at least 3 machinist on this board that should be getting back to you.

[spectramitch]

The dowels in the block are .308 DIA and the New billet caps came reamed already to .312. The new caps should just drop on with slop, they do not. It seems like the spacing between dowels on PMD is not the same as the billet. Has anyone encountered this? It sounds like I need to re-establish location with a mill cutter and maybe open up to 3/8" dowel and not just re-ream the block holes.

[shermanator2]

Originally Posted by spectramitch

The dowels in the block are .308 DIA and the New billet caps came reamed already to .312. The new caps should just drop on with slop, they do not. It seems like the spacing between dowels on PMD is not the same as the billet. Has anyone encountered this? It sounds like I need to re-establish location with a mill cutter and maybe open up to 3/8" dowel and not just re-ream the block holes.

Stock Pontiac dowels are about 0.3096" diameter. With the Milodon splayed caps that I have, a 0.3096 dowel will drop into the holes, but a 0.3125 is not even close to fitting.

And BTW, I have bought dowels from http://www.precisionautomotivespecialists.com/. That is the only place I have found proper 0.3096" dowels. I also like the extra length of his.

[Skip Fix]

Originally Posted by spectramitch

The dowels in the block are .308 DIA and the New billet caps came reamed already to .312. The new caps should just drop on with slop, they do not. It seems like the spacing between dowels on PMD is not the same as the billet. Has anyone encountered this? It sounds like I need to re-establish location with a mill cutter and maybe open up to 3/8" dowel and not just re-ream the block holes.

Yes the 400 block I had converted the shop id not really check fit. One of the billet caps drops on the other 2 are tight as the spacing must be a hair off.

[spectramitch]

Finally got it done! Everything came out awesome. Caps fit perfect, thrust is cut within .001 and the tapping went smooth with no vented water jackets.

[Scott Roberts]

Originally Posted by spectramitch

Finally got it done! Everything came out awesome. Caps fit perfect, thrust is cut within .001 and the tapping went smooth with no vented water jackets.

Good for you! You didn't need any real help, just a nudge from the forum to get it done...
Nothing like taking on a task like that and succeeding... it will feel great knowing the muscle under your hood was done by you!
Job well done!

[Mike Davis]

I hate to be the guy that advises against this... but I would use the correct equipment for the task. I have used the Van Norman, Sunnen and Rottler CNC F69A style machines. I always finish them a little on the small side and finish with an align hone after the bore. If you had a scrap block lying around then maybe. One mistake and your block is not useable.
There may be some here who have done it, but my 35 plus years as a machinist doesn't have the warm and fuzzy about it. You may be headaches ahead to find a shop. You are not far from Scott Williams, find out who does his machine work.

[spectramitch]

Originally Posted by Mike Davis

I hate to be the guy that advises against this... but I would use the correct equipment for the task. I have used the Van Norman, Sunnen and Rottler CNC F69A style machines. I always finish them a little on the small side and finish with an align hone after the bore. If you had a scrap block lying around then maybe. One mistake and your block is not useable.
There may be some here who have done it, but my 35 plus years as a machinist doesn't have the warm and fuzzy about it. You may be headaches ahead to find a shop. You are not far from Scott Williams, find out who does his machine work.

I should have clarified, I am not going to touch the main bore, i have a shop to do the align bore and hone. I am only needing to mount the caps to the block and then machine the thrust face to match the block.

[Mike Davis]

Originally Posted by spectramitch

I should have clarified, I am not going to touch the main bore, i have a shop to do the align bore and hone. I am only needing to mount the caps to the block and then machine the thrust face to match the block.

Oh well forget what I posted.....Yes,I have done a few of the drill and tap process on a manual mill.

[shermanator2]

The valley ends of a Pontiac block seem to be exactly a 6" radius. See the attached picture of a pair of saddles that I made to mount my block in my Bridgeport for a different purpose.

I have a block that I was thinking about installing splayed caps on. I have a set of the Milodon splayed caps. They come with a drill bushing and say to use that and a hand drill. The Bridgeport seems like a better idea.

The thrust surfaces on the #4 cap seem to be the tough part. I have not found anyone local to me (San Diego) that can do them.

And you probably already know this, but with splayed caps, you cannot run a dipstick in the normal location.

[spectramitch]

Originally Posted by shermanator2

The valley ends of a Pontiac block seem to be exactly a 6" radius. See the attached picture of a pair of saddles that I made to mount my block in my Bridgeport for a different purpose.

I have a block that I was thinking about installing splayed caps on. I have a set of the Milodon splayed caps. They come with a drill bushing and say to use that and a hand drill. The Bridgeport seems like a better idea.

The thrust surfaces on the #4 cap seem to be the tough part. I have not found anyone local to me (San Diego) that can do them.

And you probably already know this, but with splayed caps, you cannot run a dipstick in the normal location.

I like your saddle idea

I had a thought to address the thrust face. I was planning on bolting the No.4 cap on, indicate the amount of stock on the cap to the block face, then remove cap and cut measured step off clamped in a vise. Obviously do a semi finish and verify stock removal is on the right track and square.

[mgarblik]

The machine shop that will be line boring the 3 center caps should be able to cut the thrust faces as well. It's part of the process. My Sunnen line bore attachment for the line hone will cut the thrust faces. It's a little crude, but it will cut them. Billet caps are really tough and can produce a little chatter. Check with your machine shop. Not sure how to cut the thrust faces in a Bridgeport without a rotary table and a fly cutter. That would be pretty tough. Mounting the caps is pretty easy in a Bridgeport. I just use a transfer punch to line up the drill guide. Drill and tap. Pretty simple.

[spectramitch]

I made the plates able to hold the block square and at 18°.

[spectramitch]

Well she is back in my hands and its time to start checking clearances. I am wondering what torque sequence is proper for the Splayed caps? Do I finish torque studs then do the splayed bolts? or incrementally both of them? The engine machinist specified 100ft/lbs on studs and 65ft/lbs and splayed.

[spectramitch]

Current Progress, I think the fixture is coming along nice. Now I need to pick up locations of dowels in the block and in the cap to figure out what amount to move holes to get back in line with each other. I am going to try to make 8mm dowels work.

[Tom Vaught]

Tom Earhart, who was the Engine Machinist/Dyno guy for Marty Palbykin's 1967
400 cid 2 BBL 2 bolt main block, (no 4 bolt main drilling in the block), added the
PROGRAM Steel Main Caps to that block in the 1995 time frame.

So it has been done with success in the right block application. The issue is finding
someone capable of doing the work properly. The engine as posted, made 1600 hp
for 3 years without failure. Tom had the Bridgeport as well as the other equipment required.
He had a lot of very good Engine Machining equipment.

https://www.snowmobilehalloffame.com...s/tom-earhart/
Tom Earhart began his career building and racing drag and oval track sleds in Michigan as chief engineer for Rupp.


The point is finding the right guy to do the work. Not sure if Tom is still doing work.
If so He and You are both in Michigan. He is on the west side of the state.
Thomas Earhart's current address is listed as 10751 Gun Lake Road, Middleville, MI 49333.

Tom V.

[Mr Twister]

Tom is retired and moved to Florida.

[Rar_421]

Originally Posted by Tom Vaught

Tom Earhart, who was the Engine Machinist/Dyno guy for Marty Palbykin's 1967
400 cid 2 BBL 2 bolt main block, (no 4 bolt main drilling in the block), added the
PROGRAM Steel Main Caps to that block in the 1995 time frame.

So it has been done with success in the right block application. The issue is finding
someone capable of doing the work properly. The engine as posted, made 1600 hp
for 3 years without failure. Tom had the Bridgeport as well as the other equipment required.
He had a lot of very good Engine Machining equipment.

https://www.snowmobilehalloffame.com...s/tom-earhart/
Tom Earhart began his career building and racing drag and oval track sleds in Michigan as chief engineer for Rupp.


The point is finding the right guy to do the work. Not sure if Tom is still doing work.
If so He and You are both in Michigan. He is on the west side of the state.
Thomas Earhart's current address is listed as 10751 Gun Lake Road, Middleville, MI 49333.

Tom V.

Had no idea Tom was involved with Pontiac projects,he was very well known for his work with Kohler snowmobile race engines with Rupp and the Kalamazoo Kyotee sno pro sleds,I've been collecting parts to build a Kalamazoo Kyotee replica

[Tom Vaught]

Originally Posted by Rar_421

Had no idea Tom was involved with Pontiac projects,he was very well known for his work with Kohler snowmobile race engines with Rupp and the Kalamazoo Kyotee sno pro sleds,I've been collecting parts to build a Kalamazoo Kyotee replica

He ever take you for a ride in his 1000 hp chevy Pontoon Boat??

Tom V.