Posted By: RAY1969CARS
R block cam Journal question - 03/18/15 12:06 AM
Can a Standard step journal be machined out to a 50 mm ???
R block cam Journal question
Posted By: MR_P_BODY
Re: R block cam Journal question - 03/18/15 12:13 AM
Quote:
Can a Standard step journal be machined out to a 50 mm ???
Sorry.. I was gonna get back with you but I havent
found my stock cam yet
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/18/15 12:16 AM
Quote:Quote:
Can a Standard step journal be machined out to a 50 mm ???
Sorry.. I was gonna get back with you but I havent
found my stock cam yet
no worries bro
Posted By: 1967dartgt
Re: R block cam Journal question - 03/18/15 02:18 AM
I do not believe so, I think they measure 52 mm.
Posted By: mr_340
Re: R block cam Journal question - 03/18/15 05:14 PM
Are you talking about the block or the cam?
Posted By: MR_P_BODY
Re: R block cam Journal question - 03/18/15 05:17 PM
Quote:
Are you talking about the block or the cam?
The cam itself... does anyone know what size the large
journal is on a stock cam... I looked but cant find
the spec
Posted By: mr_340
Re: R block cam Journal question - 03/18/15 05:28 PM
If this will copy over from the 1967 Dodge Service Manual for the 273/318 engine:
1.998"-1.999" on the #1 cam journal. I couldn't get it to copy and paste from the PDF.
1.998"-1.999" on the #1 cam journal. I couldn't get it to copy and paste from the PDF.
Posted By: MR_P_BODY
Re: R block cam Journal question - 03/18/15 05:47 PM
Quote:
If this will copy over from the 1967 Dodge Service Manual for the 273/318 engine:
1.998"-1.999" on the #1 cam journal. I couldn't get it to copy and paste from the PDF.
Ray... based on this and this 50 millimeter = 1.968503937 inch
but I know that my 50mm cam had to be ground a bit
to fit the bearings so its a bit oversized... measure
that #1 journal on that stick.. its gonna be very close..
and in some cases the bearings are over sized(I have
had most of them that needed to be sized)..
or bore the cam tunnel to 50mm roller specs
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/18/15 06:11 PM
Quote:Quote:
If this will copy over from the 1967 Dodge Service Manual for the 273/318 engine:
1.998"-1.999" on the #1 cam journal. I couldn't get it to copy and paste from the PDF.
Ray... based on this and this 50 millimeter = 1.968503937 inch
but I know that my 50mm cam had to be ground a bit
to fit the bearings so its a bit oversized... measure
that #1 journal on that stick.. its gonna be very close..
and in some cases the bearings are over sized(I have
had most of them that needed to be sized)..
or bore the cam tunnel to 50mm roller specs
I'll check it as soon as I get home around 330 thank
Posted By: Leon441
Re: R block cam Journal question - 03/19/15 02:56 AM
I forget the O.D. of the 50mm needle bearings. But, yes you can have the tunnel bored for 50mm roller bearings.
Posted By: WHITEDART
Re: R block cam Journal question - 03/19/15 03:02 AM
55 mm cores are cheap from comp cams
Posted By: MR_P_BODY
Re: R block cam Journal question - 03/19/15 03:10 AM
Quote:
55 mm cores are cheap from comp cams
He has a 48* babbit block... I sold him a 48* 50mm
by accident thinking it was a babbit one.. when I
checked my stash I got rid of the babbit one along
the line somewhere .. now he is trying to see if the
50mm can be cut to babbit specs.. he could cut the
block to 50mm and use what he has now but he wants
the babbit set up
Posted By: tubtar
Re: R block cam Journal question - 03/19/15 03:15 AM
48 degree babbit blocks are not stepped journals ........ they take their own bearing sets and are all the same diameter.
http://www.jegs.com/i/Mopar-Performance/312/P4876372/10002/-1?parentProductId=1903872
I am pretty sure the 59 degree blocks use the stepped bearings like the stock blocks.
http://www.jegs.com/i/Mopar-Performance/312/P4876372/10002/-1?parentProductId=1903872
I am pretty sure the 59 degree blocks use the stepped bearings like the stock blocks.
Posted By: MR_P_BODY
Re: R block cam Journal question - 03/19/15 03:20 AM
Quote:
48 degree babbit blocks are not stepped journals ........ they take their own bearing sets and are all the same diameter.
http://www.jegs.com/i/Mopar-Performance/312/P4876372/10002/-1?parentProductId=1903872
I am pretty sure the 59 degree blocks use the stepped bearings like the stock blocks.
I didnt know that about the 48* block.. thanks but
I did on the 59*
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/19/15 06:38 AM
Quote:
48 degree babbit blocks are not stepped journals ........ they take their own bearing sets and are all the same diameter.
http://www.jegs.com/i/Mopar-Performance/312/P4876372/10002/-1?parentProductId=1903872
I am pretty sure the 59 degree blocks use the stepped bearings like the stock blocks.
Here are the only cams I know of and as. far as bearing
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/19/15 06:47 AM
mike I only have calipers no mic but I'm getting 1.995 on the cam
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/19/15 06:49 AM
Quote:
I forget the O.D. of the 50mm needle bearings. But, yes you can have the tunnel bored for 50mm roller bearings.
That would be the key to what I want to do you know any OD and what the block is actually measuring for the press of the bearings are the numbers I may need
Posted By: MR_P_BODY
Re: R block cam Journal question - 03/19/15 06:57 AM
Quote:
mike I only have calipers no mic but I'm getting 1.995 on the cam
Now you need to measure the front bearing to see what
it is
Posted By: vc360
Re: R block cam Journal question - 03/19/15 10:46 AM
Quote:
48 degree babbit blocks are not stepped journals ........ they take their own bearing sets and are all the same diameter.
http://www.jegs.com/i/Mopar-Performance/312/P4876372/10002/-1?parentProductId=1903872
I am pretty sure the 59 degree blocks use the stepped bearings like the stock blocks.
That's not correct. The early48 deg "r" blocks and "r1a"blocks used stepped journals like a 59 block but with 48 degree lobe spacing.
I have one and it uses std small block cam bearings.
Call bullet or midway cams.
Posted By: tubtar
Re: R block cam Journal question - 03/19/15 01:14 PM
Quote:Quote:
48 degree babbit blocks are not stepped journals ........ they take their own bearing sets and are all the same diameter.
http://www.jegs.com/i/Mopar-Performance/312/P4876372/10002/-1?parentProductId=1903872
I am pretty sure the 59 degree blocks use the stepped bearings like the stock blocks.
That's not correct. The early48 deg "r" blocks and "r1a"blocks used stepped journals like a 59 block but with 48 degree lobe spacing.
I have one and it uses std small block cam bearings.
Call bullet or midway cams.
Why does this not surprise me ?
Add that to the which oil pan and which crankshaft journal questions then.
I am pretty sure that the MoPar UGL cams for the babbit blocks are all gone , but cores can be sourced elsewhere.
But like everything else with these motors , bring your wallet.
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/19/15 01:57 PM
Quote:Quote:Quote:
48 degree babbit blocks are not stepped journals ........ they take their own bearing sets and are all the same diameter.
http://www.jegs.com/i/Mopar-Performance/312/P4876372/10002/-1?parentProductId=1903872
I am pretty sure the 59 degree blocks use the stepped bearings like the stock blocks.
That's not correct. The early48 deg "r" blocks and "r1a"blocks used stepped journals like a 59 block but with 48 degree lobe spacing.
I have one and it uses std small block cam bearings.
Call bullet or midway cams.
Why does this not surprise me ?
Add that to the which oil pan and which crankshaft journal questions then.
I am pretty sure that the MoPar UGL cams for the babbit blocks are all gone , but cores can be sourced elsewhere.
But like everything else with these motors , bring your wallet.
It Ain't no Chevy lol
Posted By: MR_P_BODY
Re: R block cam Journal question - 03/19/15 03:42 PM
I have 1 more 50mm cam(UGL) for the 48*.. I was hoping
that it was a babbit one but it isnt... some where I
got rid of the one I had
that it was a babbit one but it isnt... some where I
got rid of the one I had
Posted By: J_BODY
Re: R block cam Journal question - 03/19/15 03:46 PM
Our R3 project stalled for about 3 months last year as we couldn't find a core..... my R3 now has BBC cam bearings 
Posted By: MR_P_BODY
Re: R block cam Journal question - 03/19/15 03:51 PM
Quote:
Our R3 project stalled for about 3 months last year as we couldn't find a core..... my R3 now has BBC cam bearings
What journal.. babbit or 50
Posted By: J_BODY
Re: R block cam Journal question - 03/19/15 03:56 PM
was a babbit deal.... I "think" there are cores out there again, but at the time nobody had anything.
Posted By: MattW
Re: R block cam Journal question - 03/19/15 04:53 PM
And people think a G3 is complicated! 
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/19/15 05:21 PM
Is it the 50 mm needle bearing a lot thicker than a regular bearing ? I don't know off hand If it is couldn't I just bore out the cam tunnel seems to me that the 50mm care are easier to come by my experience with the 1st R block being so old and they r3 a lot newer. If anybody's done is what would be the price on doing it Machine whys is it a real big deal ???
Posted By: 408Dust
Re: R block cam Journal question - 03/19/15 05:22 PM
Call LSM 248-674-4967 I had a 54mm one made for me in 3 weeks this January. Chris Padgett at comp may be able to help also.
Posted By: MR_P_BODY
Re: R block cam Journal question - 03/19/15 05:38 PM
Quote:
Is it the 50 mm needle bearing a lot thicker than a regular bearing ? I don't know off hand If it is couldn't I just bore out the cam tunnel seems to me that the 50mm care are easier to come by my experience with the 1st R block being so old and they r3 a lot newer. If anybody's done is what would be the price on doing it Machine whys is it a real big deal ???
On my new R3 block it came with the 50m cam tunnel
but I still had to have it machined to line it up
and have the bearings fit.. the tunnel was a bit
undersize.. I had to have the mains line honed also..
it was bad
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/19/15 08:31 PM
Quote:.Quote:
Is it the 50 mm needle bearing a lot thicker than a regular bearing ? I don't know off hand If it is couldn't I just bore out the cam tunnel seems to me that the 50mm care are easier to come by my experience with the 1st R block being so old and they r3 a lot newer. If anybody's done is what would be the price on doing it Machine whys is it a real big deal ???
On my new R3 block it came with the 50m cam tunnel
but I still had to have it machined to line it up
and have the bearings fit.. the tunnel was a bit
undersize.. I had to have the mains line honed also..
it was bad
I guess this is half the fun lol
Posted By: MR_P_BODY
Re: R block cam Journal question - 03/19/15 08:50 PM
Quote:Quote:.Quote:
Is it the 50 mm needle bearing a lot thicker than a regular bearing ? I don't know off hand If it is couldn't I just bore out the cam tunnel seems to me that the 50mm care are easier to come by my experience with the 1st R block being so old and they r3 a lot newer. If anybody's done is what would be the price on doing it Machine whys is it a real big deal ???
On my new R3 block it came with the 50m cam tunnel
but I still had to have it machined to line it up
and have the bearings fit.. the tunnel was a bit
undersize.. I had to have the mains line honed also..
it was bad
I guess this is half the fun lol
If your gonna run a big lift cam you would be far
better to have the cam tunnel bored to 50mm specs..
that way the cam wont flex like the stock type core
being that you have to grind the base of the cam to
get the lift... but then you would want good rockers
also.. but you said you were going with TD if I recall
and if you go that way I would go push rod oiling
for the rockers.... nothing easy on these things
EDIT
Let me take a look around.. I think I have a set of
50mm bearing... if I have them you can have them
but they would need a washing
Posted By: rickraw
Re: R block cam Journal question - 03/19/15 11:06 PM
Indy ripped me for 750 to bore cam tunnel for 50mm roller bearings & another 250 to drill 16 holes in bores for pushrods oiling, I couldn't find a jig to do it myself. Now I know how women feel when they get rapped.
Posted By: Oyvind Mopar
Re: R block cam Journal question - 03/19/15 11:14 PM
I think I have a few 48* roller cams, and one or two are stepped. I cannot use them in my block (need 50mm roller). I can measure to see, maybe we can swap? Please tell me what measurements the cambearings should have, and I will check through!
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/20/15 02:54 AM
Quote:Quote:Quote:.Quote:
Is it the 50 mm needle bearing a lot thicker than a regular bearing ? I don't know off hand If it is couldn't I just bore out the cam tunnel seems to me that the 50mm care are easier to come by my experience with the 1st R block being so old and they r3 a lot newer. If anybody's done is what would be the price on doing it Machine whys is it a real big deal ???
On my new R3 block it came with the 50m cam tunnel
but I still had to have it machined to line it up
and have the bearings fit.. the tunnel was a bit
undersize.. I had to have the mains line honed also..
it was bad
I guess this is half the fun lol
If your gonna run a big lift cam you would be far
better to have the cam tunnel bored to 50mm specs..
that way the cam wont flex like the stock type core
being that you have to grind the base of the cam to
get the lift... but then you would want good rockers
also.. but you said you were going with TD if I recall
and if you go that way I would go push rod oiling
for the rockers.... nothing easy on these things
EDIT
Let me take a look around.. I think I have a set of
50mm bearing... if I have them you can have them
but they would need a washing
Talk to a couple shops QMP. Bob Lemback I guess it can be done boring to a 50mm one more call to Brian at Imm that's the shop that will be doing all the machine work and the assembly and put it on the pump still need to know the pros and cons don't want to back myself into a corner to go a certain way with the motor oiling etc. etc.
Posted By: MR_P_BODY
Re: R block cam Journal question - 03/20/15 03:05 AM
Talk to a couple shops QMP. Bob Lemback I guess it can be done boring to a 50mm one more call to Brian at Imm that's the shop that will be doing all the machine work and the assembly and put it on the pump still need to know the pros and cons don't want to back myself into a corner to go a certain way with the motor oiling etc. etc.
This is JMO but I would go 50mm with push rod oiling
with multi shaft rockers such as TD.. this was the
way I went and it worked well... I was turning 8200
rpm all the time but I did go as high as 9600 looking
for more power.. this was on my 405ci W-9 but I
needed another .150 lift on the cam which would have
made 750 hp... but I wimped on the cam... talk with
Brian and see what he thinks
This is JMO but I would go 50mm with push rod oiling
with multi shaft rockers such as TD.. this was the
way I went and it worked well... I was turning 8200
rpm all the time but I did go as high as 9600 looking
for more power.. this was on my 405ci W-9 but I
needed another .150 lift on the cam which would have
made 750 hp... but I wimped on the cam... talk with
Brian and see what he thinks
Posted By: 1967dartgt
Re: R block cam Journal question - 03/20/15 04:12 AM
I would go with a Babbitt cam, the factory 2" size(1.998) and predator cams has cores. A Babbitt bearing is much more reasonable then rollers and cores are cheap also.
Posted By: WHITEDART
Re: R block cam Journal question - 03/20/15 05:23 AM
You live close to the best shop in the west.stop banging your head on the key board and get it done . And get it to the track the more money you try to save the more it cost you. This is what I found out the hard way on my w8 dill
Posted By: Ian
Re: R block cam Journal question - 03/20/15 02:20 PM
my 48 r block has stepped bearings ,my new cam is not stepped seems to fit in the front nice the new cam is 21 = 1.9985 2" SB Mopar "R" Babbit
Posted By: vc360
Re: R block cam Journal question - 03/20/15 11:45 PM
http://www.cranecams.com/pdf-tech-tips/chrysler-sm-block152-153.pdf
Lists the different cams and suffix codes.
Lists the different cams and suffix codes.
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/21/15 02:26 AM
Do the 50 mm roller bearing cams have holes in the journals for oil as well as A grove cut them ???
Posted By: rickraw
Re: R block cam Journal question - 03/21/15 03:31 AM
No they don't.
Posted By: Hot 340
Re: R block cam Journal question - 03/21/15 04:20 AM
Comp also has 1.998 babbit core for flat tappet 48's, used by dirt guys..they quoted me about $100 for a ugl.
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/21/15 04:48 AM
Quote:
Comp also has 1.998 babbit core for flat tappet 48's, used by dirt guys..they quoted me about $100 for a ugl.
I need a solid roller
Posted By: Hot 340
Re: R block cam Journal question - 03/21/15 04:56 AM
Quote:Bullet had 30 of those in stock last I talked to them. Callies cores I thinkQuote:
Comp also has 1.998 babbit core for flat tappet 48's, used by dirt guys..they quoted me about $100 for a ugl.
I need a solid roller
Posted By: 1967dartgt
Re: R block cam Journal question - 03/21/15 05:50 AM
Comp had no solid roller 1.998 cams, bullet didn't have any either. I believe bullet should have some now. Predator cams had 200 cores this last summer when I got mine.
Posted By: Hot 340
Re: R block cam Journal question - 03/21/15 02:05 PM
Quote:The guy at bullet told me they have a supplier now, when they run out they get a bunch more. Pretty sure the supply problem is diminished for these.
Comp had no solid roller 1.998 cams, bullet didn't have any either. I believe bullet should have some now. Predator cams had 200 cores this last summer when I got mine.
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/21/15 02:51 PM
Quote:Quote:The guy at bullet told me they have a supplier now, when they run out they get a bunch more. Pretty sure the supply problem is diminished for these.
Comp had no solid roller 1.998 cams, bullet didn't have any either. I believe bullet should have some now. Predator cams had 200 cores this last summer when I got mine.
I be leave so dam cam cores
Posted By: 1967dartgt
Re: R block cam Journal question - 03/21/15 08:03 PM
Quote:Quote:The guy at bullet told me they have a supplier now, when they run out they get a bunch more. Pretty sure the supply problem is diminished for these.
Comp had no solid roller 1.998 cams, bullet didn't have any either. I believe bullet should have some now. Predator cams had 200 cores this last summer when I got mine.
Yes predator cams is the supplier for bullet, the reason he had 200 of them he supplies a few cam grinders. I don't know where he gets his cores made, and wish he would get one with more lobe separation.
Posted By: J_BODY
Re: R block cam Journal question - 03/21/15 08:09 PM
for some reason I seem to remember Callies coming up in the conversation. Maybe I'm wrong.... still confuses the ever lovin s##t out of me
Posted By: Hot 340
Re: R block cam Journal question - 03/21/15 08:12 PM
Quote:Steve Overmier at Callies told me they make cores, not sure if they make them for Predator, but pretty sure he said they make them for Bullet. It was a while ago.Quote:Quote:The guy at bullet told me they have a supplier now, when they run out they get a bunch more. Pretty sure the supply problem is diminished for these.
Comp had no solid roller 1.998 cams, bullet didn't have any either. I believe bullet should have some now. Predator cams had 200 cores this last summer when I got mine.
Yes predator cams is the supplier for bullet, the reason he had 200 of them he supplies a few cam grinders. I don't know where he gets his cores made, and wish he would get one with more lobe separation.
Posted By: Ian
Re: R block cam Journal question - 03/22/15 01:50 AM
Quote:they do they had 8 instock when i got mine ,110 l/c
for some reason I seem to remember Callies coming up in the conversation. Maybe I'm wrong.... still confuses the ever lovin s##t out of me
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/27/15 10:05 PM
Can anybody tell me the OD of the Babbitt bearing 50mm and the OD of the cage of the needle bearing housing ? 50mm
Posted By: 1967dartgt
Re: R block cam Journal question - 03/27/15 11:13 PM
Quote:Quote:they do they had 8 instock when i got mine ,110 l/c
for some reason I seem to remember Callies coming up in the conversation. Maybe I'm wrong.... still confuses the ever lovin s##t out of me
I have a 112 but would love more.
Posted By: Hot 340
Re: R block cam Journal question - 03/28/15 04:05 AM
Quote:specs . (Pic)Quote:Quote:they do they had 8 instock when i got mine ,110 l/c
for some reason I seem to remember Callies coming up in the conversation. Maybe I'm wrong.... still confuses the ever lovin s##t out of me
I have a 112 but would love more.
Posted By: 1967dartgt
Re: R block cam Journal question - 03/28/15 04:54 AM
Quote:Quote:specs . (Pic)Quote:Quote:they do they had 8 instock when i got mine ,110 l/c
for some reason I seem to remember Callies coming up in the conversation. Maybe I'm wrong.... still confuses the ever lovin s##t out of me
I have a 112 but would love more.
That's the core I have, only has a 106 intake lobe. Can't do that much with that.
Posted By: Ian
Re: R block cam Journal question - 03/29/15 10:24 AM
Quote:Quote:Quote:specs . (Pic)Quote:Quote:they do they had 8 instock when i got mine ,110 l/c
for some reason I seem to remember Callies coming up in the conversation. Maybe I'm wrong.... still confuses the ever lovin s##t out of me
I have a 112 but would love more.
That's the core I have, only has a 106 intake lobe. Can't do that much with that.
110 l/c you could go 2 degrees wider may be 3 depending on profile
Posted By: SB412DUSTER
Re: R block cam Journal question - 03/30/15 05:49 AM
Quote:
Can anybody tell me the OD of the Babbitt bearing 50mm and the OD of the cage of the needle bearing housing ? 50mm
The cam tunnel bore in the block for the 50mm needle bearing is 2.2820-2.2826
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/30/15 06:35 AM
Quote:Quote:
Can anybody tell me the OD of the Babbitt bearing 50mm and the OD of the cage of the needle bearing housing ? 50mm
The cam tunnel bore in the block for the 50mm needle bearing is 2.2820-2.2826
Thanks bro
Posted By: 1967dartgt
Re: R block cam Journal question - 03/30/15 04:04 PM
Quote:Quote:Quote:Quote:specs . (Pic)Quote:Quote:they do they had 8 instock when i got mine ,110 l/c
for some reason I seem to remember Callies coming up in the conversation. Maybe I'm wrong.... still confuses the ever lovin s##t out of me
I have a 112 but would love more.
That's the core I have, only has a 106 intake lobe. Can't do that much with that.
110 l/c you could go 2 degrees wider may be 3 depending on profile
Yes made 112 out of it, buts thats it. Need to do custom core for more.
Posted By: 1967dartgt
Re: R block cam Journal question - 03/30/15 04:07 PM
Quote:
Can anybody tell me the OD of the Babbitt bearing 50mm and the OD of the cage of the needle bearing housing ? 50mm
I will measure the OD of the babbit when they get here. The block is at machine shop now.
Posted By: Darryls-Demon
Re: R block cam Journal question - 03/30/15 08:18 PM
Quote:Quote:Quote:they do they had 8 instock when i got mine ,110 l/c
for some reason I seem to remember Callies coming up in the conversation. Maybe I'm wrong.... still confuses the ever lovin s##t out of me
I have a 112 but would love more.
The cam in my R3 motor is from LSM and it has 115 LSA.
I have no plans on using NOS so I think the motor would be happier with around 110 LSA.
Posted By: cknight
Re: R block cam Journal question - 03/30/15 10:14 PM
A 50mm babbit cam bearing usually requires a housing bore of 2.0985/2.0995", Regards, Chase
Posted By: dodgeboy11
Re: R block cam Journal question - 03/31/15 12:44 AM
Unless they're oddballs, should be a bore size of 2.242" 55mm fit into a 2.480. If I remember correctly.
Posted By: 1967dartgt
Re: R block cam Journal question - 03/31/15 02:04 AM
2.135 approximately. Not the most round and don't have block.
Posted By: RAY1969CARS
Re: R block cam Journal question - 03/31/15 03:03 AM
Apparently the block can't be bored out to a roller using a CNC talk to QMP they can do it it just can't be done with a mandrel type boring needs a 90° Head because of the number five journal is so small And stupid me I have all these race manuals I just looked in the first one and found all the necessary measurements
Posted By: tubtar
Re: R block cam Journal question - 03/31/15 04:58 AM
Quote:
Apparently the block can't be bored out to a roller using a CNC talk to QMP they can do it it just can't be done with a mandrel type boring needs a 90° Head because of the number five journal is so small And stupid me I have all these race manuals I just looked in the first one and found all the necessary measurements
Well..........that changed the way I look at things.
I also thought that all 48 degree blocks used the same cam bearing bore on every journal , but apparently the 48 degree R-1 and some early R blocks used stepped bearings.
I would have thought a mandrel would work too......sounds like it gets involved. Do you need to bore four , then re-set for #5 ?
One more operation and the probable tolerance stacking would have me thinking long and hard.