NOS 8RT camshaft

[GB SISSON]

My camshaft arrived yesterday from 3rd gen Automotive. Apparently this is the last one of 25. I hope to clean it off today and I could set it up between lathe centers with a dial indicater. I know very little about duration and overlap, but I could measure the lift if anyone is interested.

[Ggmac]

I would be interested to know .
Thank you , Gary

[tubman]

Originally Posted by GB SISSON

My camshaft arrived yesterday from 3rd gen Automotive. Apparently this is the last one of 25. I hope to clean it off today and I could set it up between lathe centers with a dial indicater. I know very little about duration and overlap, but I could measure the lift if anyone is interested.

I would be, mainly to see if it's the same as a standard 8BA (.307").

[GB SISSON]

Will do. Looks like the coating is a soft rubbery substance and should peel off easier than the petrified WW2 era cosmoline.

[petehoovie]

Originally Posted by GB SISSON

My camshaft arrived yesterday from 3rd gen Automotive. Apparently this is the last one of 25. I hope to clean it off today and I could set it up between lathe centers with a dial indicater. I know very little about duration and overlap, but I could measure the lift if anyone is interested.

[GB SISSON]

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Thank you Pete! I need a bit of info. I uncovered the first two lobes at the front. Directly opposite of the lobe is not the smallest diameter. There is a bit of a lower spot -.006 just before the ramp. Do I set my dial at zero on the flat before the ramp or where I originally thought, which is opposite the lobe? And from my block, looks like these are both exhaust?

[Pete]

Looks like you got a production reject.
The heel of the cam should be concentric.

[GB SISSON]

Originally Posted by Pete

Looks like you got a production reject.
The heel of the cam should be concentric.

I was afraid of that. Is it junk or could you make me something cool out of it? Smooth idle, no lopey, pulls my hilly terrain at 35-40 mph? Or I send it back?...I was suspicious when the lobes were different lift.

[Ggmac]

If the runout is less than a few thousandths I would thik the lash would not care and the lobe is going to lift the valve off the seat . Just my opinion
If you never measured the cam and just installed it , I , again my opinion, think it would be running as normal.

[Pete]

Originally Posted by GB SISSON

I was afraid of that. Is it junk or could you make me something cool out of it? Smooth idle, no lopey, pulls my hilly terrain at 35-40 mph? Or I send it back?...I was suspicious when the lobes were different lift.

To fix it I would need to know if it is a genuine Ford core. If it is there will be
Ford letters cast in the core somewhere along the line such as "8RT", 8ba, etc etc.

In the middle picture, can you clean the 3rd lobe UP from the center journal really clean. In that picture I see a wear pattern.

[Pete]

Originally Posted by Ggmac

If the runout is less than a few thousandths I would thik the lash would not care and the lobe is going to lift the valve off the seat . Just my opinion
If you never measured the cam and just installed it , I , again my opinion, think it would be running as normal.

With the heels running out .006, it is not even worth discussing.

By the way, I have been in the cam business since 1952.

[GB SISSON]

Maybe after dinner I will make a short video of slowly rotating the cam with the dial indicator in view. And Pete, running it 'as is' is not woth discussing or fixing it isn't worth discussing? I will clean that lobe for a close up. It certainly does not look used from what's uncovered.

[GB SISSON]

I retested, and as before, the very first one from the distributor gear (top in middle photo) has it's low spot at about 90 degrees from the base circle. From zero at it's base circle the lift is .300". I then tested the second one down as I had noticed the two were quite different, yet both are exhaust lobes and should have been the same. That next one had the same zero at the bottom, but no low spots along the way and a lift of .312". I then uncovered that third one up from the center bearing and the one above that. Like the first two, they both looked brand new, untouched, pristine. They were exactly like #2 above. Zero at base circle, no low spots and exactly .312" lift. I'd probably get no love from anybody if I carved a bit off that top one's base circle with my belt sander, huh? Just kidding. Where do I go from here?

[51504bat]

What does Michael at 3rd Gen say?

[GB SISSON]

Originally Posted by 51504bat

What does Michael at 3rd Gen say?

With it so heavily dipped, there's no way he would have known if it has a flaw. I checked one of the bearings on it last night and it was perfect. My best cam, the 8ba, has journals at the lower end of acceptable, so it's still of interest to see what can be done with this one. As I stated in an earlier thread, I'm kind of obsessive anout oil pressure. I will call Micheal after another cup of coffee, but I'm not sure sending back is my best option, and it was the last one.

[KiWinUS]

Put the new cam in a block wit cam bearings and check cam lift in the block. I say this as over the many years I have had many reach out to me with similar issues. I have the do as suggested and mysteriously it has correct numbers.
I have ground dozens of those same NOS cams probably from the same original source into my cams with zero issues. I also know that source was at one time a large rebuilder and used these cams straight from the box. After peeling off the protective coating.
Have fun.

[flatjack9]

I imagine that due to the diameter of the lifter, it does not see that dip.

[GB SISSON]

Micheal at 3rd Gen will give me a full refund even if I peel off the cosmoline and test it. I have my recently machined block with new cam bearings on a stand so that test would be somewhat easy. So, maybe I make up one valve/guide assembly with a light spring and set at a certain lash and move it around to all 16 places? And what is that lash? and the lift numbers I gave were with I think what is called 'gross lift'. Or maybe I set up my dial indicator to read the cam lobes in the block?

[vincent]

Set up a valve/guide assembly with light spring but adjust it to sit above the valve seat - thus no need to adjust lash for every seat. Read the lift with a dial indicator from the valves head. Watch the dial finger when rotating the cam, if there is a jerking motion due to an imperfect lobe/dip you will see it on the dial finger.

[GB SISSON]

Thanks Vincent. Sounds like a good plan. I peeled the coating and checked them all on the lathe. So far that very first one is the only one that's out much. The two pics with the dial indicator show the first and secnd lobe differences. Throughout there are some slight varaitions in lift, and the center bearing isn't all that true, maybe .005 out, but all these cams I have are about like that. I'm guessing Kiwi's thoughts involve the center bearing coming into play to stabilize the readings. And lastly you will see it is marked 8RT, and when rotated 90 degrees it reads EA. Any tricks to inserting the cam without damaging things?I also have some stripped blocks with their cam bearings still in. Would that be a smarter place to test this?

[petehoovie]

Originally Posted by GB SISSON

Thanks Vincent. Sounds like a good plan. I peeled the coating and checked them all on the lathe. So far that very first one is the only one that's out much. The two pics with the dial indicator show the first and secnd lobe differences. Throughout there are some slight varaitions in lift, and the center bearing isn't all that true, maybe .005 out, but all these cams I have are about like that. I'm guessing Kiwi's thoughts involve the center bearing coming into play to stabilize the readings. And lastly you will see it is marked 8RT, and when rotated 90 degrees it reads EA. Any tricks to inserting the cam without damaging things?I also have some stripped blocks with their cam bearings still in. Would that be a smarter place to test this?

[vincent]

Test it in a block with a cam follower - this will give the exact motion the valve will get. The cams that I got are all soft so you could regrind the wrong base circle very easily. I just reground all 16 lobes for my supercharged engine to get a bit more valve acceleration and more lift.

[GB SISSON]

Originally Posted by vincent

Test it in a block with a cam follower - this will give the exact motion the valve will get. The cams that I got are all soft so you could regrind the wrong base circle very easily. I just reground all 16 lobes for my supercharged engine to get a bit more valve acceleration and more lift.

I don't think I will be grinding this cam. I do think I have enough tools and machinery here to make a fixture to touch up the bottom of that one lobe if I had some instructions , but it would be quite scary. Out of curiosity, should all the cam lobes measure the same if they were mic'd across the long dimension? I understand that intake and exhaust could differ. First I will test the lift in a block. And what is a cam follower? I'm picturing a lifter with a slot in it for a small wheel. If so, what keeps it from turning sideways?

[flatjack9]

In this case the follower is the lifter. i use an adjustable lifter and set it so the valve is off the seat.

[GB SISSON]

Well, I just finished a full test of all 16 valves using an exhaust valve, a light spring with guide, an adjustable lifter, and my dial indicator. The forward two exhaust valves are better and all valves have a lift of .306-.307 with the exception of that one forward exhaust valve #5 cyl, which is so darn close now at .304, that the case is closed as far as I'm concerned. Had an enjoyable late evening down in my new shop space with some residual heat from today's fire in the wood stove, measuring valve lift in my bathrobe and slippers. I guess I'm just easily amused, but thanks all of you for helping me through this.

[vincent]

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Forgive me the cam follower. I am working mostly on old british bikes and being german, lifter is not the first word that comes to my mind when talking about the part that rides on the cam ;-)

[51504bat]

Originally Posted by GB SISSON

Well, I just finished a full test of all 16 valves using an exhaust valve, a light spring with guide, an adjustable lifter, and my dial indicator. The forward two exhaust valves are better and all valves have a lift of .306-.307 with the exception of that one forward exhaust valve #5 cyl, which is so darn close now at .304, that the case is closed as far as I'm concerned. Had an enjoyable late evening down in my new shop space with some residual heat from today's fire in the wood stove, measuring valve lift in my bathrobe and slippers. I guess I'm just easily amused, but thanks all of you for helping me through this.

Sounds like a perfect setting for a Norman Rockwell painting. Just need to add a corn cob pipe

[flatford8]

“ I guess I'm just easily amused, but thanks all of you for helping me through this.”
Imagining you in your robe and slippers, working in the shop …
Amuses the sh!t outta me!!……now my wife is asking what the hell am I laughing at!!….Mark

[flatjack9]

So was the "dip" noticeable?

[GB SISSON]

Originally Posted by flatjack9

So was the "dip" noticeable?

Only noticeable because I was watching for it. A very small deflection on the needle and it's just before it ramps up to where there would be any heavy spring pressure. That is if one considered 40 lbs to be 'heavy spring pressure'. The valve assemblies I have sorted through and chosen are a good set of rotator style assemblies from a friend's merc that he harvested a crank out of.
I have a feeling that this 276" stroker, with it's 4.03 first geared T5 will pull the old wooden wagon up my gravel mountain road with relative ease.

[rotorwrench]

The last new flathead cam I bought was an EAB cam. It was likely the replacement cam toward and after the end of flathead production. That purchase was back in the early 80s when there was more NOS stuff available. The local Ford garage where I grew up in Kansas, couldn't give away all the 8RT parts they had. A friend of mine, that worked there, took most of it to his Dad's shop since he was the only one around that worked on flatheads. He had new heads, cams, and all sorts of chassis stuff for trucks. He used some of it but likely scrapped a lot of it after all the old Ford trucks started to disappear. He had a 1953 1-ton that he made into a wrecker but he converted it to a later Y-block to get more power out of it.

[flatjack9]

The EAB cam was introduced in 1952

[GB SISSON]

So is this cam I bought, that says EA on one side and 8rt on the other side, more similar to an EAB cam or an 8BA cam? I have tried to find charts online that list the valve lift of various flatheads. There is a lot of conflicting info out there. I know this camshaft is no high performance cam, but I'm hopeful that it will give me the smooth Idle I like some low end pulling power for climbing Orcas Island's steep grades at 35-40 mph.

[tubman]

Looks to me to be the same as an 8BA cam (.307 lift). However, we can't be sure without the duration numbers. Have you checked out the chart on "Tilden Cam Technologies"?

[Ol' Ron]

I don't think there is any noticable difference between any stock model camshaft.
Gramps

[GB SISSON]

Originally Posted by tubman

Looks to me to be the same as an 8BA cam (.307 lift). However, we can't be sure without the duration numbers. Have you checked out the chart on "Tilden Cam Technologies"?

Denny, seems I have come across that, but I will look again. And Ron, I'm thinking the .125 over bore and the 4" stroke will be the noticable parts in this build. From 221 up to 276. No doubt I'll feel that 55 cubic inches, even with an army surplus cam from an old Canadian duece and a half.

[tubman]

That's a 25% increase in displacement. That oughta help!

[cadillac512]

If it helps, my "EA" cam in the 260" Merc will go 'round a corner at 10 mph in high gear and pull right back up to road speed no problem.This is with 3.54 gears and 29" tires. Idles smooth. You're not going to have any problem at all.

[GB SISSON]

I'm getting pretty excited about this new powerplant. I bolted up my adapter plate and hogshead, put new seals in the T5 and set it aside. Next I dug out a few old ford truck driveshafts and the 2 piece driveshaft that came from the S-10 and crawled under the wagon and took some rough measurements and it looks like I have everything I need. I will continue to collect needed parts and materials for a crossmember etc. I still need to get the transfer case I rebuilt last month installed in the Foyota and I have a list of jobs stacked up in a holding pattern for countless soon to return 'summerfolk' who continue to bug me with questions about their new entry door, or pair of rocking chairs, or whatever I said I's do over the winter. Sheesh, give a guy a break for cryin' out loud.

[38 coupe]

Now we need to figure out what valve lash this cam is designed for.
The earliest 8BA cams used the same lobe design as the 38-48 cam.
The later (late 1949 and on) cams had a new design lobe with different "ramps"

The lash is different between the two cam designs:
early intake: 0.010-0.012
early exhaust: 0.014-0.016
later intake: 0.013-0.015
later exhaust: 0.017-0.019

Looking through the 49-51 Ford F-Series Truck Shop Manual it shows 8RT part number camshafts use the later lash settings. Anyone have any other information?

[GB SISSON]

Originally Posted by 38 coupe

Now we need to figure out what valve lash this cam is designed for.
The earliest 8BA cams used the same lobe design as the 38-48 cam.
The later (late 1949 and on) cams had a new design lobe with different "ramps"

The lash is different between the two cam designs:
early intake: 0.010-0.012
early exhaust: 0.014-0.016
later intake: 0.013-0.015
later exhaust: 0.017-0.019

Looking through the 49-51 Ford F-Series Truck Shop Manual it shows 8RT part number camshafts use the later lash settings. Anyone have any other information?

Wow, great detective work. I was well aware of the settings and how different they are. Now we add in the rotator style valve assemblies on top of that. I did receive a PM about a method of determining lash on an unknown cam, but with my limited knowledge on the subject of camshafts I was hoping I might find something in print, since we DO know what this cam is labled and it is clear that it hasn't been altered. Scary thing is I'm leaning towards Ford lifters and I can't adjust out the tapping if needed. Maybe this is a clear case for adjustablkes.... I have 2 sets of used hollow johnsons.

[rotorwrench]

This link has info but I didn't see anything about the 8RT.
https://www.fordbarn.com/forum/showt...9029&showall=1

Some of the parts with odd prefixes are follow on replacement parts. The 8RT cam may have been a replacement for trucks. A lot of trucks had 8BA cams but after the EAB and EAC part change in 1952, the 8BA and 8CM parts were likely obsoleted so the later cams were called out as replacements. Sometimes they just made a new prefix for them. The EAB cam was designed to give a bit more torque than the earlier 8BA cam.

[GB SISSON]

Originally Posted by rotorwrench

This link has info but I didn't see anything about the 8RT.
https://www.fordbarn.com/forum/showt...9029&showall=1

Some of the parts with odd prefixes are follow on replacement parts. The 8RT cam may have been a replacement for trucks. A lot of trucks had 8BA cams but after the EAB and EAC part change in 1952, the 8BA and 8CM parts were likely obsoleted so the later cams were called out as replacements. Sometimes they just made a new prefix for them. The EAB cam was designed to give a bit more torque than the earlier 8BA cam.

Thanks! Lots of good info here. .

[Ol' Ron]

Boring & stroking an engine also increases the compression ratio as well. This will add more torque than cam swap. also consider NO 239 ci engine makes more than 80 HP in stock cindition, and this is with out generator and fan, JWL proved that/
Gramps

[GB SISSON]

Originally Posted by Ol' Ron

Boring & stroking an engine also increases the compression ratio as well. This will add more torque than cam swap. also consider NO 239 ci engine makes more than 80 HP in stock cindition, and this is with out generator and fan, JWL proved that/
Gramps

I have never thought about that increased compression Ron. Longer stroke, larger bore but same combustion chamber. And it gets that right outa the chute! Or I guess you hot rodders say right off the line

[Bored&Stroked]

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You're going to have a great engine and you'll be surprised how much power it has down low . . . you'll soon be a dyed in the wool hot-rodder! LOL

[GB SISSON]

Originally Posted by Bored&Stroked

You're going to have a great engine and you'll be surprised how much power it has down low . . . you'll soon be a dyed in the wool hot-rodder! LOL

Oh great, a new can of worms opens up, or is it Pandora's box? Next thing ya know, I'll be installing dropped spindles on the woodie. I actually do envision dual exhausts though, but I only have one old swingset frame in my pile, so might have to go single.

[cas3]

Save the swing set frame for the hillbilly paint booth like I got. Hang lots of parts!

[GB SISSON]

Originally Posted by cas3

Save the swing set frame for the hillbilly paint booth like I got. Hang lots of parts!

Sounds like a good idea Skip. Truth be told, I wouldn't really want to skimp on the exhaust for this project. I have been enjoying working on this engine with the best parts I can come up with. So far I have found a lot of really good pieces here on shelves at the shop and online. I have NORS main bearings from The Barn's swap meet section, rod bearings from Van Pelt Sales, Gaskets from Olson's Gaskets,Cam bearings, reconditioned rods, and pistons and rings fitted by Wes at the machine shop. I have a friend here who runs a very well equipped auto repair shop which includes full custom exhaust service. Don't be too surprised if I have him bend something up for me. With all the help, direction and encouragement I have been getting here, I feel I'm really gonna have something that will stand the test of time. Thanks to all who have steered me in the direction of a high quality, if not all brand new, engine build. GB