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]

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]

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]

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]

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]

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]

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]

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?