cam tight on reassembly.
 

during my top end rebuild I sent my cams off for a 964 grind . They came back all black and new looking and sit in there rolled up paper reasy for reassembly.

Now I have found although one of the cams fits in the housing it is fairly tight . I can turn it by hand but with a struggle ( dry without assembly lube. )
the other cam will turn in either housing without any issue at all.

I have reached out to the guy who did the cam grind but thought would seek an opinion here while I am waiting . it seems to bind up on the second journal in ( not that it matters ) as once you pass that with the cam it struggles. again happens on both housings.
Think I need to get the cam relooked at ( I had to have it sent away )or should I slap it in with some assembly lube and move on ?

More likely that the housing is slightly warped. Try re installing it

Measure both cams, A polish might take care of it: I assume this is checked not assembled on the motor?

not the housing .. the housing is fine with the other cam. I have the other housing assembled on the heads and wrapped up in plastic I will check it with this cam later ..

yes you are correct cgarr it is not on the motor . I did assemble the heads on to the cam housing so thinking thiis may have been an issue ( even though I used the correct torque sequence. ) I backed off the torque on the head - housing and checked again , exactly the same problem.
The cams did come back completely black and I was told it was some type of hardening they do. The cam guy is going to get back to me so we will see what he says.

good point on measuring the cam , I never thought of that. I might build some device so I can see if I have runout.

I have not put any lube or anything on it either to be fair as I was not sure what to expect as "normal"

You probably can't fit the back chain gear on either.
Bruce

Cam test fit........
 

Install and try to test fit the good cam in both cam towers. Repeat the process using the problematic cam. Apply some assembly lube on both cams. Keep us posted. Thanks.

Tony

Hi tony

Good cam fit smoothly.into both housings
Bad cam fit in both with some help and can be turned but with some effort and squeels like a pig

Lube is next.

Assembly lube is not going to fix it. :)

I'd recommend installing into some live centers (lathe) and check to see if its bent.

The hardening can add a smidgen to the diameter. As posted earlier I suspect you might need to polish it down a fraction (we are talking less than a thou basically). Easiest done in a lathe, but hopefully your cam guy may offer if handy close. if you had a micrometer, you may be able to measure a small difference between the two.
Alan

I have seen this B4 When back from a regrind.
From what you describe I have seen a lot worse.
Its not an emergency.
Try to determine the tight spot and polish it like said .
If not too tight no one will ever notice anyway.
BUT-
The reasons can be wrong torq sequence .
Incorrect cyl HT(s)
and
Remember they welded on the cam...It may forever have a wiggle in it.

all good advice guys .
i will start off with a polish . I actually have a buffing wheel for my tabletop grinder , would this be acceptable ? i think less than a though would be accurate as it squeeks but is turnable with a fist as oppose to fingers on the other side. ( there is a spot it is loose but tightens up when turning. )
I am glad to hear it doesnt sound too serious. its not like its jammed or wedged in there.

I will polish and update you all

Thanks again

If the journals are parkerized, remove it. Same for the nose where the back gear goes on.

+1 for John Ws thought

This is precisely why I suggested making sure it was straight.

3.0 Cams to 964 Profile?
 

I thought the stock 3.0L cams could be ground to the 964 profile - no welding required???

I'm with John W BTW - the parkerizing adds enough material to make stuff not fit right (technical terms...).

I needed to polish the ends of my cams down (removing the black parkerized surface) to get the cam gears on mine.

Good luck, Gordo

Sorry.......speed reading here.......

ok guys I have an update

so now I know "parkerize" is the black stuff on it.

I polished it for hours with a piece of jean material on all 4 bearing surafces. I thought my arms were gonna fall off by the end. the black started to lighten up to a bronze colour. I was eventually able to put it in the housing and get it to turn without squeeking and with less resistance. it had a "tighter" spot for about 45 degrees of rotation so I decided to try it with assembly lube .. success, the lube actually makes it overall a little tougher to turn as its quite thick but overall its the same as the other side .. so great success so thanks to everyone.

a related question. I have been reading how many of the experienced engine builders now put everthing together on the bench. heads housing cams and rockers , then pop it on the studs.

is there any issues with getting the chain over the cams or getting the chain boxes in place when doing it this way ?

thanks

No issue. Just need to set the engine on TDC and have the cam keyways facing up when you install the assemblies. Way faster and easier.

I am not sure what the shop guys do, but I have used 1200 wet/dry before for that. Might be a bit easier than jeans. But job done, and the finer the better if you can stand the pain.
Alan

Adverse effects........
 

John,

Any adverse effect if you do not remove the parkerized coating on the bearings of the camshaft? The cam grinders send back the newly refurbished or rebuilt cams without any specific instruction about removing or polishing 'Parkerize coatings'. Thanks.

Tony

thanks John
what is the significance of having tbe keyways up.? and i assume you mean having cylinders one and four at top dead centre when puting each respective bank on ?

is it because you are setting your valve clearance on the bench too, and with one and four at top dead centre and the keyways up all valves on that bank will be closed when you are installing the assembly ? ( just a guess)

1&4 @ TDC. Keyways up because that's basically where the cams would be @ TDC #1. Adjust #1 intake clearance, set up dial gauge, set left cam timing, Adjust #4 intake, set right cam timing, Adjust all the valves, find TDC #1 and install the distributor, install all covers.

lol wow that's awesome ...

just wrapped up my engne in about 8 seconds ... all good advice .. and appreciated.. il do the very thing you mentioned , mor elike 8 weeks for me tho. ;)

If you need another nudge to confirm the straightness of the cam, this is one more. Resist the urge to remove perhaps unnecessary material before making sure it's straight in the first place.

My reground cams had (as I recall) a .003" bow in it, enough to create a slight rotational bind in the cam housing. I took it to a cam regrinder and they fixed it in about 3 minutes with a certain technique.

Sherwood

I tape off the bearing journals before I parkerize camshafts. I don't recommend coating the journals.
Sounds like this one either has a knick in a journal or is bent. Easy to fix.

John Dougherty knows his stuff. I've been using his cams for over 10 years with excellent results. On a different note, can 3.0/3.2 cam housings (4 bearing cams with larger journals) be used on a 2.7? How about a 2.0 with the narrower valve angles? Not that I want to, just curious.

RS-VIC
While the heads don't interchange due to the different stud spacing, the cam carriers (housings) have the same bolt pattern in the 2.7s as in the 3.0/3.2s.

Pretty sure the earlier ones do, too. Other than things like center oiling of the cams, and the switch from a 6 to a 9 stud exhaust valve cover, not much change. Of course, cam journal numbers and diameters have changed, but that's not a problem with the right cam.

Hi Iceman...your quote....
"a related question. I have been reading how many of the experienced engine builders now put everything together on the bench. heads housing cams and rockers , then pop it on the studs. "..

I have been doing it like this since ever...much easier on assembly as JW said just set the cams before install...my 1st engine on my own 1st 911 back in the 1980`s, i did not and opss i bend the valves on cyl 3...that was at 5 pm so i worked whole night and at 3 am engine was running like a clock;-)

Ivan

I did some more research regarding the cam housings. According to the parts book all cam housings from 68-77 are the same part number. I then measured the valve angles on a 2.0 head and a 2.7 head and both are identical. I got 27.5 degrees on the intakes and 32 on the exhausts. The 3.0 and 3.2 heads have smaller angles due to the wider combustion chamber and larger valves. There's a lot of conflicting information about valve angles. I'm going to try and measure some 3.0 heads sometime this week.

So I would say that the 4 bearing cam housings won't work with the 2.0-2.7 heads due to the different valve angles.

I got a chance to measure a 3.0 and 3.2 head. Both are right on spec.
Intake = 25.5 deg and exhaust = 30.25 deg

"So I would say that the 4 bearing cam housings won't work with the 2.0-2.7 heads due to the different valve angles."

How would the cam carriers differ, other than having 4 larger ID integral bearings for the larger bearing cams? A different position for the rocker shafts? Higher or lower so the elephant foot kept adequate contact with the tip of the valve stem?

The rockers for sure didn't change dimensions.

If you were actually going to do this I'd dig out an early cam carrier to go with the one I have on my desk, and an early and a 3.2 head with valves installed, stick in an intake and exhaust rocker, and see what I could see about the elephant foot on the valve.

The closest direct interest I have to these angles is to wonder what the largest valves (intake only?) I could install in my pseudo 2.8 with its 2.7 heads on 92mm cylinders might be. Not as large as the factory RSR 2.8, with its different angles, but maybe a millimeter larger diameter? 47/41?

If you have ever watched a video on hardwelding and regrinding cams, you'll see what they do to straighten the cam back out. Doesn't look too scientific, so I imagine that you could have a bow in it.

Walt, if you get a chance to swap around heads and cam housings to see the difference let us know. Maybe even just looking at the sides of the 3 bearing vs. 4 bearing cam housings might tell us something. Maybe the rocker shafts are in a slightly different position.