• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Camshaft Install - how tight is too tight?

roadrunnerh

roadrunnerh

FBBO Gold Member
FBBO Gold Member
Local time
4:27 AM
Joined
Aug 21, 2009
Messages
1,729
Reaction score
2,265
Location
Pittsburgh, PA
I installed new Clevite cam bearings in my 383 build. I slid the Comp Cams camshaft in and it's tight. I read here and on FABO of some guys scraping the bearings where there's a tight fit. I used Lisle 18000 cam installer tool, and the bearings aren't cockeyed.
I pulled the cam and installed the old one which moved more freely, but tighter than with old bearings (naturally).
Before I do anything, how tight is too tight? I can not turn this by my fingers on the cam dowel. I put on the old cam sprocket and it turns with one finger - with a lot of force. A diesel mechanic buddy of mine told me it's fine and it will loosen up running on it's own quickly. Or at least that's his experience with truck engines. PLEASE HELP!
 
I cannot tell you the answer....but it has to be more scientific than "it will loosen up running on it's own quickly" :rolleyes:
 
It does sound a little tight. If there is no clearance to let oil in you will burn up the bearing or spin it.
Check for any burrs first. If I am satisfied the bearings are not the problem I install the cam with bearing blue and try and find which journal is tight.
Then I put the cam in lathe with centres and polish the journals down with very fine paper.
This is not possible unless you have the engine down and can re wash it.
I do not scrape the bearing surface it is too hit and miss in that tiny little hard to access hole.
But I do put a chamfer on the bearing edge.
I have only done this a few times it is a real pain but ignoring it could be a lot worse.
 
You need to measure each cam bore with the bearings installed and then measure the cam journals. Snap gauges will work fine and are less money than a dial bore gauge kit. And use a micrometer, not calipers.

https://www.travers.com/6pc-telescoping-gage-set/p/57-020-741/

My engine shop has been using Durabond for the cam bearings. Even then I drop off the cam so they can check the fit. The proper way is to ream the bearings when needed. The cam should turn with little effort, otherwise there isn't room for the oil film. Take your time, measure and find out which bore is the issue. Don't use a hone, any type of abrasive will damage bearings, bronze bushings etc.
 
The other possibility is that the bores for the cam are not in-line due to
overheating. cam bearings are sometimes a pain. You may need someone
to scrape in the bearings for you. Not something you want to do with no
experience. The heat generated by the tight bearings could cause that bearing
to spin in the bore and cause worse problems! You're only talking two or three
thousandths, and it also could be a high spot caused by driving in the bearings.
The cam should turn very easy with some oil on it. you're wise to stop and ask
for help when you need it. If you have a borescope or cheap endoscope that
works with your SmartPhone, you can look down the line at each bearing and
look for the "shiny" spot on the bearing. When you find it you'll know!
 
Use your old cam or get another one and cut a slot in each journal with a cut-off disk. don't dull the edges but do make sure there are no burrs. Install it turning as you install. The slots will scrape the high points on the bearing(s). Do a bit at a time, pulling the cam out to clean out the debris.
 
I have scraped bearings using an old cam , it worked great. I just installed a new cam in my 440 that I had to tap in with a hammer and would not spin until I put the timing gear on. break in went great and I'm going on 500 excellent trouble free miles. you will be fine.
run it. it WILL loosen up immediately.
 
Cam bearings are babbit. Stanton's way works, in the 70's read an article "Hoover talks Hemi's" that's what he said to do.
 
Bet it's number 4
FWIK the numbers are off by a thou
so most new bearings are tight
second
FWIK #2 MOPAR align bored the bearings after installation
replacement bearings have no such process
so if iron cam bores are off the bearings are off and no align bore to fix
I had a line bore tool that fin in 1 and 5 and the could cut 2,3,4
The notched old cam works
just make sure it's straight in the first place and your cam is straight

motor on the engine stand the dykem and scraper works
most every BBM I ever built took some work on cam bearings
If doing blueprint
align bore cam bearings then mains to the cam tunnel, then lifters, decks and bore
torque plates and mains torqued throughout
 
I use my ISO/IEC 17025:2005 Accredited zircon encrusted scraper.
 
Now my small wife can turn the cam by the bolt. She has to try, but she can do it!
So I've read so much about so many people doing the grooves cut on old cam method. Count me as another success story with this approach! It worked like a charm. I made two opposite diagonal cuts on each of the old cam's "journals," greased it up, installed, and turned a lot by hand. Then pull the cam, wipe it down very well, and repeat.
Old school stuff - I love it! I am really learning so much with this project, which was another main goal of mine. I can freely turn the cam by the cam bolt. It's not "spinning," but it feels much easier and very smooth.
I truly appreciate any and all feedback and value your knowledge I receive by your replies! Thanks again!
 
Stanton said:
Use your old cam or get another one and cut a slot in each journal with a cut-off disk. don't dull the edges but do make sure there are no burrs. Install it turning as you install. The slots will scrape the high points on the bearing(s). Do a bit at a time, pulling the cam out to clean out the debris.
Click to expand...
Someone suggested this to me about 5 years ago. I followed the advice but also packed the grooves with grease to trap the debris. It worked great.
My machinist said that he had heard a rumor though his various contacts that the Mopar B and RB block series were troublesome and that when brand new, the factory installed the bearings then line honed them to correct any off center imperfections.
To me, it makes me wonder why then would one cam spin freely while another is as tight as a ducks ***. I can see that the theory would make sense if a man took a stock cam out of a virgin build then slipped in a 2019 cam but....
I was pulling a 292/509 out of my 440/493 and slipping in a Lunati when I encountered the tight cam problem.
 
First thing I do is to make sure the cam is straight. Checking between centers (using a dial indicator) is usually a good way to check but laying the cam on V blocks is even better. Once that's done and is found to be straight then do the 'cam scrape' and install it. Also, I made my own cam tool and have never had a problem with tight cams again...so long as they were straight. Some cams I've checked had run out as much as .006"! New ones even! A buddy of mine has a Lisle cam installation tool and he has to scrap the majority of his builds and he builds a LOT of engines. It seems to be that Mopars are the worst for him but for some reason, my homemade tool seems to work. After building several and never having a problem I will never use the Lisle cam tool.....except for building Chevy moders :D
 
Cranky said:
A buddy of mine has a Lisle cam installation tool and he has to scrap the majority of his builds and he builds a LOT of engines. It seems to be that Mopars are the worst for him but for some reason, my homemade tool seems to work. After building several and never having a problem I will never use the Lisle cam tool.....except for building Chevy moders :D
Click to expand...

I agree with this 110%. I tried the way Stanton describes, and all I did was ruin a bunch of bearings. I tried my damnest, made sure no burrs, no dice, no way. I'm not knocking anyones method, I'm just saying it sure didnt work for me. Tried a bearing knife too, just not happy with what i was getting. So, in my mind there just too much trial and error with the Lisle tool, and they crap out the rubbers way too fast anyway. You need the proper sized mandrels for the install tool, and you'll find every job going way, way better. I do have to say tho, if you can turn it as easy as you say, it probably will be fine. It just no one wants to get the whole install done and running to find out they were wrong! My two cents...... I'll repost when I find a link to the maker of the tool I purchased. HTH, Lefty71
 
The shop I worked in if we had a tight cam it was checked for straightness as Cranky said . I've seen a lot of bent cams new out of the box , and they can be straighten with a whap in the right spot with a dead blow hammer . Sounds crazy but I seen it with my own eyes.
We had what we called test cams for checking cam bearings for straightness after bearing installation , if that didn't fit out came the dreaded scraper.
Chrysler and Pontiac were the worst, must of had the same drunk setting up the tooling
 
roadrunnerh said:
Old school stuff - I love it!
Click to expand...
Nothing wrong with old school. Been working all these years.
High spots on new cam bearings, normal, and easily seen by looking for the shiny spots. Yeah, it can take a good hand, using a bearing scraper, light touch does the job. A little practice on the old bearings, before you pull 'em, will teach you how their used.
Good job! And, liking letting the wife have a little hands on!

(My wife helped me drop my rods/pistons in the 440.)
 
Youtube has some good videos as well on how to use the tool to install the bearings
 
You must log in or register to reply here.

Similar threads

B
Crankshaft end play tight?
Replies
19
Views
1K
Geoff 2
G
73challenger
Camshaft brand selection
2
Replies
23
Views
2K
rumblefish360
rumblefish360
D
alternator rear bearing install
Replies
4
Views
562
RJRENTON
RJRENTON
dan juhasz
cam bearing tools
2
Replies
21
Views
2K
Krooser
K
B
Cam Bearing Journal Issues
Replies
12
Views
2K
steve340
S
Auto Transport Service
Back
Top