318 la cam bearings?

[flatheadgary]

what's with Chrysler cam bearing sizes? every one of them from front to back is a different size. i am doing a refresh of a 318 la block and found this out. i spent the last three days machining five knock out tools to remove/replace them. i know most people just have the machine shop do this work but i am CHEAP. this may be old news to most of you but it is the first motor i have seen like this. i have worked on chevy's, ford's, old's, pontiac and ford flatheads and they all have the same size, one tool. oh well, i guess i have a tool when and if i do another one. can never have enough tools, i always say.
p.s. also what's with all the casting flash on these motors? very poor quality control i would say back in the day

 

[KarNut46]

Chrysler V-8s all that way. Even gen-1 hemis and polys. Word of caution: bearings will have to be fitted as you go. Put the two end bearings (#s 1 & 5) in first and get them fitted. I use 320 emery cloth, scuff brg, install cam and rotate. You can then see the hi spots and work them down w/ emery. If you are a good machinist you can use a brg scraper for this if not use emery. Work on the remaining bearings one at a time. Best info I have on cam brgs is that they align-bored them at the factory. Flashing and poor casting: in mid 70's Chrysler was in trouble and quality suffered. You don't say what year engine you have. Casting date is on the side of the block as well as shift (day or night) and time of day. All manufacturers have had bad times. Remember helping a co-worker do a rebuild on a Ford FE block (390) and was concerned about the looseness of the cam after installing the bearings. So loose that the cam actually rattled inside the block. Found another cam and installed. Same thing. Contacted a guy at a rebuild shop and he said that it was normal. Not normal on a MoPar but OK on a Ford. Chrysler cams fit rather tight, get ready for it.

 

[dvw]

Always test fit the cam before installing ANYTHING after replacing cam bearings. You may have to scrape them to fit. In tough cases cuts can be made in a old cam at each bearing journal creating a cutting edge using a cutoff wheel.
Doug

 

[mentor70]

i had some core shift on my #2, sometimes you can hone, in my case the journals that to be bored out oversized to make everything true.

Durabond makes over sized cam bearings for Mopars.

if you stick your cam in and its tight i could be in need of a small champfering on the edges of the bearings

the scalling method that reams out new bearings so the cam will spin if its tight is a BAND-AID, NOT A FIX and should not be done....imo.

Muscle motors has a post about it on there website somewhere, which is where i learned about it.

thankfully, i found a great machinist that knew about this issue, and had the oversized bearings.

 

[flatheadgary]

thanks for the replies guys. yea i tried to put the cam in and it was real tight. so much so it wouldn't even turn. i made a jig to turn the cam gear and the crank gear with a drill motor. i put some valve grinding compound on the bearings and spun it till it got a little bit looser. i can actually turn it by hand with a little effort. i am going to ask a rebuild shop wed about it.
as far as the casting flash goes, i have bought 3 blocks '68, '69 and '70's. due to problems, cracked cylinder, stripped main bearing bolt and the last one is alright, except for the cam bearing problem. it was in all 3 blocks, on the motor mount ears and various places on the outside. the real head scratcher is in the lifter valley. it goes from one side to the other across the block in the back,including the outside of the lifter bores. i ground it all off so no big deal. just never seen so much before. thanks again for the replies.

 

[dvw]

i had some core shift on my #2, sometimes you can hone, in my case the journals that to be bored out oversized to make everything true.

Durabond makes over sized cam bearings for Mopars.

if you stick your cam in and its tight i could be in need of a small champfering on the edges of the bearings

the scalling method that reams out new bearings so the cam will spin if its tight is a BAND-AID, NOT A FIX and should not be done....imo.

Muscle motors has a post about it on there website somewhere, which is where i learned about it.

thankfully, i found a great machinist that knew about this issue, and had the oversized bearings.

Can you tell us how you would fix a tight cam? What is the problem you see with trimming the bearing with a cut cam?
Doug

 

[mentor70]

In my case the core shift on my block (440) was so bad that after a new cam was run in for a few miles, it would pull the bearing out with the cam, when the cam was removed. This happened to me twice before i found the Muscle Motors article.

if the cam journals are straight, but tight, they can be honed and trued before the bearings are installed. this eliminates the "squeezing" effect when the blocks cam hole is not in spec, which is the most common problem.

My 440 was the #2 journal was shifted so bad that opening up all the journals was required to make the #2 journal true.

the Dura-bond kit has a steel ring that is pressed in the rear journal before the bearing goes in because that one gets oversized a ton.

then all the bearings are installed normally. but now they are both straight and re-sized and not squeezing the new bearings making the fit too tight.

the scalling method works, but you loose the precision of oil control for one thing. the one most important to me.

 

[KarNut46]

Be careful w/ grinding compound (assuming you are using valve lapping compound). It will leave grit in the soft bearing material. My experience w/ small block cam bearings is that they don't take much work to get correct clearance. Usually there is only 2 or 3 high spots to work down. Just scuff the bearing w/ fine emery or scotch brite (just enough to get a dull finish). Install cam and rotate a few times and the high spots will turn shiny. Big blocks a different story, they can be real tight. Also make sure to line up the oil holes properly. Cam should spin freely after all bearings are in. Good luck on the project.

 

[dvw]

All of what Mentor 70 has said is true. But in the real world senario Ive had both BB and SB tight. Never had one that spun abearing. If the bore was that loose it would have spun long before I worked on it. Now to tight in the bore is anther story. A tight hole will always reduce clearance thus the need to open it up. Never had one that hurt oil pressure afterward. Ask yourself. If the cam tunnels were off say.005" (pretty far off). Cutting the bearing would only open up the clearance .005" . The motor wouldn't know the difference. Factor sloppy lifter bores will lose far more pressure than a high clearance cam bearing. How many spend the big dollars fix them? How many even measure the lifter bores and lifters?
Doug