New cam doesn't fit

Dylan4570

New Member
-Ta performance Hardened and grooved cam bearings
-Comp 212/212 flat tappet.
-stock untouched 109 block

cam fits fine in rear 3 bearings.

when I installed the front bearing the cam barely fits through and I can barely turn it by hand. I had to remove the bearing and scotchbrite the bore and outside of the bearing, as well as the cam journal to get it to fit through at all. the cam also has about 30 degrees of rotation that are tight versus the rest which is why i want to know if the cams straight or not.

I took the cam to the machine shop to see if its straight. I am thinking the cheapest, easiest, and quickest option is to have the camshaft itself polished down a bit. clearance spec is 0.0005-0.0025 so why not just turn the cam down from 1.7856-1.760 to 1.7850 which is the min spec for the cam journal diameter. The old cam fits decent but is a little on the tight side. I'm also going to order a new set of bearings since i wonder if the front cam bearing is a little messed up because i drove it in from the front the first time.

Machine shop wants to line hone the new bearings. I'm sure that's the right way to do things, but i really feel like turning the cam down would be good enough for who its for. this is a stock bottom end, stock turbo car with alky and 20psi of boost that might get 1000km a year at most. With the combination of the earl brown oil mods, grooved hardened bearings, and the camshaft and block having an oil groove, why wouldn't just polishing the cam down work?

in journal 1-4 i measure 1.7858 1.7856 1.7860 1.7860 on the new cam and 1.7855 1.7852 1.7854 1.7855 on the old cam
 

750H.P.V6

Brutal 6 Racing
Try replacing the cam bearing first. It may not be correctly installed and likely has some damage from troubleshooting the problem and having the cam in and out. I have never had to align bore cam bearings or re machine a cam journal, something else is wrong.

Neal
 

Dylan4570

New Member
Try replacing the cam bearing first. It may not be correctly installed and likely has some damage from troubleshooting the problem and having the cam in and out. I have never had to align bore cam bearings or re machine a cam journal, something else is wrong.

Neal
TA is out of stock now, so I'm just going to put Loctite 680 in the back and see what happens. I am very optimistic about the cam spinning fine once polished down to the lower side of spec.

Thanks,
Dylan.
 

RichieRocket

Active Member
And I trust that opinion of finding the high reading and focus on bringing it into spec slightly. Tight tolerance is still tolerated😄 put Jesus grease on everything when your done and break-er in…
 

TIMINATOR

Active Member
I take a bearing scraper and chamfer the front and rear edge on all cam bearings at a 45 degree angle, mebbie .025 thou wide before installation. Sometimes the sharp edge gets rolled over a bit and makes the cam hard to turn otherwise.
But what I really think happened is that you distorted the front shell from not having it aligned perfectly when you drove it in. Clamp a framing square to the front to help with the side to side alignment or have a couple buddies help u line it up. You can only see it from one direction at a time, and you are swinging that hammer too. One guy looks from the top, one from the side. At the very least, tap it in an eigth of an inch at a time, and measure it 4 places, then you will be able to adjust it as it goes in. The front bearing has the most load from the distributor/oil pump gear and the timing chain, and you don't have any alignment from the other bores either.
Any real parts store can order single bearing shells too.
TIMINATOR
 

Dylan4570

New Member
I removed the front bearing and polished it with ultra fine steel wool. then I put a bit of retaining compound on and reinstalled. Now the old cam fits in and spins perfect. Tech Support at TA performance said to just have the shop polish the cam down(very good to deal with). Now I just need to let the camshaft pass the obligatory 1 month dust collecting test at the machine shop then they can check for straightness and polish it down to the lower half of spec.
 

Dylan4570

New Member
machine shop says the cam is bent 2 thousandths. which I'm told is fine. I got a hold of the supervisor and he agreed the best thing to do was polish down the cam to the lower side of spec.
 
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