New cam doesn't fit

Dylan4570

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
 

Dylan4570

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

New 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

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

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

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.
 

TIMINATOR

Member
Scotchbrite and sandpaper get grit stuck in the bearing surface! You can also put sharpie/ magic marker all over the bearing or cam to see where the high spots are, then use a bearing scraper on the bearing. Thats what they are for! Or polish off any high spot on the cam journal, some are actually egg shaped from hardening.
No need to polish all of the cam journals. BTW, comp cams journals run to the large side of the spec. Check first.
TIMINATOR
 

hensleyt

Well-Known Member
If it’s ,002 bent It will be making a .004 circle.
That will be too much in my thinking of what’s I would do and after a fey miles it will destroy the bearing and it will have a big oil leak.
On the up side it will lube the chain good.
 

TIMINATOR

Member
It depends upon where the bend is, and how loose the cam bearing clearances are. A .002 bend in a new cam isn't as uncommon as you would expect! I have seen that in take out cams on a number of fine running street and race engines.
I have noticed that in the last 4 or 5 years, that cam journals seem to be oversized more often than not. A trip to the lathe, and a crank polisher takes care of that. We cam dr. all cams we install, as I have seen more mis marked or mis boxed cams lately than I would care to admit. Then again there are some companies that sell cams 3 to 5 degrees bigger than advertised, so they get a reputation for making big power. Or worse, higher lift, and that gets you in trouble with coil bind issues. We C.C. all heads, and BHJ deck all blocks before we purchase pistons too. Some companies chambers run large, and others, small, ya just can't take anything for granted.
Oh, yeah. Any competant shop can straighten a cam. Its easy. Put it on a lathe between centers, put a mag base dial indicator on each journal and read it. Then straighten it in a press on aluminum blocks. Some prefer to use a blunt smooth rounded chisel and a hammer, any of that takes experience. You probably won't get an estimate, as its hard to tell how many trips to the centers it will take to get it perfectly straight. We all sell time.
TIMINATOR
 

Dylan4570

Member
The car is back together, I put the alky kit on last weekend and have been daily driving it to work to get some mileage on it. So I can change from the break in oil over to the amsoil zrod that I plan to run long term. The car has good oil pressure and pulls good. Only "issue" is that the lifters clatter for the first 3 seconds on startup. other then the the car runs and drive awesome.
 

TIMINATOR

Member
Hydraulic lifter clatter is a function of: How much spring pressure is trying to collapse them when anywhere open "on the ramp or nose," while the engine is off.
How hot (thin) the oil is when the engine is initially shut off.
How many valves are open while the engine is off.
How long the engine sat before restarting it.
How many miles are on the lifters.
How high is the cam lift, and duration.
(more valves open or on the ramp)
Oil viscosity, and type (i.e. synthetic or dino.)
Brand of lifters.
Lifter travel and preload.
How quickly the oil pump picks up prime and pressurizes the system.
Is the oil pump where it is supposed to be, immersed in oil (flooded suction), or does it have to suck the oil back up to the pump upon startup? The idiots that designed the "wonderful" LS motors made that giant leap backwards too, but those "engineers" employed a small, undersized cheap ass "o" ring on the pickup tube that shrinks, splits, and causes an air leak on the suction tube, resulting in excessivey long prime time.
Which tends to wear out the lifters around 100,000 miles, sometimes sooner, and on those "not well designed" engines, you have to pull the heads to change the lifters too!
Some of those engines have "cylinder deactivation", and a set of those lifters cost around $900.00 from Chebbie. Dealer prices for lifter replacement on those engines, and "o" ring replacement runs $3000.00! Unless its a 4x4 and the engine needs to come out to replace the underdesigned "o" ring!
It is important to start any engine and let it idle until the oil pressure is normal, Buicks, and LS engines, with the pump up and not submerged in the oil, even more so.
As usual, another long post, but good info!
TIMINATOR
 

Dylan4570

Member
Hydraulic lifter clatter is a function of: How much spring pressure is trying to collapse them when anywhere open "on the ramp or nose," while the engine is off.
How hot (thin) the oil is when the engine is initially shut off.
How many valves are open while the engine is off.
How long the engine sat before restarting it.
How many miles are on the lifters.
How high is the cam lift, and duration.
(more valves open or on the ramp)
Oil viscosity, and type (i.e. synthetic or dino.)
Brand of lifters.
Lifter travel and preload.
How quickly the oil pump picks up prime and pressurizes the system.
Is the oil pump where it is supposed to be, immersed in oil (flooded suction), or does it have to suck the oil back up to the pump upon startup? The idiots that designed the "wonderful" LS motors made that giant leap backwards too, but those "engineers" employed a small, undersized cheap ass "o" ring on the pickup tube that shrinks, splits, and causes an air leak on the suction tube, resulting in excessivey long prime time.
Which tends to wear out the lifters around 100,000 miles, sometimes sooner, and on those "not well designed" engines, you have to pull the heads to change the lifters too!
Some of those engines have "cylinder deactivation", and a set of those lifters cost around $900.00 from Chebbie. Dealer prices for lifter replacement on those engines, and "o" ring replacement runs $3000.00! Unless its a 4x4 and the engine needs to come out to replace the underdesigned "o" ring!
It is important to start any engine and let it idle until the oil pressure is normal, Buicks, and LS engines, with the pump up and not submerged in the oil, even more so.
As usual, another long post, but good info!
TIMINATOR

I have a feeling that the straight 30 weight amsoil break in oil gets very thin when hot and that is likely a large part of the issue with my buick. i am just running comp 980's so nothing insane with the springs.

I have a 370CI LS based engine in my street truck, and can confirm that the lifters are noisy.

Good info indeed
 

TIMINATOR

Member
I run Amsoil in all my HP stuff, its great!
I think I mentioned before, but Harley synthetic to Amsoil gains around 3 to 5+ HP in built Harleys, on my dyno. Thats only 2 cylinders too!
When we were annexed, and they built houses around us, I had to sell my chassis and engine dynos, but since HDs run Chevy hydraulic roller lifters, I can experiment with them, and oil.
TIMINATOR
 
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