? about cam bearing fitment

[mightymopar]

Would it be possible to fit the bearings in a SB or BB by running an engine hone through them to make them fit on the cam before intalling them in the cam tunnel? When they fit then install them?

 

[69Bee]

No. These are the reasons why:

1) A hone will clog with babbit, and destroy the bearings

2) The bearings ALREADY fit the cam out of the box

3) The reason the cams bind after installation is due to one or more of the following; improper installation, cam bores galled (high spots), drilling burrs around the oil hole (high spots), and the most likely reason, a twisted block from seasoning.

When blocks are new, the cam tunnel is straight, the cam bearings are installed, and machined to the cam. These were called FIT (fit in place) bearings. After the block seasons (hot/cold cycles), the metal shifts, but nothing binds because the bearings wear in the process to compensate.

NOW, you replace the bearings with precision bearings made to a size. When they are installed, any block distortion will bind the cam. The solution is to SCRAPE the bearings with a bearing scraper (or a pocket knife) to lower high spots and make the cam spin freely. As long as you can turn the cam with the timing gear on it by hand, and it turns relatively free (a technical term learned by experience :icon_thumright, the bearings will finish wearing in during operation.

The worst case scenario would be to have the block align bored to realign the bores. I tend to have more problems with Mopars, Chevys seem to work the best, with Ford somewhere in the middle. Just pay attention to the bores and fix any problems first, and that will help the most.

 

[mightymopar]

No. These are the reasons why:

1) A hone will clog with babbit, and destroy the bearings

2) The bearings ALREADY fit the cam out of the box

3) The reason the cams bind after installation is due to one or more of the following; improper installation, cam bores galled (high spots), drilling burrs around the oil hole (high spots), and the most likely reason, a twisted block from seasoning.

When blocks are new, the cam tunnel is straight, the cam bearings are installed, and machined to the cam. These were called FIT (fit in place) bearings. After the block seasons (hot/cold cycles), the metal shifts, but nothing binds because the bearings wear in the process to compensate.

NOW, you replace the bearings with precision bearings made to a size. When they are installed, any block distortion will bind the cam. The solution is to SCRAPE the bearings with a bearing scraper (or a pocket knife) to lower high spots and make the cam spin freely. As long as you can turn the cam with the timing gear on it by hand, and it turns relatively free (a technical term learned by experience :icon_thumright, the bearings will finish wearing in during operation.

The worst case scenario would be to have the block align bored to realign the bores. I tend to have more problems with Mopars, Chevys seem to work the best, with Ford somewhere in the middle. Just pay attention to the bores and fix any problems first, and that will help the most.

Thanks for such a quick answer, sounds like you are quite versed on the subject.

 

[bm02tj]

I was shown you install front and rear bearing and install cam and when it turns freely you install another bearing and test so you only fight one at a time

and 1st poster was right never hone a bearing

 

[Meep-Meep]

I have seen cams bent right out of the box so do check that as well.