Lifter bore

[Steve Quinn]

Jay for lifter bores is there and advantage to having bronze lifter bores over just bored out cast iron bores. This will be a Dart big M with .903 bores.

Also when going to a 55mm or 60mm cam you will shorten up the lifter bore is this anything to worry about?

[Jay Allen]

Jay for lifter bores is there and advantage to having bronze lifter bores over just bored out cast iron bores. This will be a Dart big M with .903 bores.

Also when going to a 55mm or 60mm cam you will shorten up the lifter bore is this anything to worry about?
My experience is that bronze bores wear much more true.

The roller bearing is a great idea. I am not understanding your question I guess. How can the cam tunnel shorten the lifter bores? Am I understanding the question properly? Or am I on crack again.......LOL!

[Damn Yankee]

Am I understanding the question properly? Or am I on crack again.......LOL!

Dude, you need to leave that chick alone !!!!! She had a crack big enough for a small Army:butthead: :butthead: :butthead: :Sheep :Sheep :Sheep

[Unlimited Resources]

My understanding is the reason you go to a 55 or 60 MM roller cam bearing is so you can go to a larger cam core (read larger base circle) to enhance lobe profile. This larger base circle would cause the lifter to ride higher in the lifter bore.

[383Malibu]

My understanding is the reason you go to a 55 or 60 MM roller cam bearing is so you can go to a larger cam core (read larger base circle) to enhance lobe profile. This larger base circle would cause the lifter to ride higher in the lifter bore.I agree with the physics here, but have no idea whether it (the lifter riding higher in the lifter bore) is an issue or not. Regardless, the typical insert extends up out of the bore more than enough to compensate.

[Jay Allen]

Yes and No.

Base circle = Bearing diameter - [2(lobe lift)]

Thus, if you had a .450" lobe lift cam and it was on a reduced base circle SBC cam core it would come in at .900" b/c. The biggest the b/c would be is .968" in this example. However, at 55mm the b/c becomes 1.265". Yes this becomes FAR more stable. Keep reading.

But.......

If *I* were going 55mm I would not just stop at .450" lobe lift. A 1.150" b/c circle is still extremely stable. Now work backwards:

I have a 55mm core. I want a 1.150" b/c. My lobe lift must be less than .507" to achieve this. Now we're talking.

What we all are forgetting is the stock style stuff. Take a pretty mild application with a .375" lobe lift. The b/c on that cam (again SBC) is 1.118".

The problems with oiling occurs when the base circle becomes too small and the lifter oil hole is below the hole in the block. To date, I haven't seen an application were too much base circle is a bad thing.

And we haven't even gotten to a larger diameter lifter/wheel!.