[chadman]

I have a set of offset intake Crower solid roller lifters that I will be installing. The block is a factory BB Olds. Right now with the factory lifter bores I have .0024-.0030 lifter bore clearance. I know this is more than ideal but will it cause me any problems if I run it as is or do I need to bush the bores to get them to .0015-.0020?

 

[Chris Uratchko]

That clearance is fine. Run it.

 

[BWise]

Chad, no more than .002 is what we run, better more clearence than not, run it.

 

[scott foxwell]

That clearance is fine. Run it.

 

[Chris Uratchko]

Not confusing. It's on the high side but there are MANY engines and shops out there that target 003+ that run great. I don't like it, and I don't work to that tolerance, but it does not scare me, and I have engines that are .003-.0032 that are fastest in their class because the block was honed for one lifter and I use another....

I guess if I follow the internet .003 would never work.

Would I want .003 in an aluminum block? No because .004-.0045 would be a flood. .003 is moving some oil for sure.... but not the end all be all.

 

[Pancho]

With the way the BBO's oil, unless you've restricted flow in the mains, there'd be more than plenty of oil at lifters (which you prolly already know).

 

[CNC BLOCKS]

I have a set of offset intake Crower solid roller lifters that I will be installing. The block is a factory BB Olds. Right now with the factory lifter bores I have .0024-.0030 lifter bore clearance. I know this is more than ideal but will it cause me any problems if I run it as is or do I need to bush the bores to get them to .0015-.0020?

I seen where .003 is to much clearance as lifters come out all scuffed because they cocking in the bore and its good way to break lifter banging around the bores more so at idle.

Plus why would you want all the oil bleed off as that causes a lot of unwanted windage.

With that small lifter that's a lot of clearance.

 

[Chris Uratchko]

I seen where .003 is to much clearance as lifters come out all scuffed because they cocking in the bore and its good way to break lifter banging around the bores more so at idle.

Plus why would you want all the oil bleed off as that causes a lot of unwanted windage.

With that small lifter that's a lot of clearance.

All good points.

 

[cstraub]

When Morel was asked to develop a bushing lifter back in the late 80's the R&D was paid for by an OEM that ran in a particular high rpm class of racing. Lifter diameter to lifter bore and its clearance was found to be very critical. In testing morel built a spinning fixture with a 100HP engine inside a shipping container that was lined with extra steel.

As rpm grew the lifter would become less stable in the bore. Morel experimented with finish RMA levels and tighter bore clearances. These were a dry sump engine with at that time the best oiling systems around but at the end of the day, the tightest lifter bore clearance possible yielded the most stable valvetrain.

 

[CNC BLOCKS]

When Morel was asked to develop a bushing lifter back in the late 80's the R&D was paid for by an OEM that ran in a particular high rpm class of racing. Lifter diameter to lifter bore and its clearance was found to be very critical. In testing morel built a spinning fixture with a 100HP engine inside a shipping container that was lined with extra steel.

As rpm grew the lifter would become less stable in the bore. Morel experimented with finish RMA levels and tighter bore clearances. These were a dry sump engine with at that time the best oiling systems around but at the end of the day, the tightest lifter bore clearance possible yielded the most stable valvetrain.

I am sure an unstable lifter has got to cause some harmonics some where.

 

[6T6mustang]

its a bbo, flexy block anyways, probably wont see over 6000 rpm, I would be more concerned with oil drain back mods than an extra thou. on the lifters.. imo

 

[chadman]

its a bbo, flexy block anyways, probably wont see over 6000 rpm, I would be more concerned with oil drain back mods than an extra thou. on the lifters.. imo

It will see 7000-7300 rpm.

 

[Smitty275]

It'll be fine. But if you want to come down and bush the bores I'll gladly get bushings and let you rent the mill & tooling for a day. Or I can do it for you. By no means would I run less than .002. Its a long skinny bore.

 

[CNC BLOCKS]

It'll be fine. But if you want to come down and bush the bores I'll gladly get bushings and let you rent the mill & tooling for a day. Or I can do it for you. By no means would I run less than .002. Its a long skinny bore.

Hell I get away with .0014 on a .904 and has worked on .842 lifters with zero problems for many years now.

I guess if you know what your doing. Just saying


Couple of links to look over

http://www.yellowbullet.com/forum/showthread.php?t=594824

http://www.yellowbullet.com/forum/showthread.php?t=341502&highlight=carl+hinkson

 

[Pancho]

It will see 7000-7300 rpm.

:shock:
Sorry, I took it as a milder build.