Align Bore Advice Needed
- C J Murray
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Re: Align Bore Advice Needed
So you do a spot on perfect case and install a camshaft that is FOURTEEN DEGREES WRONG? That must give a great result.
Hey, you started it Dad.
Hey, you started it Dad.
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- Jacques Lefriant
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- C J Murray
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Re: Align Bore Advice Needed
Jacques just likes to wind people up. No harm done. We enjoy it.Steve Hatfield wrote:Sorry if my question initiated any ill will.
But if I am reading Jacques' recommendation correctly and taking in Vic's, CJ's and Dick's inputs: while I'm not prepared to strip my customer's case mating surfaces to lap into spec, if I can make sure the new bearings are NOT steel-backed, then we should be okay without boring.
Is this correct?
The steel vs aluminum thing is not a big deal to me but it is to some. Measure the bearing ID with the case torqued and see what you think.
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- Jacques Lefriant
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Re: Align Bore Advice Needed
CJ
That aftermarket cam has been around for at least 30 years every shop that has replaced a camshaft has used them. When someone takes a cam to a cam grinder they usually opt for a regrind with a little more performance.
j
That aftermarket cam has been around for at least 30 years every shop that has replaced a camshaft has used them. When someone takes a cam to a cam grinder they usually opt for a regrind with a little more performance.
j
- C J Murray
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Re: Align Bore Advice Needed
Jacques, I will bet you one of your Carrera 2s that the faux stock cam makes less power than the factory cam.
What still baffles me is that you are talking about "better" and "more performance". S_T_O_C_K is defined pretty clearly and stock is not what the faux "stock" cams are. They aren't even close.
What still baffles me is that you are talking about "better" and "more performance". S_T_O_C_K is defined pretty clearly and stock is not what the faux "stock" cams are. They aren't even close.
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- Jacques Lefriant
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Re: Align Bore Advice Needed
CJ
I don't use faux stock cams for the Carrera 2 the other cams that are available make more power anyway.
i know that the aftermarket 356/912 cams are not stock but almost everyone seems to like them. Also if you like numbers the stock .002" or .05mm of crush will vanish at 100*C/212F if you use the steel backed bearings yes the ID will be better but the case will pound out and require rectification. I consider the bearing/line bore issues to be of more importance to the longevity of the engines than camshaft specs. I hope that our readers will benefit from our discussions and i only wind you up to keep it interesting keep the faith and AMDG
j
I don't use faux stock cams for the Carrera 2 the other cams that are available make more power anyway.
i know that the aftermarket 356/912 cams are not stock but almost everyone seems to like them. Also if you like numbers the stock .002" or .05mm of crush will vanish at 100*C/212F if you use the steel backed bearings yes the ID will be better but the case will pound out and require rectification. I consider the bearing/line bore issues to be of more importance to the longevity of the engines than camshaft specs. I hope that our readers will benefit from our discussions and i only wind you up to keep it interesting keep the faith and AMDG
j
- C J Murray
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Re: Align Bore Advice Needed
With your "stock" cam you need to keep the rpm around 7000 to move the car so you had better have a good bottom end!Jacques Lefriant wrote:I consider the bearing/line bore issues to be of more importance to the longevity of the engines than camshaft specs.
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- Jacques Lefriant
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Re: Align Bore Advice Needed
Just one question: why the factory had a very tight tolerance for the main line bore?
- Jacques Lefriant
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Re: Align Bore Advice Needed
Salut Olivierm
I would think that the crush and roundness are important if your oil pump is working well even extra clearance is no big deal.
j
I would think that the crush and roundness are important if your oil pump is working well even extra clearance is no big deal.
j
- Steve Hatfield
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Re: Align Bore Advice Needed
Me again, line bore question but a different engine but also for the street:
Case #s over”
Main no. 1: .0005”
no. 2: .0025”
no. 3: .001”
Align bore or no? If no then
Looking for alloy std case, first over (.010”) 50mm B (solid #3) vintage mains.
If yes then.010/.010 s
Thanks
Case #s over”
Main no. 1: .0005”
no. 2: .0025”
no. 3: .001”
Align bore or no? If no then
Looking for alloy std case, first over (.010”) 50mm B (solid #3) vintage mains.
If yes then.010/.010 s
Thanks
Steve Hatfield
Fort Walton Beach, FL
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- Jacques Lefriant
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Re: Align Bore Advice Needed
try EBS racing in Reno I think they are out of +10-10 but they have alloy bearings. I always say first under on the crank but you are correct that the shell is bigger.
j
j
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Re: Align Bore Advice Needed
The camshaft doesn't have any bearings to support it in the case.
There's a lot of emphasis on crankshaft measurements and line bores, but little or none regarding the camshaft.
I would have thought that you cannot do one without the other.
A great discussion, thanks gentlemen.
David
There's a lot of emphasis on crankshaft measurements and line bores, but little or none regarding the camshaft.
I would have thought that you cannot do one without the other.
A great discussion, thanks gentlemen.
David
- Ron LaDow
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Re: Align Bore Advice Needed
The cam does have bearings; the cast-iron cam, well oiled, spins in aluminum bearings, exactly as the Cosworth DFV cams operate, for instance.David Nicholls wrote:The camshaft doesn't have any bearings to support it in the case.
There's a lot of emphasis on crankshaft measurements and line bores, but little or none regarding the camshaft.
I would have thought that you cannot do one without the other.
A great discussion, thanks gentlemen.
David
Back when the cases were not as 'used' as they are now, the typical process was to lap the case halves on the mating surface and re-cut the mains to standard size. In which case the cam bearings were cut back to standard also.
More recently, when the mains need a cut to oversize, the cam bearings aren't affected at all.
The loads are not drastically asymmetrical as are the mains and the rods, and then they are generously-sized and get a good supply of oil. So there's rarely a reason to fiddle with them.
Ron LaDow
www.precisionmatters.biz
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- Craig Richter
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Re: Align Bore Advice Needed
Thanks for the terrific discussion. Reminiscent of many talks with Ray Litz years ago, which always left my little pea-brain spinning. What a pleasure it was to work with such a great machinist, and you guys are cut from the same cloth.