Align Bore Advice Needed

[Steve Hatfield]

I have a '63 Normal under rebuild right now. The crank is out for possible 2nd under grind and nitrating. It was cut once by a PO.
I've measured the 1,2 and 3 bearing bores several times with the same results with my new very nice and expensive B&S three point:

#1 .00075" over the published max of 2.3717 at 2.3726"
#2 .00155" over at 2.3734"
And
#3 .00065" over at 2.3725"

I've found no published wear limits for case bore beyond the proscribed 60.24 + or - .005mm.

So, do I really need to send it off for align boring?

If so, recommendations, please?

Thanks all

[Vic Skirmants]

My personal opinion; it doesn't need to be bored.
And where did you find a bore gauge that goes to 5 places after the decimal point??

[Steve Hatfield]

Just my sharp eye I guess (interpolating)
Thanks Vic
Any other opinions?

[Chuck House]

Just my sharp eye I guess (interpolating)
Thanks Vic
Any other opinions?

Vic's opinion in this area is about the best, but Vic, I would have thought that .0015" over wear limit on #2 is too much, but I guess I've always been a bit conservative on clearances. At what point do you get concerned about losing crush and the bearing moving - for next time I measure a case?

[Vic Skirmants]

My gauge has only found a couple of cases that were less than .001" over. For a street engine, I consider .002" over to be adequate.
Years ago, when line-bore bearings were extremely hard to find and priced very high when you did find them, I was forced to use worn cases even in race engines; with no obvious problems. When the case halves start showing "fretting" at the #2 saddle, it's time for a shave and cut.

[Martin Benade]

Vic, this amount of wear is still not concerning with steel-backed bearings?

[C J Murray]

Loose Baby, that's where the power is! Just kidding. I do think that there is a phobia about getting the line bore perfect that is not justified. Some shops have had a policy of machining every case they rebuild. Since I have never had to line bore a case I am pretty sure many line bore jobs are done unnecessarily.

[Vic Skirmants]

"many line bore jobs are done unnecessarily."
Ditto, ditto, ditto.

[Jacques Lefriant]

Hi Steve
Yes you can use it without line boring but if you can find someone who could line bore it properly you may as well get it done. an alternate method is to lap the cases and line hone/ream it back to std. your decision is more a function of the availability of the repair shops and the bearings.
j

[Dick Weiss]

I agree w/Vic and Jacques

Dick

[Jacques Lefriant]

Hi Steve
a 3 point mike is great for a precision measurement of round holes. using a 2 point bore gauge will give you a better feel for the ovality.
i congratulate you for your dedication. since i imagine you are doing this for yourself it is your call.
j

[Jacques Lefriant]

CJ
Phobia? you can get away with a lot when building engines and some things are not possible to do easily. When you get the reputation that Vic has you can render an opinion. You have insisted that we should consider using perfectly stock cams but why if possible should we not restore the original dimensions and use the original bearing alloys. It is a tough call on Steve case (pun) i would definitely line bore it if all i could get were the steel bearings if it was my customer.
j

[C J Murray]

Jacques, did I render an opinion on Steve's case? NO! I have a machinist that measures at least 100 line bores a year. He has only been doing my work since 1975 but I am beginning to gain trust in him. I have yet to take him a case that he felt needed line bore machining. Counter that with a certain legendary CA shop, out of business, that reputedly machined every 356 case they touched. Draw your own conclusions.

When you get the reputation that Vic has you can render an opinion.

This is a hurtful statement.

You have insisted that we should consider using perfectly stock cams but...

More accurately, I have insisted that suppliers should provide stock cams that are stock, not faux "stock" cams that have 14 degrees more duration than stock AND are advanced 4 degrees! Considering the facts I have been extra kind to the suppliers who are ruining the intended performance that the customer wanted. All the major suppliers have been selling their customers a totally wrong part for many years and supposedly they didn't have any idea the parts are wrong. Should I be embarrassed for actually measuring the cam and pointing out the problem or should others be embarrassed?

[Jacques Lefriant]

Hi CJ
what does your machinist line bore and how does he do it. The factory shows 911 cases being rectified using Hunger adjustable reamers. In the states VW line bores are usually done using single point cutters that are supported by discs that catch the seal bores. I have never seen the Lukes and Shorman set up and they didn't do us any favors by going to the second oversize. When std OD bearings were still available from the OEMs CE and Ollies brought a lot of cases back to std. We are fortunate that most of our cases are made out of aluminum and if you use aluminum bearings you can have a good bit of latitude. Not only have i measured hundreds of 356/912 cases i have line bored a lot of VW Type Is 356/912s Type IV and 911s and 4-Cams personally and also had machine shops do it for me. I also was aware of the wrong cam being supplied but the feedback i received the replacement was very well received.
j
j

[Steve Hatfield]

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?