[Fot] Doug Still Guides Me...

[Enquiries Road & Track]

firstly, are you 100% sure the caps are correctly fitted both round the
right way and in number order?

you need to decide if the caps are misaligned across the block or if the
tunnel is simply oval because the hole in in cap is too far up or down.
this will need a combination of feel and measurement

if the alternative caps have a significant step to 1 side, so you will
clearly feel a ledge at the mating faces when they are tightened up

if the stap is very minor, like a few thousandths of an inch, then the
faces of the cap are machined down to create an oval hole, then it it is
align honed

if it is really bad, like many tens of thou, then you have to firstly move
the cap sideways by machining the register on 1 side and peening it on the
other, and effectively moving it sideways, followed by boring/honing

sometimes, the bolts are too neat a fit to allow this and if thats the
case, its usually easier to find some other caps or make them

if the tunnel is simply an oval because the cap is too far up or down, this
is usually easily fixed by facing the cap mating surfaces and reboring the
tunnels

not all engine machine shop have a line borer...mine did not, so
subcontracting the job is not uncommon

the end result should be a perfectly round hole with a super fine hone
(cross-hatch) mark on the bearing faces, to ensure perfect bearing
shell contact

 Terry
Australia




On Tue, Mar 24, 2020 at 1:32 AM Bud Rolofson via Fot <fot at autox.team.net>
wrote:

> Speaking of main caps I bought a block that turned out to not have the
> original main caps. The caps on there did not match up with the block but
> I’ve been unable to find a machine shop that can machine them so there’s a
> round hole for the crank. The shop I had do my last block (and they do 427
> race engines among others and are well respected) told me that the result
> would be ovaled out holes (not round) which obviously is not good.
> Certainly there’s a way to make this work but I haven’t found it. I
> checked out another block shop but said they subcontract line-boring to the
> the shop that said they couldn’t do it.
>
> Has anyone else encountered this problem? I’ve heard that steel mains
> might be an answer but they’d still have to be line-bored to make them
> match. I hate to ship a block to get this done before I have reassurances
> that they can make it work but does anyone know of that has successfully
> made main caps match the block? Given I’m spending a lot of time these days
> staying home and catching up on car projects in the shop I figured it would
> be a good time to start building the next engine.
>
> Solutions or recommendations?
>
> Thanks
> Bud
>
>
>
> On Mar 22, 2020, at 9:33 PM, Brad Eells via Fot <fot at autox.team.net>
> wrote:
>
> Amici,
>
> In typically rookie race engine builder mode with the block I selected for
> rebuild, I pulled the main bearing caps (with my new fancy DeWalt 20V
> Impact Wrench) and then couldn't remember which way around they went.
>
> This led to visions of catastrophic failure somewhere down the road. Yet,
> I had several other blocks I could flip over and make a determination if
> need be.
>
> I was examining one of the caps when I discovered the faintest engraving
> on the surface of each cap:
>
> Eng #2 Front Fwd
> Eng #2 Mid Fwd
> Eng #2 Rr Fwd
>
> Doug Brown, my original owner/builder/driver extraordinaire had engraved
> each cap for me to make sure a mistake didn't occur. He rotated 3 engines
> during each season in a quest for Divisional and National Championships.
>
> I guess that is the way a aeronautical/mechanical engineer and very
> successful racer thinks.
>
> Thanks again Doug!
>
> <IMG_8745.jpg>
>
> Cheers,
>
>
> *Brad Eells*
> *Chino CA*
> *#72 FP 1969 Triumph Spitfire Mk3*
> *#35 DP 1962 Triumph TR4*
> *1965 Triumph TR4A IRS...for the road!*
>
>
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>
> Bud Rolofson
>
> Extreme Parts Racing (more than just a haircut)
>
> 71TR6 CC57365 (Good 6)
> 71 Spitfire MK IV Race Car #3
> 69 Spitfire MK III (back up FE engine/dinghy car)
> 93 Minnie Winnie Race Support Vehicle
> 77 Z-50A Hardly Davidson Honda Mini-Trail Bike (Triumph Pit Bike)
>
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