Line boring is indicated if the main tunnels are out of round or
don't line up. The job is done (in theory) so as not to remove
material at the top of the tunnel - you shave material off
the mating surfaces (which means you no longer have a circle)
then machine the circle again - you remove material from the
caps and as little as possible from the block. In practice, you
do end up losing metal in the block. If your rear main tunnel
is out of spec, a line bore will help oil control!
You can (and probably should) graft an A+ timing chain tensioner
onto the front of the engine to cope with the reduced crank-cam
distance. Otherwise you'll notice more slop in the timing. I did this
on my 1380 after a line-bore was necessary.
Use Cooper S head studs, they are stronger than spridget ones but
not as strong as the ARP. More than adequate for hot road. You can
happily use stock rod bolts for a hot-road, you can use just the ARP
nuts on the standard rod bolts if you like, else standard ones.
BTW, you should consider getting the two extra (short) head studs added
to your head/block ala the Cooper head. It seems to be worth it on
higher output motors. You motor is probably on the boundary of this
being worthwhile, but I personally think that with the reduced area of the
head gasket from the big-bore, I'd be doing it. (I did on my bugeye's 1380)
IMHO, the ARP stuff, while magnificent, is not worth it on road motors.
I only use it on my race motors.
At 6500 rpm, you won't have *any* problems with stock components in
good condition.
You should have heaps of fun with that motor!
Mike
-----Original Message-----
From: Ulix Goettsch <ulix@u.washington.edu>
To: spridgets@autox.team.net <spridgets@autox.team.net>
Date: Friday, July 10, 1998 3:27 AM
Subject: Line Boring?
>Now it is my turn to ask engine rebuilding questions. I took my block to
>the shop last night. This is a LBC garage that farms out to a machinist.
>They recommended line boring the engine. His reasoning was that this
>would help to get the rear oil slinger seal to actually seal.
>Is this true?
>
>Also, I don't really understand line boring. Is significant material
>removed so that bearings with a bigger OD are required? Or is a drill run
>through that doesn't remove any material unless the mains don't line up?
>
>Furthermore I can't decide if I need new head studs and rod bolts.
>Any advice?
>I have three choices:
>a) use old hardware
>b) use new stock hardware
>c) use ARP hardware
>
>Of course c) would be safest but would also cost over $200. I feel that
>if I go for the best solution in every aspect I'll end up with a
>$2500 motor, so I need to save some money somewhere. So, is the stock
>hardware marginal and do I NEED better hardware?
>
>This will be a 1380cc, 9.5:1, VP7 cam (not too radical), torque motor.
>Max rpm probably 6500rpm.
>
>Thanks!
> Ulix __/__,__
>.......................................................... (_o____o_)....
> '67 Sprite
>
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