Good question Mike/George,
The answer is most likely yes. On our race and street motors for the TR6 we
overbored the lifter holes and fitted them for the Ford solid lifter. Of
course this would not be legal for SCCA. But would be fine for
Vintage/Street applications as internal engine parts are "Free" in many
sanctioning bodies. This mod will open and close the valve sooner but will
not effect maximum lift...and good lifters are available. What we did was
use a CNC and wrote a program to get the job done. You must be very
conscious of the relationship between the cam and the lifter bore angle and
offset. We also found that this mod interfered slightly with the
distributor drive...to get around this problem we offset the bore
centerline for that particular valve...it didn't take much.
Chip
U K Motorsports
> [Original Message]
> From: George Harmuth <harmug@us.ibm.com>
> To: <fot@autox.team.net>
> Date: 2/4/2011 3:58:53 PM
> Subject: [Fot] Oversize lifter bore
>
> I have a spare racing engine, 1296, that broke two cams. I thought the
> first one was a bad cam blank but when the second one broke in the same
> spot, cylinder #3 intake, after 5 hours run time, we took a closer look at
> the block. It appears that there's excessive wear in the block (hole is
out
> of round) and the (new) lifter is cocking enough to put excessive side
> loading on the cam lob (radial fracture marks on the cam remains).
>
> I don't have the exact measurements here, the mechanic does, but we were
> discussing options. He was wondering if a sleeve could be used to get the
> bore back in spec. I was wondering if anyone here has seen this and has
> another solution. Is it possible to bore it out and use a larger lifter
> from another series engine? Custom lifters?
>
> Thanks in advance
>
> mike
>
> 63 Spitfire
> HP and HRG1
>
> G. Michael Harmuth
> _______________________________________________
> fot@autox.team.net
>
> http://www.fot-racing.com
>
> Donate: http://www.team.net/donate.html
> Archive: http://www.team.net/archive
> Forums: http://www.team.net/forums
> Unsubscribe:
http://autox.team.net/mailman/options/fot/tr6racer21@earthlink.net
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Donate: http://www.team.net/donate.html
Archive: http://www.team.net/archive
Forums: http://www.team.net/forums
|