CBG modifications

[britloon]

Hi all, The. Rules state that a classic engine must use original head,barrells, etc. Can those original components be modified and is there a limit to how far?
Specifically I'm looking to cut a port in the barrel of a four stroke and run it as a two stroke.
Thanks in advance for your help.

[nrhs sales]

changing it from a 4 stroke to a 2 stroke would definately put you in a modified class IMO.

You definately need to speak with Drew or Curtis.

[wobblywalrus]

Lots of year ago when I was a heavy equipment mechanic I worked on in-line some engines with four stroke style crankcases and two stroke barrels and cylinder heads.  They were fed by forced induction rather than crankcase pressure.  I do not remember much more than that, except they were old, grey, and big.

[Seldom Seen Slim]

Bo, were those engines the old style diesels?  I remember learning a bit about them -- two-stroke with the blower mounted directly on the side of the block.  They wound up to higher RPMs than today's diesels - and were very recognisable by their sound when in use in semi tractors.  I don't know much technical detail about them -- just remember them from my youth.

[jauguston]

Slim,

Those were GM diesels. Most commonly 71cu in per cylinder. The 6-71 series powered every landing craft in WW-2. They just sounded like they turned high rpm but didn't turn any higher than the 4 strokes like Cummins. They were later called Detroit Diesels. They would not meet recent emission standards so they are no longer built.

Jim

[Old Scrambler]

Also well known as the 'road oiler'

[Old Scrambler]

Regarding the original question.............I have a modified classic contender.........still needs a lot of tuning.............when in Tech............they called to the AMA offices for clearance of non-oem-to-the-model rods and valves..............OK.........but if you change the angle of the valves.......NO

Yours.............as Drew

[Chris V]

Fun to reminiscence, back in the 60's GM had a V6 almost 500 ci Diesel named tora flow or something similar

[AHG]

Drew Gatewood
AMA/F.I.M. technical steward
email: gears55(at)frontier.com
tele/fax: 219-926-5647 (Indiana)