ThunderV12, LLC

V12 Clutch

Joe McCoy has some insight on putting the Lipe-Rollway twin disk clutch behind a 702.
He has used and recommends for clutch parts.


If rebuilding your V12 we recommend all rotating assemblies be checked for cracks, straightness, and balance.
Although we have inspected over 100 702 cranks, we have never found a broken crank. We have found all sorts of defects that you would expect from high-time industrial cranks.

At the very least support a crank in a block on its two end bearings only. Indicate at the center journal. Max total indicator reading is .006". This step is often overlooked and can find many problems.

We balance all assemblies +- 5 grams. Replacement pistons will vary +- 50 grams and replacement rod bearings can vary 10+ grams between brands. If you want a smooth free-revving v12, don't skip this step.

Engine Oil

All ThunderV12's ship with Brad Penn 30wt break-in oil. Replace with high quality 10w30 or 15w40 after first 20 hours.

Fuel Pumps

All the stock replacement fuel pumps we have found have sat in the box for 25 years and are of little value. A ThunderV12 fuel demand will outstrip the mechanical pumps' output. We use the mechanical pumps in-house for test stand running but recommend fuel pump block-off plates be used and dual electric street pumps to be plumbed in.


When re-using the stock rods, be sure to check all rods for straightness and resize any rod that has had the rod bolts replaced.

Oil Supply

We do not consider the stock oil pump viable for rpm's over 3,500. The stock V12 used two different oil pumps that fit v12 blocks of different years. This greatly adds to the problems of a "fix".

ThunderV12, LLC has fabbed external oiling systems to the 702 that provide very good and reliable service.

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