gjz30075 wrote:181 hp with 40s? No replacement for displacement? Excellent torque!
Displacement is 1700 (actually a little less). Lot of things went into this type of performance, not just displacement:
1. Modern, "replica", Weber head (SAS Engineering). With Vegher tweaks.
2. Valves (Manley): Intake: 1.625" Exhaust: 1.375"
2. Original short deck block
3. Cams (Kent): High lift (.440), short duration (250 degrees at .050" lift). I guess similar to McCoy's and others.
4. CP racing forged pistons, custom. Further machined to achieve 10.2 CR (pump gas).
5. Long (4.928") rods (Formula Ford) with ARP 2000 bolts. Dave was not interested in the "Bean stroked" approach of using the stock rods (4.8") coupled with special pistons when I brought it up - only said he knew what worked (obviously).
6. Balanced/shot peened SCCA/SCAT crank
7. Big bore exhaust
8. Very large, custom "26r" airbox (stock version robbed 7 hp).
Primary factor has to be Dave Vegher and his many decades of building twincams and knowing how all the bits work together. There are a number of "master" twincam builders (though perhaps not a lot) out there that can work their similar "magic". I just hope their skill/knowledge gets passed along to the next generation.
The use of 40 DCOE's and 32mm chokes seems to belie the common wisdom that you can't get something like 181 hp and 143 torque out of a twincam in such a configuration and need bigger chokes/carbs to get to these levels. For a road car, the smaller configuration would seem to lend itself to better tractability. I can only attest that the car does well on the road, from a standing start and picking up cleanly and with power through low to higher revs. It has been a long time since I drove the car in stock form, so the memory fades. But it is definitely quicker now without discarding its road manners.
Posted: Mon Dec 18, 2017 8:19 am
