Mornin', Jack -
Mark has an early version of the Pipemax program - It suggested direction toward two headers I currently have hanging on my wall in the garage - both of which are un-dyno-ed. (that's weird - the auto correct forced me to stick in an additional dash - otherwise the word comes up un-dynode.)
A confession here - last year when we tested, we used headers set up for a Mini Cooper, and while the pipe lengths and diameters led me to the Winners Circle header I did run at Bonneville, we never actually tested with that header, because I didn't get my hands on it until July. I just picked up a really decent used Maniflow racing long center branch header which Pipemax indicates should be an improvement, but we will have definitive numbers when we head back to the dyno.
Regarding the cam we're currently using, it's ground on 108 degree centerlines with lobes Fordboy and Dema came up with. It's my understanding that it's a borrowed profile. I'll take a look at Swiftune's cam offerings, but other than Elgin's grinds, most are knockoffs of APT/Vizard designs or works grinds.
The biggest problem we have with topping 100/liter is that with the small capacity of the cylinders, it's difficult to raise compression ratio. I think we're at ~13.2:1 - most rippin' race prepped 1275s are at 14.5:1 The head is shaved to a point where any additional milling will weaken the face around the combustion chamber, and we're already running a bit of pop-up. By spreading out the LCAs to 108, we gained a bit of clearance between the valves and the piston and compensated for a relatively long dwell at TDC due to our 2.45 rod/stroke ratio.
Mark is - as I write - flowing my head with the complete intake - including the carb - and stubs for exhaust. There are 5 other racing heads he has flowed this last month. One is a relatively untouched Swiftune head, the other Swiftune was butchered by a nameless shop, one was cut by my guys at C&S in Milwaukee, one is a Longman of unknown origin, and I'm not sure of the other one. He's also testing my head with anti reversion exhaust valves. So a raft of information will be coming our way probably by next Monday, and will help us chart engine development for this year.
What is likely going to occur will be honing the cylinders with a diamond hone and a deck plate, which will let me go to gapless rings. Leak down was at worse 5% on one hole, but if I can keep it in the combustion chamber, it's as good as a CR pop.
One other thing, too. We worked primarily on the fuel and exhaust end of things last year. What we didn't explore too deeply was cam timing - which we will be able to adjust very quickly on the dyno with the belt drive setup I picked up, and the ignition curve, which we just set and didn't dick with.
I do need to be cautious with the cam timing - don't want the valves and pistons to get too friendly.
Topic: Milwaukee Midget (Read 3295127 times)