Whew! We've been humpin' it pretty good lately, and it felt good to see some results. Jay summarized it pretty well in his post. We basically built a "normal" Super Stock 427, but took out compression, added inches, and used alot less cam by comparison to a SS camshaft. I was hoping to trade off the stock stroke, compression, and big cam for the bigger engine, less C/R, and little cam, to arrive at similar power with greater reliability from the lower operating range. The unplanned surprise was all of that torque. I was surprised about that. I think I hit the combo just right. This manifold would be too small for a 500" engine at high revs, but it worked great in the range we want to run it. We really did not set out to make big power with this thing..........we wanted to build as much of a SS engine as we could so the owner would not have to redo anything except the cam, springs, and rotating assembly. It has 2.19/1.72 diameter 3/8 stem valves, 66 cc chambers that I have spent alot of time on, and just enough of a bump on the piston to get back to 13 to 1. It has a Swartz/Patrick billet tunnel ram that we built originally for the 427 that we took out of the car, and two 715 CV/CU carbs inline in the OEM configuration. The small cam has only 250# on the seat, 750 open, and does not even have titanium retainers. We went with light tool steel just to save a few bucks, knowing that we will change them later. Same for the pushrods. It has .145 wall 3/8 one piece pushrods for the time being. It was supposed to be a test mule, but now we have to figure out how to deal with all of that torque. The clutch set up will be interesting, and we have to gear the car to operate 1500 rpm lower, so a new third member is in order.
I was happy to see that the chamber worked well. On the pull Jay posted, we had 30.5 degrees of timing in it. It made a little more power at 34.5 degrees, but for the intended use, I'd rather run the lower timing with this much stroke involved. The block is 4.280 bore for later use, but we stuffed in a 4.400 Crower billet crank to give it a little grunt. The cam is .700 lift, and in the 270's at .050. It is a mid-grade roller in terms of lobe profiles. On the high end of streetable, and will live forever on the drag strip. I'm still beaming about this engine..........then I start thinking about the what if's............some big 7mm stem valves, a little more plenum, a huge cam, and what about carbs............no doubt this engine could top 1000 HP with some changes. I think I would stay at 500 inches, but I would go as big as I could on the bore, and plug in the stroke that got me to 500 cubes. Then, it would feel at home at 8500 or so rpm, and the power would come. I could also open up the heads some for some 2.300 valves. These heads are "legal" runner volumes of 185 cc intake and 128 cc exhaust, but with no rules, there would be more to be gained with the same port design with more cross-section.
All in all, it was fun. Alot of times the "fun" goes away when it becomes work, but on this one, the fun factor got involved. I also had a 511 on this trip that made 880 hp and 755 torque. It had Pro Ports, a modified MR tunnel wedge, and two 850's. A stout engine, but just not as far out on the cylinder heads and manifold. I should have stuck those 850's over on the 506 just for grins..................