Quote:
Originally Posted by 70mach1
So I have read through all of the posts with interest but my situation is different than the OP. Here is a little background: I have a 28 AV8 Closed Cab Pickup that I am setting out to rebuild the 8BA that I installed into it earlier this year. I bought the engine locally dressed out with some performance items. The engine has Offy .400 heads and a dual carb intake with 2 -97s on it. I have an HEI distributor on it as well. It is supposed to have a Potvin 3/8 cam in it. The truck drives great and feels quick, even with the 3-3/4 stroke and .030 over it currently is. The only real performance issue I have with the truck is torque related. I have an RTS Overdrive behind the engine and 3.78 gears with a 7.00X16 rear tire. That translates to 2000rpm at 70. The truck does not have enough power to pull hills in overdrive at 70-75mph. I have a LOT of blow by and excessive oil consumption, hence the rebuild. I plan to do any porting and relieving myself, I am a toolmaker and have done other engines, this is my first Flathead. I have already purchased a SCAT 4-1/8" stroker kit with the .125 over Ross pistons, bearings and gaskets for a 284" build. Here are my questions:
1. I get that relieving might not be worth the money if you are paying someone to do it, but doing it myself is it a bad idea for any reason? I would think that the main point of this mod is to unshroud the valves to use OHV speak. So, maybe not a full relief, but at least bringing the block down around the low side of the valve and blending with a more gentle slope up to the deck? This would serve most of the benefits of relieving without as much of a compression loss.
2. My performance issue can also be solved by changing my 3.78 gears for an already purchased set of 4.44. But I was hoping to gain enough power with the extra bore and stroke to keep my RPMs in the basement while cruising. I have gotten advice to ditch the Potvin cam for a 1007B Isky. Do y'all concur?
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I'll admit that I didn't read your post that closely, but it sounds like your motor is on the decline, so I'm not sure it's fair to judge performance modes done on a weak engine.
Somewhere on the interwebs is Mike Bishop's porting guide. Google it and when found, print two copies. One for your night time reading and one to keep next to you as you are working on the engine in the shop.
Other may know, but I'd do the math of what the O/D will make those 4.44's. That is a steep rear. I also believe that Potvin 3/8ths will wake up a bit with the large CI and stroke.