I want to thank
all you guys who post their engine tips, "secrets", tuning know-how and experiences with different combinations because I used a lot of that information to build a 260" Merc that far exceeded my expectations on it's first drive tonight. It's in my '41 Merc Town Sedan with 3 spd and 3.54 rear gear.
Compared to the tired 239 that I'd been running since getting the car last March...it's a monster! It almost defies logic it runs so well...I can't stop grinning like an idiot.
EASILY accelerates to highway speed and keeps up with traffic doing it.
It's really not super special, just an EAC Merc with an older .030 overbore that I ridge reamed,honed and freshened up with new rings (it was worn .003-.004 at the upper ring travel). Crank polished standard and got new bearings after a few strokes through the block's housing bores with a line hone just to make sure. The cam is an 8CM that I chose after checking both it and an EAB with a degree wheel and finding out they are REALLY close to the same grind. I thought the numbers of the 8CM would fit my needs well. Stock lifters, new LZ springs, new guides and valves.
Heads are 8CM milled enough that with a light surface cut on the block decks gave me piston to head clearance of .033"-.040"--I like 'em tight! Fortunately the pistons were a set that were nearly "0" deck when checked during disassembly (no identifying brand marks or numbers) so I didn't need to do a lot of metal removal to get what I wanted.
Intake is 4 bolt Merc bored to 1 7/16", carb is 2GV Rochester, Distributor is modified Chevy with proper Flathead curve (20 deg centrifugal all in by 2200) and vac advance (also limited travel to add just a few degrees at light throttle cruise).
Exhaust is stock single and I now see no need to change it.
Honestly, this thing is better than the sum of its parts...it hauls butt in this big car!
There were "interesting" challenges along the way building this engine (I'm sure glad I work in a diesel engine machine shop/rebuild facility) and I'll post some of that in the next few days. For now-
Thanks Again for all the shared knowledge here! It helped me immensely.
Special thanks to JWL , without whose book I surely would have gone wrong directions and wasted money, and to Ol' Ron for tuning tips.
And posthumously to Mr. Bruce Lancaster whose posts were Flathead Gospel.
Time to call it a night now. Later....
Terry