Mercury Cougar Owners banner

1 - 5 of 5 Posts

·
Premium Member
Joined
·
5,758 Posts
Discussion Starter #1
HI ALL,
well i found out by my buddy mark piechowski that the 351c i got has 351M heads on it. I guess another felow sunshine state cougar club member had a similiar problem w/ a intake gasket problem where it was sealed but after startup you could feel exhaust gas under the intakewhere it was sealed.Now are 351M heads worthless on a 351c? Do all 351c, boss351,boss 302 and 351c 4v heads have the number stamped in the corners to verify its a 2v or a 4v? The heads i have dont have the number stamped in the corners of either 1 thats how he figured out they were modified heads.Should i look for a set of 4v heads? 2V aussie heads? The car will be mostly cruising and a occasional strip action.. Any and all info be greatly appreciated.
thanks
pat
p.s. i owe mark alot for the info he has provided me to show me what exactly i have. THANKS MARK :)
 

·
Premium Member
Joined
·
3,404 Posts
Pat, 351M heads have a 78.4cc chamber and have a comp. ratio of 8.0-1 (351C 2v heads have 76.2 chambers for a 9.5 comp) The valve size is the same as 2V 351C heads. Ive heard good things on the auzzie heads, but the price is scarey for a few horse extra. Go with 2v heads 351C heads, or if running a standard trans, go 4v heads. You can do wanders with 2v heads to make them breath pretty good and run good comp. ratio on gas today. Just my opinion :D

Rick
 

·
Contributing Sr Motorhead
Joined
·
5,470 Posts
AFAIK, all Cleveland style heads had the provision for exhaust gasses routed through the intake manifold. That's how the choke stove is heated on both the stock 2V and 4V! Additionally, the 73-74 Cleveland intakes would also have a passage off the crossover passage that went to the carb base plate/EGR spacer. M heads are no different in this regard.

If, by chance, a later M had an air pump passage drilled to each exhaust port, that would mean that there should be a plug on either the front or back of the head. One end would have a plug and the other would have a threaded pipe fitting for the air pump tube. At least that's how the 429/460 heads and the Windsor heads are. I've never really dealt with a 351M/400.
 

·
Premium Member
Joined
·
5,758 Posts
Discussion Starter #4
think i will save up some cash n build the spare block n put a set of powerheads on it n drop it in the cat .
thanks
pat
 

·
Premium Member
Joined
·
414 Posts
Pat, that was me that had the same problem but I drove the car for 16 years without knowing it. Ran nice but lacked power, not really noticeable with the 2bbl carb on it. Change back to the 2bbl heads if you are going to do any mods.
 
1 - 5 of 5 Posts
Top