351w vs 351m

goinbroke2 · 03-11-2017, 04:09 PM

Looking at the guide got me thinking, a 75 or so wagon came with both and was wondering if there are any opinions from those who are familiar with them, what would be the better choice?
351w
Lighter overall, good pistons and rods available but terrible heads and intake. 1.78 / 1.46 valves and .419 lift

351m is heavier with massive long rods with no replacement rods or pistons. But, 2.05/1.65 valves with better flowing heads and intake. .409 lift

Both run the same 1.21 carb.

Not sure if the heads will overcome the extra weight.

Thought?

Mike Graham · 03-11-2017, 04:57 PM

M has almost 20cc bigger head cc. some of that is recovered in the difference in piston dish. The carb will be the limiting factor. Not valve size. Plus it looks like M carries 10 more hp factor. 351w W all the way.

Rory McNeil · 03-11-2017, 07:17 PM

I have not checked the Guide for a 75 Ford, but I seem to think that the 351Ws had 1.84 & 1.54" valves, up until about 77 or 78. Also, with a 2 barrel carb, the 351Ms larger valves won`t have much benefit. Depending on what chassis you are looking at, the 351W engines came in more models, the 351M was mainly full sized cars, and PU trucks and vans.
With the 74 Ford 460 smogger engine rather popular in S/Stock, one has to wonder how it would fare in Stock. All pretty heavy cars, but a 460 cube engine at 300 HP.....

rawhide · 03-12-2017, 11:31 PM

I believe that the valve size was reduced in 1975 for the 351W.

Roland

goinbroke2 · 03-12-2017, 11:41 PM

Thanks for the replies guys.
Yes '75 was the first year of small valves. Just happen to know where a 77 Torino with a 351m is and it got me thinking. Both have the 1.21 carb, I just thought maybe the bigger valves and ports would be better. My biggest concern with the m would be the crappy oiling system and having to run stock cast Pistons.
As far as the factor I thought I saw both at 230 and the 400 at 240.

Anyway, after reading the thread about reducing hp 20 percent it sent me looking through the guide and kijiji! Lol! A 351 at 184hp might actually be able to hit the index with enough work, 230? Not a chance.

03-11-2017, 04:09 PM	#1
goinbroke2 Senior Member Join Date: Mar 2002 Location: NS CANADA Posts: 885 Likes: 1,570 Liked 384 Times in 149 Posts	351w vs 351m Looking at the guide got me thinking, a 75 or so wagon came with both and was wondering if there are any opinions from those who are familiar with them, what would be the better choice? 351w Lighter overall, good pistons and rods available but terrible heads and intake. 1.78 / 1.46 valves and .419 lift 351m is heavier with massive long rods with no replacement rods or pistons. But, 2.05/1.65 valves with better flowing heads and intake. .409 lift Both run the same 1.21 carb. Not sure if the heads will overcome the extra weight. Thought? Last edited by goinbroke2; 03-11-2017 at 04:14 PM.

03-11-2017, 04:57 PM	#2
Mike Graham Member Join Date: Jul 2002 Posts: 410 Likes: 1 Liked 341 Times in 67 Posts	Re: 351w vs 351m M has almost 20cc bigger head cc. some of that is recovered in the difference in piston dish. The carb will be the limiting factor. Not valve size. Plus it looks like M carries 10 more hp factor. 351w W all the way.

03-11-2017, 07:17 PM	#3
Rory McNeil VIP Member Join Date: Jun 2007 Location: from Vancouver BC Canada, now in Nova Scotia Posts: 1,311 Likes: 315 Liked 1,103 Times in 301 Posts	Re: 351w vs 351m I have not checked the Guide for a 75 Ford, but I seem to think that the 351Ws had 1.84 & 1.54" valves, up until about 77 or 78. Also, with a 2 barrel carb, the 351Ms larger valves won`t have much benefit. Depending on what chassis you are looking at, the 351W engines came in more models, the 351M was mainly full sized cars, and PU trucks and vans. With the 74 Ford 460 smogger engine rather popular in S/Stock, one has to wonder how it would fare in Stock. All pretty heavy cars, but a 460 cube engine at 300 HP..... __________________ NHRA 6390 STK M/S 85 Mustang

03-12-2017, 11:31 PM	#4
rawhide Member Join Date: Feb 2010 Posts: 270 Likes: 1 Liked 7 Times in 5 Posts	Re: 351w vs 351m I believe that the valve size was reduced in 1975 for the 351W. Roland

03-12-2017, 11:41 PM	#5
goinbroke2 Senior Member Join Date: Mar 2002 Location: NS CANADA Posts: 885 Likes: 1,570 Liked 384 Times in 149 Posts	Re: 351w vs 351m Thanks for the replies guys. Yes '75 was the first year of small valves. Just happen to know where a 77 Torino with a 351m is and it got me thinking. Both have the 1.21 carb, I just thought maybe the bigger valves and ports would be better. My biggest concern with the m would be the crappy oiling system and having to run stock cast Pistons. As far as the factor I thought I saw both at 230 and the 400 at 240. Anyway, after reading the thread about reducing hp 20 percent it sent me looking through the guide and kijiji! Lol! A 351 at 184hp might actually be able to hit the index with enough work, 230? Not a chance.