351W Build

js66coupe

Member
May 10, 2009
49
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7
Florida
I'm looking to have a 351W built for my 66 Mustang. Plan is it will be mostly street/some strip use. Looking for 400+ HP with maybe a small shot of N2O on top of that. The top end will be AFR heads w/ a custom cam. But, for the shortblock, I'm wondering if there are any "must do" items as part of the build. Weak links? Double roller timing chain, forged pistons, etc? TIA
 
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since you want to run nitrous, i would go with forged pistons. as for the timing chain a good double roller chain is a very good choice. one thing to have you machine shop check carefully is the number two main cap. the last two 351Ws i pulled apart, the number two main bearing was loose, in one it had actually spun ruining the main cap. the other was close to spinning, it was also loose.
 
You should look into a 408. By the time you turn the crank, buy pistons, rod bolts and resize the rods, you are getting close to what a stroker rotatating assembly would cost. 500hp with a 351 is not too hard these days and even easier with a 408. The only reason I built a 351 vs a 408 was that it was harder/expensive to get compression to 9:1 for a turbo. If I was building a normally aspirated motor it would have been a 408 for sure. With a 408, AFR heads and a custom cam 400+ at the wheels is not too hard.
 
Guess I'll have to check with my builder. I was considering just doing a 351W non-stroker to hold down costs although a 408W would be nice. Given that the engine is going into the 66 I don't really need to go overboard on the torque and HP. But if the cost differential isn't that much, might as well stroke it. By the way, how come I don't hear much about 4 bolt mains?
 
from a lot of the info I have read, I dont think ford did that except for maybe some of the boss engines. I hear several people have put a main girdle on the bottom end to help, but I am sure some of the more experienced engine guys will have better info
 
do you plan on using a cast 351 crank? it might not be that much more to go with a forged stroker crank

personally, I still like engines that wind up well in the high rpm range. a 408 will not rev as well as a 393 or 383. im not saying you cant take a 408 to high rpms, but it wont have good of a rod ratio as a 383. the 408 will still have montrous amounts of torque and will work with taller gears.
 
A forged crank in a 351 is a waste of money unless you plan on making over 1000hp or road racing. I can't remember ever hearing about one breaking. I would not worry about rod ratio either. Some of the most powerful engines have what most would consider horrible rod ratio. I will take cubes over rod ratio any day. Also a 393 with a stock length rod has the same ratio as a 408 with a 6.2" rod. Most 393 kits come with stock length rods so they can use common 302 pistons. A 393 kit with a 6.2" rod will most likely cost more and make less power than a 408.
 
A forged crank in a 351 is a waste of money unless you plan on making over 1000hp or road racing.

that's odd. my engine shop talked me into going to a forged crank in my 418. the cost difference was minimal considering i was already getting a new balancer and flywheel. i believe the primary reason was so it would go internal balance.

i easily took their advice given the fact they build these motors everyday.
 
that's odd. my engine shop talked me into going to a forged crank in my 418. the cost difference was minimal considering i was already getting a new balancer and flywheel. i believe the primary reason was so it would go internal balance.

i easily took their advice given the fact they build these motors everyday.


I think he was getting at if your staying with a 351 engine size its not worth going forged over the cast piece if he is only looking to make <500 hp. Of which I agree.

However, with the prices of kits, it would do the 408. and even then if your under 600hp I wouldn't be afraid of a scat cast crank one bit. However the price is so small anymore for the Forged it would be the way I go. Just never know when your going to get tired of 500hp and want more.
 
if i were to build a 351w based engine, and i was going to replace the crank anyway, and if the price difference between a forged and cast crank was no more than $50, i would go forged. more than that though and i would look at what i wanted from the engine before i made the jump to forged.
 
I would buy a forged crank for internal balance, but not for fear of a cast crank breaking. Internal balancing is a lot easier on the main webs which I beleive is the weak point on a 351 based motor too. We are talking about street/strip, not race engines...right?
 
does anyone have fitment experience with raised exhaust ports on a windsor in a 64-66 mustang?

js66coupe, what AFR heads were you looking at?
383/393/408 would probably all benefit from something larger than a 185cc head

once i put some more miles on my 5.0, id like to build up a windsor and may just go with shorty headers for simplicity. my current long tubes took some fabricating to clear my AOD. with the windsor, i may want to just jack the motor anytime i change plugs
 
I have a question along the same lines in regards to a stock 1994 roller 351W. Can I use AFR 205 heads at the stock displacement and CR with a cam change? Later down the road I want to build a 408W and don't want to buy heads twice.
 
No need to build a stroker for around 400hp in a 351...You are right around the limit of the stock rods though so I would look into an aftermarket I beam rod instead of getting the stock ones resized with good arp bolts..Especially if you plan on spraying it with a little nitrous...

If you haven't started on the 351 yet I would consider doing a 289/302 based 347 stroker..It fits in the 65-66 chassis a little better and header selection should be a lot easier..