I was thumbing through my new jegs catalog just now and see that they offer a Ford Racing Boss 351 block for $1900. But I had some questions I wanted answered for anyone that can answer them here.

1. Is it basically the same as a 351W just a stronger block?

2. If I had to could I use basic 351W parts on it (example. reuse the 1978 Dura Spark II dist and ignition box out of my 78 351W) ?

3. Would the bolt patterns be all the same as a 351W (example. bell housing and engine mounts) ?

Reason I am asking is I am thinking I might go ahead and pick up that block and build a custom rollerized Boss 351 for my 78 Mercury Cougar XR7 but I dont know if it would be a simple straight drop in requiring no modifications. I know in the photo I cant see the engine mounts but I do see a rubber gromet hole just below and off to the side of the passengerside waterpump opening. Not exactly sure what thats for but I am sure I would need to use a Boss 351 timing cover and everything. But if anyone can help I would greatly appreciate it.

 

Nevermind, went to ford racing`s website and got good photos of the block and I just dont see anything that looks close to engine mounts like my 351W has. So apparently it uses a 351C sized crank but has apparently Boss engine mounts I guess.

~Update~
Well now I am not sure, it shows the same exact timing chain cover housing for the Boss 351 as my 351W and my two 302`s uses. So the question still remains as my orignal post. Might have to email ford racing to get down to it.

~Update2~
I was looking online for more information and came across a blog that was basically saying that the new Boss 351 blocks uses alittle of each of the 302, 351W, and 351C. The heads on ford racing`s site recomended were aluminum turboswirl 302/351W heads. On the blog how ever they had photos of the block and I am posting them below. It appears after looking at it it uses the same 302/351W engine mount pad but I dont know if its just me or what but they look alittle too far spaced still.

<a href="http://s148.photobucket.com/albums/s8/Rusty_S85/1978%20Mercury%20Cougar%20XR-7/?action=view&current=M-6010-BOSS351.jpg" target="_blank"><img src="http://i148.photobucket.com/albums/s8/Rusty_S85/1978%20Mercury%20Cougar%20XR-7/M-6010-BOSS351.jpg" border="0" alt="Photobucket"></a>

<a href="http://s148.photobucket.com/albums/s8/Rusty_S85/1978%20Mercury%20Cougar%20XR-7/?action=view&current=boss-351-1280-1.jpg" target="_blank"><img src="http://i148.photobucket.com/albums/s8/Rusty_S85/1978%20Mercury%20Cougar%20XR-7/boss-351-1280-1.jpg" border="0" alt="Photobucket"></a>

<a href="http://s148.photobucket.com/albums/s8/Rusty_S85/1978%20Mercury%20Cougar%20XR-7/?action=view&current=boss-351-1280-4.jpg" target="_blank"><img src="http://i148.photobucket.com/albums/s8/Rusty_S85/1978%20Mercury%20Cougar%20XR-7/boss-351-1280-4.jpg" border="0" alt="Photobucket"></a>

<a href="http://s148.photobucket.com/albums/s8/Rusty_S85/1978%20Mercury%20Cougar%20XR-7/?action=view&current=boss-351-1280-5.jpg" target="_blank"><img src="http://i148.photobucket.com/albums/s8/Rusty_S85/1978%20Mercury%20Cougar%20XR-7/boss-351-1280-5.jpg" border="0" alt="Photobucket"></a>



It looks like its a well built block though, and $1,900 for the block isnt bad in my book, jegs is selling a ford racing 351W block with the non factory 9.2" deck heigth for $1,854. A dry sump version of the same block is $2,604 and a aluminum 351W race block is $3,700. So I think jegs charging $1,900 for a cast iron 9.5" deck heigth Boss 351 isnt that bad of a price that is of course if I can bolt on all my factory 351W accessories to the front of this block and my Bellhousing and engine mounts all line up and work the same. I might even be able to get it cheaper considering Summit doesnt carry the Boss 351 but then again I am getting ahead of myself since im not sure if it would be a direct drop in as of yet.

 

Biggest difference is the four bolt mains. The mount holes look similar to later Windsor mounts.

 

Thanks for the reply, so basically it appears very much like the basic windsor block as far as mounts goes.

That was my concern if I used it as a drop in replacement. Next thing is the bell housing. I might have to contact Ford racing directly to get an direct answer on that. But I ran some different specs for compression ratio estimates. It is interesting considering my oem 351 if I stroked her out to a 393 cid like I was going to at one time the compression with 25ish cc dished pistons was still around 10:1. But going with a 387 CID displacement with 4" pistons, 3.85" stroke with 5.956" rods I can get 10.85:1 compression with 6.8cc domed pistons or keep it around 9.61:1 with 4.80cc valve releif pistons. So it looks like I am way more flexible on a build up with this block than using the stock block and components. Im also starting to like the threaded core plugs. I am even thinking bout using one of the thumper camshafts with headers and dual exhaust on the car with this block. But before I get ahead of myself again I would have to do some DD2000 runs to see what power output I am looking at. Might not be cost effiective.

 

~update~

It would appear that this wasnt a too good of an idea. The block uses Cleveland crankshafts which is pitiful selection wise. I found one I would like to go with a 4.25" stroke which is the max the block can take but that crankshaft is made by a company I never heard of and carries a $1,500 price tag I dont know how good Howard is at making crankshafts but they must love their crankshafts with that kind of price. The only decently priced one I found is Eagle at $289 but its a 3.85" stroke which isnt a deal breaker for me but the deal breaker is the block is a 1 piece rear main seal, uses a 351W seal and that crank is for 2 piece seals. Then the heads are GT40 aluminum turbo swirl heads but yet they require pedistle bolt down rockers which Ford Racing sells but for something like $300 - $400 where as I was planning on a Comp cams roller cam and they recomend their stud mount magnum roller rockers which comes out to $160.

So to cut it short, its a pain trying to match parts because this block is mismatched between 302-351W based and 351C based. I see the rod ID on the big end is the same on the 302-351W as it is on the 351C so that opened up more options for me but in the end the best lowest price tag I could get for getting everything for the engine is $8,321.52 and I have to say for that price tag its not worth it to have a 427 CID Boss 351 block putting out just 350HP at 4,000 rpm and 530 Trq at 2,500 rpm. I mean hell that price tag is more than the car is worth in its current condition. Even after paint and redoing the interior and replacing the cracked windshield its still only valued at $12,000.

So unless someone here can direct me towards cheaper 351C cranks or cheaper parts in general it appears I will stick with the oem 351W.

 

This is a update, Summit responded to my "tech" question and they told me that they carry the Boss 351 as well as the Boss 302 (the Boss 351 isnt listed on site). They also told me the bell housing bolt pattern and the engine mounts are 351W/C based. Saying that the 351W and C used the same bell housing bolt pattern and mounts.

Besides that I posted a crankshaft question in the 351C section cause all cranks I am finding in my price range are listed for 2 piece rear main seals when this block uses a 1 piece main seal. I cant justify spending $1200 for a forged steel crankshaft rated up to 800 hp for a 350ish hp 450-500 trq street engine.