69 351w blower build

Don't use a 69 "low deck" block! They have a 9.480" height where the 71 and up blocks have a 9.503" height. That difference in height means the difference between your pistons having negative deck clearance (sticking up out of the block), and having ample clearance.

No one makes out of the box pistons for low deck blocks. Of course you can always have a shop mill them down if you really wante to use a 69 block, but why do that? We have built a lot of blown race and blown street 351 W's, some where the customer just had to have a low deck block. It's no big deal to mill the pistons down, but it isn't something I really recommend doing. It lowers the area above the top ring which on supercharged pistons, it pretty important so you don't implode the upper ring land under high boost / high heat conditions, or if you had the bad event of running lean or detonation problems. That area above that ring is there for a reason. Milling it off by "about" .020 or so" might not sound like much but it can be in some cases. Isn't it just easier (and cheaper) to just use a taller deck block?

69shocktower said:

Lets say I wanted to build a 351w block w a supercharger blower that would bolt right into my 69 coupe with a small bell C4. What do I need to think about. Id like to be able to use my cylinder heads too. Would 69 heads work on the second gen block with the higher deck height and bolt to the same tranny with same flywheel?

Im guessing for simplicity Id want to find the same older block.?

I know theres a website somewhere that has the diffs between the older and newer block.

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All of the 351W blocks (and all 351C blocks for that matter) have the exact same bellhousing bolt pattern, and it's the same as the 302/5.0L.

The cylinder heads were the same between the years with regards to fitment, with the differences in the areas of port and valve sizes, type of rocker arm mounting, etc. Each of these heads will physically bolt onto any of the blocks

HOWEVER--you probably wouldn't want to use them, because there is a SLEW of aftermarket heads out there that flow FAR better than the heads you have, and cylinder heads are the key to making power.

You can get a set of iron heads that flow really well for around $800 (several manufacturers), and a set of really nice aluminum heads for $1100-$1500, new--and quite a bit less if you shop around for a set of used ones.

Many consider the AFR 185's to be the best out-of-the-box heads for either the 302/5.0L and the 351W engines (and all sorts of engine sizes in between, like the 331, 342, 347 strokers), and I found (and bought!) a barely used set of them for $1100 a couple of months ago.

For factory iron heads, the GT40 or GT40P heads are hard to beat, but there are problems using the GT40P heads, including fitment problems with headers, due to the different spark plug angle, smaller combustion chambers, etc.

While you can build an engine yourself, if you're not completely familiar with the process, it might be a good idea to let an engine builder choose the parts and put them together for you . . .

Arron Johnson said:

No one makes out of the box pistons for low deck blocks.

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I'm sorry, but with all due respect, that statement is simply not correct.

Probe Industries

1.772" compression height

http://www.wiseco.com/Catalogs/Automotive/Ford.pdf

1.769" compression height

United Engine and Machine Co.

1.774" compression height

JEPistons.com | FORD - 351W FLAT TOPS

1.774" compression height

Block deck height: 9.48"
Rod length: 5.956"
Stroke: 3.5"

If you add the rod length and half of the stroke length together, you get 7.706"

If you subtract that from 9.48", you get 1.774", which is the compression height needed to have a zero deck on these blocks.

As a matter of fact, when I researched building my first 408 stroker several years ago, it appears that the OPPOSITE of what you stated is true--just about every single manufacturer I found built their pistons based on the 9.48" deck height blocks, NOT the 9.503" blocks; there are several examples of popular piston manufacturers listed above to illustrate this . . .

"I'm sorry, but with all due respect, that statement is simply not correct.

Probe Industries

1.772" compression height

http://www.wiseco.com/Catalogs/Automotive/Ford.pdf

1.769" compression height

United Engine and Machine Co.

1.774" compression height

JEPistons.com | FORD - 351W FLAT TOPS

1.774" compression height
"
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I'm sorry.... I thought he was building a blower engine. All of the links you provided seem to be for 11:1 flat top pistons. I didn't see any in the 9:1 or so area.

Maybe a few manufacturers are now making dished pistons for a 9,480" deck, but for years, they have all been making them for the 9.503" decks (SRP, JE, Sealed Power, KB, etc.). I don't use Probe pistons or the United Engine & Machine. Usually JE, SRP, or Mahle.

By the way, you don't want to use iron heads on a blown engine. It's just asking for detonation problems.

Arron Johnson said:

I'm sorry.... I thought he was building a blower engine. All of the links you provided seem to be for 11:1 flat top pistons. I didn't see any in the 9:1 or so area.

Maybe a few manufacturers are now making dished pistons for a 9,480" deck, but for years, they have all been making them for the 9.503" decks (SRP, JE, Sealed Power, KB, etc.). I don't use Probe pistons or the United Engine & Machine. Usually JE, SRP, or Mahle.

By the way, you don't want to use iron heads on a blown engine. It's just asking for detonation problems.

Click to expand...

while there were links I provided that listed an 11.0:1 flat top piston using the smallest combustion chamber size (58cc), that is irrelevant. Your statement was that there isn't any off-the-shelf pistond available for a 351W, and like I said, that's just plain incorrect.

The Probe link I provided shows pistons that have between 8.75:1 and 9.66:1 compression, based on combustion chamber size.

JE and SRP are the same company, but for the sake of argument, here is the SRP website link for the only pistons they offer for a 351W:

SRP.com | FORD - WINDSOR INVERTED DOME

There are four SRP pistons listed for that application with an inverted dome (for lower compression) and a 1.784" compression height, and two pistons with a 1.774" compression height in the same chart. The ones with the lower compression height are the lower compression of the two (under 9.0:1) . . .

Point being--one of the manufacturers you said you used for a low compression 351W has either the same compression height as the pistons I linked to, or they're .010" above the deck. Naturally, you wouldn't want to use those.

I wasn't able to find a Mahle piston catalog link that shows the compression height of their pistons, regardless of ratio, but I'd imagine they follow what appears to be the industry standard of building their pistons for the 9.48" block.

UEM is KB pistons, so if you've ever built an engine using KB pistons, you've used UEM. UEM is *also* the maker of Silvolite pistons, which are used far and wide.

Again, my point is that there are indeed a multitude of manufacturers that have off-the-shelf pistons available for the 9.48" block, and several different compression ratios including low compression.

As a sidenote--I was able to find very few actual 351W dished pistond from all of the manufacturers I looked at except for stroker applications.

Regarding iron cylinder heads . . . I'm not sure I agree with that one, either.

That's too broad a statement to make. There are mitigating factors, including any turbulence introduced by the port, the shape of the combustion chamber, whether there are any sharp edges in the chamber, the deck height clearance of the piston, etc.--those all play a factor in detonation.

69shocktower said:

So what are the options here? Last time I read up, the whipple twin screw sounded promising. But Id like some suggestions so I can contact them and get recomendations for a block setup.

Thanks,

Click to expand...

I haven't researched whether there are any bolt on supercharger kits available for this application, but there may be . . .

As far as the supercharger you use, that would be dependent upon the intended use for the car--positive displacement superchargers provide instant increases in torque at the bottom end, and centrifugal type blowers generally provide a higher peak HP figure.

Both of these options would use up some of the increased power because of the amount of power required to drive them.

As far as the block is concerned--it is said that the early blocks are the strongest, but the later blocks are far more prevalent.

Also, I believe in the mid-'80's, they started using 1-piece rear main seals (which is a LOT easier to replace, if required), and in the mid-'90's, the blocks were set up so that a roller camshaft could be used.

I am using one of the latest blocks for my 393 stroker, which came out of a '96 F250, and it has both the 1-piece rear main seal AND the roller cam setup.

It is said that the stock 351W block is capable of handling up to around 750HP--well more than what my combination will produce.

If you are really concerned about the power output, you might want to look into aftermarket blocks; you can get upgraded blocks from Ford Racing, DART, World products, etc., but you will be paying dearly for them--they are NOT cheap!

Therefore, if you are on a budget, my recommendation would be to use a stock block and build the engine with a combination of parts that will not exceed the capabilities of it.

I don't know if I've said this to you before, but if you are not familiar with the process of choosing the right combination, these choices are best left up to a competent engine builder.