CLEVOR ENGINE BUILDS The most popular, low-buck heads for making power from a small-block Ford are the 351W versions with a nice port job, which makes for a snappy 289/302 without selling the farm. But Bush Performance Engines in Fort Smith, Arkansas, has taken the concept a step further by bringing back the Clevor engine, a package that mates the large intake ports of the 351 Cleveland heads to the 289/302/351W blocks for affordable small-block performance. This is the next step up when 351W heads just don't get it done. Performing the swap requires some minor machining and a special intake manifold to mate the Cleveland-style heads to the Windsor block. Back in the '80s, B&A Performance offered these manifolds in both Street Boss (dual-plane) and Track Boss (configuration), with versions for the wider 351 Windsor blocks as well, but manifold production was discontinued several years ago. Bush Performance Engines has picked up the rights to produce the manifolds so they are once again available, except for the 351 Street Boss, for building street or track versions of the Clevor smallblock. To understand what it takes to build a 351C-headed small-block Ford, you need to know the differences between the Windsor-style and Cleveland-style engines. Because the 351C employs vastly different cylinder heads, with canted valves, than the 289/302/351W, the pistons are designed for a different combustion chamber. The 351C was available two basic ways: with four-barrel heads with large ports and closed wedge chambers, or with two-barrel heads with smaller ports and open chambers. The 4V heads perform best at high revs, making the most of those huge intake ports and high-compression wedge chambers. It does not make a good street head because torque is available only at high rpm. The 2V heads sport smaller, more street-friendly intake ports and open chambers for lower compression, facts that make the 2V head more useful on the street where good low-end torque is needed. The 2V head was also used on the later 351M and 400M engines. Heads Of The Pack When building a Clevor Ford small-block, the 351C-4V head is the best choice only if you're reaching for high revs. This head has huge ports and closed, high-compression wedge chambers. The larger ports work best at high rpm because that's where we have air velocity, which makes torque. Closed chambers yield higher compression ratios, which means power. The 351C-2V head is designed for lowrpm street use. It's perfect for a street driver because the smaller ports provide air velocity at lower engine speeds. Again, air velocity makes torque. The larger, open chambers yield a lower compression ratio for use with today's pump gas. With the right piston, you can achieve 10.0:1 compression with this head. The Australian Cleveland head offers the best of both worlds--smaller ports (like the 351C-2V head) for low-end torque and closed wedge chambers (like the 351C-4V head) for power increases. Aussie heads are also available from Bush Performance. Bush Performance modifies 351C heads for installation on the 289/302/351W block, eliminating one water passage while creating another. Bush closes off the 351C water passage between the head and the block. Then a passage is bored in the forward-most part of the head at the intake manifold, which allows coolant to flow to the 289/302/351W manifold and thermostat. The two 351C head types call for two types of pistons--one for a closed-wedge chamber and another for an open-chamber design. The 351C-4V piston is the same basic slug used in the '69-'70 Boss 302 engine because the Boss head is virtually the same as the 351C-4V head except for water-passage differences. (The '69 Boss 302 was actually the first application, from the factory, of the 351C-4V heads on a Windsor block). The common denominator for 289/302/351W power is the Cleveland head. Your mission determines head selection. For the street, choose the 351C-2V heads with the Street Boss intake. For track use, step up to the 351C-4V heads with the Track Boss single-plane intake.
The 351C-2V is the perfect street head due to its is right-sized ports and open chambers designed for loweroctane fuels. Bush Performance bores a cooling passage (arrow) in this head, which makes it a perfect match for the 289/302/351W-style intake.
The 351C-4V head is great for high-revving engines thanks to huge ports and closed wedge chambers. Bush Performance takes this head and bores a water passage (arrow) for the 289/302/351W induction. Bush Performance likes to build quality engines that stay together. This is one example, an E4AE 351W block that s machined and ready for a Clevor buildup.
The bottom end includes a balanced stroker assembly with forged pistons, cast crank, and cap-screw connecting rods. Piston selection depends upon head choice. These are pistons for the 351C-2V head with open chambers. This is a strong cap-screw I-Beam rod for Bush Performance s Clevor stroker. Because this is an I-Beam rod, it is affordable yet nearly indestructible.
The Street Boss Clevor gets the 351C-2V head. Bush Performance builds these heads with screw-in studs and pushrod guide plates from Competition Cams.
Bush Performance s 351C-2V heads get stainless steel valves and hardened valve seats, making them a street head for the long Special engine packages call for specialized gasket needs. Clevor Street and Track Boss engines get head and intake manifold gaskets available only from Bush Performance.
The 351 Windsor has a wider block than the 289/302 small-blocks, so it requires a wider intake manifold. This is the Track Boss intake for 351W applications with 351C heads. Because this is a single-plane design, it only makes sense for high rpm use. It is not designed for the street. Street Boss Clevors get forged pistons designed for the 351C-2V head with open chambers. Figure on 10.0:1 compression with this piston depending on compression height.
The beauty of the Bush Performance Clevor package is these guys have done the homework, making it easy for you to groove into 351C power without the Cleveland block.
351 Cleveland heads to a 351 Windsor block Looking for B&A Ford?? They are gone. However - Brand new news. Edelbrock is now casting a new intake manifold just for this swap! Yes! A brand new intake for you Clevor guys. Available in two variants, part number 7129 for a 302 block and 7183 for the 351w block. We are currently stocking the 302 intake for $319.95 and should have the 351 variant available soon (as of 1/1/08, check for current pricing). More updated info - Was sent an email referring to Price Motorsport in Indiana who manufactures various intake adapters and other parts for those interested in doing this swap. Anyway, back to the swap info :)... Follow me along and I'll give you all the details. Most of the pics here were scanned in from other places, I don't personally know where, but they have been useful to me anyway. Take a look! Well. Why would u want to do this? 351 Clevelands are great. What makes them great? Their heads. When Ford designed the first cleveland heads (aka Boss 302) back in '68-'69, they took a look at everything else out there and squished all the best ideas from everything into one neat package. Huge ports, big canted valves.. The first appearance of these was on a machine known as the Boss 302. This was basically a hipo 302 block with 351c heads on it. The 351c itself, however, did not appear until 1970. Unfortunately, the 351c block does have its shortcomings. A poorly designed oiling system combined with the thinwall casting leave some to be desired for heavy duty use. Not to say that the Cleveland's block is going to bring the average person problems (I have personally had a Cleveland with over 300,000 miles on it in perfectly good running order), but if you are building a real performance machine, this is the alternative. As for 351 Windsors - Their heads are nothing special really, simply a slightly larger version of your generic 289/302 heads. Smaller ports and valves don't flow anywhere near the way Clevelands do. The blocks, however, are well-designed, have a decent oiling system and are far less prone to failure. Not only are they stronger, but they are cheap and easy to find. Here's some specs to compare the two blocks: Engine Bore Stroke Main-Journal Diameter Rod-Journal Diameter Connecting Rod Length Firing Order 351 W 4.00 3.50 3.00 2.311 5.954 13726548 351 C 4.00 3.50 2.7492 2.311 5.780 13726548 There's a few basic areas that need to be modified to accomplish this swap.. I'll go thru each one:
Intake manifold: You'll be needing a special intake manifold. Obviously, for those of you building a 302-based motor, you could use a Boss 302 intake. Of course as time passes, these get harder to find and more expensive when you do. For many years there was a company called Bush Performance who was casting new intakes, both dual and single plane versions. They eventually became B&A Ford and continued production, however they are now gone as well. Their intakes are still out there to be found, but like the Boss intakes, are few and far between. Luckily, in late 2007 Edelbrock stepped up to the plate and is now casting brand new intakes in their Performer RPM/Air Gap series, calling them the "E-Boss 302" and "E- Boss 351", fitting either the 302 or 351w block respectively. As of this update, they are only available in a dual-plenum configuration, however are based on Edelbrock's "Air-Gap" design to increase the effective RPM range from 1500 to 6500 RPM. Oh, and in case you're wondering what's so special over a regular cleveland intake - Notice the water outlet - cleveland motors have a dry intake. Intake Gaskets You have a few options. Boss 302 intake gaskets have been known to work for the guys running 4v heads. FOr 2v heads you can take 2v 351c gaskets, and cut out water passages. Edelbrock claims that with their new intake manifolds, the answer is to run their intake gasket number 7265, but does not specify what head it's meant to work with, other than they say the port size is 1.52" x 2.16". The 7265 is their standard 351c intake gasket but it appears they are stamping out coolant passage holes that would just be left unused on a standard cleveland installation. If anyone's used a set of these for either a clevor or cleveland motor and can confirm any part of this, please let me know and i'll update this accordingly.
Pistons: Special pistons are also needed for correct compression and valve clearances. There are two types; flattops and popups, depending on the compression that you want to get. They are available from KB Performance Pistons, reachable at 800-648-7970 (Note: NOT "Keith Black" pistons, "KB" pistons www.kbsilvolite.com). They enable you to use the stock Windsor rod and work with either 2v or 4v heads. Table of compression ratios: KB 110 Piston (flat-top) KB 117 Piston (pop-up) Head Volume Compression Ratio Compression Ratio 62 11:1 12.7:1 66 10.6:1 12.1:1 76 9.5:1 10.6:1 Heads: A couple of modifications need to be performed to the heads themselves for coolant passages. [A] Coolant passages need to be plugged. [B] 0.80 inch hole must be drilled on each head. Use the intake gasket as a template for these holes.
[C] Remove these alignment pegs. [D] Use freeze plugs to block these end holes, if the heads have them. Head gasket and block: Head gaskets designed specifically for swapping Cleveland heads onto the Windsor block are available from Ford's SVO department at 313-337-1536. There are 3 holes that you must drill in the Windsor block, however, to match up with the Cleveland water passages. Use the head gasket as a template to mark these holes (3 on each side), then remove the gasket and carefully drill them out. Alternatively, you should be able to run Boss 302 head gaskets. Any notes on this from experience? Let me know and I'll update this page. Click here for the diagram of where to drill the block. That's about all that you will need to do this head swap. It's fairly straight-forward and doesn't require machine work besides drilling a few holes.you'll soon be making tons of power with your very own 351 Clevor!!