The 302 Clevor

The Clevor Engine,

The Clevor Engine is an engine that can be called a rare build. Now a days, people get horse power out of alu heads, strokers and other power parts. In the early days people made power with the parts at hand or with junk yards parts. This oldskool method got my attention when a friend and mustang enthosiast, Michel, shared this info with me.

The Clevor is a windsor block with cleveland heads. Cleveland & Windsor
There are many methods for building a clevor as long as you mix Cleveland style with Windsor style blocks. The Boss 302 engine in 1969 was basicly a clevor, they fitted a Cleveland ( that came out in 1970 ) to a 302 block for race. They used a 4V head for the race
Before we go start the technical bit, something about my own build.
As you might have read i'm a sucker for old-skool stuff and love the stock look.
The overal outside needed to be plain and simple. I searched the net for the correct parts for the correct look. I wanted to give it the 1970 Boss 302 look, but not being a Boss.
I found a set of NOS alu valve covers, a 1993 5.0 roller block and a pair of 302C heads !!! Yes, 302C also know as aussie heads.

HEADS:
Normaly the thumb rule bigger is better applies, but in this case 2V heads will do the job for street use more then fine !

In this case I used a pair of 302C closed chamber 2V heads with a combustion chamber of 58-62cc.
We milled the 5/16 to fit ths boss size 7/16 studs and used a 1.72  ratio rocker with roller tip.

Example of stock aussie heads.  

( the ported flow test does not concern in my build )

The reason why its so rare is because its not an easy fit. Its needs manufacturing, some welding and measuring. The problem is that the water on Clevelands flow through the block and in a Windsor through the intake manifold so it needs a water passage in the head and a freeze plug in the original passage of the Cleveland head ( see pictures ).

with the Cleveland style square water passage still in place ! 

 With the Cleveland style water passage blocked with a freeze plug

Close up:

Close up blocked:

The close chamber 302C 

Water passage needs to be drilled

Use the gasket for measurement and make the hole large enough for better cooling.

[ note : I made two mistakes, I let the hole drilled a little to small in the first place and for some reason I drilled two holes in each head ! stupid I know, only one is needed. Because I used the gasket for measurement, that gasket had 2 placed ! you only need on on front for each hole head. 

Before milling the 5/16 to 7/16

Sorry for the quality of this articel, its a scan from an old magazine. I tried to enhance it the best I could buts you might be able to make it out and I'm happy to send it to you by mail if needed !

A interesting artikel in Mustang & Fords

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 small-block. 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 low-rpm 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.

source: http://www.mustangandfords.com/techarticles/engine/30220_clevor_engine/viewall.html#ixzz2K8RxpoSq




The entire engine is build up from bottom and all is checked, cleared, decked, ported and such at Post & Drost in Dronten ( Holland ) 
BEWARE: Pics are not in order ! 

The intake ported and matched to the heads

Stuppid as I am, I put 2 water passages holes in the heads... ofcource, the intake has only one passage so this has to be plugged agian 

TDC 

 Fluid damper

 Boss oil pickup

 Rocker studs resiced to 7/16 boss specs !

See interesting articles for Clevor related articles and scans ! 
http://302clevor.blogspot.nl/search?updated-min=2013-01-01T00:00:00-08:00&updated-max=2014-01-01T00:00:00-08:00&max-results=5

The intake manifold

Getting an intake manifold for this build was rather easy althoug this wasn't a few years ago. 
In the mid 80's B&A made a few good Clevor intake's. One for the street and one for the track.
Now, you can get those at Tim Meyers shop : http://tmeyerinc.com/B&Aintake.html
These are re-casts from the originals as far as I know.
Every once in a while you can score one on ebay, an original.
I decided to get one from Edelbrock because of the price. It is a nice intake and does its job as far as we can concluded. One detail, the head gaskets don't line up that good on the intake. 
In the pictures above you can see clearly how much matching was needed to fit and flow propper.

the B&A 302 Street Boss

 the B&A 302 Track Boss
better used with 4V Cleveland Heads !

The  302  E-Boss from Edelbrock



Some extra pictures of the build and detailing of the engine