The 351 C Swap is mostly bolt in. The best move is to puchase a tubular k member--mainly for header clearence. The cleveland makes torque through a wider band than all modern engines. It still remains the most modern push rod engines. If I did not have it would likely build a mod engine. The modular engines are great, but more costly than the cleveland.
All you have to do is look at one. The 335 series was designed by Gapp and Roush at FoMoCo in the late 1960's--early 70's. It has a dry intake manifold canted valves, and large valves: .205 for the 2 barrel version, .219-.225 for the 4 bbl. The ports for the exhaust and intake are huge. The Chevy sb2 are an atttempt to capture some of the aspects of the cleveland. The Cleveland is the basic design used in NASCAR for the Fords.
It is what as known as a semi hemi. The spark pluge is not centered, but it is rotated slightly to the exhaust valve. As far a hemi is concerned it is also a throw back. It is hard to say what numbers the 335 series engines would be like using modern fuel injection and more products available to it.
The benefit(s) of swapping in an engine for whatever reason trips your trigger
will pretty much be helped/hurt by what you intend to do w/ it after it's done.
A 600 hp Cleveland w/ 4v heads that is cammed big enough to make that power N/A is doing it well over 5500 RPM. That, coupled to the fact that the compression forces you to use non-pump gas, and that imo makes it a short drive cruiser at best. Gas mileage will be laughable, off-idle drive-ability will be sluggish, and it'll just be a P.I.T.A.
And as big as the 4v intake port is, the exhaust is a mess, and most racers, including Glidden heavily modified the port to fix the crappy design, raise the floor, and reduce overall exhaust port size.
Now if your building a dual-use weekend warrior, and you want to impress the cruise-in crowd w/ the smell of burnt $7-8.00 dollar a gallon gas, then I say go for it. Don't expect any wow factor, at the show circuit, as most of the current crop of "enthusiats" will just think you've thrown a set of cleveland heads on a windsor.
If you're gonna drive it more than 50 miles a week, otherwise fix the 4.6 and save the cleveland for a drag car or whatever off road project you wanna throw it in.
will pretty much be helped/hurt by what you intend to do w/ it after it's done.
A 600 hp Cleveland w/ 4v heads that is cammed big enough to make that power N/A is doing it well over 5500 RPM. That, coupled to the fact that the compression forces you to use non-pump gas, and that imo makes it a short drive cruiser at best. Gas mileage will be laughable, off-idle drive-ability will be sluggish, and it'll just be a P.I.T.A.
And as big as the 4v intake port is, the exhaust is a mess, and most racers, including Glidden heavily modified the port to fix the crappy design, raise the floor, and reduce overall exhaust port size.
Now if your building a dual-use weekend warrior, and you want to impress the cruise-in crowd w/ the smell of burnt $7-8.00 dollar a gallon gas, then I say go for it. Don't expect any wow factor, at the show circuit, as most of the current crop of "enthusiats" will just think you've thrown a set of cleveland heads on a windsor.
If you're gonna drive it more than 50 miles a week, otherwise fix the 4.6 and save the cleveland for a drag car or whatever off road project you wanna throw it in.
The exhaust port is an area the Cleveland can be improved by "extensive welding is often employed on the exhaust port floor to raise the flow activity higher in the port. The roof is also ground away as much as possible to maintain and adequate cross section. This is not as effective as the port-plate method used in Pro-Stock drag racing, but any reduction in the exhaust restriction will greatly improve cylinder head perfornance" SA Design Ford engines book page 101.
The Cleveland heads include the 4bbl, CJ, Boss, H.O. and 2bbl. Either of these heads are superior to other pushrod small block heads. I have never heard of anyone puting a set of the Windsor heads or 302(5.0) heads on a 335 series engine.
The compression on the stock Boss head was the highest in 1971, and it was 11.7 :1, it would be wise to not to use the pop-up pistons on a engine using today's pump gas. Flat top pistons would reduce it to 10.7:1, this might be pushing the limits and require some additives.
Another point of the 335 series is that the coolant passes through the head and then the block; this is another aspect the later model chevy engines now use.
If I had a Mustang with the 4.6 mod motor in it I would stick with it. A rebuild for use with a supercharger would be the path I would take. Most people with the 4.6 want more CI. A super charger would be the closest replacement for CI.
I have had a cleveland for the past 19 years, a 2bbl, 4bbl--CJ, and now the BOSS. I have searched the net and my local area and have not found anyone with more knowledge of the 335 series than myself. The post by MadMike is evidence of the general ignorance people have of the 335 series engines. The best example is his post
I suppose the 335 series, short run contributes the general lack of knowledge. Most people the purchase an early 70's model Mustang the still has a 335 series engine in it pull it and install a 5.0 or 5.8 Windsor not knowing what they have.
The modular motors of today has been around 4 times longer than the Cleveland motors. One thing I wonder about is that the early 90's models in the lincoln MKVIII had 4.6 modular engine that had 285 horse power. Why did it take as long as is did to break that HP rating.
The Cleveland engine program was ended in 73 with Ford destroying all perfomance research data and throwing parts in dumpsters and Gapp and Roush departing from Ford and relocating down the road. One can only guess at why this happened. I feel that the only reason Ford and other manufactures are producing High horsepower cars now is all of the safety features that have been added to cars now.
That last bit of advice I do not understand at all. Why would you want to restrict the exhaust? Baffling. I have some literature to back up my claim.
You would only need this modification if you intended on high rpms over 8000.
I suppose the 335 series, short run contributes the general lack of knowledge. Most people the purchase an early 70's model Mustang the still has a 335 series engine in it pull it and install a 5.0 or 5.8 Windsor not knowing what they have.
The modular motors of today has been around 4 times longer than the Cleveland motors. One thing I wonder about is that the early 90's models in the lincoln MKVIII had 4.6 modular engine that had 285 horse power. Why did it take as long as is did to break that HP rating.
The Cleveland engine program was ended in 73 with Ford destroying all perfomance research data and throwing parts in dumpsters and Gapp and Roush departing from Ford and relocating down the road. One can only guess at why this happened. I feel that the only reason Ford and other manufactures are producing High horsepower cars now is all of the safety features that have been added to cars now.
I have worked on many Clevelands and a couple Boss 302 (the first "Cleveland" actually) over the years. If you look at the exhaust port the floor drops and expands too fast at the exit. "Real" race Clevelands you would machine off the outer 1" or so of the head and run a 1" plate which raised the port properly.
Basically the intake port was ahead of its time and the exhaust port was designed around easily fitting the package in a late 60's Mustang shock tower which really hurt it.
Cleveland heads continued on in the "Modified" 400 and 351M series into the late 70's. Some of those had even worse exhaust ports with large water filled exhaust valve guide bosses. Australia continued the 2 barrel closed chamber Cleveland head for a much longer time as well.
Fords original idea for this series was a Tunnel port head like what was used on the FE motors. In the Tunnel port the pushrod went through the center of the intake port in a tube. The race shop I used to work at still has a set of these rare 302 Tunnel port heads hanging on the wall........Anyway the head design was changed from tunnel port to canted valve like a baby 429 head (which also uses many of the same parts) and used first in the Boss 302, then in the Cleveland series the next year.
Ford has done some stupid crap over the years and building both the 351 Windsor and Cleveland at the same time was one of them, not to also mention 2 completely different big blocks series were still being done those years as well.
You are only restricting them in the area that has near zero flow anyway (floor of the exit) This raises the velocity which is something people forget to look at (and something the Cleveland head is definitely not know for in street RPM ranges)
I have the 351 BOSS and have turned 8500 rpm's and it really comes to life after 5000 RPM, and I will add it is not a slouch through the lower rpms either. I have addressed the low rpm velocity in the intake with an Offenehauser 360 dergree duel Port intake manifold. As far as the Exhaust is concerned the port plates are superior to any other mod.
One problem I have had with the BOSS head is finding the right Spring cups. I ended up using some that I had to modify. The only thing I found online is a fellow that used freeze plugs that he drilled out.
One problem I have had with the BOSS head is finding the right Spring cups. I ended up using some that I had to modify. The only thing I found online is a fellow that used freeze plugs that he drilled out.