351 Cleveland Cylinder Head Question / Opinions - Ford Mustang Forums : Corral.net Mustang Forum
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post #1 of 13 Old 05-10-2019, 04:44 PM Thread Starter
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351 Cleveland Cylinder Head Question / Opinions

I have an 89 coupe roller that's setup for racing (tubular k-member, fuel cell/system for carb, original 5-speed, etc....)

I am thinking of putting a 351 Cleveland motor in it? Its an original '71 351C CJ with 4V heads. If I go this route, I am going to rebuild it, as at this point I have 0 money in it.

I have a brand new set of original aluminum Trick Flow High Ports that are stage 2 ported with upgraded springs, retainers and keepers.

My question is, would these heads be good enough to make good naturally aspirated power over the reworked cast heads?

I have no experience with the High Ports, just understand they are a good cylinder head on the windsors.

All opinions are welcome!

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post #2 of 13 Old 05-13-2019, 04:15 PM Thread Starter
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Anybody? Anything?

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post #3 of 13 Old 05-13-2019, 04:38 PM
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I would think the modern design aluminum Trick Flow High Port heads would be superior to the 40 year old iron 351C 4V heads in every way. Would be a no brainier to me. I'd run the TF heads. If I didn't have a car to restore with the Cleveland heads I'd sell them to a numbers matching restoration guy.
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post #4 of 13 Old 05-13-2019, 05:18 PM
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The High Ports are for any 8.2(302) or 9.5(351W) block, and won't work on a 9.2" Cleveland block. So I gather you're talking about installing either the rebuilt Cleveland, or building another engine using the HP heads. That's an apples and oranges question.

I agree I'd try to find a person who needs the original Cleveland engine parts, and build a Windsor based engine with the HP heads possibly. It takes special thought and work to build a nice Cleveland, mainly due to the scarce intake choices, the different rare headers needed, and what to do for the heads. Stock 4V heads are light years ahead of any small block head, any makers, but they do have ports that all need adjusting to improve airflow and quality. Most people don't want to learn what they need, and hunt the parts to make the best of it all. It's a shame there aren't more intakes and headers to choose from, if there were there may be better aftermarket heads based on the Cleveland instead of the Windsor.

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post #5 of 13 Old 05-14-2019, 11:18 AM Thread Starter
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Quote:
Originally Posted by CDW6212R View Post
The High Ports are for any 8.2(302) or 9.5(351W) block, and won't work on a 9.2" Cleveland block. So I gather you're talking about installing either the rebuilt Cleveland, or building another engine using the HP heads. That's an apples and oranges question.
I didn't realize the windsor heads wouldn't work on a cleveland so thank you for that.

I have always wanted one (351C) because I know they are wicked and can make big power. For me the difference is the 351W can be made to be great whereas the 351C is already great but has a few flaws that need worked out. They were bred for racing in my opinion.
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post #6 of 13 Old 05-14-2019, 12:08 PM
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I don't know of an intake made for a Windsor head on a Cleveland block, but the aftermarket would be the only possibility, and it would be super rare if there was one. That's the reason Cleveland heads are hardly used, the few aftermarket intakes to put them on a Windsor block are tough to locate etc. Most stuff is aimed at aftermarket Cleveland heads and intakes, Edelbrock being some, and the cost of any of those would be $2k-$3k I think.

I'm aiming at a 351 Clevor, but not anything radical, just a solid 6000rpm 351 sized engine. Most people will want to take advantage of the possibilities, stroke it to 408-427 etc, rpm shifting at 7k or more. So your choices end up expensive and with very rare parts, some fab work etc, and thus hardly anyone will go to that much trouble.

A stock Cleveland like you have now is not expensive to rebuild. Though decent(few) intakes are available, you have to decide on headers, then carb, or whether to push to roller cam/lifters, maybe EFI(tuning trouble and costs). Your type of car and how it is driven should answer those questions.
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99 Limited mail vehicle, SOHC 4WD, later 306/4R70W swap. 1998 Mountaineer spare. 72 Ranchero 351 Clevor project.
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post #7 of 13 Old 05-15-2019, 10:46 PM
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The 351C CJ which stands for Cobra Jet came with the low compression 4 barrel heads and not the desirable high compression 4 barrel heads.

They called it a CJ because it came with a hydraulic cam that had the same specs as the 428 CJ cam.
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post #8 of 13 Old 05-16-2019, 11:28 AM Thread Starter
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The 351C CJ which stands for Cobra Jet came with the low compression 4 barrel heads and not the desirable high compression 4 barrel heads.

They called it a CJ because it came with a hydraulic cam that had the same specs as the 428 CJ cam.
With the engine coming from a '71, this makes sense.

With the heads being lower compression heads and I'm going to rebuild the motor anyway, would it make more sense to buy a domed piston set or mill the heads to raise the compression, IF I want to stay with the original heads?
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post #9 of 13 Old 05-16-2019, 05:01 PM
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If the head's ID mark (the #2 or #4 up on the top corner of each head) has a dot next to it (like .4), it is an open chamber, which is not as desireable. They are "ok" for a numbers matching build, but from a performance standpoint, not so much. They are known for spark-knock, at least more so than the closed chamber 351c 4V heads were.

Now if I were building one, I'd have to greatly consider head choice as part of the build. If all I had was open chamber heads (2v or 4v) , I certainly would reconsider using a 351c based engine in favor of a 351w stroker, especially in a Fox body. Don't get me wrong, I love the 351c, but I also love other engines too including the 5.4 4v and 5.0 4v, however, it needs to be weighed: How much are you willing to spend, how much work at you willing to do in order to make it fit, against the cost of doing a 9.5 deck, or for that matter a 460-based engine, modular or anything else.

If they're 4v closed chambers, they could be worth building but again, have to look at cost vs budget (among many other things). The 4v closed chamber heads are good heads even by today's standards. Thing is, though, they are heavy, and can get expensive to re-work with new seats, guides, springs, valves, seals, rockers, etc--not counting any porting. While they ARE good heads, they aren't all that great on the exhaust side, which can be fixed (with more money). Cut the exhaust ports off and then put a set of port plates on, then blend & port normally. Helps them out dramatically. They can easily put as much into a set of 4v cleveland heads as a new set of aftermarket aluminum 9.5 deck heads cost brand new.
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post #10 of 13 Old 05-16-2019, 05:01 PM
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Quote:
Originally Posted by Tom.S760 View Post
With the engine coming from a '71, this makes sense.

With the heads being lower compression heads and I'm going to rebuild the motor anyway, would it make more sense to buy a domed piston set or mill the heads to raise the compression, IF I want to stay with the original heads?

You need to take the heads off, to see which they really are, or diagnose the part number stamped in them under the VC. There were both kinds in the 71 models, CJ too, closed and open chamber. 1971 was the transition year, changing to lower compression. So a 71 CJ definitely has less compression, but early 71's had closed chamber heads. I never read of a date point that it changed during 1971.


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92 Mark VII LSC SE - soon OBDII and 4R70, GTC kit and 347, custom paint.
98 Explorer Limited project to add 4WD, XP8 parts, KB blower, paint, 337.
99 Limited mail vehicle, SOHC 4WD, later 306/4R70W swap. 1998 Mountaineer spare. 72 Ranchero 351 Clevor project.
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post #11 of 13 Old 05-17-2019, 08:11 AM
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Open chamber heads usually have a dot (or dome) next to the #4 on the corner of the head.

One can take a look at the head's corner and it will distinguish whether they're 2v or 4v. 4v will have a 4 stamped into the corner, 2v has either a 2 or sometimes no marking at all. It is visible with the intake on and the heads still on the engine. Some of the 351M and 400 heads just has no marking at all on them. Pic below shows a 351c 4V open chamber head.

One of the bad parts about a 351c is that the factory blocks aren't all that great. Sort of like a 302, but it's not so much the mains that are weaker, on the 351c it's the cylinders. The heads (4V) will support a ton of power, more than the block will take reliably. It hasn't been uncommon to split a cylinder or two on the factory blocks, particularly with detonation. I've done it with methanol and no sign of detonation; however meth engines need a LOT more fuel in the cylinder to run properly (A/F in the 6:1 range, or in my case bracket racing, we run them richer at about 5:1 for consistency and no appreciable power loss), and combine that with about 13:1 compression, there's a fine line to walk between destruction and good performance. Even with iron heads. That's where the open chambers aren't "as" desirable. In order to achieve 13:1+ with open chambers, it needs a big dome on the pistons + long stroke; and finding pistons with the right dome for open chamber heads usually means custom pistons. Most are designed for closed chambers. So that's one of those areas where little costs add up. Fixing the weak cylinder issue is a matter of sleeving all 8 cylinders. At $100+ per, it gets expensive, then add in all the rest of the machining costs such as line honing, stroker clerancing, lifter bores machining, and all the rest of the stuff that a 40+ year old block will need, and you're at Dart 351w block territory, not counting the heads, pistons, rods, packaging, etc.

The 351c has a following but one should put the pen to the paper and figure out a budget before choosing to use it.
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post #12 of 13 Old 05-17-2019, 01:04 PM
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I would do a custom hyd roller cam retro fit. In the right hands Cleveland 4V engines have great potential .Open or closed chamber......

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no one knows. thats the issue with EFI, too much guessing.
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post #13 of 13 Old 05-17-2019, 09:56 PM
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Back in the early 80's as a teenager I had a 72 Mach 1 Mustang with a Q code 351C CJ engine.

I eventually rebuilt the engine and replaced the low compression 4 barrel heads with the high compression 4 barrel heads.

I still have the low compression heads in my garage.
The 351C CJ also had a 4 bolt main block.
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