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Since I got my car I have spent a lot of free time freeing up the engine that sat for over 15 years.

My plan was to get it running and then slowly freshen up the car one system at a time instead of doing the complete teardown and not driving the car for a year or more.

I got it moving, then I had to deal with some stuck valves. Then I did a compression test with some cylinders being great and others being awful.

I did the rope in the cylinder trick, removed the springs, and spun the intake valves back and forth in their seats with a right angle drill.

When I was done, all but two of the cylinders were 155-165 psi on compression (dry), which I thought was pretty impressive under the circumstances. I was attempting a do-over on one of the low cylinders when I dropped one of the valve locks into the nether regions of my engine compartment (not the engine thankfully). I can't find it. I have run a magnet everywhere and blown compressed air all around as well. It must have fallen into a frame rail, be sitting in part of the engine mount, or I inadvertently kicked it across the garage. I even dropped the other half on purpose a bunch of times to try and see where it might have gone.

In searching for a replacement valve lock (located one that I can pick up in the morning) I discovered many tales of woe involving the stock valves.

My dad has 2 spare Cleveland blocks in his garage that came out of Mustangs headed for the crusher so I was willing to stick to my plan above and just run what I have until I got fairly strong evidence this morning that this is probably the original block. I don't have either motor or body tag, but apparently this car and others made around the same time never had them. My engine is stamped with a number that is 5 away from the number on a car that is 6 away from my VIN.

If I am keeping it under 6000 rpm and just driving back and forth to cars and coffee type stuff am I risking catastrophic block damage with those valves?

If it matters, I think I have closed chamber heads - 4 on the corner with the dot but the date code shows they were made in December of 1970.
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The valve heads are brittle. Clamp a normal steel valve in a vise by the stem, grab the valve head with a wrench that has some leverage (large channel locks, pipe wrench, etc) and you can bend the stem. Do the same with a Cleveland valve and the valve head snaps off.

They develop cracks below the section where the valve head is welded to the stem. The cracks start-off very small, microscopic, and grow larger over time. The cracks lead to the valve head breaking completely off the stem and bouncing around inside the cylinder while the engine is running. Often putting holes in pistons, cylinder heads, and/or cylinder walls.

The question is what starts them cracking? For that I have no answer. Now the Cleveland is not the only gasoline engine that has had this problem, others have been plagued by this same malady. I've read all sorts of theories about what starts them cracking ... constituents in fuel for example ... but there is nothing definitive that I'm aware of.

I remember walking into a wrecking yard circa 1974, and inside the office they had not one but two Cleveland engines sitting side by side in the corner. Both engines had one head removed, exposing a cylinder with damage from a broken valve head. Both engines had come in within the last month. They were almost new, no more than 2 or 3 years old. On the other hand I know several guys who put 200,000 miles on a Cleveland without a problem. There are Panteras still today, like yours, equipped with the OEM valves. I know one guy who had a valve head fall off the stem while his Pantera was warming up, idling, in the driveway. I also know guys who raced with the stock valves. RPM doesn't seem to have anything to do with valve failure.

Nobody can guarantee you that out of the 16 valves in your car's engine, one of them won't fail. But nobody can predict if and when they will fail either. A failure is usually quite expensive to repair as at least one of the castings will end-up with a hole or crack in it. Each day you start an engine equipped with the OEM valves is a toss of the dice. That's really the best answer I can give you.

The only sure way to avoid failure is to replace the valves. You don't have to install an expensive set of stainless valves, a good quality set of steel replacements designed for 4 bead locks will suffice for applications up to 6200 rpm rev limits, at a much lower cost than the stainless valves. The last time I checked Speed Pro (Sealed Power) had the 2.04 intake valve and the 1.65 & 1.71 exhaust valves in low cost steel replacements, but not the 2.19 intake valve. But I haven't done an exhaustive search.

351-C valve breakage has to do with metallurgy and that is not visually ID-able. The safest thing is to replace the stock valves with one-piece valves. Being one piece, they will NOT be 45-yr old OEM (which is good) and will not have been welded. Warning: cheap stainless steel valves can also be made by welding a head and stem together, and whether the cheap alloy or the welding is to blame for breakage is irrelevant. YOU are the one that has to sweep up your engine and start over. The offshore valve makers will not care either. Good luck- you've been warned.
So if someone (OK, me...) was planning to replace the stock original valves with good steel or stainless-steel valves, what specific valves (make/part numbers?) would you recommend for an original '71 high-compression Cleveland?

What's the cost/benefit differential between stainless and regular steel?

stock replacement valve lengths are listed as;


MELLING V1172 4 groove, Head Dia 2.19", 5.234" OAL

MELLING V1174 1 groove, Head Dia 2.19", 5.234" OAL

SEALED POWER V2075 4 groove, 2.04" Head Dia, 5.231" OAL


SEALED POWER V1879 Head Dia 1.71", 5.05" OAL

SEALED POWER V2030 4 groove, Head Dia 1.65", 5.05" OAL


Ferrea 5000 series are popular 1 piece single groove SS upgrade valves

F5037, Head Dia 2.19", 5.30" OAL

F5045, Head Dia 1.71", 5.06" OAL

size variations, 6000 & Competition series also


Si Valves came up the other day too,

Alex's Parts has a good reputation on the Old Cleveland Forum


FWIW it may be a good idea to let the shop take a look & see what you're working with before buying anything. you could have or need oversized guides and valve stems, and/or you may want an oversized valve head diameter to avoid having to replace seats. there's all kinds of repair tricks available. then you can source proper springs, retainers and locks the first time or better yet let the shop order the smalls in case they need to be returned / swapped for a different part number. it can take some jumbling on the bench to get all the clearances right, let the man work LOL. 'homers' get into all sorts of twists & fits trying to beat the learning curve

Originally posted by Mark Charlton:

... What's the cost/benefit differential between stainless and regular steel ...

Everybody wants guide lines. So for folks who need benchmarks, guidelines, and limits I tell them 400 horsepower and/or a 6200 rpm rev limit. If you want to have more horsepower or a higher rev limit you'll need to spend the money on ALL the parts needed for higher rpm.

If your Panteras engine is to be rev-limited to 6200 rpm it doesn't need stainless valves. Sealed Power has 2.041/1.655 steel valves (p.n. V-2075 and p.n. V-2030) for $136 USD per set. Sealed Power has no current listing for the steel 4V intake valve, I've found steel 2.19 intake valves to be currently hard to find amongst my normal sources. The Melling V1172 listed by 4V&Proud would be a good recommendation if you can find it. But the 1.710 steel exhaust valves, Sealed Power p.n. V-1879, are available for $128 USD per set of 8.

If your Panteras engine is to be rev-limited at higher rpm it DOES need stainless valves because (1) they are lighter weight and (2) their stems are designed for tight fitting single key locks. The valves are just one set of several parts that must be upgraded to operate the engine reliably at higher rpm.

But those are only two of the reasons for choosing stainless valves. Stainless intake valves (3) are available as “Racing” valves which are equipped with valve heads which increase air flow and are lighter than standard stainless valves. If the cylinder heads are equipped with 2.04 intake valves then (4) stainless valves make it possible to substitute 2.12 diameter valves in place of the 2.04 diameter intake valves. Manley 2.125/1.655 stainless steel valves (p.n. 11344-8 and 11807-8) are $438 USD per set; Manley 2.19/1.71 stainless steel valves (p.n. 11872-8 and 11805-8) are $390 USD per set. All these prices are from Summit Racing.
Gentlemen, thank you very much for your detailed and clear responses. I don’t push my stock 22,000 mile engine much, but really don’t like the thought of it grenading itself on a diet of valves. Since I’m contemplating pulling it out of the car to deal with replacing oil seals, valve guide seals and the timing assembly, it seems it might be worth doing the valves as well. I appreciate your input and suggestions.


Great thread here. I just bought a set of 4V heads (D1AE closed chamber) that I need to take apart to see what has been done to them. Looks like the guide seals were changed but not sure if the valves are still OE, if they are OE I will be changing them. Interesting to see the mention of Alex's Parts in this thread, I was always surprised and frankly a bit leary that their prices are so low, yet the reviews (as 4VANDPROUD mentioned) were pretty good. 

Last edited by tomsealbeach

If you are going to pull the engine for this work, have someone check valve-stem-to-guide clearance to ensure new unworn valves fit properly. With all OEM iron heads, the valve guides are part of the casting. To use replacement guides, the originals must first be drilled out, the holes reamed to size and new replacements pressed in, then reamed again to valve stem size. Or you can have good guide bushings installed and avoid the drilling step. All this at about $100/hr costs $$$$, which is why it's often cost-effective to buy new aluminum heads that already have the guide work done, a competition valve job and  thick, flat, uncut deck surfaces. They will be configured to Boss-351 specs.

Plus you lose around 30 lbs from each head, which makes later working on an installed engine far easier, and you gain better airflow & more power from repositioned intake & exhaust ports. But if you do this, stock headers will not bolt on without rework. If the wt savings interests you, another 40 lbs can go away with a matching aluminum intake & aluminum waterpump & pulley, to total over 100 lbs gone from your engine. That's like NOT always having a passenger riding with you, in terms of fuel mileage and performance gains.

Note that nearly every advantage above becomes iffy when cheaper chinese castings and/or valves are involved. Also note that ''CHI'' brand aluminum heads are made in Australia and are fine to use. If you paint aluminum heads Ford-blue, all but the most anal onlookers will think it's 'stock', if that matters to you. One early racer (who shall remain nameless) once used a coat or two of iron-based paint, then Ford blue on top so a magnet would stick to his alloy heads during inspections. If your locale still has smog checks, this could help.

I would certainly enjoy not having to heave those heavy beasts around again.  I took them off the engine solo with the engine still in the car.

Are there aluminum heads that will work with my existing headers (that bolted up to the factory heads)?

They look like these.  I thought they were Hall big bore headers, but not sure given the independent flanges.s-l400 [5)


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  • s-l400 (5)

Perry, stock iron 4V heads weigh 60 lbs each plus the weight of all steel valves, springs, retainers, pivot-studs & rockers.  I use block studs to hold the heads  more securely against blown head gaskets but they preclude pulling even my aluminum SVO heads with the engine in the car. As for those stock GTS headers not fitting some alloy heads, it's the bolt pattern in the header flanges that doesn't match up. If you own a drill and some hand skills, that can be remedied at home- as I did on mine in the '90s.

Ok.  Good to know.  I definitely have a drill.

I am still not sure these are GTS headers.

The collector looks different from the GTS headers - at least the ones sold here (I don't have any other frame of reference, so you guys that have been doing this longer than me may know better).
lso at Hall:


The ones in the attached photo are like mine (from an eBay ad).

Here is an old post where the 3rd message shows a ceramic coated set like these that the owner thought were Hall Big Bores...



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  • s-l500

Be careful with cheap on-line BBC valves; OEMs had 3/8" valve stems while aftermarket are 11/32" and will fit a 351-C. I suppose one could have stock Ford iron guides bored out to 3/8" and gain considerable weight- which will limit rpms. Stem lengths also vary, making pushrod length a variable as well with such a combination. To use an adjustable valvetrain, the engine needs hardened pushrod guides so at least 3" of one end of all 16 pushrods will need to be hardened. Stock 351-C pushrods are not and will wear in two, while spreading steel scrapings throughout your engine. There are no cheap shortcuts in building a 351-C.

Check your "ss" valves for magnetism; some places weld ss heads to plain steel stems so some parts of such a valve will be magnetic. What we're advocating is NOT having a weld (and potential failure at speed) to deal with, not whether there's stainless in there or not. And there are some odd mixes of stainless steel that are no good for severe service like in an engine valve. A few will actually rust and are weakly magnetic. Far east backyard shops also make up their own "grades" of stainless and other metals that the SAE have never seen before. Name brands with years-long good reputations are best.

Hi Jack...good advice as usual. I checked my valves that are out for a head rebuild (71 4V) and very interesting, the intakes are VERY magnetic, yet the exhausts (with rusty tips) are still magnetic but barely. I would love to know what they are, but the heads have been rebuild and there are things I don't like, so anything but the actual head casting is likely going to be replaced.  

Way back in the mid-60s, GM, Ford and others used a nickel alloy for the hotter-running exhaust valves, welding them to a mild steel stem for penny-saving. My '65 Corvair had such exhausts that were thus magnetic only on the stems. Back then engines seldom turned even 6000 rpms so most owners didn't notice the weld was a potential weak spot. Except on hard working air cooled VWs or 400 Ford motor homes climbing a long hill in summer towing a trailer....

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