General Consensus on Replacement 351C Heads

Help Support

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Jun 16, 2021
Reaction score
My Car
1973 Convertible, Q code, 4 speed, 3.25, A/C, P/S
I'm slowly building up the engine in my '73 351C 4V Vert.

I've added an Edelbrock intake, AVS2 carb, and FPA headers (still waiting on the exhaust). I haven't touched the heads yet. I'm aware that the valves are a weak spot here, and I'm sure the springs are tired. Depending on cost, I'm thinking of forgoing the head rehab and dropping in some aluminum heads.

1. Is there a go-to aluminum "ready to go" head that people are using on the 351C 4V?

2. Will I have any issues mating an aluminum head to a cast iron block (expansion etc.).

This is probably a project for next Summer, but starting the research now.

I thought about aftermarket heads when I rebuilt my engine but the shop that cleaned everything suggested a head rebuild with new springs, better valves, viton valve seals, and hardened seats. I walked away with the total head rebuild for under $400 which I think is considerably lower than the cost of new heads. Good luck on you decision and build.


From what I understand, for aluminum heads you need to look to Ausie heads, such as CHI, AFD and Scott Cook (SCM). You will have to fork a lot of money for these plus I think you will need their own intakes. Cleveland Iron heads are excellent and even better if ported by someone that knows their stuff. Off course, you can reduce probably about 50 lbs from the front if you go with aluminum.

Edit: I forgot to include AFD - thanks Kevin!

Last edited by a moderator:
Trick Flow Twisted Wedge heads are good - but as vintageman said, expensive. Any quality aftermarket set of 351C aluminum heads will break the $2000 mark. Choices (as I recall from my build) were Edelbrock, Trick Flow, and CHI - There just aren't that many manufacturers making Cleveland heads. I do believe you could get good small chamber heads worked and ready to run for quite a bit less.

For the record, I went aluminum (Trick Flows) because I don't know a good local shop for head work, and I wanted some of the upgrades like a real quench chamber and 7/16 studs for adjustable rockers.

8F4C8197-E247-4D8D-9123-7F827110B1ED.jpeg71CB7F94-071B-49F0-AB40-2673D0B34417.jpegA0593372-06A7-4912-B23E-5962820AE6B3.jpegI got my heads from a manufacturer in Australia by the name of AFD.  Air Flow Dynamics. I love them. Work really well but as others stated they are not cheap. I believe Roy, Tnfastback, has the same set on his car. 

Last edited by a moderator:
I am kind of in this same situation you are. I know that I have to do my heads, and definitely change the valves. Aluminum would be the best way to go, but they are so expensive, and the small chamber Cleveland 4V head that my car came with is a really good head. I am leaning towards just doing a rebuild on my heads, as for the very mild build I am doing, I will not see a huge power increase with the aluminum heads. If this was a regular 302, or an earlier 289, I would definitely go with Aluminum, as the heads are cheaper, and those old cast iron heads just do not flow any air. Even on a mild build on a 289/302 you would see a substantial increase in performance. Having said that, if you have the funds, and do not care about originality, go with the aluminum heads. There will be no issues with good gaskets when it comes to mating the aluminum head to the cast iron block. I have always used the good Felpro performance head gaskets on cast iron block with aluminum heads with no issues. 

What do you plan to do with the car? I've kicked around the idea of alloy heads for a while but the only real benefit to what I do with the car would be knocking a few pounds off the nose and appearance.  And... I don't much care what people think about my engine. LOL!!

I don't need to go fast, I wanna go LONG!!

Last edited by a moderator:
I have heard good things about the Trick Flow Power Port 351C heads but, it is still going to be over $2K for the heads. The iron 4V heads (big and small valves) make good power with only a good valve job. Chuck

Thanks for the input, everyone. If I stick with the stock 4Vs, does anyone know an engine builder in New England that can rework stock heads?

To answer a previous question about what I'm trying to do, I don't have a firm answer. I'm not trying to make a race car, just something fun to drive that can push you back in your seat when you want it to. I don't have a horsepower goal in mind. I'm guessing something around 400 horsepower might do the trick?

I suspect I will do a cam after the heads. Nothing crazy as I want the car to be completely drivable.

Thoughts on a New England engine builder?

Thanks for the input, everyone. If I stick with the stock 4Vs, does anyone know an engine builder in New England that can rework stock heads?

To answer a previous question about what I'm trying to do, I don't have a firm answer. I'm not trying to make a race car, just something fun to drive that can push you back in your seat when you want it to. I don't have a horsepower goal in mind. I'm guessing something around 400 horsepower might do the trick?

I suspect I will do a cam after the heads. Nothing crazy as I want the car to be completely drivable.

Thoughts on a New England engine builder?
Then you are looking for a stock 351C 4V. That is exactly what you described. Trying to re-engineer this motor to meet your goals is just a way to empty your wallet.

It's all up to you, and the thickness of your wallet really. The Cleveland engine platform responds well to mods, however, keep in mind the realistic perameters of how the car will be used/driven. Almost all modifications will generally only show benefits at more elevated RPMs. Street engines need only to be "warmed up" ( better intake, better exhaust, ignition updates, carb update ).  As to an aluminum head swap, know that bigger valves and ports can hurt the lower RPM driving, so a gear change in the rear end may be extra cost not talked about much. If your stock 4v heads are replaced with aftermarket aluminum heads, you will be looking at aftermarket rockers, ( suprise hidden cost ), since the new heads will be fitted with guideplates, rather than the stock fulcrum guided rockers, This will require replacing the stock pushrods with case hardened pushrods, ( another hidden cost ), and the new heads may or may not require different length pushrods as well. Now that the stock 5/16th rocker hold down bolts are of no use, you will need to purchase, more than likely, a set of poly-locks for the screw-in studs, to hold your rockers down. More $$$$$. The stock valve covers likely won't fit over the new valve train, so you'll need to purchase aftermarket covers that will clear, along with new breathers most of the time, and fasteners to secure the covers. You shouldn't use stock un-washered bolts to hold down aluminum heads, add aftermarket head fasteners with washers.  If your spark plug wires are tailored around the stock height valve covers, many times a new wire set is going to be in your game plan, and of course, a different set of spark plugs. And so it goes.   Its all do-able, and my point is NOT to be a buzz-kill here, but simply to remind people of a thorough game plan when attempting modifications, and that cyl head "bolt-ons", rarely are.

Not sure where you live in proximity to Price Motorsports but they are the authority on the 4V Cleveland. Most headwork I know of with the 4V's end up with a car that kicks ass in the high RPM range but dogs it at the low end. The 4V heads are notorious for low airspeed until high RPM. These guys make port stuffers that you can glue in to the 4V head that make it massive in the low to mid RPM range. You will know the difference when you hit the gas. If I were you I would keep most of the money in my wallet and check these guys out to rebuild you 4V heads. You can also get your heads planed down slightly to increase compression then port matched to ensure you intake, port stuffers and valves all work together to produce the mid range power that is so much fun in these cars.
I have a set of 71 closed chamber iron heads on my 72 351Q code engine and it’s not a dog at all on the low end. A half throttle punch from a standing start and I’m spinning the tires with no problem. And at a 45 mph roll if I put the throttle to the floor it breaks the tires loose with no problems. My car is just a street driven car and it runs very well. I just got the right combination of high quality components and I couldn’t be happier with it. I completely rebuilt the engine, didn’t just try to slap on some heads.
The 4V heads work well with matched components. The problems start when a 9.0:1 CR engine is paired with a cam that has wrong timing events and way too much overlap (think Chevy guy selecting the cam). The first step is knowing you don't know how to select matching components. Step two is finding someone who does know how to select matching components. There is a lot more to building a well performing engine than most understand. The devil is indeed in the details, and all of them matter. Do what you can to raise the CR (mill heads, .035 head gasket) and have a 351C expert select an appropriate cam and valve train. This is a good place to start. Chuck
My own engine upgrade is very pragmatic. I drive on the street and will never see a dragstrip. My street racing days are behind me as well, still, I dig performance. I haven't finished a blog I started about the heads I'm using, but they are Aussie 302 closed chamber 2v port and valve sized, cast iron heads, no port work done. The custom pistons are forged DSS dished, ending up around 9.2 to 9.5 compression. The heads have been machined for screw-in studs and guide plates, and use single groove locks, stainless valves of stock 2v size. Rocker arms are big block Chevy stamped steel pieces. What these heads will give me is QUENCH, a much more efficient port velocity at street rpm's, and a ping-free chamber for use with todays ever-worsening pump gas. Aftermarket performance heads are all using some type of quench, as the stock 4v closed used . I have a valve train now that will handle more RPM than I will ask of it. The cam and kit is a conservative hydraulic Crane grind, .508", 266/280 on 112 LS (I have an automatic trans and power brakes,and A/C, so big cams are OUT ) dual-plane Edelbrock intake, 600 cfm Holley. ( I may try 750 ) Still running manifolds on exhaust as of now, but that may change . An aluminum head swap would have cost me more, for benefits I'll never use, but as it is, It's very responsive and hauls arse.
Last edited:
This video gives you an idea of what you can obtain for a relatively stock vs a mildly modified 4v cleveland. Many of the low-RPM complaints are due to an improper combination of parts and/or incompatible (bowtie-esque) cam profiles. That's not to say that a set of heads with modern port design won't perform even better, but these heads performed quite well, in their prime.

Did you guys catch, in the video preceeding about the 351 "M" code, that the builder chose to run the BBC style rockers, as I did? Pause the video at 6:39. The ball-pivot style rocker offers a more "self-aligning"lower friction action than the "sled" type used in factory 351c rockers. I, and they, are using aftermarket long-slot stamped rockers, ( mine are Crane),and are supplied with grooved balls which help in the lubrication department. I am using Ford factory stamped steel valve covers from a solid lifter 351c , kinda scarce these days, which have oil "fingers"on the underside to deflect the oil from the squirting pushrod hole in the rocker, to the rocker's pivot. Unlike the engine above, I am using the factory style "crimp- nuts"supplied withn the Crane rockers, they work just fine with the flat tappet hydraulic cam, and don't stick up above the screw- in stud, allowing room for the factory steel valve cover fingers to point down to the studs to oil the rockers.
Last edited: