351 2v to 4v conversation

[73FastBk]

So fellas I’ve been doing plenty of research but wanted to talk to the guys here who know or have done similar swaps. I have a 351C 1973, I just got a set of 4v closed chamber heads. As of now I need a carb and also looking for a good dizzy.

My question is what is a great intake manifold that’s a true 4v size and also dizzy combo. I’d like to keep the dizzy smaller size not the huge cap.

Also what’s a good stall rpm? I’m still learning about that stuff which is over my head atm haha. Ty in advance!

 

[Sheriff41]

It really depends on your goals for your car. Dual plane intakes are more street friendly (better low-end response) while single plane intakes provide top end performance. Either will work with the right combination of engine parts and driveline mods.
Blue Thunder makes a dual plane intake that works well on the 351C 4V heads. If you have Ram Air, though, you may have clearance issues. The Edelbrock Air Gap intake is designed to work on both 2V and 4V heads and has decent dyno numbers, according to some online reviewers -- do a Google search and see for yourself. I run an Edelbrock 351 4V Performer RPM since it was what was available back then. No complaints. There's a few others out there from Offenhauser and Weiand, but I'll defer to other's opinions on these.
There are several good ignition systems to consider. If you're running a carburetor I like the Ford Duraspark 1 setup. There are different Pertronix setups members on here use -- some have opinions on these.
If you're planning to go fuel injection ask some of the members on here which ignition systems work with EFI.
Stall speed depends on you cam profile and gear ratio. You'll want to do your homework on these to get a combination that works well before spending your money on anything.
You need to think about a cam that will help you take advantage of the 4V heads. Many are converting to roller cams for the benefits provided. Again, you need to think about how you want to use your car and choose a cam that helps achieve your goals.
Also, consider what gear ratio will compliment your combination and objective.
Finally, ask plenty of questions on here. We are fortunate to have some knowledgeable straight shooters that will give you some honest feedback.

 

[kcmash]

So now that you have the "cool" heads, yep, ask yourself what your goals are. I am set up like Sheriff41. 351C with quench chamber 4V heads, adjustable valve train, roller cam ground to Boss 351 Specs by Cam Research, an Edelbrock Performer RPM intake that reduces the intake port size and a Pertronix 1 electronic conversion. This is backed by a 4 speed and a 3:25 limited slip rear end.

I don't race mine. I do like to have fun with it. It's very driveable on the street and to cruise nights and shows. On the highway I turn about 2100 RPM at 70 MPH, so its fun on the highway too.

I have a couple Duraspark Dizzy's in the garage. That will be my next performance upgrade, mainly for a smoother ignition.

Remember the 351 4V was developed for NASCAR performance. The intake and exhaust ports are great for higher RPM, but struggle on intake velocity at idle. That is why the Edelbrock is a good choice for daily driving.

 

[jpaz]

I have a 72 Q code mach1. I changed the heads to the 71 quench heads with a Blue Thunder intake and a 735 cfm vacuum secondary Quick Fuel carb. 350 gears and a True Trac Posi. C6 auto with a 2800 stall converter and it runs great! It has a Crower flat tappet cam and hydraulic lifters with Crane Gold roller rockers, it’s a really great set up. I need wider tires though, it will break the tires loose at a 45-50 roll. I can give you more specifics if your interested. The guys on this site really helped me out with figuring everything out, especially Chuck. He has an extremely nice 72 Mach1, one of the nicest restored cars on this site, along with quite a few others too.

 

[73FastBk]

I have a 72 Q code mach1. I changed the heads to the 71 quench heads with a Blue Thunder intake and a 735 cfm vacuum secondary Quick Fuel carb. 350 gears and a True Trac Posi. C6 auto with a 2800 stall converter and it runs great! It has a Crower flat tappet cam and hydraulic lifters with Crane Gold roller rockers, it’s a really great set up. I need wider tires though, it will break the tires loose at a 45-50 roll. I can give you more specifics if you’re interested. The guys on this site really helped me out with figuring everything out, especially Chuck. He has an extremely nice 72 Mach1, one of the nicest restored cars on this site, along with quite a few others too.

First Thank you for the response. This is more or less what I’m going for, I want something that isn’t crazy but I’d like to have enough power to make the tires break at 45-50 mph ). My dad bought this stang when it was new and he gave it to me with the promise of taking care of it and giving it a nice refresh. Right now ive got the heads and a 4v performer intake. But I wanted to see what was the best options since I still have time before sending it to the shop. Im basically sending it for a full rebuild from the front to the back. I just want to buy all the part now so that the shop has everything the need. Im super excited but still have a LOT to learn. I had no clue how many variations of Cleveland’s there were until last year. Haha

 

[73FastBk]

So now that you have the "cool" heads, yep, ask yourself what your goals are. I am set up like Sheriff41. 351C with quench chamber 4V heads, adjustable valve train, roller cam ground to Boss 351 Specs by Cam Research, an Edelbrock Performer RPM intake that reduces the intake port size and a Pertronix 1 electronic conversion. This is backed by a 4 speed and a 3:25 limited slip rear end.

I don't race mine. I do like to have fun with it. It's very driveable on the street and to cruise nights and shows. On the highway I turn about 2100 RPM at 70 MPH, so its fun on the highway too.

I have a couple Duraspark Dizzy's in the garage. That will be my next performance upgrade, mainly for a smoother ignition.

Remember the 351 4V was developed for NASCAR performance. The intake and exhaust ports are great for higher RPM, but struggle on intake velocity at idle. That is why the Edelbrock is a good choice for daily driving.

Sounds like my idea of 3.55-3.73 gears might be too high then. Like I was telling sherif, I don’t play on going faster than 65 on the highway. Unless of course I was break the rear tires from time to time. I do want to take advance of the high RPMs though. Just trying to figure out what’s a “tried and true” setup no matter the price. I’ve been debating on ordering the Pertronix/duraspark dizzy or just go all out on the ICE ignition made in Aus. I just haven’t seen enough reviews on them to know if it’s worth the $1200. Thank you guys!!

It really depends on your goals for your car. Dual plane intakes are more street friendly (better low-end response) while single plane intakes provide top end performance. Either will work with the right combination of engine parts and driveline mods.
Blue Thunder makes a dual plane intake that works well on the 351C 4V heads. If you have Ram Air, though, you may have clearance issues. The Edelbrock Air Gap intake is designed to work on both 2V and 4V heads and has decent dyno numbers, according to some online reviewers -- do a Google search and see for yourself. I run an Edelbrock 351 4V Performer RPM since it was what was available back then. No complaints. There's a few others out there from Offenhauser and Weiand, but I'll defer to other's opinions on these.
There are several good ignition systems to consider. If you're running a carburetor I like the Ford Duraspark 1 setup. There are different Pertronix setups members on here use -- some have opinions on these.
If you're planning to go fuel injection ask some of the members on here which ignition systems work with EFI.
Stall speed depends on you cam profile and gear ratio. You'll want to do your homework on these to get a combination that works well before spending your money on anything.
You need to think about a cam that will help you take advantage of the 4V heads. Many are converting to roller cams for the benefits provided. Again, you need to think about how you want to use your car and choose a cam that helps achieve your goals.
Also, consider what gear ratio will compliment your combination and objective.
Finally, ask plenty of questions on here. We are fortunate to have some knowledgeable straight shooters that will give you some honest feedback.

ya that’s the issue I see, after a ton of research I’ve noticed there isn’t many options if you want to have your hood functional :/. The good thing is I have a edel performer intake sitting around but I was kinda discouraged using it since the intake ports are much smaller. I guess I’ll just have to go with that.

Thank you for your time and knowledge sheriff. I’ve got a long way to go but able and willing. My dad bought this mustang new and kept it ever since. I wanna make him proud and also scare him a bit on his first ride

 

[AcesArneson]

Before you buy another part really ask yourself exactly what you want from this engine when it is finished. It will save you from wasting time and money. Those heads will flow way more air than you will likely need but choking them off with a tight intake will kill any performance you desire. Think about getting the intake ported if the flow numbers are not high enough for your desired horsepower. And use port stuffers on those 4V heads to keep the flow going to the cylinder. Talk to some old timers about design issues too, if you are sending it in for a rebuild. These old things have some real oiling issues that can be overcome in a good shop if the guy knows Clevelands. The heads hold back way too much oil at high rpm so you need good head work to keep it flowing back. If you are thinking of EFI you can also look at a transmission upgrade to a 4speed auto if that’s your game. Tons of decisions to make so ask yourself what you really want.

 

[73FastBk]

Before you buy another part really ask yourself exactly what you want from this engine when it is finished. It will save you from wasting time and money. Those heads will flow way more air than you will likely need but choking them off with a tight intake will kill any performance you desire. Think about getting the intake ported if the flow numbers are not high enough for your desired horsepower. And use port stuffers on those 4V heads to keep the flow going to the cylinder. Talk to some old timers about design issues too, if you are sending it in for a rebuild. These old things have some real oiling issues that can be overcome in a good shop if the guy knows Clevelands. The heads hold back way too much oil at high rpm so you need good head work to keep it flowing back. If you are thinking of EFI you can also look at a transmission upgrade to a 4speed auto if that’s your game. Tons of decisions to make so ask yourself what you really want.

Ya that’s the fear, I wanna make sure I get most things right now before it’s out back together. I shop Im taking it to is a classic mustang shop, I did hear about the oil issues. I’ll make sure to bring that up in the build! Im option to any option tbh, my main priority is to wake the engine up a bet but without killing the reliability. I want to drive this regularly to the fire station when I work. So many 4-5k miles a year.

 

[AcesArneson]

Ya that’s the fear, I wanna make sure I get most things right now before it’s out back together. I shop Im taking it to is a classic mustang shop, I did hear about the oil issues. I’ll make sure to bring that up in the build! Im option to any option tbh, my main priority is to wake the engine up a bet but without killing the reliability. I want to drive this regularly to the fire station when I work. So many 4-5k miles a year.

Ok if you’re looking for Drive ability really consider the port stuffers. Talk to Price Motorsports, Mary can send you a set. They glue right in. I know it seems counter-intuitive to reduce space in the intake but trust me, there is WAY too much space there for a daily driver to perform like a monster occasionally. Check the numbers on your intake. I would think you are looking for 400 hp which is fairly easy with these things. Compare the factory CFM with what is needed with your bore and stroke to see if you’re in the ballpark but I think you’ll be fine as long as it is a 4V intake. Hopefully it’s dual plane so you have some bottom end terror to exhibit. These things are torque monsters so if you are looking for a setup to roast the tires in your midrange of 2500-4500 it’s best not to overplay the top end. It works as a system so if you want good low and mid-range power use some shorty or mid length headers with a cam designed to open in this range and you will be more than pleased with the driveability as well as the ability to knock you back in the seat. The long plenum of the Ram Air nostrils plays to low and midrange power too. Keeps it tight and builds velocity which really helps build rpm with power. Just let the mechanic know what your target hp is and where you want your peak power then he can guide you towards cam, liftersWhatever you need. Incidentally I went to my builder with dreams of making 450hp out of a 2V with 2V heads and he said no problem. I got greedy later on when parts were on back order for the valves I needed and just ordered new aluminum heads instead. Then the cam billet was delayed and I got more greedy and decided to go with extra lift a sacrifice a bit of drivability for some extra hp. Should come out on the dyno around 530hp next week when he is finished. Can’t wait.

 

[Bill Kanode]

So fellas I’ve been doing plenty of research but wanted to talk to the guys here who know or have done similar swaps. I have a 351C 1973, I just got a set of 4v closed chamber heads. As of now I need a carb and also looking for a good dizzy.

My question is what is a great intake manifold that’s a true 4v size and also dizzy combo. I’d like to keep the dizzy smaller size not the huge cap.

Also what’s a good stall rpm? I’m still learning about that stuff which is over my head atm haha. Ty in advance!

I have a Edelbrock F351 aluminum manifold that has been blasted which looks like new for $225.00. I does not have any repair cracks. Pictures can be sent. Thx, Obi One

 

[c9zx]

So fellas I’ve been doing plenty of research but wanted to talk to the guys here who know or have done similar swaps. I have a 351C 1973, I just got a set of 4v closed chamber heads. As of now I need a carb and also looking for a good dizzy.

My question is what is a great intake manifold that’s a true 4v size and also dizzy combo. I’d like to keep the dizzy smaller size not the huge cap.

Also what’s a good stall rpm? I’m still learning about that stuff which is over my head atm haha. Ty in advance!

A lot depends on how you intend to use the car MOST of the time. In town cruiser, highway cruiser, bracket race, or something else. The Edelbrock performer RPM intake would work for all of those uses. A good Dura-Spark style distributor, or MSD, triggering an amplifier box (dura Spark I, MSD, Daytona) would also work for all of those uses. However, the advance would need to be tailored somewhat to the intended use. Convertor stall speed, gear ratio, camshaft, and compression ratio, carb size and type, all interact and would need to be selected based on usage MOST of the time. It is very easy to pick a cam that is too aggressive, too much or not enough compression, a carb that is too big or too small or wrong style, a convertor that is not matched, and a gear ratio that is wrong for the intended use.
You must also consider the BUDGET, your skill level and determination before starting this project. What ever way you proceed, I wish you the best of outcomes. Chuck

 

[351c1971]

Horsepower is king for the 1/4 mile. Torque is what moves the car on the street. For a street cruiser, IMHO, I think it makes sense to match maximum torque RPMs to your street driving. For example if you normally shift at 3500 RPM that should be the target peak torque RPMs for the motor.

 

[AcesArneson]

Bench flow the intake manifold runners and compare that to the heads. Put port stuffers in the heads and get them port matched and get the intake manifold up to the same flow of the heads then get a cam to match your desired power range in rpm.

 

[Randyi00]

On my 72 Cleveland I have the 70 4V quench heads with Crane’s adjustable roller rocker kit. Block is .30 over and stroked to 393. I can’t remember the exact cam specs but it’s an Extreme Energy Comp hydraulic cam, nothing too crazy but has a bit of “wild” in it. I also run the MSD “Ready To Run” electronic ignition and it’s been great. On this set up I’ve tried 3 different Edelbrock intakes, RPM Performer, RPM Airgap and the Torker. For my combination I’ve found the the Torker gives me the best overall performance. Even though it’s a single plane I don’t notice any lack of bottom end grunt compared to the other 2 and it has better mid to high range performance. And for reference, I have a C6 with a 2500 stall and 3:89 gears. My set up isn’t too crazy but it’s enough for some tire smoking fun and it’s super reliable!

 

[Spike Morelli]

73 FSTBK, So, it sounds like, and correct me if I read your post incorrectly, but you currently have a stock "H" code '73......and you want to warm it up a bit for STREET driving, right? You've acquired 4v quench chambered heads. I think just to get started here, that year engine may have the retarded cam timing that Ford did for emissions, and upping the compression and slowing intake velocity on Factory retarded timing may not get you where you want to be. If you have A/C, then, your car came with a higher rear end ratio ( more freeway friendly ) to keep the RPMs down, which again, isn't what any hop-up parts are about. So this then, is what you're working with, if I have it correct. A camshaft change along with lower rear end gears should be considered to aid in making those heads and whatever aftermarket intake ( which is designed for elevated RPM use)work for you. For the greater majority of us, all you need is a good dual plane aftermarket 4v intake, duals or headers, likely a carb of 600 CFM, 750 if you go big, and a functioning properly set up ignition. A stock distributor in like new working order, with a trigger and hotter coil will light what you got with ease. Always remember, big carbs, cams, compression ( the big 3Cs )give an engine the POTENTIAL to deliver, all things being correct, but usually not delivering their potential unless being used in it's intended RPM range. And don't forget what RPM stands for......ruins people's motors ! If you buy equipment with the intention of spinning your stock cast pistoned, stock fastenered, un clearanced, borderline oiling Cleveland at 6000, you likely will not be happy with the results. Just stay away from race car shit, a big flat Torque curve, not horsepower, turns your wheels, warm it up, dress it up, and have a ball!

 

[Superbond]

I have a 72 H and changed it from 2v to 4v
I put a idelbrock performer with a Holley 600..used a CJ cam. Long headers and 3:50 rear end. I found I had tons of power top end. Did like that so I put the 2v heads back on and found I have better bottom end. Did I do it right I don’t know. Probably not. I wish I had little more power.
I heard that the 2v Aussie heads are want you want. I spent too much money changing back and forth that I’ll just live with what I have. And I’m ok with that. Good luck

 

[Spike Morelli]

Superbond,
I'm currently building a new engine for my "71 Mach, the current engine is a 2v, which so far, has run excellent, for all that I use it for. The only addition on it is a Pertronix trigger in the distributor, and dual exhausts. At one point some years back, I had a 4 barrel carb and manifold on it, then, went back to the 2v as I saw gas prices grow. Driving it everyday, ( my only car ), meant that I might save some coin going back to the 2v, but, in reality, I get the same mileage either way, like 10 mpg. The engine is stock otherwise. BUT......the NEW engine is purposely built to be more efficient. The new build is using Aussie 302 closed chamber heads to give the chambers a good "quench area", screw-in studs and guide plates, all new single lock S.S. valves, from SI.. DSS dished, forged pistons are being used to keep the compression ratio at pump gas friendly levels, 9.5:1 to be exact. No porting will be done. The 2v ports and valves should give good velocity , and my intake is one of 3 prototype castings made by Edelbrock prior to releasing their 4v manifold for 2v heads, so in theory I should have snappy throttle response and improved power. The camshaft is a roller grind, very mild at .510"/ 260, 110 LS, 205 @ .050. Should have good vacuum. I have done a few oiling mods. The new distributor is a Pertronix "Stock Look" unit My FMX trans has been re-built with a Trans-Go kit, giving positive shifts. If I put 'er to the floor and let her wind, the car shifts at 4000, right in the torque range, and within the envelope of my components . Rear end is a Traction-Lok with 3.50 gears, that I added years ago. However, I really just drive the car, I don't care about maximum H/P numbers or street racing , just looking to improve , not max-out, the engine's potential. I've even considered headers, but road clearance precludes not using anything other than FPAs. I like the quietness of the manifolds though. We'll see how everything works and feels when I finish the build and get it installed this summer coming up. You can follow the build thus far at the "Australian heads Project" blog, here on 7173 Mustangs.

 

[Superbond]

I am happy for you as I would have like to go with the Aussie heads. Wasn’t in the budget at the time. I to upgraded to a 3:50 rear end which forced me into putting in a AOD. It takes awhile to get used to it but I’m looking the extra gear. 69 mph @ 2000 instead of almost 4000.
Where did you purchase the Aussie heads and how much if you don’t mind me asking?

 

[Spike Morelli]

The Aussie 302 heads that I have were $200 pr. A man walked into the shop, gave me his card, and said he was from Australia, just here in the States for a few months. He had shipped a truckload of heads over here with him and inquired as to if we were interested, or knew anyone who was interested, in those heads. I bought two pair, one for me and one pair for a customer. He said they're not rare at all over there, you can find them everywhere. He was delighted that so many here thought they were rare. I feel they may give me the best of both worlds for my new engine, again, we'll see how they run. I surely will be posting lots of info/photos in my "Australian Heads Project" thread.

 

[AcesArneson]

I have a 72 H and changed it from 2v to 4v
I put a idelbrock performer with a Holley 600..used a CJ cam. Long headers and 3:50 rear end. I found I had tons of power top end. Did like that so I put the 2v heads back on and found I have better bottom end. Did I do it right I don’t know. Probably not. I wish I had little more power.
I heard that the 2v Aussie heads are want you want. I spent too much money changing back and forth that I’ll just live with what I have. And I’m ok with that. Good

I sure wish 'a guy' would walk into my shop with $200 Aussie 302 heads.