OK after years of putting it off I need to have them yank the engine to repair some issues with the mounts and frame so I figure with that already going on it would be a good time to upgrade this otherwise stock 69' 351W to really accelerate like a beast. What would you do in my shoes? (Note: the engine has already been rebuilt (6-7k on it) and the intake/carb swapped from 2 bbl to 4 bbl...its also got brand new tires to support any upgrades I do)


What to do then, and in what order? 4.10 gears ? roller cam, headers?

Everyone will have a different opinion in what to do as everyone has different tastes in modifications.
A 351 will be no slouch, especially a freshly built one.

4.10 gears are good if you are going to be driving from a standing still a lot but will hurt with both engine noise and fuel economy on the freeway, 3.50 gears is a good mix of both.
Headers will be a good option but won't really impact the power too much, they will just help with getting the exhaust gases out more efficiently.
A mild cam and heads will need to be matched for whatever power gains you need out of the car.
If you are planning on building a beast of an engine then you really have to consider a brake upgrade.

Since you've already gone to a 4 bbl intake system you may be able to justify short tube headers. You can then have a custom exhaust built with some carefully chosen mufflers that give you the sound that you want. You still have the heads designed for a 2V engine so swapping a cam without swapping the heads isn't going to do much for you. Since the engine has less than 7000 miles on it it is difficult to justify doing all that.

So many guys overbuild their engines with hot cams and then decide later that what they really want out the car is to turn the heads of the woman in their life, and most gals don't like to ride in a loud car with a terrible idle. They want something that looks great, doesn't take over their boyfriend's life and doesn't leave them stuck on the side of the road.

4.10 gears will get you off the line much quicker but you're going to hate driving on the highway. If you do that then consider a transmission swap that will give you a tall overdrive.

The goal of my build was smooth and quiet (but not mousy quiet), leather interior, flawless AC system, instant starts, no stink in my basement garage, flawless electrics, and that jewelry box effect when I open the hood. Blowing my budget to do that wasn't a problem.

I don't think you want the 4.10 gears. I got 3.80 gears on my 65 and its very noisy on highway but with the AOD i do around 2800 rpm at 75 mph which is very good. if you decide to rework the differential go with a limited slip differential. 69 Mustangs are tanks compared to the earlier models i really think a LSD will perform great and give you better take off, if you keep your c4? i'd go with 3.55 gears. I'd hate to see the engine taken apart with such low mileage but if you want more power spend the money on some good heads and while you are at it go with a roller cam set up as you planned. Keep in mind if this is in fact an original 351W block from late 60's it will need some work for a roller cam set up. I like my Hedman ceramic coated shorty headers i'm lucky if i'm getting 5 hp out of them but do well at low end torque.





J

What intake and carburetor do you have?

One of the very best bang-for-the-buck things you can do is getting your engine tuned right. You may need to recurve your distributor to make that happen.

Normally, I'd say "get better heads" but the '69 351 heads can be made really good, with modest porting. Having a professional work them over would cost less than a set of aluminum heads, and the cool factor of saying they're original would be nice too. Or, you might consider selling them and just getting a set of AFR 185's if you have the money. I would expect you to see at least 40 HP from that alone; perhaps as much as 80. On a horsepower-per-dollar basis, nothing beats a good set of heads.

I'm not a big fan of shorty headers, because they don't help scavenging. They DO help get the exhaust out because they're lower restriction than the old cast iron manifolds. A set of Tri-Y's will do the same, but give you a nice boost at midrange, and another as you near your top end, as your tuned exhaust helps pull the burnt stuff out and draw fresh air and fuel into the chamber. Longtubes only help on the very top end, but they have a very strong scavenging effect. For a street car, Tri-Y headers are king.

As far as cams go, 'mild' is often better than 'wild' even if you really want a fast car. That's because a cam with lots of overlap will not make very good power on the bottom end, sometimes not even midrange. High performance cams tend to move torque production up to higher RPM, because horsepower is all about torque being made at high RPMs. For a car that will melt tires at any speed, get decent mileage, and not sputter and stall when you stomp on it, a much better recipe is to use really good heads (like the AFR's) and a *modest* cam. You will have far better average power, and that means you don't have to 'wait for the sweet spot' for your engine to come alive and start feeling fast. Because your '69 351 is a pretty desirable engine, unlike most people I think I'd recommend you stay with your flat tappet cam. Just don't neglect to ONLY use oil with ZDDP, or make sure you use additives unless you want serious damage.

Don't forget, there are other aspects of your car that can be just as important as its power. These old Mustangs are pretty floppy. If you don't already have them, think about adding better brakes (discs up front!), swaybars, an export brace, and some chassis stiffening to help keep it from twisting when you go around corners. Those changes will help your car's handling tremendously, and let you stop or turn at high speeds with confidence.

I just went through this with my 1968 302. Couple of bad head gaskets last opened up in 1983. The builder asked me what I wanted from the engine rebuild You can read about it and what I learned at my web page 1968 Shelby Cobra. I told him I'd like to see 350 HP. That is a whole different path than staying "stock". He blueprinted and balanced the engine. Put in forged pistons, Edelbrock E-Street aluminum heads, Comp cam with a .509 intake lift, original Cobra Offenhauser aluminum intake, Tri-Y headers, and a new Holley Brawler 4 bbl with mechanical secondaries and dual gas feed. My car came with a 3.89 rear end. Toploader 4 speed. I ended up with a pretty cool 1968 Mustang. But my wife calls it "loud and obnoxious", which it is. Added about 100 horsepower to it.
Observations:
1)My rear end is pretty low. At 65 MPH I'm running about 3200 RPM. It's even more noticeable with this engine. Unless you plan on doing a lot of drag racing, I'd go with a 3.50 rear end. Or a 5-speed. I'm pondering a 5 speed for the OD to get the highway RPM down. Be aware though if you go 5 speed that the T-5 comes in different flavors and some of them don't do well with 400+ HP.
2) I have a race car engine in my street car. Is that what you want? That is what I wanted. It's loud and real obvious it's got a big cam in it. My Mustang is set up for torque coming in at the lower end rather than high Horsepower at the top end. The heads, the Comp Cam, the Tri-Y headers, the Cobra intake all work towards good torque at the low end. 1500-5500 RPM is the band. How often do you max out the RPM? 5000 RPM is a lot of RPM. This setup will take you there quickly.
3) If the suspension and the braking are not up to par, you might want to start there. I replaced and upgraded both of those before doing the engine rebuild. You want to enjoy the engine and do it safely. Going fast is great but being able to stop the car is also great. It will be a lot more fun if the suspension is fresh and tight. Plus there are upgrades that makes it even better. If you don't have disc brakes, put that as number one on your list. Front discs for sure. Rear discs if you can swing the extra cost.
4) Before you choose a cam or heads, pick the path you want from that engine. A racing engine is one path, or you can go with a strong stock or some place in between. "Beast" says you want a racing engine. Read up on what you can do with a 351 W. Stock they are rated at 300+. How much HP would you like? 300 takes these parts, 400+ takes those parts. Find a good shop that has experience with old Ford engines with a carb. Most of the shops I talked to only work with EFI. Edelbrock says a good set of heads can add 35+HP. Choosing a cam depends on your path for this rebuild. Roller cams are a big upgrade in these old blocks. I'd be surprised if you could even find a shop that has done that. Extra cost over staying a flat tappet cam. In my build, a roller cam would have added about $500 to the valve train cost. My builder really wanted to stay flat tappet with roller tips. But if you want 400+ HP you need to go roller cam.
5) side effects: I promise if you give your car an extra 50-100 HP you will have a different car. And you are going to see flaws. I ended up with lower vacuum which now affects my power brakes. This cam shouldn't have done that but it did. My builder told me to get a new Holley with an electric choke. Sounds good. I do not have the choke worked out yet. None of these guys know how to tune a carb or an engine with a carb. The shop I got the carb from is going to tune my car next spring. I put Wilwood 4 piston discs on the front of my 68 Mustang so stopping is not an issue. And replaced all the front and rear suspension, dropping the car an inch on both ends. My car can handle the extra horsepower. Will yours, as it sits?
That's exciting. I just went through it, got my car back in August 2019. I documented what I learned on that web page. Click on "My GT350" and read what I did to my car. I added "why" I did those things. I did hours and hours of research on each part before I did the upgrades. Much of that info is on those pages.
Decide what you want your car to be. Make a plan and make it happen. If I had a 69-70 Sportsroof, I'd build a Boss 302, only better.
Good luck

I'd upgrade it to concourse original. You can't do any better than that.

Contrary to my own actions, I'm finding out that I agree: original is the one thing that is lasting - alterations are quickly out-of-date, and just make your car into an altered, non-original, low-performing old car that has old non-original mods.
I think of all the cars I have modified in the past, and how SOMEBODY will (or has) reversed all my mods to revert back to original.

Here's the thing though:

WHY do you have the car? Do you see it as an investment, and intend to sell it later? Or do you want to drive as much as you can, because you love it? Is it a weekender? Highway cruiser? Daily driver?

If your car is a fastback, or has some rare options, and you suspect that some day you might sell it, sure, go stock. No one can ever fault you for that.

But if you want to ENJOY the car, and you intend to maybe drive it? A lot? You have every reason to improve your car's performance, economy, and reliability. If you know in your heart that you would rather die than ever let it go, you have every right to make it the best it can be, in your eyes.

I love my Cougar with the fury of a thousand burning suns. My intention is to make it the ultimate GT cruiser. It started out pretty good in that department, with its all-leather interior, AC, and power brakes. But the 289 2V it came with was a tired old thing. Its few remaining horses were destined for the glue factory. I don't for a moment regret upgrading it, and I don't regret adding disc brakes or better suspension parts either. The car still has all of the original qualities that made it a killer. It has all of its vintage character, including a Windsor small block between the fenders. But my cat's claws are a little sharper than stock. It handles, goes, and stops in a way that makes me a lot happier.

If your idea of happiness is to putter down the street in parades, or drive your car to shows, then best get busy polishing your fender bolts, and carry some diapers to wipe the fly specks off your bumper. Meanwhile, I will be burning down the highway somewhere, grinning ear to ear as I drive the wheels right off my Cougar.


I should add: If you don't know exactly what you're looking at, you would probably never guess that my car wasn't stock. I really love vintage stuff. But that didn't keep me from gutting my original AM radio and putting new guts in it, and nice speakers too, so I can listen to bluetooth or drop in a USB stick with some MP3's. Vintage, but better. =)

If you are saying a person cannot really enjoy driving a stock classic car, then I have to disagree with you on that point.

Not saying that. Just saying that I enjoy mine a lot more, modded. Your mileage may vary.