Advice on engine upgrades.

[Cole]

Mines a 71 H code car with what looks like stock 2 barrel carb and manifold. No headers. With my tax money I'm thinking a 4 barrel carb and manifold combo from summit racing. Was going to add headers to that order too. That order would run about 900.

I saw Auron's post selling his 4v heads, manifold and carb and maybe thinking that might be the better route to go. I don't have any real working experience with engines and was wondering if someone could answer a few questions.

* Going from a 2v to a 4v is basically heads, carb and manifold? All those are just take out the old put in the new?

* Headers from a 2v won't work on a 4v right?

* Going from a 2 barrel to a 750 would the stock fuel pump be able to keep up?

Any insight would be appreciated. Especially from guys that have gone the 2v to 4v route. Thanks in advance.

 

[MotoArts]

. Yes. Add a few hundred for the exhaust (after the headers) change.

. Correct

. Should be fine, if it's in good shape.

You won't be impressed with the induction swap/"upgrade". It will actually run about the same, except for a bit of top end improvement. If you're lucky.

It all works as a package.

To feel a real change, compression and cam would need to be changed as well. Exhaust too.

Somewhere along that line, a gearing change will be desired.

Then a torque converter change.

So on and so forth

My Dad used to call it "lighting the fuse..."

My opinion? If that's all you're going to change, or can afford to change, save the 900. It won't go from a 15 second quarter mile car to a 12 second car. Yes, I've been down that road before.

 

[Cole]

Thanks Pete. I don't mind spending more in the future on other things like a cam. And kind of leaning to not limiting the potential by sticking with the 2v heads. Appreciate the help!

 

[CZ-75]

I have a 73 H code, which means my engine is less powerful that yours due mostly to reduced compression ratio and a really pussified Cam shaft.

I'm going to do a few things at a time to see how much I can get out of this car before I have to tear into the engine.

First, I'm going to change from the FMX 3-speed automatic transmission to an AOD (also automatic), which is basically the same first thru third gears, but adds an overdrive "4th" gear to improve MPG at highway speeds. But, I'm not going to go with your run of the mill AOD. I'm going to go with a "wide ratio" AOD. There are a few commpanies that specialize in putting the gears from a 4R70W trnsmission into the housing of an AOD. What this does, is gives you a very agressive 1st gear, which will help a weak motor get off the line quicker. Couple the tranny swap with a more agressive rear end (someting like a 3.5 or 3.7:1), and you get the best of both worlds... an even MORE agressive first gear, and the same benefits of highway cruising.

Once I do that change, I'm going to drive it for a while to see if I'm happy. If I'm not, then I'm going to put on an Edelbrock Performer Intake Manifold and a new Edlebrock 650CFM Thunder Series AVS Carb. This should get me another 30-40 HP. The Edelbrock Intake Manifold is designed to sit on top of the stock 2V heads, but they allow you to use a 4-bbl carb. And my 40yr-old carb is really needing rebuilt... So I'd rather replace it. Then, I'm going to drive it and see if I'm happy. If not then:

If all the above doesn't get me to where I want to be, then it is time to rebuild the engine. New Cam shaft, new pistons to get the compression up to 10:1, and a new valve train. This is where the big increase in HP will come from. And after you swap the tranny and rear-end gfears, you don't need much... A really moderate new CAM will get any 351c into a HP range approaching 400HP, with torque approaching 425lbs leaving the compression ratio alone (no new pistons, but maybe some valve train work).

The reason I am doing it in this sequence: 1) I want to drive the car to the lake where keep our camper, which is an hour away. With a 4th gear, that will not put undue stress on the motor/drivetrain. 2) My rear end needs some work anyway. So may as well swap gears to really fine tune the final gear ratios available with a wide ratio AOD. 3) This leaves the most expensive part for last: diving into the engine.

 

[marks73]

The 4V heads and carb are perfect. I would add aluminum intake to the set up and headers. Think it would put a smile on your face and make you give some serious consideration to 3:70 rear end gears. JMHO

 

[MotoArts]

Thanks Pete. I don't mind spending more in the future on other things like a cam. And kind of leaning to not limiting the potential by sticking with the 2v heads. Appreciate the help!

The 2V heads aren't really the limiting factor for an average healthy street engine, truthfully. They flow pretty well as is. It already has larger valves than the competitors offerings from the same vintage.

It's the open chamber and dished piston that gives it relatively low compression that is the heart of the limiter.

Combine that with a weak cam that doesn't let upgrades shine like you think they would/should.

Not saying the upgrades won't do a thing, but from experience, components must be matched to get the big bang.

Again, it's all part of a system.

And the desire to make a thick wallet get thin

 

[mach71351c]

The 4V heads and carb are perfect. I would add aluminum intake to the set up and headers. Think it would put a smile on your face and make you give some serious consideration to 3:70 rear end gears. JMHO

+1

 

[71_resurrection]

The 4V heads and carb are perfect. I would add aluminum intake to the set up and headers. Think it would put a smile on your face and make you give some serious consideration to 3:70 rear end gears. JMHO

+1

+1 more!

I would personally go with long tube ceramic coated headers, Jegs has some pretty solid ones for about 400, after that 2.5 to 3" piping into an x-pipe and a good set of magnaflow mufflers. That is my setup and it sounds and flows wonderfully, and I have no issues with the pipes scrapping with a 1" drop on the car.

 

[ishootstuff]

EDIT: Sorry, I'm sick and I didn't see you had the 351.

...or you could go a different route like I am doing and get more horsepower and better economy for free or little out of pocket. The 5.0 HO is 225 horse - I think, vs your 140. Buy a wrecked Fox body GT Mustang or even better a 5.0 Explorer. Take what you need and sell the leftovers. I bought a Lincoln for $600 (not an HO, but just an example) with a 5.0 and AOD. I sold the original 302 & C6 out of the 72 for $750. I'll get about $300 for scrap out of the Lincoln, so I had $450 to get gaskets, custom crossmember etc. Yes, it's a lot of work, but not difficult work and I'll end up with no points distributor to mess with, overdrive transmission, and the consistency and reliability of fuel injection. There is also a huge aftermarket for the 5.0 if you want to spend that money later.

 

[wwhite72]

The 71 351c 2v is not a bad engine at all. Id drop money on brakes, tires/wheels, shocks and ignition before i went for Heads/intake/carb/headers package, because you really do need he entire setup and a cam to make a difference. For exhaust you can get a dual intermediate pipe for the stock manifolds, a pair of new stainless Magnaflows and a set of rear downturned pipes. That exhaust alone would take a some of the cash in your pocket and the pair of mufflers can be used later if you decide to go wih 4v heads, as long as you get the 2.75 pipe size i believe. Want to go faster just push down harder on the pedal on the right. But you can always use more brakes!

 

[droptop73]

The best "power" upgrade I have made was swapping from the C-6 to a T-5 5 speed. It takes about 50 horsepower less to run the manual than the automatic.

2v or 4v doesn't matter, like has been said the components need to match for best power production. Decide how much and how you want to drive the car and build the engine to suit. My views on engine packages differ than most on here so I hesitate to get into the debate again.

 

[cazsper]

Cole,

What would you like your car to be when you're done?

 

[Boss1Ray]

Cole,

What would you like your car to be when you're done?

+1

Ray

 

[Cole]

Just an occasional driver that runs really good and pretty fast. One thing for certain I NEVER want some rice burner getting me at a stop light. Buying the 4v heads, manifold, 750 Holley and some headers from a fellow member. Go 4v or go home I guess. LOL I'll research cams before these go in. Back to my get her running mode for now. Brakes are finished, fuel tank going in and just got the stuff for plumbing from fedex this morning. Thanks everyone. This is a great forum with tons of knowledge.

 

[hyena429]

Just an occasional driver that runs really good and pretty fast. One thing for certain I NEVER want some rice burner getting me at a stop light. Buying the 4v heads, manifold, 750 Holley and some headers from a fellow member. Go 4v or go home I guess. LOL I'll research cams before these go in. Back to my get her running mode for now. Brakes are finished, fuel tank going in and just got the stuff for plumbing from fedex this morning. Thanks everyone. This is a great forum with tons of knowledge.

4v heads work best with a dual pattern cam..Make sure you dont get a single pattern...Im putting together just about the same set up...I got a 750 holley vac sec...Edelbrock dual plane manifold...Some hooker headers...Comp Cam 5.30 lift with 280 duration...10.1 compression...According to jegs and my desktop dyno...Im expecting 430 too 450 hp at the fly wheel...And still able to run on 91 pump gas...powerfull yet reliable is what im after...Go too much father and you start runing into special gas and special head work"more powerfull springs and such" You have to run shims under the perches to handle 5.30 lift....But with out major machine work i figured it was the best ticket to get lots of power with out making it too much of a problem child..lol

 

[turtle5353]

I had the 2v heads on my 351c and they ran great. I had a fair amount of work done to them. Roller rockers, healthy comp cam, intake, holley 750 dp, and hedman ceramic longtube headers, with msd ignition. I was told by the engine builder est hp was 400-425. It was fun in a street car and dont ever remember being past by a rice burner. My trans was a c4 with a 3000 stall converter and 3.73 gears, so that helped wake up the whole package. i sold my whole topend setup to theJ. When he gets it bolted all together he can let you know how well a nicely massaged set of 2v heads can run.

 

[wwhite72]

Jon Kaase made +700 hp on a 400m with CHI 3v heads at Engine Masters. Not sure what a street car would do with +700 hp though.

 

[Jeff73Mach1]

700 hp in a 3500 pound street car sounds like a perfect power to weight ratio to me. It is comparable to a sport motorcycle and rider.

as to engine building questions my 4v heads and low compression shortblock run quite nicely with a single patter solid lifter cam. I'll bump up the compression if I ever build a new shortblock and may even try one of those fancy dual pattern cams, but even at 350 RWHP traction is far more important than more horsepower

 

[turtle5353]

Jon Kaase made +700 hp on a 400m with CHI 3v heads at Engine Masters. Not sure what a street car would do with +700 hp though.

ANYTHING IT WANTED TOO !!!! My new 408C stroker with AFD heads should be in the 550-600hp range.