I'm new to the site so I hope I am doing everything right. I am looking for an opinion. I have a 66 mustang coupe with 60K actual miles. Pony int, fact air, nice car. I have a 3:55 posi I plan to putin the car. My question is whether or not I should modify the engine. I want more power, but am concerned about hurting the value, or if I should be concerned. I am kicking around everything from intake and carb only, to cam, head work, ignition etc. Please give me opinions. I also have another 289 with approx 60K miles out of an 68 I used to have. I have thought about doing the mods to that one and saving the original engine.

 

Tough call on that one.
I think as long as your using the numbers matching engine and heads you are limited to how much power you can get.

I found out the hard way a 350-400 horse motor is enough to break and trash the stock drivetrain behind it.
If you do decide to build just the motor keep that in mind.
Any big dose of torque kiss your stock motor mounts goodbye.

 

I wasnt thinking of major hp. I just want to warm it up a little. I had a toyota camry beat me out of a light last summer, and my kids made fun of me.

 

the 355 gears will help with that.
A lil call to comp cams and tell them what gear your planning and your using stock heads and block they will grind you one perfect for what you want.
Set of tri y headers a wieland low rise intake 600 holly or 525 edelbrock carb shell wake up. If nothing else put in a petronix and a hotter coil.

 

I agree with cmanf's plan. A cam, ignition,intake, carb, and exhaust(in addition to the gears) would all help and wouldn't hurt the car's value, as long as you keep all of the factory parts.

If you do want to go high-hp, then yeah, I'd recommend building up the '68 engine. That way you could build it the way you want while driving the car, then just swap when the time comes and not worry about hurting the original motor.

 

That sounds more like what I was thinking. I thought I would have the heads rebuilt to stock so that I dont change the engine. I didnt know comp would do that. A lot of what I hear says the stock heads dont breathe well so that was why I was wondering about changing them. They are smog pump heads too so I dont know if that changes anything. I doubt it. I was thinking of an edelbrock performer intake and carb. A 525 is better than a 600 for that car? If I did all of that do you have any idea of performance. I would imagine with the rear end change it would be a big improvement over stock. Thanks.

 

I also forgot to mention that the previous owner had installed dual exhaust and hipo headers on the car. I want the engine to look stock but I like the cam lope etc. (This all started because I was planning on replacing the rear main seal and detailing the engine. I am driving my wife nuts!)

 

the smog heads wont let it breathe as im told, i have the same prob on my 351.
but before you put big hp in the car, make sure your brakes (should swith to dish at least up front), suspension, rear end are up to it. good luck!

 

Thats part of what I have been wondering. I thought about looking for a regular set of heads and having those rebuilt. As far as brakes etc, I was thinking split manifold forsure. I'm not sure on suspension other than shocks, as I am not looking for huge hp. Thanks

 

If you changing your heads there goes the originality.
If you going that route switch to the other engine and put the old one on a pretty stand in the corner.
A set of alu or world products cast will get you more power for less cash in the long run btw.

GT 40s are a good deal for the cash, but doesnt make the big power.
That being said I have a 289 with gt 40 heads (cast ) .30 over and a
the biggest cam I could use without dished pistons.
Edelbrock performer rmp intake.
525 carter AFB carb and a Mallory unilte dist.

Made enough torque to break 3 drive shafts and 2 were twisted from putting drag slicks on the car.
Could get it to hook up but out ran a 440 cuda in the 1/4 every time we raced @ the strip.
Was as fast as most of the non NOS and s/c 5.0s that were there that day.