[KiwiLeigh]

Hi all, first time on here so please be gentle if I make a ****-up!

I have a 1973 Mustang with 351 Cleveland, FMX auto and 2.75 rear end. Also just has stock exhaust manifolds and a fairly restrictive single pipe.

Engine appears to be stock apart from 600cfm Edelbrock carb and Performer manifold.

Am only doing about 16.4 sec for 1/4 mile. Is this all I should expect from this combination? Car is used on street 99% of the time so I'm not overly keen to put much shorter diff ratio in. On a budget what is my best bang for the buck to get down into 15's or maybe even 14's? Would a better cam do it?

Thanks
Leigh

 

[Charles Reeves]

I'm surprised that it came with that rear end and exhaust. I had a '73 Torino with the same engine but with a C6 transmission; don't know what the rear end was, but it came with huge dual pipes. But that was when the anti-pollution stuff started coming on strong, and the engine really suffered for it. My impression was that Ford was still trying to figure out how to meet the standards. If I owned the car, my first change would be to get some decent gears in the rear, headers and dual exhaust. Not sure about the FMX; the C6 is much stouter, and I have no idea how much these changes will help your quarter mile time.

A friend told me at the time that the Cleveland engine in the Torino was worth more than the entire rest of the car. It was the engine the local dragsters liked to run. It certainly would scream; I pegged the tach more than once in the Torino. That was before computers and rev-limiting.

 

[rex1965]

I'm not a quarter mile expert, but there are a few things I do know, traction is probably the most important thing, it doesn't matter is you have 100hp or 1000hp, if you can't get it to the ground it is useless,

1: so to improve traction, you need weight in the trunk (full tank of gas for starters) plus more weight,

2:tire pressures are also important a few lbs either way could make a difference, you will have to experiment, I would start with less first

3: you need weight transfer, the front end comes up and the rear is neutral, some run 90/10 shocks up front so once it lifts it stays up longer, and a 50/50 shock in the rear

4: a traction lock type rear axle would help, so you can apply torque to both wheels, a stock diff applys torque to both wheels but the torque applied is equal to the least amount of traction used X2, as if one wheel slips more than the other, it reduces the torque to both.

5.A better tire composition, street tires are designed for mileage and several other things like traction in the rain, not for the drag strip, also warm or hot tires are better than cold tires.

6: If you have rear wheel hop you may have to install some type of traction bars.

7: I think most with automatics, have a special type of automatic that uses the transmission as a trans brake, (these are the serious guys), with a stock automatic, you will probably power brake, foot on the accelerator to the floor, and the other foot on the brakes to hold it, then when you get the go, release the brakes, you may have to experiment some to get it right, and this may increase the wear on the transmission, most of the torque should be spent in the torque convertor.

8: HP determines how fast you go through the lights at the end, it also has an effect on the ET.

Like I said , I'm not a quarter mile expert, I have track raced which is a lot of fun, the one time I took my 65 fb to the strip, on the first pass I couldn't get any traction, at half track I still didn't have enough traction to put my foot in it, in 2nd I had some traction, I don't remember my time, but I think a volkswagon would have given me a good run. On my 2nd pass I shifted to 2nd at 7500 rpms and the zoom clutch disc disintegrated, so I coasted to the end. And that was the end of my 1/4 mi days. I would rather have my stiff suspension for handling. I was just curious, how my car would do. My 2 cts. Good Luck.

 

[RF Mustang]

Everything Rex has advised about is absolutely essential to strip racing. As to whether or not your getting the most from your drive train becomes questionable as well.

That rear end gearing is not something that will help you get the most from your motor at the strip especially if your Cleveland happens to be using the 4-V heads instead of the 2-V. Should also mention the HP rating for the 73 351C was dropped considerably.

On that same note, as a fan of the 351C, they ALL have the potential to be built to produce incredible HP and TQ.

 

[mafraziersr]

I'm going to get yelled at here but here goes...

2.75:1 (I'm assuming) open rear? I don't know if you have an 8" or 9" but as someone who's made a few rear end changes, it makes a difference! Start watching Craigslist for an 8" nor 9" limited slip third memeber often called the "pumpkin", don't worry about the gears. Gear set can be had from Summit racing for about $100. Pick it up, order a set of 3.73:1 gears, seals and bearings. You can do this a number of ways; 1. pull the rear and take it to a good shop you trust and have the bearings, seals and gears installed along with the third member. have them check the clutches too. OR, 2. get the service manual and do it yourself. 3.73:1 or lower (numerically higher) will make a noticeable difference but the engine will howl (turn a much higher RPM's) at higher speeds. Get some new stickier rear tires, around 24-26" tall! Eagle GT's work pretty good. New U-joints too!

Try it out..want more? keep reading...

Second, pull the exhaust and scrap it. Install a set of 1-5/8" primary tube headers, full length are the best just because you don't have the hassle of trying to fabricate pipes to meet up with 3/4 length or shorties. Some shorties will hook up in the factory exhaust location but working in that vicinity is no fun. Won't be easy with PS or just keep the manifolds. Headman makes an affordable set. Get some 2-1/2" mandrel bent pipes and make up an exhaust system with some inexpensive glass packs. Don't forget the "H" pipe!

Try it out..want more? keep reading...

Third, and here's where I get yelled at, Nitrous Oxide! Buy the cheapest NOS 100HP shot wet system. Follow the directions! Hit that motor with a 100HP shot with the above mods-13's here you come!

You could also grenade your motor or the FMX may get ripped apart or both but that's the chance you take when trying to go fast(er). Above all, have fun and be SAFE!

Oh, empty the trunk and get the junk out of the car before you run it.

OK guys, start yelling! :yelwacko:

 

[KiwiLeigh]

Thanks for all the great feedback and suggestions guys, very much appreciated.

At the moment I don't have traction problems.....not enough horsepower Although the track is new it's pretty grippy already after only 3 meets, and a quick burnout to clean the tyres ("tires" in USA) is all it takes to get off the line cleanly.

For some reason the FMX box seems to be a bit of an issue with header manufacturers, but then probably most headers will need a little modifying no matter what engine/box etc. combination is used.

Diff ratio is certainly a no-brainer I guess but I was trying to avoid changing diffs for race meets, or running a low ratio diff on the street (you guys probably have no idea how much we pay for gas here!!). I can see I'll need to give this one some careful thought and see what is available locally. The US car scene is huge here in New Zealand so sourcing parts locally is not too much of a problem generally.

Many thanks again, I'm glad I registered to be able to hear everyone's views on here. Might save me making costly mistakes

 

[Neko-]

Welcome to the forum from Europe

 

[TommyK]

Distributor recurve

3.25 rear gear

Cam

Torque converter

Shift kit

These are the basics and might get you into the 13's and still be a good cruiser.

Only so far you can get with bolt ons with the low compression these engines have in stock form.

 

[KiwiLeigh]

Thanks TommyK, much appreciated. I guess it's always a compromise trying to get a foot in each camp (cruising and dragging), and what you have advised makes good sense.

Leigh