How can I get better performances ? 351 2V

7173Mustangs.com

Help Support 7173Mustangs.com:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
You should wait for your big cam dreams until after you switch to a manual transmission. I noticed a huge increase going from my C6 w 2400 stall to a top loader. Probably around 40hp I would guesstimate.

A big cam behind a stock stall auto box will kill the streetability. Hp gain for roller rockers, pushrods are around zero. You will not perceive the difference but they are nice/necessary parts to install with higher stressed valve train. Pistons will only give you power if they gain you more compression. They may be forged and lighter but then you need to basically balance and rebuild the whole bottom end of the motor. 4v heads, intake and headers would likely be the same money but gain you more. MSD box may gain you maybe 7-10 hp if all your stock stuff is in good shape. A Pertronix ignitor should be first on your list for ignition mods.

I believe your hp increase goals are optimistic. A GOOD cam may gain you 20 hp and keep most of the drivability. A cam with the gains you are after will kill street manners completely and have little to no drivability. You can't expect those kind of gains without totally reworking and matching the combination. Keeping your auto trans, I'd reccomend something like a Comp Cams XE262H. With matching valvesprings, etc.

 
Last edited by a moderator:
Switching to manual trans is the first next mod I'll do :) Then we'll get the motor out of the car and completely rebuild it with new matched parts. My motor is all stock except intake/carb, headers and 2.5" Pypes exhaust (I have 3.5 rear gear ratio stock too so it's cool).

I'm satisfied with the drivability right now but i do want a manual trans for sure, it's the next big mod on my list (here in Europe 90% of the cars use manual trans). Then the decision to have a modified motor will be taken or not I guess.

Before all this I have a bit of work/invest to do : changing wheels and tires, suspension shocks (my idea is to get Konis or Bilstein shocks for a tighter and adjustable suspension) ; this should be done until 1 or 2 months :)

Mezapu, which top loader did you get ?

The original four speed looks good and my father in law used to drive an imported 71 Mustang Coupe with 4 speed toploader and 300 HP stock, he could manage crazy accelerations :) so I want one of course.

And where did you get all the trans components ? Ebay ? Was it difficult to get it built right ?

Thanks !

 
Last edited by a moderator:
This flow chart does a lot to explain the differences between 351C 2V and 4V heads and camshaft requirements. http://www.mustangandfords.com/techarticles/engine/5288_small_block_engine_heads_flow_test/photo_02.html

There is a misprint on the exhaust valve size for the 4V, it is 1.71 not 1.67. Notice where the intake flow stops climbing on the two heads. This accounts for the power difference and lift needs between the two. The Exh/Int ratios explain why the 2V heads do not need much, if any, split in the intake and exhaust durations where the 4V benefits from split durations. This is one source for top loaders. Chuck http://www.4speedtoploaders.com/remanufactured.htm

 
Before all this I have a bit of work/invest to do : changing wheels and tires, suspension shocks (my idea is to get Konis or Bilstein shocks for a tighter and adjustable suspension) ; this should be done until 1 or 2 months :)
Mezapu, which top loader did you get?

he's constantly saying that he could manage crazy accelerations :) so I want one of course.

And where did you get all the trans components ? Ebay ? Was it difficult to get it built right ?

Thanks !
To tell you the truth, the best bang for the buck to improve handling was installing a bigger front sway bar. I installed every new suspension component one piece at a time on my car(when I had the time) and the 1 1/8" sway bar made a world of difference. I'm so happy with the handling that I still only have cheap parts store Gabriel gas charged shocks on the car. I am a firm believer in high performance shocks as I have Koni's on my two fox body mustangs, but didn't deem them necessary on the Mach 1.

I ended up with a wide ratio small lock top loader out of a 68 mustang according to the RUG tag on my transmission. I did the swap years ago (1997 ish) before eBay really started getting big. I managed to find the transmission in the local newspaper classified section, advertised simply as a small block 4-speed. After calling the number and establishing that the 4-speed was in fact a top loader, I explained what I wanted the transmission for. Low and behold it was out of a 73 Mach 1 that he was parting. I managed to get almost 80% of the 4-speed conversion parts in one fell swoop. I got the trans for $250 and the rest of the parts for another $250 to include,

- cast iron bell housing

- flywheel

- OEM Hurst shifter and linkage

- Z-bar and various linkage

- clutch fork

- crossmember

- driveshaft and yoke

- pedal box

It was one of those once in a lifetime deals. All these parts were quite worn out and needed substantial restoration. It took almost three times the amount of money to restore the parts and purchase what was still missing to complete the conversion. Even after all the work, it was still the best thing I ever did to the car. I had to sort out broken motor mounts and bad wheel hop after the conversion but it's so worth it.

 
Last edited by a moderator:
Thanks for all the precious info on cams, heads, trans, suspension !! Really interesting stuff here ! Especially the bigger sway bar thing. What is cool with the Konis is that they are adjustable, unfortunately the front one are difficult to find because they're not produced anymore. I have staggered shocks on my Grande but they are really worn and need changing.

There are some used but reconditionned 71-73 4 speed toploaders on US ebay, I think they look good for me as there are no chances to find one in the local ads ahah. Then getting the right bellhousing, Hurst shifter, clutch etc etc. deosn't seem that tricky. I think a lot of people actually look for more power in their Mustang forgetting they have an automatic transmission ; manual trans is the way to go for street performance and funnier driving.


Mezapu what is the reference of those Gabriel shocks ?

Is this the sway bar you installed ? http://stang-aholics.com/showitem.aspx?&id=103010&name=71%20-%2073%20Mustang%20Front%20Sway%20Bar%20%201-1%2F8%20Inch

 
Last edited by a moderator:
The hardest parts to find for the 4-speed swap are the pedals and z-bar parts. As long as you find a clutch pedal you have options.

- You can install a hydraulic type clutch as it may be better and cost less than finding all the original z-bar and associated parts to make it work.

- You can install a T-5 and have an overdrive gear if you want to. It isn't as strong as a toploader but as long as you don't put on sticky tires and beat on it they are great transmissions.

- Most mustang toploader transmissions will work. You don't need one from a 71-73.

- Bellhousings for T-5's or toploaders are not hard to find. Most are aluminum.

- Clutch forks (new)

- Driveshafts and yokes (new or made custom)

- Shifters and linkages (new)

- Crossmembers shouldnt be hard to find.

- speedometer cables (new)

- Flywheel (new)

- clutch kit (new)

I got my suspension kit from www.MustangsPlus.com.

The shocks are literally the cheapest gas shocks I could get. There is nothing fancy about them. I think they cost me $16 ea.

 
Back
Top