what are some good and cheap ways to get more power out of a bone stock 400M??????

 

Read the article on this link (Hot Rod 400 Build) for a good idea of a inexpensive 400 build up. I believe they use a Comp Cam. You will have to substitute Ohio Piston flat tops in it (p/n #1282P) instead of the Silv-O-Lites they used.

 

Depends on what you call cheap. The cheapest - put in an open air cleaner with a K&N air filter, and install a free flowing muffler. Also, change your ignition timing from the specified 6 or 8, to 10. You may need to re-jet your carb due to the aircleaner and exhaust changes, but probably not. These changes may gain you 20 HP.

The next things you could do would be to install a dual plane 4V intake and a 600 or 750 CFM 4V carb. Along with this, install a set of headers. To take the best advantage of the intake/carb/headers, you will need a different cam. As long as you are swapping the cam (and springs/lifters) you should swap the timing gear and chain - using one that is 'straight up' rather than retarded.

The changes up to this point would cost you perhaps $1000 to $1500 depending on whether you do the work yourself and how much you save by shopping around. You would see the HP increase from 172 to perhaps 300, with a big improvement in low-end torque.

To go further, you would need to increase compression to 9.5:1 or 10:1. This can be difficult on a 400 as there are not many high compression piston options. Search this list for specifics. While you are doing this, you should figure on a rebuild with new bearings, gaskets, seals, oil pump, valve job, etc. Figure another $1000 to $1500 (pistons will not be cheap) and HP could jump as high as 380. Somewhere along the way, figure on converting to electronic ignition. Good luck!

Tom

 

muddogin400,

I guess it depends on what you mean by "cheap." Also, you didn't say what year or model your truck was, and that could affect your options. In general, short of rebuilding your engine, the simplest and cheapest things you can do are tuning.

Make sure the engine is tuned up to spec, with new plugs, good plug wires, and a good distributor cap and rotor. Like Tom said, you can bump the ignition timing 2-4 degrees advanced from spec, as long as it doesn't ping. Keep the fuel and air filters clean.

Make sure the vacuum advance diaphragm on the distributor is not leaking, and the advance mechanism moves freely when vac is applied. You can adjust the vac advance on the distributor to make sure you get the most ignition advance you can use at low-mid rpm. Use a 1/8" Allen wrench to adjust the vac advance. Turning the adjusting screw clockwise increases sensitivity on OEM vac advance units. If you have low-rpm or part-throttle pinging, you'll need to decrease sensitivity.

Make sure the carb is clean and adjusted properly. You can get rebuild kits for the stock Motorcraft 2150 2V for about $25. It's easy enough to work on that a careful amateur can do it. Once the carb is clean, and working well, a cheap and easy mod worth a few hp is disabling the EGR and re-jetting the carb richer to take advantage of the change.

After that, a basic 2.5" single exhaust system with a high flow muffler (maybe $150) will help a little. Then consider a high-output coil (about $60-75) and re-gapping plugs out to 0.050-0.060" for a little more mid range power.

All this done right could give you an extra 20-25hp above the stock rated output.

If you want more, then your wallet's the limit.

BTW: In my experience, a K&N air filter is a waste of money on a stock M-block. An open element filter housing will have you sucking in hot air under the hood, so you're actually better off with the OEM snorkle unit and ducting to get cool air.

BubbaF250

1980 F250 4x4 Custom, 351M/NP435/NP208/D44HD-TTB/D60-FF/3.55s 6750 GVW, Rust & White.

 

if you are willing to use 351c pistons you can raind the cr a whole bunch.

 

351c pistons will not interchange with 351/400m pistons without modifying them.

 

>351c pistons will not interchange with 351/400m pistons
>without modifying them.

Actually the pistons don't have to be modified. The rods have to have bushings installed because the wrist pin on the 351C is smaller than the 400.