Most Power Out Of A 401

**thegriz** · 02-23-2010, 06:29 PM

anybody have some pointers to building up a 401 with some serious power (more so than stock of course). just doing a bit of dreaming and wondering how to go about doing it in the future. is there much more power to be coaxed out of the 401? would a three duece setup or 2 4's setup make a big difference than a 4 barrel q-jet?

**kitabel** · 02-23-2010, 07:02 PM

Sure - how much money have you got?

**wkillgs** · 02-28-2010, 01:59 PM

To get past the breathing limitations of the heads, you need lots of compression or a supercharger to make big power gains. Nirtous would work well too.... but that's cheating!

**DocModisett** · 05-16-2010, 05:32 AM

Walt and the guys are right power is relative to money

but,,,, there is stuff that you can do that will give good returns for the money spent.... I do the ''Doc dual plane'' mod where I cut the divider from between the front and the rear barrells of the intake, leaving the center divider to keep the torque.... cost, less than 10 bucks and picked up a good amount of power... port matching the intake to the heads and exhaust manifolds to the heads....
recurve the dist advance for less than 15 bucks... real good power increase....
A ''cold air'' package will add 8% of the total hp that an engine puts out according to Buick....
That said ,, my favorite set up is all of the above plus a holley 1050 cfm three barrel carb... it is a simple, efficent, intake system that adds a lot of power , fits under the hood of my cars and is no more trouble to maintain than a single 4 bbl......and with the vacume secondaries, it doesnt over carb the engine...because untill you kick it , you are running on a 2 barrel... the throttle linkage is simple , and there is only one rebuild kit to put in....

**Airy Cat** · 05-17-2010, 06:16 PM

Try running a tank full of 100LL Av gas. That will wake up your 401 or 425!

**kitabel** · 05-17-2010, 08:04 PM

What will that do?

**Airy Cat** · 05-21-2010, 10:01 PM

401s and 425s have 10.25 : 1 CR. You need at least 100 octane to get the full power potential out of these engines. 91 octane will hardly light my bar-b-que.

**DocModisett** · 05-21-2010, 11:28 PM

Rapidly empty your wallet......

**telriv** · 05-22-2010, 12:20 PM

In reality, if you actually measured the CR on a stock, never taken apart "Nail" you will find the TRUE CR will be closer to 9.6-9.7. This is not even close to being correct at 10.25. Then add the composite head gaskets over the shim steel & lose another .4 or so CR. Many things cause pinging. 1st. & foremost is the distributor advance rate. After 40+ yrs. the rubber stop bushing has fallen off & allows TOO much advance. Someone may have put in the WRONG vacuum advance. Again allowing TOO much vacuum advance.
Using higher octane fuel that's really not needed will actually make the engine produce LESS power. The higher the octane the slower the burn rate. Because of this you can advance the timing over & above what's called for & run better. If the engine runs better just by adding this fuel the advance rate in the distributor is WRONG.

Tom T.