I am new to the straight six area, and I have a 78 f100 with a 300 six in it. Can any of you give me a little advice on some way to get a little more performance out of the engine but not for a huge price. I am a college student and on a very limited budget. Any help is much appreciated. Thanks.

 

Well, I'm new to 300 6 cylinder engines but some things hold true regardless of engine type; Raise the compression ratio and give it a hot ignition system like an MSD or Jacob's.

I think a head swap might help with the compression ratio, but I'll have to defer to the experts on this board. BTW, don't bother screwing around by removing emissions equipment. You won't make any extra power, you'll probably lose power, lose MPG, and hurt the engine in the long run. Learn to diagnose and maintain the EGR, thermactor/smog pump, and pay attention to the cats.

Best regards,

Paul

 

If you do have the emissions equipment still hooked up...: The air pump or "Thermactor system" doesn't rob a whole lot of power on a stock setup. The EGR does. Best smog defeat improvement on your '79 is to disconnect the vacuum line going to the egr valve and use a rubber cap to cap the vacuum line that the hose to the egr runs back to. You'll notice an immediate improvement..

 

have it geared higher i think, and headers, manifolds 4 barrel carb ect. but then that's getting pricey

the 300 6 has a lot of low end torque, but the only weak point is the 1 barrel. that carter carb has really killed the horse power potental of the 300 6

 

I guess I've am near the top on money spent on my 300-6. Look at my sig.....gotta go.

 

I would disregard what tetraruby said about EGR for these reasons; EGR is only active when there is vacuum in the manifold, in other words; part throttle. You don't need extra power at part throttle. At full throttle the EGR closes and there is no impact on power.

EGR will improve your gas mileage and help the engine run cooler. Oh by the way, it helps with emissions but who cares, right .

Because your engine is tuned for EGR, disabling EGR will cause the engine to run hotter, and probably it will start to knock. Knocking is very bad for engines. If you still insist on removing EGR, you should have the ignition curve retuned, and the carburetor or fuel injection adjusted.

Still want to remove EGR? I didn't think so.

Best regards,

Paul

 

[updated:LAST EDITED ON 23-Mar-02 AT 02:06 AM (EST)]FOR A '78 = '79:

The EGR valve is a positive back pressure transduced valve. The vacuum signal to the EGR valve is from a PORTED vacuum signal from the carb that opens when the throttle is above idle - Dah! Furthermore, there is a valve in the coolant elbow that opens (once the engine is up to temp) up to allow the "ported" vacuum signal (from the carb) to reach the EGR. On these older YFA carbs, there should be a (W)ide (O)pen (T)hrottle valve that releases any ported vacuum signal to the atmosphere - this is when the pedal is to the metal...
HERE's HOW IT WORKS!!!
There is a metal tube (~5/8 I.D.) that goes from the exhaust manifold to the plenum that sits between the carb and intake. Through this tube exhaust gasses are routed into the EGR. If there is enough exhaust backpressure, the valve is forced back a small distance. If a vacuum signal is present on the other side if the diaphram of the valve (meaning ported vacuum signal making its way to the EGR) the valve will completely open, effectively allowing the exhaust gasses back into the intake to be recycled.
The previous post about knocking and increased temps is B. S.

Allowing hot exhaust gasses back into the combustion chamber does not cool the engine. It helps raise the combustion chamber temps and reduces unburned HC's...why do newer engines run at higher temps above 190???
I've done the conversion (on my '79) from no emission equipment to meeting stringent CA SMOG regulations. I think I know what I'm talking about! Regardless, the orginal post hasn't mentioned a thing about if he has an EGR or not. You're welcome for the lesson. Best thing to do, is try it and see what happens...that is...on a '78 '79 300.
-Supporting FTE member

 

tetraruby, you are uninformed about the whys and whereabouts of EGR. You ought not to be giving 'lessons' about it. Because of your attitude, I won't waste my time explaining it to you.

To the original poster, I stand by what I said, EGR is not bad, it's good. It DOES reduce combustion temperatures, it DOES increase gas mileage, and your engine is tuned for it so don't remove it.

I did a little surfing and found out that the 87 and newer heads have smaller, better designed combustion chambers. That's worth considering.

Best regards,

Paul

 

Any of you guys know anyone beside Clifford makes headers for the inline six? And what would be the best kind of carb to change to if I choose to go that route? Thanks.

 

A forever-incomplete list of readily available 300 parts:

Makers of Camshafts:
Clifford Performance
Crower
Crane
Comp Cams
Lazer Cams
Accelerated Motion
ultraDyne
Blueracer (owned by crane, but different grinds)
Schneider Cams
Iskanderian

Header:
Clifford Performance.
MAC
Dynomax
Pace Setter
Hedman
Hooker

Intake:
Clifford Performance
Offenhauser

Roller Rocker:
Crane Roller


-=Whittey=-

 

>I did a little surfing and found out that the 87 and newer
>heads have smaller, better designed combustion chambers.

Makes sense. '87 is when they started fuel injecting the 300 and at the same time changed to the dual exhaust manifold and long, long "torque tube" intake manifold.


INLINE SIX POWER! Wanna hear that inline grunt!
300 Cubic Inches of Low RPM Truck Torque! And twin-I-beams too!
"Drive a stick young man! There'll be plenty of time for automatics when you're old and unable."

 

>To the original poster, I stand by what I said, EGR is not
>bad, it's good. It DOES reduce combustion temperatures, it
>DOES increase gas mileage, and your engine is tuned for it
>so don't remove it.

>
>Best regards,
>
>Paul


Can you explain how the EGR decreases combustion temperatures? I'm not saying you're wrong.... It just makes no sense to me. If you increase the intake temperature, air expands and becomes less dense. That means there is a lower mass of air in the combustion chamber, but still the same amount of fuel resulting in a leaner mixture. Leaner mixtures burn hotter and are more prone to detonation.

So how can the EGR do the exact opposite of that?

 

[updated:LAST EDITED ON 25-Mar-02 AT 06:51 PM (EST)]Ok, here's how EGR works. I apologize in advance if I am pedantic.

First of all, EGR is NOT an attempt to 're-burn' unburned hydrocarbons in the exhaust. That would be pointless; you couldn't get enough through the engine to make a difference.EGR is much more subtle than that.

To reduce HC emissions, car makers leaned out the air/fuel mixture. But when they did that, they increased NOx (a Nitrogen and Oxygen compound such as NO2) emissions. NOx is caused when the Nitrogen in the air is exposed to Oxygen at high temperatures, which is exactly what happens when you lean out the mixture; high combustion temperatures and extra Oxygen. If you've ever been to Los Angeles you've seen the NOx in the air, it's what causes the brown color.

When you burn air and fuel in a combustion chamber, it creates heat. The air that was sucked into the combustion chamber is what is heated. Since air is 20% Oxygen and 80% Nitrogen, most of the heat goes into heating the nitrogen. (Of course, the Oxygen is now in the H2O and CO2 by-products from the combustion).

If you could increase the percentage of Nitrogen in the air that is sucked in, you could spread the heat over more air, and the average temperature in the combustion chamber would be lower. Lowering the temperature reduces the amount of NOx that is formed. Since exhaust has very little Oxygen in it, just Nitrogen, water vapor and CO2, you could use the exhaust to 'dilute' the intake charge.

It's like using a teaspoon of gasoline to heat two quarts of water instead of one quart. The same amount of gasoline is used up, but its heat is spread over more water.

EGR also slows down the rate of combustion. For this reason, more ignition timing is required. If you remove the EGR, you could get into a spark knock problem if you don't recurve your distributor.

There are other significant side-effects of EGR, changes in pumping losses, increased cylinder pressure (higher compression) at part throttle, and more. Complicated, but clever stuff.

And finally, EGR is turned off at full throttle, so it doesn't effect full throttle power.

Bottom line is that a good working EGR is helpful to an engine.

Best regards,

 

 

That's why drag racers use them in all their engines