Power Tuning

[PMS]

I gave my son a 72 GMC 1/2 ton long bed for his 16th birthday. We installed a new GM crate engine. He has finally got the engine broke in, the 1000 mile mark. The engine is a 350 HO with 330HP with 380TQ. We installed a 3.42 posi and a 2800 stall converter in front of the turbo 350 with a shift kit. We installed the GM aluminum intake, Holley 650 dual feed vac. secondary, headers and HEI distributor. I don't think the truck runs as good as it should. I know we are dealing with a 4000 pound truck but shouldn't it destroy the tires from a dead stop? Sorry about being long winded but my question is where should I start to power tune this combo? Is there a web site or a specific order I should try? Thanks for the input.

[Brainchild]

What color are the ends of the plugs after an all out run?That is the best way to tell what the engine is doing.
My Stocker runs better with a AC R44 plug than it does with an AC R45.Seems that it has more bottom end,and performs smoother.Plug temp is another thing to concider.Along with timing,and fuel mixture.The end of the plugs should be a chocolate brown color,meaning all the fuel is being burned.White is lean,and black is rich obviously.

Here is a chart to help ya

What kind of plugs are you running,and with what ignition system.You might have to rejet the carb,or even swap it out for a 750.The more fuel you can burn efficently,the more power you make.

Oh I forgot my manners

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Enjoy your stay

[Blue Beard]

Welcome to the board from SW Washington State....

I prefer to use NGK plugs now days since you can play with the heat range you want for the application.

As far as destroying the tires, what the rear gears? You may have very tall gears.

[super72]

I had that same set up with the same gears and could hardly take off without going up in smoke if I was racing. I let the shop that installed and sold me the motor do the tuning. Very nice combo IMO when it's running right. You can embarass more than your share of 5.nothings

[Dean23]

check and see what your timing is at, try 10 or 12 degrees base timing, also it may be starving for air as well, or possibly getting too much fuel. start with the basics, like timing plugs, fuel and air

[Ricks69]

Hi,
First start with the timing. Borrow or buy good dial back timing light and check total timing. Should be 32-36 degrees total without vacuum advance. Keep advancing the initial timing untill you get pinging and drop back a few degrees. Once you get the timing dialed in work on the carb. Adjust your idle mixture screws to get the highest reading on a vacuum gauge. These two things can really effect the bottom end of the power curve. After this, check your plug color after a full throttle run to determine if you need more or less main jet. Much of this can be done in your garage with available tools and experience, however it usually pays to take your vehicle to a dyno tuning shop which can verify that the fuel curve and timing is exactly where it needs to be at every rpm. You'll probly pay 75 to 150 dollars but you will know you are maximizing all potential horsepower, and compared to the amount of money you have invested in your project it really isn't that much.

[Spoof]

Maybe it's just as well.