![]() |
|
![]() |
#1 |
Registered User
Join Date: Aug 2004
Location: Overland Park, KS
Posts: 79
|
Power Tuning
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.
|
![]() |
![]() |
![]() |
#2 |
Still drivin' a Rat Rod
Join Date: Sep 2004
Location: Monett Missouri
Posts: 4,925
|
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 ![]() Welcome to the asylum,we're all crazy about the place. ![]() Fill in the location in the user CP ![]() Enjoy your stay
__________________
Rusty Member #13872 Instead of saying.....you are a discomfort in the back of my front.....one should be able to say...... you are a pain in the *a$#* 71 GMC LWB 49 Chevy 85 Chevy G20 Check out my website Last edited by Brainchild; 10-18-2004 at 09:07 PM. |
![]() |
![]() |
![]() |
#3 |
Registered User
Join Date: Jan 2003
Location: Washington State
Posts: 8,834
|
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.
__________________
1970 Chev CST 2003 Harley Fatboy 1975 Chevrolet Step Van 1956 Chev Bel Air 1977 Blazer 2WD For Sale $3000.00 1978 Blazer 2WD For Sale $7000.00 1978 Silverado 2005 Monte Carlo |
![]() |
![]() |
![]() |
#4 |
Registered User
Join Date: Jan 2004
Location: South Carolina
Posts: 207
|
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
![]() ![]() |
![]() |
![]() |
![]() |
#5 |
68cst_ss490
Join Date: May 2001
Location: edmonton,canada
Posts: 1,363
|
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
__________________
Dean edmonton,canada a winter wonderland 2005 Chevrolet Avalanche LT cold air intake, performance exhaust, Comp cams cam, jba shorty ceramic headers. http://www.cardomain.com/ride/3090973 |
![]() |
![]() |
![]() |
#6 |
Registered User
Join Date: Oct 2004
Location: San Diego
Posts: 13
|
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. |
![]() |
![]() |
![]() |
#7 |
Registered User
Join Date: Jul 2000
Location: Victoria,BC, Canada
Posts: 1,300
|
Maybe it's just as well.
![]() ![]()
__________________
71 GMC 1500 LWB |
![]() |
![]() |
![]() |
Bookmarks |
Thread Tools | |
Display Modes | |
|
|