Since I decided to push the build up on the 425 out of line for this winter project (NorthStar took it's place) I was thinking what I could do to get a little more power from the beast....
my first thoguht is the cat... it's gotta go... my father mentioend something about thee first gen cats having a "drain plug" that you can take out, and the beads inside fall out, kinda like gutting the cat? On his '79 Coupe, he had a test pipe on it.. but I can't seem to find them anymore.... I don't think I could take it to a shop , even though it is now over 25 years old, and there is no emmisions testing... so what would the best thing seem to be?
While under the car, the whole exhuast system seems to be restriced... especailly all the bends going over the rear axel... what is this, 2.5" piping (my 4.9 has 2.5") but I am not messing with the exhaust system now... I was thinking maybe a cheap after market muffler... might flow better? something like $40 or something? also give it a nice tone... but not too loud... would I even benifit form that? or just keep what it has.... Also the resonator... from what i coudl find out, they don't seem to restric the flow of exhaust at all.. do they?
Then it would be some sort of an intake... I bought, and tired to fit a 14" open element on it, but it hit the AC compressor... somebody menitoend about a 1" spacer? should I do that or see if a 9" kit will work (but probably look bad)... also would I gain anything from the open element over the factory air cleaner assembly?
the tune-up I first did on it consisted of:
new air filter
new fuel filter
new spark plugs
oil change
I suppose I should rrepalce the cap&rotor and wires also... just for the extra touch, and maybe even the plugs, although they are new... they are basic AC Delco, $2/each... nothing special (platnium, double tipped etc...) do you think they are ok to keep in there? should I replace the cap/rotor and wires, or leave them? the wires are 8mm Whitiker....
What else can I do for a tune up? I know my carb needs to be rebuilt as it acts funny when the enigne is cold... anything to restore some power?
I do need to change the coolant, as it is really ugly... but that really isn't anything for performance...
my AC dosn't work (leak in the lines) no big deal, but should i remove the AC belt... less rotating mass?
Abotut he carb... here are the problems... when the enigne is cold.. after I first started it, if in park I put my foot to the floor for a second.. it'll sputter, run rough and want t quit... if i drive it.. there is an off-idel dead spot where it'll shutter and have a hard time accelerating, and if the engine is cold enough.... stall out... also until the engine has fully warmed up, if I try to floor it... well, to the point where the secondaires would normally start to open... when it gets to that point, the enigne looses alot of power, the car shakes and shutters, engine RPM really dosn't build, it may back fire, then depenging on how warm the enigne is, either rev up in RPM like normal, or just keep doing that.... maybe a problem witht he secondaires?
Everythign else with the carb is fine, when the engine warms up, there is no delay or anything, runs great... if it hasn't been ran for a day or 2, a cold start can be hard.. I heard all Q-jets have a drip down problem? I pump the gas 3 times, crank it, stop, pump twice then crnak and it'll start... although when warm, it'll start up within a split second of turning the key...
Maybe if the carb is out of adjustment, and I fix it, that coudl improve power and gas millage.... IIRC my father said the caps on the adjustments have been removed, so it is adjustable now...
I am just looking for some cheap ways to tya nd improve the power a little... I know the enigne isn't running how it hould be (well, have the power it should... she runs nice) so maybe I can get some help from the crew
my first thoguht is the cat... it's gotta go... my father mentioend something about thee first gen cats having a "drain plug" that you can take out, and the beads inside fall out, kinda like gutting the cat? On his '79 Coupe, he had a test pipe on it.. but I can't seem to find them anymore.... I don't think I could take it to a shop , even though it is now over 25 years old, and there is no emmisions testing... so what would the best thing seem to be?
While under the car, the whole exhuast system seems to be restriced... especailly all the bends going over the rear axel... what is this, 2.5" piping (my 4.9 has 2.5") but I am not messing with the exhaust system now... I was thinking maybe a cheap after market muffler... might flow better? something like $40 or something? also give it a nice tone... but not too loud... would I even benifit form that? or just keep what it has.... Also the resonator... from what i coudl find out, they don't seem to restric the flow of exhaust at all.. do they?
Then it would be some sort of an intake... I bought, and tired to fit a 14" open element on it, but it hit the AC compressor... somebody menitoend about a 1" spacer? should I do that or see if a 9" kit will work (but probably look bad)... also would I gain anything from the open element over the factory air cleaner assembly?
the tune-up I first did on it consisted of:
new air filter
new fuel filter
new spark plugs
oil change
I suppose I should rrepalce the cap&rotor and wires also... just for the extra touch, and maybe even the plugs, although they are new... they are basic AC Delco, $2/each... nothing special (platnium, double tipped etc...) do you think they are ok to keep in there? should I replace the cap/rotor and wires, or leave them? the wires are 8mm Whitiker....
What else can I do for a tune up? I know my carb needs to be rebuilt as it acts funny when the enigne is cold... anything to restore some power?
I do need to change the coolant, as it is really ugly... but that really isn't anything for performance...
my AC dosn't work (leak in the lines) no big deal, but should i remove the AC belt... less rotating mass?
Abotut he carb... here are the problems... when the enigne is cold.. after I first started it, if in park I put my foot to the floor for a second.. it'll sputter, run rough and want t quit... if i drive it.. there is an off-idel dead spot where it'll shutter and have a hard time accelerating, and if the engine is cold enough.... stall out... also until the engine has fully warmed up, if I try to floor it... well, to the point where the secondaires would normally start to open... when it gets to that point, the enigne looses alot of power, the car shakes and shutters, engine RPM really dosn't build, it may back fire, then depenging on how warm the enigne is, either rev up in RPM like normal, or just keep doing that.... maybe a problem witht he secondaires?
Everythign else with the carb is fine, when the engine warms up, there is no delay or anything, runs great... if it hasn't been ran for a day or 2, a cold start can be hard.. I heard all Q-jets have a drip down problem? I pump the gas 3 times, crank it, stop, pump twice then crnak and it'll start... although when warm, it'll start up within a split second of turning the key...
Maybe if the carb is out of adjustment, and I fix it, that coudl improve power and gas millage.... IIRC my father said the caps on the adjustments have been removed, so it is adjustable now...
I am just looking for some cheap ways to tya nd improve the power a little... I know the enigne isn't running how it hould be (well, have the power it should... she runs nice) so maybe I can get some help from the crew