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  1. #1

    Default probably answered my own question but

    when i downshift cruising down my hill recently my exhaust goes from bluish to almost brownish, ik i cylinder head had a smallest leak off the one side, coolant only no coolant in the oil...yet so im guessing somehow its leaking into the combustion chamber a little which is good for the motor,
    i plan on buying new heads from the junkyard and having them checked out and machined a just a touch unless you guys say no
    if its possible while i do this project is a port and polish worth it on the 4.3 V6 TBI, any different swappable throttle bodies, different intake manifold, ect ect. the usual performance stuff

    also plan on swapping to an electric fan and lose the belt im only getting 13 mpg when i used to get almost 22, i do have taller tires but only 30's i dont see that being a 9mpg loss

  2. #2
    Sr. Apprentice DanPruski's Avatar
    Join Date
    Jan 2012
    Wasilla, Alaska


    man, ive got a 4.3 also. You would get bettermileage putting a 305, or 350 and ignore the heads on it. I had to replace my engine from throwing a rod bearing and wish i had gotten a 350 for it, its in a regular cab step side. The engine i got is supposedly bored over to a 308 instead of the 268.
    Anyways all the performance stuff wont do anything hardly for the little v6's. yeah you put a little more fuel and air to it, guive it a few more horse, but with the weight of the truck you wont feel much difference at all in it. i would say its not worth the money for the parts.

    on mine im getting about 14-15MPG, i have 33x12.5 tires on it too, the mileage sucks but might go up from switching to the bigger engines.

    05 Silverado 1500 LS 5.3L.
    6" fabtech lift, 35x12.5 Nitto Mud Grapplers, 20x10 XD Monster wheels. MagnaFlow dual exhaust, AEM cold air intake, custom tune.
    35W 5K HID low,fog, 55W highs, Hi-6 Mod, black tail lights.
    Color matched front and rear bumper caps, fully debadged.
    5% tint all around, 35% full windshield with 10" 5% brow.
    7" pioneer touchscreen Double Din, 2 Rockford R1-12's under the seat with Rockford P300-1amp, Rockford prime speakers all around, LED interior Lights.

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