1994 new engine issues

[tposeno]

I have a 1994 k-1500 with 302k miles on it. This truck ran like new until it failed inspection because of a both main seals leaking. The wife and I decided to replace it with a new motor because of the mileage. We loved this truck until this happened: We opted with an updated motor, 4 bolt mains, melling pump, towing cam, etc., all the goodies. To make a long story short, the motor idles fairly smooth, but skips under load. I personally changed the wires, plugs, and distributor after the shop that did the work said there is nothing wrong. when I pulled the plugs, the last 2 on the drivers side were like new, not tan like the others, which i interpreted as an intake leak. I changed gaskets, no difference. The other problem is mileage. the old motor got 15-17mpg, this new motor struggles to reach 8mpg. with no power, the skip, and no mileage we dont want to even drive it which is a shame because we used to use this to haul anything we could throw at it. Now it struggles to haul itself. Any ideas?

[436'd skylark]

what are the cam specs?

[jdfenske]

tsk tsk tsk

no offense, but the best work is your own.

buddy had a clutch put in his truck
9 months later calls me up saying he lost all except 4th.
took tranny apart and the input gear on the cluster burned out
no one put oil in it (!!) after installing the new plate and disc.

too many chefs spoil the soup.

[tposeno]

didnt hang on to any of it

[Hayden]

Run compression tests on those Cylinders. Valves, springs, seals, pushrods, or lifters might be screwed up or outta whack. I'm sure you already checked for spark in those cylinders.

[436'd skylark]

its possible the lash was set to tight, or the cam is not compatible with your computer.

[88fivespd]

I would suspect the fuel injectors on those two cylinders that had the new looking spark plugs. Either the injectors themselves or the signal going to the injectors to fire(for lack of a better word) them off. I think there's something called a noid light you can use to check and see if the injectors are geting their signal.

[gmctrucks]

I agree with Joe all the goodies have to match with the other stuff or it won't run right. A buddy of mine put a bigger carb on his car thinking that it will get up and go but you have to get the right heads, cam, and so on it never ran right I told him so.

[Case 7230]

I`m with 88fivespd.

[436'd skylark]

Originally Posted by 88fivespd

I would suspect the fuel injectors on those two cylinders that had the new looking spark plugs. Either the injectors themselves or the signal going to the injectors to fire(for lack of a better word) them off. I think there's something called a noid light you can use to check and see if the injectors are geting their signal.

good point, however a 94 would have TBI, which means there is only 2 injectors that pulse all the time for all 8 cylinders. really primative. he could have round lobes on those cylinders though.