Punt in new 250 v6 - so slow - am i getting ripped?
March 5th, 2012, 8:53 AM
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Punt in new 250 v6 - so slow - am i getting ripped?
So I have a 75 Chevy stepvan... and just put in a remanufactured 250 v6 motor in with all new parts - radiator, carb, oil/fuel pump, distributor, etc. Motor goes in and have two issues that are driving me insane.
When going up even the slightest of hills, this truck will not go over 30-40 MPH. Now I am not expecting it to fly up the hill but this is quite dangerous. Im pressing on the gas so hard that it keeps going into overdrive. Let up and it stops but then trying to get uup the hill it happens again and again.
When I get to a light...it idles horribly...shaking the entire truck almost like it is going to stall type of idle.
Fuel pump has been replaced 2x as has carb. The mechanic now seems to be grasping for straws on my dollar..wants to pull off exhaust manifold to see if it tight to block... thought he should have done that when he put the new motor in no? I have almost no confidence left in him as Ive spent so much downtime and money trying to just get it roadworthy.
So I bring to another mechanic who insists it that the cat is clogged?? Is this even a possible reason that would cause these symptoms?
Other 'home mechanics' I speak to are convinced of a timing/distributor or vacuum type issue. These make the most sense to me but again I am far from an expert.
I sure could use some help, advice or even things to check as I am running out of money and patience. I want to be as informed as possible and understand so that I have a clear mind when I bring it in. Heck...wonder why I cant just do it myself if someone could help me out here...Id love to dig into it myself. Just need some assistance.
Thanks Kevin
When going up even the slightest of hills, this truck will not go over 30-40 MPH. Now I am not expecting it to fly up the hill but this is quite dangerous. Im pressing on the gas so hard that it keeps going into overdrive. Let up and it stops but then trying to get uup the hill it happens again and again.
When I get to a light...it idles horribly...shaking the entire truck almost like it is going to stall type of idle.
Fuel pump has been replaced 2x as has carb. The mechanic now seems to be grasping for straws on my dollar..wants to pull off exhaust manifold to see if it tight to block... thought he should have done that when he put the new motor in no? I have almost no confidence left in him as Ive spent so much downtime and money trying to just get it roadworthy.
So I bring to another mechanic who insists it that the cat is clogged?? Is this even a possible reason that would cause these symptoms?
Other 'home mechanics' I speak to are convinced of a timing/distributor or vacuum type issue. These make the most sense to me but again I am far from an expert.
I sure could use some help, advice or even things to check as I am running out of money and patience. I want to be as informed as possible and understand so that I have a clear mind when I bring it in. Heck...wonder why I cant just do it myself if someone could help me out here...Id love to dig into it myself. Just need some assistance.
Thanks Kevin
October 8th, 2012, 6:49 PM
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I would check the distributor and the advance, both vacuum and centrifugal. There are old school machines that can do this. You say it is a re-manufactured engine, were the heads done, too?
I have seen engines that had the wrong pistons, and/or the wrong cam that behaved like this. Using a high performance cam on an engine that is not designed high compression can really rob your power.
Cutting the pipe before the cat converter and running it loud (off road of course) would be an easy test, and then welding it back up. Some cat converters can be un bolted, they even make "test pipes" for them. A muffler shop could be able to help out with that cheaply, if you do it on a slow day
I have seen engines that had the wrong pistons, and/or the wrong cam that behaved like this. Using a high performance cam on an engine that is not designed high compression can really rob your power.
Cutting the pipe before the cat converter and running it loud (off road of course) would be an easy test, and then welding it back up. Some cat converters can be un bolted, they even make "test pipes" for them. A muffler shop could be able to help out with that cheaply, if you do it on a slow day
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