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From 24 valve to 12 valve


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I currently own a 99 24 valve 4-door, it is being sold to my younger brother because it is a 5 speed and uncomfortable for me to drive. I had no intention of replacing it now but to wait and look for another 24 valve automatic.A young man who owns a A/C and automotive repair shop did some work for me and I explained what I was doing. He brought in a 97 which automatic, it needs paint but not too bad condition inside or out. 229,000 miles and was used for hauling a 40 ft toy hauler all over the country from coast to coast. The owner owns a transmission shop and at one time was big into racing. This 12 valve is quite compared to my 24 valve. The 12 valve also drives great, transmission shifts hard and deliberately up and down depending on speed. Dash is in great shape and everything works. Asking price is $5,500. Completely stock as far as I know but I could be wrong. What do I need to look for from a buyers prospective, what should I be inspecting or looking over. What are some of the issues with 12 valve trucks that are common. I can't believe how smooth this truck is to drive. What kind of mileage can I expect to see in town and highway. Are there any companies that sell all of the interior items to rebuild it?

 

I'm asking too many questions I know but if anybody has an opinion and feels like adding to this post please do. One is better than none and I could use some advice. Thanks.

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sounds like a nice truck and, as long as the engine is all stock only thing that comes to mind is to ask if anything has been done with the KDP, and see whats been done with the transmission, other than that just cover the basics like on any vehicle, being a 97 if they haven't been replaced already some things to check on are shocks, front end parts (ball joints, track bar, etc.), fuel lines, and other rubber parts, like the tappet cover gasket. 

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I haven't found anything bad about 12v trucks like the 24v's have. Injector pumps last forever and the lift pumps are pretty reliable too. P7100 pumps are quieter by nature than the vp44, my 24v got quieter after I p-pumped it. You can buy a new dash top from dodge but most of the other parts will have to be sourced from parts trucks.

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sounds like a nice truck and, as long as the engine is all stock only thing that comes to mind is to ask if anything has been done with the KDP, and see whats been done with the transmission, other than that just cover the basics like on any vehicle, being a 97 if they haven't been replaced already some things to check on are shocks, front end parts (ball joints, track bar, etc.), fuel lines, and other rubber parts, like the tappet cover gasket. 

I started reading the posts under 12 valve, lots of information already. I've had time to think about some of what I asked. Thank you your post, Your right, I need to check the front end, shocks, and fuel lines as suggested. I don't know anything about the 12 valves but what I have looked at tells me it is a good engine to work on. If this truck had a new paint job it would look great. I need to look at the fuel system and find out what kind of lift pump is used on the 12 valve. This is a good start...thanks

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I haven't found anything bad about 12v trucks like the 24v's have. Injector pumps last forever and the lift pumps are pretty reliable too. P7100 pumps are quieter by nature than the vp44, my 24v got quieter after I p-pumped it. You can buy a new dash top from dodge but most of the other parts will have to be sourced from parts trucks.

It's hard to believe the difference in sound between the two. Pretty big job to P-Pump a 24 valve, someday I would like to ask you some questions on how you did it. I am going to buy this one after all. My 24 valve stopped on me before I put 250 miles on it. The transmission is great, I'm going to find out the details tomorrow on how the transmission is built. Thanks for your reply.

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I started reading the posts under 12 valve, lots of information already. I've had time to think about some of what I asked. Thank you your post, Your right, I need to check the front end, shocks, and fuel lines as suggested. I don't know anything about the 12 valves but what I have looked at tells me it is a good engine to work on. If this truck had a new paint job it would look great. I need to look at the fuel system and find out what kind of lift pump is used on the 12 valve. This is a good start...thanks

12v's use a mechanical piston lift pump that is run off a lobe on the cam, very reliable. only thing I've ever seen go bad in them is the return spring getting weak over time.

Edited by bjytech
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It's hard to believe the difference in sound between the two. Pretty big job to P-Pump a 24 valve, someday I would like to ask you some questions on how you did it. I am going to buy this one after all. My 24 valve stopped on me before I put 250 miles on it. The transmission is great, I'm going to find out the details tomorrow on how the transmission is built. Thanks for your reply.

It wasn't to big of a job, could have done it in a day had I not been waiting for weeks on parts. It was a good learning experience too! Yes, the pump is what makes them sound different and the exhaust actually smells different too. I will try to help with any questions you have.

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I'd imagine that part of the reason it sounds different is the static timing.  I'd imagine that the VP44 can run a lot more timing overall than the P7100.  

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I'd imagine that part of the reason it sounds different is the static timing.  I'd imagine that the VP44 can run a lot more timing overall than the P7100.  

Tell me this, how does timing advance with a 12 valve or does it stay at one point that satisfies and idle and WOT?

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Tell me this, how does timing advance with a 12 valve or does it stay at one point that satisfies and idle and WOT?

I'm 99% sure the p7100 is static timing. Still a good pump.

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I'm 99% sure the p7100 is static timing. Still a good pump.

I guess I am going back to school to learn 12 valves. One thing for certain according to Michael, there is no hidden secrets about the P-7100 pump so I should be able to understand it better than the VP44.

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For a stock truck, a 12v is hard to beat. It's kinda like an anvil.

I knew I would like the truck as soon as I went down the road in it. I think it was faster than my 24 valve, much smoother too. I have always been fond of Anvils since I started learning the metals trade. I started out Oxygen/Acetylene welding and beating and banging was a big part of it.lol

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The pump is run off the cam lobe like an old car. Pretty reliable. There might be a boost pump In the back but I'm not sure. Unfortunately our resident 12 guy is gone.

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The pump is run off the cam lobe like an old car. Pretty reliable. There might be a boost pump In the back but I'm not sure. Unfortunately our resident 12 guy is gone.

passed on? Sorry to hear that. No pump in between fuel tank and lift pump?

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I'm 99% sure the p7100 is static timing. Still a good pump.

 

97 auto trans truck like Paul is looking at would have a 180hp p7100 so would have static timing, if you get a 96-97 with the 5speed and 215hp p7100 it retards timing some as rack travel increases(giving it more fuel), up to about 4°(if I remember correctly) retarded from whatever the static timing is set at.

 

 No pump in between fuel tank and lift pump?

There are no fuel pumps other than the one that is mounted on the engine on a 12v.

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No, he just left. 

Sorry to hear that, it's like all the great men and women that fought in WWII and all the special skills they had. Not taking away from Vietnam veterans at all. I worked with a lot of these men, they were fearless and if you were lucky enough to win their friendship what they shared about life was priceless. 

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97 auto trans truck like Paul is looking at would have a 180hp p7100 so would have static timing, if you get a 96-97 with the 5speed and 215hp p7100 it retards timing some as rack travel increases(giving it more fuel), up to about 4°(if I remember correctly) retarded from whatever the static timing is set at.

 

There are no fuel pumps other than the one that is mounted on the engine on a 12v.

this is amazing, I am still learning about 24 valve trucks and now I find the truth about 12 valve trucks, I think this will be a winner for me and what I want. What I don't understand is how loud some of the 12 valve trucks are and why are they louder than most. The last job I worked was a Boiler job in Marissa, IL, we would come to work an hour or longer early to get a parking space. I was driving my beloved Duramax. There was an old man who drove an old 12 valve with the new body style. If you were trying to sleep the loudness of his truck caused many ugly conversations, he didn't have to be concerned about anyone parking next to him until 7:45 am. It made your teeth rattle at 25 yards. I am excited about getting this 12 valve.

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