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I have a carbureted 1987, 460, C6 automatic motorhome. I bought this heap with over 50,000 miles on it. I've been chasing a lack of power/loss of speed/increase in engine temp since I bought it. I've done a lot to it, and right now, I'm concentrating on the carb.

I am not sure if it had the original carb from the factory. That carb was rebuilt by me and then by a pro to no appreciable difference in performance. Then I put a re-manufactured carb on it. Unfortunately, I think this carb is specific for a van - not a heavier vehicle like an rv. Based on my experience with replacing the distributor (another thread on this very forum), I'm thinking there was supposed to be a very specific carb for this application. When I go to parts stores or online, I don't get asked if its for an rv cut away model - only that its a van. I don't believe any van weighs between 11,000 and 14,000 pounds and has a dual rear wheel axle. It may be that, since it's 30 years old with only 50,000 miles on it, it's had long stretches where it sat idle. Maybe a former owner just swapped the carb instead of rebuilding the original and put a van carb on it way back when.

Anyone know what I'm supposed to have? I'm thinking I can change the van carb (#E5HE-EB) by re-jetting it. But now I'm wondering if there are other components it's supposed to have - power valves, specific spring rates, or even specific metering bodies.

Any help is appreciated.
 

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I have a carbureted 1987, 460, C6 automatic motorhome. I bought this heap with over 50,000 miles on it. I've been chasing a lack of power/loss of speed/increase in engine temp since I bought it. I've done a lot to it, and right now, I'm concentrating on the carb.

I am not sure if it had the original carb from the factory. That carb was rebuilt by me and then by a pro to no appreciable difference in performance. Then I put a re-manufactured carb on it. Unfortunately, I think this carb is specific for a van - not a heavier vehicle like an rv. Based on my experience with replacing the distributor (another thread on this very forum), I'm thinking there was supposed to be a very specific carb for this application. When I go to parts stores or online, I don't get asked if its for an rv cut away model - only that its a van. I don't believe any van weighs between 11,000 and 14,000 pounds and has a dual rear wheel axle. It may be that, since it's 30 years old with only 50,000 miles on it, it's had long stretches where it sat idle. Maybe a former owner just swapped the carb instead of rebuilding the original and put a van carb on it way back when.

Anyone know what I'm supposed to have? I'm thinking I can change the van carb (#E5HE-EB) by re-jetting it. But now I'm wondering if there are other components it's supposed to have - power valves, specific spring rates, or even specific metering bodies.

Any help is appreciated.
I believe what you have is a Holley 4180 4 barrel vacuum secondary emissions carb. If that is the case you can use any Holley style vacuum secondary carb to replace it, however it will need tuning for your specific application which may involve more than simply a jet change.

Something like this: https://www.summitracing.com/parts/hly-0-1850s/overview/
 

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HI I don't think a carb change is going add power... 50,000 is a good chunk when pulling 14,000 lbs. how many miles have you put on it? 87 did not have much power like in the 60 and 70's.. best run a health test on the motor compression test, leak down test . check timing if it bounces around at idle the chain is bad. first thing I'd change would be the timing gear and chain set to 0* early set. check for plugged exhaust dragging brakes. thick fluid in rear end. wheel barrens need greased?
good luck
tim
 

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A few years back, my 1988, 460 powered, Class C motor home went down on power, and about the same time, a man that owned a motor home rental company called me and wanted to know if I had any idea as to the cause of his motor homes going down on power.

We were not aware that the engine oil had been reformulated with a significant reduction in zinc and phosphorus content. Therefor, the camshafts in our engines failed.

I ordered a custom camshaft in an effort to increase torque in the RPM range that is used, reworked the heads, removed all smog equipment, supplied fresh air from the grill to the modified air cleaner, and retuned the carb and distributor.

I now use an oil that is formulated for flat tapped camshafts, and the engine runs much stronger and millage is better.
 

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Discussion Starter #5
I ended up changing the power valve last year, and all of a sudden I had mid-range acceleration (above cruising, under flooring it). Whatever PV I had in there, it wasn't opening when it needed to. I took a manifold vacuum reading at idle and, per online information, got a PV that opens at about 1/2 that idle reading. Now, this thing can pull like a bear. However, I'm still chasing the heat buildup. I can do inclines no problem as long as they allow me to stay in third gear. Once I hit second and the RPMs increase, I can watch my temp go up from 200 to 230, where I back off.
We went over the Berkshires, staying behind a truck who was doing 45, tops. I stayed behind him, in second, and got to my 230. Sometimes, it went back down in temp - which was odd. That was new. It usually returns to normal only once I'm back in 3rd and leveling out.
So I'm looking at the carb again. The jets are stamped "219" which Holley tells me is a #68 (.068" bore). I found a drill bit that fits, and measuring that, my cheapo micrometer says the bore is about .055" (a #56 Holley jet). I'm inclined to believe my micrometer. I had earlier spoken to another person at Holley, who said a 460 van would have been equipped with a #61 (.060"), while a truck would have had a #63 (.062"). So, throw a #61 in there and see what happens?
 

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I have a 1986 Ford Class C RV with a 460 and also experienced the engine running hot. I replaced the radiator – some cores were blocked and replace the water with little success.
At one time in my work history I worked in the test lab for a large agricultural machinery company and was involved in lot of tests of cooling packages and one the problems we dealt with was air recirculation. The air would pass through the radiator and loop around and the hot air would get drawn through again instead of being expelled away from the inlet side of the radiator. In reading different forums people complained about air flow around the engine due to the size of the 460 in relation to the engine compartment. One day laying on the ground looking up at the radiator I noticed the back side of the radiator was not isolated from the inlet side. I purchased some dense foam form Amazon – one side sticky. I started to seal the sides of the radiator so air that passes through the radiator could not recirculate. On the bottom I took a sheet plastic and fasten from the lower side of bumper to the radiator support to block off an air ingress area. Th goal is to only allow ambient temperature to pass through the radiator. An engine running hot could have a lot of root causes but this worked for me, engine runs cool now and I can pull long hills and not worry about overheating.
Take a look at a new vehicle and see how they handle radiator air flow.
I have a 1986 Ford Class C RV with a 460 and also experienced the engine running hot. I replaced the radiator – some cores were blocked and replace the water with little success.
At one time in my work history I worked in the test lab for a large agricultural machinery company and was involved in lot of tests of cooling packages and one the problems we dealt with was air recirculation. The air would pass through the radiator and loop around and the hot air would get drawn through again instead of being expelled away from the inlet side of the radiator. In reading different forums people complained about air flow around the engine due to the size of the 460 in relation to the engine compartment. One day laying on the ground looking up at the radiator I noticed the back side of the radiator was not isolated from the inlet side. I purchased some dense foam form Amazon – one side sticky. I started to seal the sides of the radiator so air that passes through the radiator could not recirculate. On the bottom I took a sheet plastic and fasten from the lower side of bumper to the radiator support to block off an air ingress area. Th goal is to only allow ambient temperature to pass through the radiator. An engine running hot could have a lot of root causes but this worked for me, engine runs cool now and I can pull long hills and not worry about overheating.
Take a look at a new vehicle and see how they handle radiator air flow.
 

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Discussion Starter #7
fourstroke141: Could I trouble you to put up a couple pictures of where you placed your air dams? I want to give that a try before I go re-jetting the carb.
 

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See below image. Picture taken below vehicle looking up at the bottom take of the radiator. The small hoses are for the auxiliary transmission. The black with silicon sealer is dense foam stuffed between the bottom tank of the radiator and the radiator support, the white is plastic that closes the open gap between the radiator support and front bumper. The black at the bottom of the picture is a air dam of of a Ford Ranger truck.

91677
 

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91678


The above picture shows the front bumper with the Ford Ranger air dam. The biggest improvement was the white plastic sheet from the radiator support to the front bumper. Not sure the air dam did much. Whish I could of found one that was wider, the theory is to cut down on air turbulence below the vehicle and create a positive pressure in front of the radiator. Just got back from a RV trip traveling the PA turn pike and if you are familiar with the PA turn pike there are several long hills, with ambient temperatures in the mid 80 degree range and towing a trailer with a Goldwing 1800 motorcycle the temperature gauge never went above the mid point on the long hills when gong high way speed. It will climb when speeds are below 35 pulling a hill but I believe at that speed the fan starts to become a factor for cooling rather than air flow. There are numerous things that can cause overheating but the above is what resolved my issue. The other suggestion is to purchase a heat gun. I found out my gauge needle indicated a higher temperature that what the actual temperature.
 

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Discussion Starter #10
Thanks very much for posting those pictures, fourstroke141. I did not consider hot air re-circulation (not once, in five years) until I read your post. I did some more poking around and this other guy got me thinking more about it: Some Thoughts on Air Flow, Radiator Cooling and Engine Bay Temperatures - Ford Truck Enthusiasts Forums

Between the two of you and your pictures, I came up with the following made from: 3 aluminum door kick plates, two door sweeps, a pair of 6" and a pair of 4" brackets, 90* angle aluminum, some insulation and hardware. It drops down 9" from the bottom lip of the bumper. Hopefully, it will protect the cross member from catching a ton of wind. The insulation is stuffed in there with channels cut to allow the transmission lines through. I'm not sure how well the insulation will put up with 200 degree temps, but I'm going to give it a shot. They are just jammed in there and squeezed against the radiator with another kick plate and the 4" brackets. Both sets of brackets were bent with a sledge to a bit more than 90*.

I may be hitting the Berkshires at the end of the month, so that will be a good test before I start messing with the jetting of the carb.

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