My 1976 dodge sportsman motorhome after 1.5 years
Uploader Comments (hchelfman)
All Comments (9)
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how many cfm is the carb you need atleast 600 for a bigblock , i would check timing , see how much slack is in the chain they can jump a tooth .
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Runs good *BANG* hahaha sounds great
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Good thing is, I see your lucky, as am I, and your rig has a big block. So, once dialed back in, she should provide some pretty decent power.
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That firing back through the intake can be caused by several things. In a nut shell, it indicates the plug on a cylinder is firing, when the intake valve is way opened, and way out of timing from when it should be firing. Whether a simple screwed up plug, or plug wires jumping spark to another cylinder, or some other causes.
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Sounds like a plug is miss-firing. Kinda similar to timing being way off. I'm about to resurrect my own 76 Sportsman van, after she has sat for many years. Similar situation to how yours appears. I'd just do some regular ignition and carb maintenance, as well as double checking timing chain and fuel pump. See how she does then. I may go so far on mine as to dig into the engine a bit, just to double check condition, and more thoroughly clean.
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hows your motorhome running these days?
Valves are probably not sealing all the way...spray some top engine cleaner down the carb while keeping a steady idle until the can is spent and then let it dies while still spaying when the can gets low...timing chain might be moving aroing a bit but try the TEC first.
rancheroman1961 7 months ago
@rancheroman1961 I had been thinking that it probably has a leaking valve and was wondering if I'll pull the heads after doing a compression test next time I'm in that thing. Didn't think about top end cleaner. Maybe I'll try some of that snake oil first!
hchelfman 7 months ago
Yes it's a 440 in a 1977 (coach model) year built on 1976 chassis. Obviously it's not running on all 8. Cap & rotor are new. Fuel pump is new but timing chain is probably original with about 100k miles. I haven't done a compression test or pulled plugs recently, but it still backfires on a pretty wide timing range whether or not the vacuum advance is connected. Previous owner swapped carb to edelbrock performer with auto choke. Does anybody have any other suggestions?
hchelfman 10 months ago