different 318 question

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I know its not a mopar but i had a bronco 2 that did the same thing with a 5spd trans. it would pull well up to 3 or 4k rpms then just go flat. Unknown mileage on the engine. I advanced the distributor and it picked up really well. It pulled great thru all gears and improved fuel mileage. The only thing is it put the timing strobe clean out of range on the harmonic balancer. That told me the timing chain is stretched pretty bad. If your chain and gears are stock and havent been replaced, and you try this and it picks up, I would check your chain and gears.
 
Mikes270dart said:
Car starts easily. The gears are brand new. the tires are 26". The exhaust is new. The tach is cheap, it could be out. No back fire, sputtering or strange noises, it just "lays over", I am thinking it is valve float but not sure. Carb could be an issue will check it out as well this weekend.
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If the car starts easy, then I doubt the problem is in the engine, but now I favor restricted exhaust, or maladjusted throttle cable. Or, I suppose, the secondaries opening too far too soon.
If you were to shut the car off right after she has gone flat, and the car RE-starts easy, then it is not likely to be valve float.
BUT
If it's valve float, it will also go flat in Park/Neutral; just rev her up and listen for the change in engine sound, signalling the onset of float.(I haven't tried this, but if you had a vacuum gauge plumbed in, you should be able to see the rapid loss of vacuum as the lifters hang open.) Right after that it will go flat as the lifters pump up and prevent the valves from closing. Usually the heavier intakes float first. Then the pistons start pushing the A/F charge back up into the intake. If you allow the throttle to slam shut when you hear the change, the engine will not produce enough vacuum to stay running and so she stalls. Then it will not restart without a lot of cranking until the lifters bleed down,or until a few hours later. When you do get it running again, it will run very rough until things return to normal.
If you prove this, there is a pretty cheap fix.
 
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Mikes270dart said:
Car starts easily. The gears are brand new. the tires are 26". The exhaust is new. The tach is cheap, it could be out. No back fire, sputtering or strange noises, it just "lays over", I am thinking it is valve float but not sure. Carb could be an issue will check it out as well this weekend.
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I see you spent a chunk of change on her recently. And some of the new changes, could be the source of your troubles.
With 26" tires the rpm at 60 should be 2750 at zero slip. With a bit of slip in the TC it could be about 100 rpm either way.
 
Something seriously wrong.... not fixing this by bumping timing a few degrees on the distributor. I've seen small block mopars jump timing on the chain (plastic gear... yeah!!) but still do 100 a minute earlier. I had a 318 2bbl with the heat flap froze solid on the passenger side due to rust, and she'd still do 100. Sounds like you don't have the power of a stock 170 slant six missing 2 spark plug wires. 5 lobes flat on the cam??? Carb only coming open a tenth of an inch???? My point is you are looking for a MAJOR issue if it takes everything you got on a downhill run and tail wind to hit 75 mph....
 
I've turned a 360 7200 rpms with a 1 7/16inch restrictor plate and a 350cfm holly 2 barrel with stock 340 manifolds and 2" pipes ( just saying) and It was out of air at 3600 rpm's so its not a air problem. NOW I have run across a /6 that the timing would retard after 2400 rpm and the only way it showed up was to set the timing to 35 degs at 4000rpm's not much fun with the fan blowing hot air all over you and dangerous but I found what other didn't and was well rewarded for it same way I set all racing engine at top rpm.
 
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It's a 4spd. Had a bad storm today lost 4 mature trees, be a couple of days before I can play with the car

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Mikes270dart said:
Car starts easily. The gears are brand new. the tires are 26". The exhaust is new. The tach is cheap, it could be out. No back fire, sputtering or strange noises, it just "lays over", I am thinking it is valve float but not sure. Carb could be an issue will check it out as well this weekend.
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With valve float, I would expect some irregular 'noises' as cylinders misfill and misfire. (At least that is what I have heard in the very, very few times I managed to float anything; it gets kinda ragged sounding.)

Dang on that windstorm! Rare for that area?
 
Another area to check is if the push rods are bent or punching through one or more of the rocker(s).
I had one punch through a rocker in a '69 318 Coronet and it still ran well at idle but had no power at all (all of a sudden).
No noises before, during, or after either.
I thought the timing chain jumped, and i found one of the rockers with the push rod sticking 1/4'' through the other side and a few of the others with cracks in them where the push rod fits.
The engine was a high miler so i just decided to pull it out.
 
Insurance isn't covering anything, going to cost me a small fortune. Going to have to hold back on engine upgrades. Thanks for all of your input.
 
Thanks for everyones input, valve float seems to be the issue. House insurance doesn't cover trees that don't hit the house. Sold the Dart to free up some funds, it sucks but can't do much about it. Hopefully next year I will be back behind the wheel of another Mopar
 
SOMEONE would've loaned you their chainsaw rather than have you sell the car! Well, I am sure you'll get back in the game.
 
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