68 camper special trouble
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68 camper special trouble
i recently rebuilt the 360 engine on my f250 and after a couple of months of perfect runnning i have a very rough idle. ater changing my timing chain (cause i thought my timing chain skipped a tooth) and my distributor. i have a perfect idle at around 800-850 rpms. the downside is when i put a load on and hit the gas i get a backfire from my carb. any ideas as to what the cause is? im going to check my point gap... i checked my fuel and air ration and thats fine as well. could my vaccum advance hose be faulty? or crossed wires? any help would be awsome
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backfire
When you adjust or change your point gap you are also changing the ignition timing. Lazy or retarded timing will cause a backfire through the carb. Temporarily disconnect your vacuum advance hose and put a timing light on it. Set it a 10 degrees advance, reattach the vacuum advance hose and try that.
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WOW SO I HAND CRANKED MY ENGINE TO TDC AND IT DOESNT MATCH UP WITH MY TIMING MARKS AT ALL ITS AROUND 10-15 DEGREES OFF. ANYBODY SEEN THIS B4? WHAT COULD CAUSE IT? MAYBE MY CHAIN WAS PUT ON WRONG?
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From: Faibanks Ak.
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The harmonic balancer is assembled from three separate parts:
(1) Inner damper / (2) rubber spacer / (3) outer pulley.
The spacer is placed between the pulley and damper, then the three parts are pressed together forming a one piece assembly.
What happens: The rubber spacer cracks apart, causing the outer pulley to "walk away" from the inner damper, this will throw off the timing.
If not caught in time, the pulley will separate from the damper and may end up in your radiator core. Not pleasant.
IF this truck has T/E = Thermactor Emission (smog pump), it will have an "Anti-Backfire Valve."
(1) Inner damper / (2) rubber spacer / (3) outer pulley.
The spacer is placed between the pulley and damper, then the three parts are pressed together forming a one piece assembly.
What happens: The rubber spacer cracks apart, causing the outer pulley to "walk away" from the inner damper, this will throw off the timing.
If not caught in time, the pulley will separate from the damper and may end up in your radiator core. Not pleasant.
IF this truck has T/E = Thermactor Emission (smog pump), it will have an "Anti-Backfire Valve."
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all true numberdummy except for the fact that there are three bolts holding the pieces together so that 1 does NOT "walk away". how can my timing marks be off though? if the harmonic balancer is placed only 1 way with the key? all my emmisions pumps and sensores were torn out when i bought the truck. to get tdc i used the old fashioned pencil method then pulled my valve covers off to check valve placement.
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The three bolts do not hold the balancer/pulley together.
The three bolts are used to attach outer pulley(s) to the balancer.
Depending on what accessories (P/S, A/C, T/E, two belt alternator pulley) are installed, there may be one outer single sheeve pulley, or there could be a double or even a triple sheave outer pulley.
Over 35 years, I sold 100's of harmonic balancers, you wanna know why?
Because, the outer pulley SEPARATES from the inner damper...due to the fact that...over time...the rubber spacer cracks apart.
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From: Faibanks Ak.
The outer ring on the balencer is pressed on with some sort of rubber in between, they can walk and it is very common for them to.
It should be very easy to time it by ear good enough to determine if timing is your problem.
It should be very easy to time it by ear good enough to determine if timing is your problem.
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check my balancer and the rubber piece is just dandy. timing it by ear does no good i can get super smooth idle but when i put into drive and step on the gas i get constant backfire and no power like i used to