360 driveability problem

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74360duster

JEREMY
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Jan 21, 2006
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JAMESTOWN,MO
i have a 360 duster.when parked at a stop light with wet pavement.i can floor car and will take off pinging and spark knocking w/out spinning the tires
as soon as the car reaches 3000 rpm's.it breaks the tires loose and is all over the road.it is a stock 360 less the 340 cam.has factory 4 bbl intake and thermoquad carb.it has absolutely no power until it reaches 3000 then it flat *** screams.while idling the engine shakes terribly bad and idles bad.like has vacuum leak.but i have replace intake and gaskets,bought new carb,removed heads and had checked,checked for leak at booster.all seems ok.but still has low rpm problem.power brakes do not work well at idle.engine not making any vacuum.
My question is:Can the top timing gear be 1 tooth off and cause this engine to run terrible from idle to 3000 rpm then scream from 3000 to 6500 rpm as well as affect my power brakes??
this is the only thing we can figure.or if maybe it is a wore out timing set??
any help would be greatly appreciated.... and yes every time u take off from a start the engine is pinging and spark knocking.i am running 91 octane in it
 
What cam is in it? I'm inclined to think it's not a cam thing. It's a tuning thing. Have you verified the distributor is in properly? Did someone swap cams or timing sets? What is your timing curve like?
 
timing is at 12 deg.at idle range.if i remember correctly.the distributor points at 1 when on tdc.the cam is supposed to be a like a 340 cam? i am kinda baffled on the situation and was thinking about pulling the front cover and inspecting the timing marks on the gears.but would hate to go through all the work if it could be something simpler.thanks for any help.i did not install this engine,it was already in the car..
 
It still sounds like a vacuum leak situation to me. While the engine is idling and warm, take off the air cleaner and if it has a choke butterfly, slowly close it and see if the idle improves. If you quickly slam the butterfly shut, the engine should very quickly die with little or no change in idle speed and quality. If it is a vacuum problem and you quickly close the butterfly, the idle may increase very notably and then die. If you find you can slowly close the butterfly partway and reach a point that smooths the idle and increases the idle speed, you have a leak. If you don't have a choke butterfly, you can use your hands or a rag.
 
when you ajust the timing and turn the distibutor is it real touchie,or it dont change the rpm hardly any,If it is sensetive when you move it the the timming set should be ok. Make sure the spring's in the distibuter have not jumped off or the advance mec is not sticking. Are you running point's, I will quess you are not
 
checked the distributor today.all springs hooked up.everything seems to be working there. i turned the motor past tdc.then turned back to tdc.had the cap removed and found the engine will turn approximately 8 deg.before the rotor moves.so i figured timing chain worn.tore it apart.has double roller.bottom sprocket has 3 key ways.it is set in the 0.has one with an A and one with a R.is it a possibility it should have been set on one of these instead of the 0??
 
not necessarily. the "A"dvance and "R"etard is for changing when the powerband comes in. retarding it brings it in sooner. advancing , later. did the dot at 12 o'clock on the bottom sprocket line up with the dot at 6 o'clock on the top sprocket? if worn , your in there.....

when you have it back together, what is total timing? 35 btdc? what rpm? what color are the plugs?
 
Well it could be a few things.

The cam timing could be off a bit. Retarding the timing would make it soft down low.

It could have more cam then you think it does and be under geared and not have enough converter. This could be lugging the motor down low and causing the detonation.

It could be a timing issue. Try giving it some more timing at idle. My distributor is set for 18* initial.
 
Well.timing Chain Showed 8 Degrees Of Play Before The Rotor Would Move.so I Installed A New Chain And Sprockets.no Improvement.did Away With Vacuum Advanced.set At 36* At 2500 Rpm
Still No Improvement.any Ideas What I Am Doing Wrong.or What I Should Do.
Have Been Thinking Of A New Motor And Junking This One.but Can't Afford Crap Right Now.twins Are Getting Expensive.7 Months Old,crawling And Into Everything.gotta Love Fatherhood
 
If you're new timing set has the 3 keyway's in it you could try the cam in the advanced spot. Advancing a cam will give you more low end power. I would also use a degree wheel and see were your can is at now and when you advance it. Like Adam says it may be more cam than you think. Or it could be mis-ground, checking it with a degree wheel will tell you what you have. I'm thinking it is a camshaft problem given the problems you list and the things you have already tried.

Chuck
 
i bought a new single key way double timing set.so they are on the right notch there.but it almost has to be cam issues:(the stall convertor did help the dogginess alot.but engine at idle shakes so bad u would think it were out of balance..
 
The knocking and pinging at low rpm concerns me. Have you checked to see if the "0" mark on the harmonic balancer actually is at TDC? The outer rings have been known to slip.

As Moper said, do you have access to the cam specs?

Is your PCV valve stuck open? That would create a nasty vacuum leak at low RPM's (high vacuum conditions).

The pinging indicates a high compression ratio. If the heads and block have been milled more than .020 combined, and if the correct amount of material was not taken off the intake manifold sealing surface of the head, the intake manifold will leak from the underside (inside the engine) and is very hard to diagnose.

If you have a propane torch you can just turn on the gas and run it around the sealing surfaces and see if the engine picks up RPM. This also works to diagnose a lean idle condition if you add propane to the intake horn of the carb.
 
Is the distributor reluctor point in line with the pickup point when the rotor is pointing at any given terminal, if it isn't the reluctor is in the wrong position and the engine will be retarded and run like crap at low engine speeds. I have seen reman distributors put together this way because the people that they have working for them don't either know or relize they are doing it wrong. Just another thought.
 
Sounds like you have messed around with the timing quite a bit, to include the timing chain and gears and distributor, you say no notable changes, in my opinion, time to move on.
You mentioned very poor idle quality, engine shaking, etc. Did you try to "smother" the carb like I suggested, there are a million places to develop vacuum leaks, you need to rule this out, my method is quick and simple and if nothing else, will eliminate vacuum issues from the list of things to try. If and when this fails, there is always the next step...... Don't give up though, as frustrating as it may seem, you will find it, and when you do, you'll probably kick yourself. As far as fatherhood, I have 5 kids, know what you're talkin' about!!!
 
i agree with the carb trick. leave your four fingers slightly open and smother the carb, mainly the two front bowls. if it picks up, your lean. if you don't have the cam specs, do you have access to a dial indicator to check lift @ lobe? this will help narrow down what the cam specs might be. im thinking you have the timing coming in too fast since you say the power starts around 3000rpm. what is the stall on the converter? if your powerband starts @ 3000rpm, your total timing needs to be at least by 3500rpm not 2500rpm.
 
bjr.could you explain what u are talking about with the distributor deal.i would like to check this maybe tomorrow.just not real acquinted with inside the distributor.so alittle more info would help me.thanks.i am also going to try to do the carb smothering deal.and check the pcv valve.i hope it isn't something as simple as the pcv valve.as far as the internal engine vacuum leak from milling on the engine cylinder heads.it could be a possibility.it ran bad with the LD 340 intake that came on it.so i removed it and put the cast 4bbl intake on it.no change-could it be that is my problem?only time will tell.i have been trying to get ahold of the guy who sold me the car 4 years ago and built the engine.he won't call me back.and he is a good friend of my fathers.u would think a friend would call u back.
i really appreciate you all taking time out of your day to scratch your heads and give me ideas on how to get my car running right.and by the way the convertor i put in the car stalls at 2600 rpm.compared to the one i took out that only stalled at 1100.yes thats right 1100.car would barely run in gear.at least now in gear the rpm doesn't change even when u turn the a/c on.we are supposed to get upto 20 inches of snow with ice between sometime tonight and monday.so this coming depends if i can drive to the farm and check the car out
 
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