Lack Of Power

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jpeshelman

jpeshelman

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This has been a problem since i got this car......the carb was bad so i just replaced that.....now the car will idle fine, free rev fine, and will drive fine, BUT it has no power at all....you can floor it and the car wont pull past 2800-3000 rpm.....I have checked the timing and it was on, the vacuum advance is working the car does have valvetrain noise on the top end...so the next step should be check the valve lash? or do you think the timing could of jumped in it? Im looking for any advise possible at all any ideas throw them at me.
FYI-Its a 170 from a '67 Plymouth im working on.
Thanks
 
it could be the trans is going away.. BUT it is a 1 barrel, you cant expect a whole lot from it. i would set the lash, and tune the carb
 
it could be its running out of fuel. it could be a lean condition. the float level could be too low. could be a weak fuel pump. theres a number of things it could be. i would rebuild the carb myself and make sure the fuel pressure is adequate. also set the valve lash for sure, and all the regular maintenance tune up stuff plugs/wires/cap etc
 
Just did the tune up and put a new carb on it, have tryed 3 carbs and all do the same thing...only thing i have not done is set the valve lash on the engine.
Never done it on a slant six....any guidance?
 
Were it running out of fuel,, - under full throttle,... does it go good for a few seconds,, then fall on it's face??,.. then go like hell again, just to fall off again???

Perhaps Catylitic converter???

are your passenger floorboards exceptionally hot??

Under hard acceleration, does the exhaust "whistle"??..

just a thought.. grant..
 
Hard to say. What is the general health of the engine? approximate miles? Have you run a compression/ leakdown test? Does it use oil?

The timing could be somewhat late (retarded) and or the advance mechanism could be rusted/ sticky and not advancing enough. Ya might want to check that out

Simple: Have you checked that the throttle, with pedal to the floor, is ACTUALLY fully opening the carb butterfly? How about the exhaust, any chance the heat riser is plugged?

Does it miss at RPM or just seem to flatten out?

VALVE adjustment:

"Some people" insist that adjusting valves while "running" is the only way. I say "doodley squat"

outlaw-josey-wales-3.jpg


I use what is known as the EOIC method, which works on any 4 stroke engine with poppet valves from a Briggs to a P&W turbo compound radial

I use the feeler "you want" and one or two thousand's larger, as a "no go." Warm the engine up, lay out your tools, so you can work fast to remove the valve cover and do the adjustment. Look things over closely so you know you can get the cover off. One quick thing you can do is pull the no1 plug wire off at the plug AND at the cap to "mark" no1, then pull the cap and wires off as an assembly to keep oil off and get it out of the way.

So EOIC, what does it mean, how do you use it? First, you can go "down the head" front to back, and after you get "good" at this, you can go in firing order, which will reduce the amount of turning the engine over. So for now, just start at the front, and work to the rear

Bump the engine until..............

the EXHAUST valve just starts to OPEN, and adjust the intake valve on that cylinder

then bump the engine until.......

the INTAKE valve opens, then nearly CLOSES, and adjust the exhaust valve on that cylinder

Take care to slide your feeler(s) in straight, and you should be able to insert the gap you want without much force at all, and the "no go" +.001 or .002 not at all

BE SURE your adjustment wrench is not applying force to the rocker which will affect the adjustment.

See? easy.
 
inertia said:
Were it running out of fuel,, - under full throttle,... does it go good for a few seconds,, then fall on it's face??,.. then go like hell again, just to fall off again???

Perhaps Catylitic converter???

are your passenger floorboards exceptionally hot??

Under hard acceleration, does the exhaust "whistle"??..

just a thought.. grant..
Click to expand...

Catylitic conveter???
 
jpeshelman said:
This has been a problem since i got this car......the carb was bad so i just replaced that.....now the car will idle fine, free rev fine, and will drive fine, BUT it has no power at all....you can floor it and the car wont pull past 2800-3000 rpm.....I have checked the timing and it was on, the vacuum advance is working the car does have valvetrain noise on the top end...so the next step should be check the valve lash? or do you think the timing could of jumped in it? Im looking for any advise possible at all any ideas throw them at me.
FYI-Its a 170 from a '67 Plymouth im working on.
Thanks
Click to expand...

Set the lash as instructed. Made a big difference in mine. I also changed my points to Pertronix, another big difference.
 
Setting lash will probably improve idle and on road power. Fully warmed up engine gap at: 0.010” intake – 0.012” exhaust. Remember front three cylinders have valves EI, EI, EI, back three valve sequence changes to IE, IE, IE.

You can remove all plugs, and roll engine over with fan while pushing on fan belt to bring up each adjustment. You will discover that in a straight six valve adjustments can be made in pairs such as 1&6. Wiggle rockers when both I&E lifters are on back side (no lift) of cam rotation. This method requires only three rotations of crank to make all 12 lash adjustments.

A 170 stock engine won’t make a late sixties A body into a rocket ship, so don’t expect pavement pounding performance after adjusting lash. What you will feel is better throttle response, smoother idle, and higher rpm range.
 
wjajr said:
A 170 stock engine won’t make a late sixties A body into a rocket ship.............. higher rpm range.
Click to expand...

Truer words could not be found. Especially if the car has a 2.xx rear gear, but it ought'ha be able to wind up a little, for certain.

Remember, though, a six is not a 5000 RPM v8
 
Maybe a restriction from tank to fuel pump. Had this happen on a 71 Newport Chrysler.The fuel "sock'' in the tank fell apart and got sucked into the fuel line. Idled fine, revved fine, wouldn't go over 30 mph.Quick check, blow air from line at pump back to tank (cap off).It "may" work for a while. We had to take the sending unit out and run a wire through the bend at the unit to clear it.Thus clean out the tank and installed a new sock. Just a thought....
 
jpeshelman said:
i can turn this engine over by hand with all the plugs in it
Click to expand...

You shouldn't be able to do that.

It may just be worn out...

Have you run a compression check on it?

That will tell you a lot.

If your ignition timing is correct, and you haven't advanced it, it's probably not a jumped tooth on the timing sprocket.

I'd start looking around for a 225... and a turbo... :cheers:
 
You may have a timing advance issue. I'd check the vacumn (old way of spelling vacuum) advance unit in the distributor to see if its working. The diaphragm may have a leak. Mine was bad and had the exact symptoms you have.
 
You should feel a noticeable surge of torque around 2500-3500 rpm. That is the effect of the long intake runners. If not, I agree with others to verify the throttle linkage and see that you can fully open the throttle plate with it floored. I don't think it is due to compression, unless you see blue smoke when you floor it (bad rings). I would suspect the ignition timing. Verify with a timing light that the mechanical advance works. Your weights could be rusted stuck.
 
I did not read everyone's input/help, have you checked the heat riser in you exhaust manifold ? a restricted exhaust will do this..
 
The vacuum advance works, its in time, the throttle does open the whole way, im gonna do a compression check tonight...turning it over by hand it does not feel like the engine has any compression
 
jpeshelman said:
The vacuum advance works, its in time, the throttle does open the whole way, im gonna do a compression check tonight...turning it over by hand it does not feel like the engine has any compression
Click to expand...

I think you'll learn a lot by a compression check.

Let us know what the outcome is.:happy1:
 
How many miles are on this engine? Stock 170s are not known for their necksnapping torque, especially not in cars heavier than the original '60-'62 A-bodies and with taller rear axles and bigger tires. You don't mention what kind of car this is in.

Inability to rev beyond 2800(ish) RPM suggests possible exhaust restriction. Do you own (can you get hold of) a vacuum gauge?

Have you checked for timing chain slack? See here.

Of course, don't forget the basics; Tune-up parts and technique suggestions in this thread, and you'll want to make sure to keep on top of the valve adjustment.
 
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