engine knocking on acceleration

[Charger72SE]

I'm getting some engine knocking on acceleration and under load (going up hills)

is it bad gas?  I'm burning Mobil 93 octane.

thanks!

[mikepmcs]

Could be a bad batch of gas causing the ping.  Maybe check your timing as well just to make sure that is dead on.

v/r
Mike

[1969chargerrtse]

When I hear knocking and I'm using good fuel I just loosen the distributor and retard it a hair.  The direction that slows the engine rpm downward.

[Charger72SE]

I think the timing is good - I did a number of vacuum tests and the reading was steady with no movement in the needle.  Also, I had a new distributor put in and they set the timing at 10* BTC and checked it again.

I think it's the gas - I had one batch this summer that was terrible, and my car was stalling out 5  miles from the gas station!!

I was wondering if adding octane booster would help at all?

so knocking has nothing to do with the air/fuel mixture?

thanks for your comments!

[mikepmcs]

quick search found this interesting read.

http://www.misterfixit.com/deton.htm

v/r
Mike

[aifilaw]

10% ethanol can have that effect as well.
Won't go into it, as its a long long debate. But suffice it to say that I lost 2mpg in my wife's 8:1 CR honda and it knocks now, and 1 mpg in a 11:1 chevy SB when the gas changed... I'm still playing with the timing and fuel delivery trying to get it back, but no luck so far.

[Charger72SE]

thanks guys for the comments

I've been driving out of the county to get the gas without ethynol, but you never know what you're getting any more

I'll look over the plugs and see if I'm too lean on the a/f mixture

the detonation article was really good - thanks a lot!

[Charger72SE]

I pulled 2 plugs and there wasn't any tan color, so I was probably a little lean.  I used a vaccum guage ansd adjusted the A/F mixture screws on both sides.

I've noticed that the knocking gets worse the longer I drive.  Today there was no knocking at all for the first 15 minutes and then the knocking got progressively worse going up hills and after accelerating.

does this give any indication of what it is?  bad gas or adjustment?

[aifilaw]

as the engine temp increases the possibility for knock will increase as well.

knocking generally occurs under light acceleration and when heavy loads are applied (going up hills)

pull your timing back a little and run it a little richer

[craigandlynda]

i was in gasoline retailing from 1973-1984...sometimes, a load of regular will get delivered and be too much for the storage tank, so they dump the excess into the mid grade or premium... sometimes vice-versa...anyway, you can never be 100 percent sure about the octane rating of what comes  :Twocents:out of the hose...stations are checked by weights and measures for metering a gallon within a few CC's; but no one really checks for octane...drain it, or run it out, and get a fresh load from another location...see if the problem goes away...

[Charger72SE]

thanks craigandlynda & aifilaw for the replies

yes, I was going to do both - richen the carb a/f mixture screws by 1/2 a turn and burn up this tank of gas.  If things don't get better, I'll retard a bit.  I'm also going to rebuild my heater box and put in a 180* thermostat - I think there's a 195* in there now to cool things down a bit.  Purple Ice additive is also suppose to keep things cooler.  These 440's run hot!

take care!