Odd Sound/Loss of Power/Timing?

[Anonymous]

Okay - I've reset my timing and double checked it, a couple of different ways...by light, vacuum gauge, tach, etc etc...but i still find that when i'm lugging a warm engine up a slight hill or try to step on the gas I get this rattling noise that I just can't shake. When I play with the timing it seems to go away for a while but then, sure enough when the engine gets warmed up or I need to step on it, here comes this rattle/knock/ping...If my timing is set, is there anything else you can think of? Oh and did I mention, my power/acceleration seems to diminish when this occurs??

By the way, my father can't put his finger on this sound but he claims it's not pinging from pre-detonation, or advanced timing - even though when I play with the timing again it seems to go away...for a while....

 

[addo]

Is the motor running hot? Got a thermostat in there? Really does sound like pre-ignition.

 

[ludwig]

If you are running too lean, this can cause overheating and loss of power. This happened to me as well. Once the timing AND the fuel/air mix was adjusted, the heating and sudden drop in power on a long grade went away.

 

[powerband]

Before rebuilding that sucker, see if the PCV valve is doing the rattling. My '71 170 in the '61 Comet will rattle and buzz at certain rpm's and tuning settings. Haven't figured out why and puzzles me but only happens occasionally.

Powerband.
. 8)

 

[pedal2themetal45]

With those semtoms it sounds like a timming prob.. to me... What do you have it set at..
Tim

 

[rbohm]

8) sounds like detonation to me. i have a similar problem. it is usually caused by a lean mixture or timing that is too far advanced. both of which by the way will cause the engine to run hotter, making it detonate easier.

 

[JackFish]

Maybe a dumb question for some, but does your setup have vacuum advance? Too much advance under load, maybe you need a dizzy recurve?

 

[CZLN6]

Howdy marvista and All:

Please verify the initial advance setting, your elevation, and octane rating of gas you're using. Also what temp thermostat are you using?

It is possible that the vacuum advance plate is sticking, or sticky. When your engine transitions from high vacuum/most advance, cruise conditions to low vacuum/least advance, lug or accelerate- if the advance plate is sticky, or stuck momentarily you will experience knock.

The solution is to verify that- the SCV is working properly, the vacuum hose and all hose connections are tight, the vacuum diaphram is working correctly, and that the advance plate and springs are free and moving properly.

Being it is improved by your messing with the timing causes me to think that the advance plate might be sticky. After messing with it, it improves for a short time and then sticks again.

Check it out and give us some feedback.

Adios, David

 

[JackFish]

Being it is improved by your messing with the timing causes me to think that the advance plate might be sticky. After messing with it, it improves for a short time and then sticks again

Would you prescribe a shot of WD40 in there? Just for a check/quick fix?

 

[CZLN6]

Howdy back Jackfish:

I'd start with a visual and auditory inspection, looking for cracks and listening for vacuum leaks, of the outside of everything. I'd watch the link from the diaphram on the distributor that goes into the distributor, as the engine is running and the throttle is worked. If all appears to be functioning, I'd remove, engine off, the hose to the carb, suck on it to actuate the mechanism and verify that it holds steady vacuum. If it is a slow leak in the diaphram this will show it.

If all is still good, I'd take off the cap and rotor and inspect the springs and pivot points. Springs should be intact and have some tension on the posts. Pivot points should be clean and operate smoothly. Clean out all the dust and crude buildup. A dab of dialectric grease on the pivot posts is a good idea. Make sure the advance plate is moving smoothly.

Recheck initial timing upon reassembly.

Adios, David

 

[Anonymous]

If you are "luggin" the engine, it sounds like it is a relatively low rpm problem and you might have too much initial advance & vacuum advance or the vac advance may be sticking. Assuming you have a vacuum advance equipped distributor, you may not be getting any contribution from your vac advance. If it is not working, and timing is set to spec, you will be retarded at idle. However retarded timing will quickly contribute to elevated temps / overheating at idle. So maybe as the car warms up you are seeing some pre-ignition.

If you time by ear or feel, and the vac advance is not working, then you will be putting a greater portion of the timing on the initial static or fixed timing in order for the idle to smooth out. This would tend to have too much initial timing at part throttle loads since there would be no vacuum advance component to drop out of the equation when the throttle plates are openned. Pull the cap and suck on the vac line to the distributor, you should see the mechanism move.

The outer ring on your balancer may have slipped. In addition to what David has pointed out, I would pull the spark plugs and verify the TDC of the #1 cylinder and compare it to the timing mark on the harmonic balancer. Also pull the cap and check to make sure that the rotor is pointing to the #1 post when the engine is set at TDC. If the ring has slipped, it will be difficult to time it with a light, especially if the balancer continues to shift.
Doug

 

[Anonymous]

i hate to post and bail out for a bit but i've been working 50 plus hours this week plus i got to school (hopefully i'll graduate before i turn 22!) on nights but here's the most i can say in regards to all the great responses...

i'm running a pre-68 distributor. timing had been set to 14 degrees (this is where it seemed best) although we've readjusted by ear/vac. gauge so i can't be precise anymore, i have a newly refurbished pony carb. w/ a functioning SCV valve. Also, i live about 3 miles from the beach here in los angeles....

My engine never seems to be running hot which led me to believe that my thermostat wasn't working but i've pulled it and heated it up in hot water to ensure that it opens....also, i have a 5 blade fan and a 3 row raditor on board ensuring plenty of cooling (thanks to the prev. owner).

My next venture is to inspect the dizzy inside...i'm ALMOST tempted to drop a new/rebuilt one in there w/my pertronix to see if that solves it....as far as recurving, what's the deal, is it worth it for a basically stock daily driver? Dynamic Distributors wants a hundred bucks to send me a properly curved and refinished dizzy....your thoughts?

Vacuum is a steady 19-20 inches at idle and doesn't fluctuate (which would typically indicate a leak...per the FSP handbook). I'll be sure to check back as soon as i inspect more!

 

[Anonymous]

i have been reading this post and, altho I usually am a car-condriac, think I might have something similar

here are my symptoms: when I start the car it idle, kinda smoothly...but if I goose the gas, it starts chugginn and sputtering and blowing black smoke until it is warmed up...strange

I checked under the dizzy yesterday. It seems to hold a vacuum (sucked on it) and it did seem to be a little dusty...so I cleaned it a little

WOULD WD40 HURT INTHIS CASE?

I may go for a professional carb tune and timming set. something is OFF that I cant get right...choke or something...

 

[CZLN6]

Howdy Back Marv and All:

Marv- I understand about the time and obligations. Do what needs to be done. We'll be here when the time comes.

If you have a Load-a-Matic (Pre '68) distributor it cannot be recurved, as it does not have a centrifugal advance system.

Chaz- what you're describing sounds like a choke problem. Either a "Pull-off" problem or a sticky opening choke. Start by getting a can of spray on carb cleaner and give the choke area a good hose-off, both inside and out. Especially where the shaft goes into the body.

Using WD40 inside the distributor is not necessary. A shot of low pressure air is adequate. Be sure to re-grease the pivot points of the advance plate and the point rubbing block.

Adios, David

 

[Anonymous]

glad I didnt start spraying

Thanks for the adviuce David...I am on it

 

[Anonymous]

Chaz, i have the same exact problem w/cold morning starts...since you can only check your choke adjustment here in LA once a day to verify if your choke is set right, i got it close enough and then just said screw it...after about 3 minutes she's good to go....but in case you don't already have it hooked up, make sure you run the heater hose along the black choke cap housing via the std. bracket. This helps heat the bi-metallic spring in the choke cap, essentially helping to warm up the carb faster. Once i hooked that up, my choke conditions improved dramatically on cold start. Oh, and fyi: i'm running a newly rebuilt autolite 1100 w/auto choke, done by pony carbs....

I am looking for some dialectric grease (that white stuff right?) for the plates in my dizzy for when i crack her open...which will hopefully be this weekend...until then.

 

[ludwig]

You got a HOT WATER choke pulloff? Not a hot air tube to the exhaust?

Edit: Oh yeah. I remember the clip there at the cap. I really don't need the choke, though. It always started right up anyway. Well, maybe a little effort but not hard at all.

 

[Anonymous]

yep, i have a hot water choke pull off in addition to a choke tube running to the exhaust. I didn't bother to run the heater hose to the choke housing but it became necessary since my choke tube had to be jury-rigged from the stock set up...in other words, i wasn't getting enough heat - quick enough - from the exhaust so the heater tube helps out a bit...not to mention i think it looks better, for what its worth!

 

[Anonymous]

Chaz, i have the same exact problem w/cold morning starts...since you can only check your choke adjustment here in LA once a day to verify if your choke is set right, i got it close enough and then just said screw it...after about 3 minutes she's good to go....but in case you don't already have it hooked up, make sure you run the heater hose along the black choke cap housing via the std. bracket. This helps heat the bi-metallic spring in the choke cap, essentially helping to warm up the carb faster. Once i hooked that up, my choke conditions improved dramatically on cold start. Oh, and fyi: i'm running a newly rebuilt autolite 1100 w/auto choke, done by pony carbs....

I am looking for some dialectric grease (that white stuff right?) for the plates in my dizzy for when i crack her open...which will hopefully be this weekend...until then.

exactly....i now have it close....

my old carb didnt have a heat tube (broken) but started evreytime. Mt new pony rebuilt is a little more picky but I think I am getting it. I too need some dilitium grease or whatever...and some carb cleaner.

the hardest part was EXACTLY what you said...you can only adjust and observe once a day for 3 minutes

chaz

 

[Anonymous]

BTW...once it gets warmed up...it runs like a bat outta hell