| [ Total Views: 1819 | Total Replies: 8 | Thread Id: 424 ] |
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 OvalGlen
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 posted on September 6th, 2002 at 07:35 PM |
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High Load - pinging, why?
The neglect 1916cc (still strugling with the old standard fuel pump) tends to ping up in the rev range after a couple of gears have been revved out.
I'm thinking that it is running lean on fuel - due to pump not keeping up. What do you think. Using Premium Unleaded. Cant get it to ping in 1st
or 2nd, usually worse when hot.
Also if I accelerate sharply in 4th at say 4000 Rpm or above, will ping.
Regards,Glenn>
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Baja Wes
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| posted on September 6th, 2002 at 08:47 PM |
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Definitely sounds like it is running out of fuel. Check for a dirty fuel filter or something. The float bowls will usually supply enough fuel to keep
the engine happy through 1st and 2nd, it isn't until the higher gears you really start running low on fuel.
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Menangler
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| posted on September 6th, 2002 at 09:09 PM |
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Glen, does it do it on premium unleaded? what comp is the engine?
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Experienced when a car and it's driver are in mutual harmony, A unique driving experience, Pleasure, Satisfaction,
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70AutoStik
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| posted on September 8th, 2002 at 08:23 PM |
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I seriously doubt you'r running out of fuel, unless you have a faulty or incorrectly installed diaphragm. The fact that the problem is worse at
high speeds and a warm engine also suggests this is not the case - fuel starvation would be worse when cold. It sounds like you're heads are
getting a little hot, could be carbonisation (ever run LRP or overly rich?) or too lean a jetting.
Give us a few more details, such as what carbs, heads, dizzy, cam and compression you're running and we can probably give you the answer.
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KruizinKombi
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| posted on September 9th, 2002 at 09:30 PM |
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Pinging
I'd retard it by a few degrees and see if it is any quieter.
Kruizin Kol
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Kafer Lover
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| posted on September 9th, 2002 at 11:16 PM |
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Exactly what is pinging?
I told someone I was using unleaded in the stock engine (after all that discussion in the old forum) and they asked if I had any pinging?
I just acted like I knew what I was talking about and said, no its no problem (which it doesn't seem to be), but so that I don't feel quite
so stupid next time, can someone enlighten me?
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70AutoStik
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| posted on September 10th, 2002 at 01:54 AM |
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Pinging (or pinking) is the sound of "pre detonation" in the combustion chamber. In an engine that is running correctly the mixture burns
at a rapid rate, but does not "detonate" as it is often incorrectly decribed. If the ignition is too far advanced, the mixture too lean,
the plugs too hot or there are "hot spots" in the combustion chamber the peak burn rate (or flame rate) will occur at or before the piston
reaches TDC (it is still not truly a detonation,) causing the force of the expansion to be down the rod into the crankshaft, instead of turning it.
This obviously is a bad thing.
I hope this isn't too much information, the important thing to know is that you can usually hear this "pinging" as a kind of rattle in
the engine. If you put your foot down and hear a rattle, this is pinging and means you need to recitfy the problem, as it is robbing power and will
probably cause damage to your engine. If you hear such a rattle and find little bits burned out of your spark plugs, find out the cause in a hurry,
it may be simply a matter of fitting colder plugs; but it can cause problems ranging from holed pistons to "thrown" (broken) rods if not
controlled. If you are running a stock engine with stock compression, exhaust and timing - and it is fairly healthy, standard unleaded should be just
fine; if not, back your timing off by a few degrees (or re-jet your carb if you are running extractors.)
[Edited on 9-9-2002 by 70AutoStik]
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Baja Wes
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| posted on September 10th, 2002 at 08:19 AM |
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I'm still thinking it's running out of fuel.
In the US some of the golfs came with a small strainer hiding in the fuel inlet to the carb. It was there from the factory to catch all the crap in
the fuel system during manufacture, and was supposed to be removed on the first service. But most vw dealers forgot and the strainer stayed there,
slowly getting clogged more and more. This led to a lot of drivers complaining the car accelerated good in the lower gears then apparently died in the
taller gears. But if they backed off for a bit (let the fuel refill the float bowl) and then reaccelerated it went Ok again, for a while.
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70AutoStik
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| posted on September 11th, 2002 at 11:09 PM |
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Ah, yes, good point. I'd forgotten that one momentarily. Also, there is another strainer in the tank on many cars as well...
:thumb
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OvalGlen
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| posted on September 12th, 2002 at 09:48 PM |
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I really need a kick up the B- side. Thanks for the ideas. I kept meaning to re-do the fuel line. At present its a 1957 .. 3mm approx fuel line
- running through the "reserve tank " switch with the guaze filter element, inside a tank which has 45 years of corrosion inside it.
- A couple of notes on eng data. . Using Prem Unleaded, C.R. 7.8 :1 , Very mild cam - very little overlap - probably similar to a 15 / 55 cam . Now
you'd think that if any thing it would ping down really low with such a high dynamic compression due to the very slight overlap but it does Not.
Prob fuel starvation but could be heat in heads.
I tried to fit a Cylinder Head Temp guage but havent installed it correctly, it only showed very low readings.
I'v really got organise some time to work on the Oval...................
Regards,Glenn>
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aussiebug
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| posted on September 13th, 2002 at 02:04 PM |
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Wow Glen - here's another thought for you.
You have a 1916cc engine in a 57 I think you said.
With a 1600 doghouse fan shroud I bet.
If you have a solid engine lid with the doghouse fan, then your engine WILL run short on cooling air from about 2600rpm up (50mph and higher) (I speak
from experience).
The slots under the back window were designed for the 18cf/sec 24 blade 1200 fan. They cope OK with the 22cf/sec of the 1300/1500 28 blade fan (solid
engine lids up to 69), but WILL start to run short of air with the wider 28 blade 25cf/sec doghouse fan.
And you say it's starting to ping at high rpm/speed....sure sounds like a hot-engine problem at high rpm to me.
If that's what you have, you have several solutions.
1. Use standoff hinges (look ugly in my opinion - spoils the lines of the car).
2. Try cracking the bottom of the engine lid open by placing a 1/2 teniis ball etc over the catch, and drive the car. If it improves the
cooling/pinging, you can leave it this way and just remove the tennis ball to shut the lid if needed - it's hardly noticable to other drivers but
increases the cooling intake area significantly.
2. Use standoff number plate mounts and put hidden holes in the lid behind the number plate.
3. Graft slots from a later lid (or sections of Kombi front air grill) into the lid. If you can import a carbio lid for the right year, these have
two sets of slots (like the 70/71 lids) in already.
4. cut slots in the engine bay sides - into the rear wheel arch area. This works but it also pulls in road grime for a dirty engine (there is a
company in WA which creates 2-seater convertibles and removes the under-window slots completely - they use the wheel-arch method with solid engine
lids).
A few other thoughts.
Have you got the air correction jet right for the engine capacity - not letting in too much air for a lean (hot) mix at high rpm?
Got a fuel filter in the system which is getting partially blocked - I had this once and it took a few days to find the problem - it was runnig the
carby dry at higher rpm but JUST letting enough fuel in at lower rpm to keep the engine running. Yes - the fuel tank gauze could indeed be part of
that too.
Rob
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Repairs and maintenance for the home mechanic
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OvalGlen
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| posted on September 15th, 2002 at 01:19 AM |
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Rob , very insightful. I think that you have many problems with my engine covered in your comments.
1. When I first got the car going , it ran Extremely Hot. (I also dislike the Gaping Eng lid) So I opened the bottom of lid 60mm. This was done with a
bracket that could lock catch on.
2. Yes it has offset fan with 34mm blades, It sure would be running low on air at the 3400 rpm where it tends to ping.
3. The carb jetting definately could be improved. I Only ever ment it to be on for short time to run in. Sort of got side tracked. Growing families
will do that .
4 I think it may be a combination of fuel / air / heat / and jetting for top end.
- Good to see I'v still plenty to learn.
Thanks for the pointers.
[Edited on 14-9-2002 by OvalGlen]
Regards,Glenn>
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 kombi_kid
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| posted on September 15th, 2002 at 04:30 PM |
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hey
sounds familiar!
on our notch back its a standard 1500 engine it goes alright downlow but once you give it a bit it just coughs and splutters away! we have replaced
the plugs, condensor,coil,points, done all the timing right done the tappets checked compression it is good and strong: 150 ! the only difference is
that there is plenty of fuel getting into carby so its not starving!
we can here this pinging noise (a mechnic saying it is the little end bearings) but not sure
any ideas?
cheers
rhys
[Edited on 15-9-2002 by kombi_kid] |
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