1946 Cadillac Flathead. My harmonic balancer has NO Visible markings, So I have NO way of setting the timing correct.
First thing I did was to put #1 piston at top the center & marked my harmonic balancer along with timing chain cover pointer dead on.
My question is. Is #1 cylinder supposed to fire before the markings or after when engine is at idle 1000rpm. testing out with a timing light. Engine seems to run ok when firing 3degrees before T.D.C. Would this be correct?
Thanks to all that have help so far with other issues I have had.
L Lopez
1946 Cadillac 61series
The manual states 5 degrees.
I read somewhere that today's gasoline burns at a different speed compared to what was available back then, so the original timing recommendations may not be well suited.
The 346 generates a lot of heat so I usually just advances timing to the max which does lower engine temp, and has no impact on performance from what I can notice.
I set timing to the point right before pinging happens on acceleration under load (uphill etc..). It has been running fine that way for years now.
I use the highest octane fuel available at the pump, which also totally solved my valves sticking issues I had on regular gas.
Rob,
The use of high octane fuels in a low compression engine will cause carbon build up. You can not get a complete burn, on the fuel.
This can be researched on Google if you like.
One I found .
http://answers.yahoo.com/question/index?qid=20090213121625AA0UCK6
Also a good article about using additives. Check out the plugs at the bottom of page.
http://www.autohausaz.com/html/spark-plugs_spark-plug-wires.html
Roy
Roy,
Wouldn't you think that the "fuel burn percentage" as mentioned in your link, is related to the timing ?
If set early enough this should ensure a near complete burn whatever the octane number and compression ratio combination is...within reasonable range of course.
I've driven a lot on my 346 since I setup timing for high octane fuel, and never had spark plugs foul like the discussion in that link.
Also, where I live they clearly do advertise High Octane fuel as "burning cleaner" than regular...and based on my experience this seems to be the case indeed because my valves never stick on premium but most often do on regular fuel, even after sitting only one day.
In Japan, we do need to pass a basic emission test of CO (5%max) and Hydro-Carbon (HC) of no more than 1200ppm (particles per million) even for classic cars.
HC is the indication of unburnt fuel - the higher the number, the lesser amount of fuel is burnt.
I found that advancing timing in my 1935 Lasalle did significantly lower the HC number - from 2450ppm using textbook timing, to about 1200ppm with advanced timing. This was using regular fuel.
It would be interesting to fill it with High Octane fuel and run it through that emission machine again - just to see what happens.
Also, having a too lean setting did increase the HC number as well - low compression engines seem to need a rich setting for a good combustion rate.
Rob,
I'll have to give you this one.
When I first read your posting, my brain read, low compression, high octane, normal timing.
Now that it is a day later and I am having my coffee, I reread your posting, and what you did is good.
During idle and cruise speed you mixture is lean. Lean mixtures do take longer to burn. So, by advancing your timing to just before it pings is good. Engines should run like this.
This is probably giving the engine enough time on the stroke to burn the premium gas , at idle ,and the cruise speed. Yes , it also makes the engine run cooler.
Since I own a 78, I tend to think more about all the restrictive devices on the engine to burn the fuel to satisfy the emission standards. California being the worse , since they run a ported vacuum for the vacuum advance. Doing this keeps the timing retarded more and causes problems if your running premium gas. No vacuum advance at idle speeds.
With the government trying to control the Hydrocarbons HO, Carbon monoxide CO, and Oxides of nitrogen NOx, they have managed to pretty much de-tune an engine.
Myself, I run mine advanced a hair more, no EGR valve, and my new catalytic converter is neutered, if you know what I mean by that. Engine runs strong and smooth. We dont have to get cars tested here if there old.
So, sorry, I should have read your posting slower.
But , if your running one of these de-tuned , low compression, California specials ,watch out if your burning premium gas. Stop and go driving with a ported vacuum advance is going to cause problems down the road.
Roy