The Stovebolt Site Forums The Shop Area Engine Shop Timing and Dwell set up

I just spent 2 months learning that if the points don't produce a strong spark the truck stalls when shifted out of 1st gear. That takes me to the subject of this post.

I installed a new cam in a 1958 235 and made sure the gears meshed in the right place. The book said to set the timing at TDC, the points at .016 and the dwell at 27-35. I've checked the dwell with the engine running and it is 26. The engine runs pretty well but I've been told over and over to set the timing at 8-10 BTDC.

The engine is in great shape, 115 plus in each cylinder, 14 pounds of vacuum, (I live in Salt Lake City, just shy of 5,280 feet) I installed a new stock 261 cam. I drove the truck just after installing the cam and it is very strong through the gears and had plenty of pull at 65 when I slowed down

Where should the timing be set to get it running at it's peak and once done what should the dwell be?

Ted,

Timing marks will get you no closer than the technique of adjusting/rotating the carburetor to achieve maximum vacuum at idle.

Here is a carburetor/timing tuning procedure.

I feel the dwell needs to be set first, before adjusting the timing. Changing the dwell will effect the timing.

The dwell angle provides the coil with the time it takes to saturate the field and make enough Volts to produce the spark. Think in terms of time. More dwell(points closed) equals more time,with current flow through the coil. That said, the timing is a function of the points opening(spark) so the two are related. Set the point gap(that is what controls the dwell angle along with the number of cylinders). Make certain you have the dwell you need. Then proceed to set the timing. There are more than one way to set the timing. That is because the original fuel standards have gone away and new fuel is just different. I like to set the timing with a vacuum gauge(opinion here) at idle to the maximum vacuum I can get(Ogden is at the same altitude as SLC) and then retard for about a 1 inch drop. Test is to pull a hill in top gear and if it "pings" retard a little until it just about stops (pinging that is). If no "ping" advance until it just begins to "ping". It seems to be the best compromise to drive-ability and performance. Also I don't have a timing light with the advance function. With one of those you could get a timing reading in degrees of advance, if you know what year and markings are on your flywheel. But since those have moved a bit from year to year I don't(opinion) bother too much with them. The BB will get it started, good enough for me.

Steve is right on the mark, timing is subject to change from city to city and fuel station to fuel station. His way of setting the timing by way of driving, is going to be the best for your truck. All modern cars use computers to hold the timing right below the "ping" point at all times. They do it with a knock sensors, your knock sensor is your ears. If it pings under a decent load up a hill, but goes away if you give it full throttle, you are really close.

Dwell, timing, and fuel mixture are all related and need to be tweaked for optimal performance.

Joe

Guys, thanks for your advice, I appreciate it. I keep forgetting how much information is available, all I have to do is ask.

I'm installing Tom Langdon's "Mini HEI" system this week and once it's in I'll get back with a final update.

Thanks again to all of you,

Ted