The Stovebolt Site Forums The Shop Area Engine Shop 1962 261 ignition timing mark

OK I searched and searched and found nothing definitive on this: Where and what is the TDC mark on the late 261s for ignition timing purposes? Mine came out of a 1962 Chev 1/2 ton.

I just got the used 261 w/ 3 spd and OD into my 53 half ton. I'm having to rewire from scratch and got the ignition so it cranks over with key start and throws a good spark but when I looked on the flywheel I could find no timing marks that I recognized. I am used to seeing lines scribed about every 5 degrees with a larger line in the center with maybe a zero above or below it. What am I missing here?

As an alternative I estimated TDC watching #1 cyl rocker arms and that puts #1 cyl about 3-4 O'Clock position. (After reading the stuff that came up on search it seems I should have pulled the rocker arm cover and watched both 1 and 6 to be sure.)

Using starter fluid I can get popping and what sounds like one to three cyls firing but never all six smoothly. Pump finally got gas out of gas can and up to carb and the accelerator pump puts a good stream in but I cannot get it to fire at all on gas, only starter fluid.

The carb is a Rochester that has a paper tag saying it was rebuilt by Holley. The PO who pulled the 261 to install a 350 said the truck had been running fine right up to when he pulled the 261 and tranny out. Assuming it was running then--about two months ago--I doubt the carb is gummed up and the fuel filter looks OK.

Got frustrated and quit for the night before I did something really dumb. Would appreciate some assistance re. timing marks, setting up the distributor correctly etc.

Jerry

jbinwa,

I don't know if this will help. The timing marks you describe are usually found on the crank pulley of more modern rigs.

I think your engine still has the window above the starter with pointer and mark. On a 261, the mark might be a triangle...or it might be the traditional BB inserted into the flywheel.

Using a timing light, factory timing is with the pointer, and which ever mark you have, lined up perfectly. This of course is done with the vacuum line pulled and plugged at the carburetor.

Again, I think that this alignment will give you about 5&deg initial advance. For most purposes, this alignment is referred to as TDC (#1).

The marks on the flywheel become dirty and are hard to see...the pointer in also hard to see.

Clean both these items and give them a dot of a bright paint.

If you are pulling the engine over by hand searching for the marks in the window, keep in mind they will appear twice in two rotations of the crank..once when the piston is TDC on the power stroke (correct) and once when the piston is TDC on the exhaust stroke (not correct). You must determine the proper one.

Remember your firing order..153624, and the clockwise rotation of the distributor.

I hope this has helped...I hope it is correct!!

Stuart

Yep, the timing marks are through the window above the starter. It all depends on which flywheel you used where exactly they align, some are actual TDC and some are a few degrees advanced. Either one will get you started. Since these engines are designed to run on pretty low octane fuel they run well a few degrees advanced from factory spec.

Are you using the original bellhousing/flywheel? If you've got a 6 volt foot starter then you likely have a 216 flywheel and the timing mark is off by a mile for a 261. Try timing it with a vacuum gauge.

Stuart

I'm using all the original stuff including the 261s bellhousing and flywheel as far as I know. The bellhousing is a light green color and the clutch is hydraulically actuated with the slave cyl mounted on the pass. side. Starter is 12V key start type. I got underneath and took off the flywheel cover and cleaned the flywheel as well as I was able and have not found any marks but will try again to see if the triangle or BB marks are there.

i won't be putting my 261 in till spring, waiting till after christmas for the rest of my parts. just got the flywheel turned, and mine has a bb and a triangle. guess i'll find out wich one to use..

Was that transmission a truck or a car transmisssion (maybe some else knows if a 261 w/3-speed and overdrive was available on a 1962 1/2 ton truck)?

My 1960 261 came with the timing-bb on the forward side of the flywheel. This engine (and flywheel and clutch assembly) is now in a 1954 1/2 ton truck, using the '54 clutch/bell housing, with no hydraulic clutch (converted to 12v).

I couldn't provide absolute verification that 62s were available from the factory with 261/3spd/OD. I saw the pickup the engine came from and it was a 1962. Also NAPA parts books make reference to that engine being available though some mistakenly call it a V6 while others correctly identify it as an inline 6. The engine had 12V coil, starter and generator. Also check
http://en.wikipedia.org/wiki/Chevrolet_C/K for their reference that the 261 straight six at 150 hp was available in the 1962 pickup. Finally I remember reading that the light green color of the bellhousing was correct for 261 truck engines of that year. Being a newbie its highly possible I may not be absolutely correct. If not I'm sure more experienced members will correct this post.
Jerry.

I got my 261 out of a '62 suburban, and it was original equipment according to the guy I got it from. It had an SM420 behind it though.

The 261 was available through 1962 on Heavy Duty trucks (some say into 1963). Even though the Wikipedia says it was used on Light Duty trucks in 1962, it would be nice to see information from a GM document.

( Note that there is incorrect information about Stovebolt "Era" engines in the Wikipedia).

Was the 261 engine an option on a 1/2 ton 1962 truck, as Wikipedia states?

And, was a 3-speed overdrive transmission an option on a 1/2 ton 1962 truck?

If the answers to either or both of the above questions are "no", then there is an even better chance that you do not have a 235/261 truck bellhousing (it might be a passenger car bellhousing or ???).

Someone with an ID numbers book, or a 1962 Truck data book, or a 1962 Restoration Book (Specifications Manual) might be able to give informative answers?

I was under the impression 4x4s still used the 261 & 235 in 1963. Brian

the 261 was offered as an option for the 1/2 ton truck for the first time in 1962. It was option code 293 which was still on the firewall of my 62. The engine and bell housing were a light green and the timing marks on mine were a vertical line, a triangle (used as a reference to measure valve lift) and a 0 stamped into the flywheel, which is TDC. I have the factory shop manual which states such and a repto brochure and RPO code sheet which shows the 261 as an option {code 293}. It makes sense as they were probably trying to ,ower their inventory to make way for the 1963 230 and 292.