Make sure you are using a conventional timing light and not a ‘dial back’ timing light.    Your timing at 30-40° at idle sounds excessive.  Also keep in mind that you should be checking the timing with the vacuum advance unhooked.
 
I’ll suggest checking that the damper ring has not slipped on the damper hub.  Assuming that checks out okay, then the camshaft timing comes to mind.  Did you degree in the camshaft when assembling the engine?  A cranking compression test at this point could provide some additional information regarding the camshaft timing.  Lower than expected compression readings will point to the camshaft being retarded while advanced will have the compression readings on the higher side.
 
While not as nearly as accurate as a degree wheel and dial indicator for checking the camshaft timing, you can put either the #1 or #6 cylinders at ‘perfect’ overlap at the intake and exhaust valves and then check where the timing mark falls on the damper.  With the exhaust valve closing and intake valve opening, find the point where both rockers are level or depressed the same amount.  This is somewhat difficult with the factory iron rockers but very easy with aluminum rockers where a flat straight edge can be placed on top of the rockers.  If the damper reads between zero and eight degrees advance, you are in the ball park.  If you find it reading 15 or more degrees out in either direction, then this would bear further examination.

Lorena, Texas (South of Waco)

If that is 30 to 40 degrees at a normal idle speed, then yes, it is too much.  Most likely, you are getting a false reading rather than that being the actual timing, because most engines get hard to start at about 20 degrees of advance.  With 30 - 40 it just would not be happening.

More likely, you either had vacuum advance connected, providing an false indication of your initial timing.  Also, since it is the first start, it should be set up to run much faster than idle for break in, in which case, you are also seeing the effects of the added mechanical timing.


Lawrenceville, GA

Thanks Ted,

Yep first mistake- timing was with vacuum on and I forgot I had it running up on the rpm. I guess I was a bit excited and went at it with the timing light too keen.

Also the dampener is brand new from summit.

I didn't degree the cam, I guess I really should have, but I haven't spent enough time to exactly understand the process.

I have a water leak at the timing cover so I won't be starting it until I fix that (see my water leak post if you have any ideas)😊 But I will read up on cam degree, and have a mother res of your post, thanks.

But I'll be sure to get the advance vacuum plugged and engine idling before I whip out the timing light again.


Thanks, Dennis.

56 F100 - 272 Y Block
NSW, Australia.

Thanks, Dennis.

56 F100 - 272 Y Block
NSW, Australia.

Charlie thanks mate, as I said to Ted I was a bit excited and bungled everything up. I will reset and try again and let you know how it goes.


Thanks, Dennis.

56 F100 - 272 Y Block
NSW, Australia.

Ok, so I checked the timing again.

-I pulled the vacuum advance off the dizzy and plugged it up
- set the rpm to 800 and put the timing light on.

The engine was running pretty rough at 800rpm 10btdc but it didn't too bad.

I revved it up to about 2500-3000 and the timing went up to about 35. Then I idled again and was back to 10.

I then hooked up the vac advance and the rpm jumped up to 1100 and the engine sounded smoother but faster.

This is the timing light I'm using. The rpm is on the right and you can set degrees on the left. (Not sure what that's for)


Anyway I'll fix the water leak and have another go at it. Seems like vacuum is in the range of 15.


Thanks, Dennis.

56 F100 - 272 Y Block
NSW, Australia.

That is probably an electronic version of a dial back timing light Ted mentioned.  You set the timing on it for the advance you are looking for.  When you check on the engine, 0 degrees, as indicated by the damper will be the number of degrees you entered on the light.  It can be useful for stock dampers that don't have marks the whole way around but they are often less accurate.

Idling rough at this point is not necessarily a bad sign, as the engine is not yet tuned and if you have a bigger cam, then it simply will not idle smoothly, but do not ignore things and simply push through the break in.  If something seems wrong, shut it down, fix it and then continue with break in.


Lawrenceville, GA

Thanks for the info Charlie.

So if I set no1 piston at TDC and TDC on crank dampener I should leave the degrees on the timing light at 0. What happens when I advance the dizzy 10deg, do I change the timing light or leave it at 0.

I have a new cam. It I'm not sure what it should sound like at idle, this is the cam card if it's of any help.



This "break in" isn't going as smooth as I had expected but I guess it's all valuable experience and that's what I'm in it for!

Could I have made a critical mistake not degreeing my cam? Is it possible the cam could be that much out? Ps I got the cam from John M.


Thanks, Dennis.

56 F100 - 272 Y Block
NSW, Australia.

Assume nothing with new parts.  That means double checking that the TDC on the new damper aligns with the timing pointer when the #1 or #6 piston is indeed at TDC.  Simply eyeballing the piston for TDC can still have it off 3-4° from actual so extreme care must be taken when determining the actual piston TDC.
 
Due to manufacturing variances with all the various pieces involved in the cam timing, the camshaft timing itself can be off considerably.  I’ve had more than a single instance where the cam timing was off by as much as eighteen degrees and this with the gears properly aligned either by marks or link count.  The various places for the cam timing to be off besides the camshaft itself would be the various points that the cam gears attach to the camshaft and crankshaft.  What contributes to more error than normal would be stackups and this is where the manufacturing variances are all positive or negative in nature.  In these cases, the variances all add up thus compounding the amount of error.  All this is easily fixed or compensated for by degreeing in the camshaft and moving either the crank gear or cam gear accordingly.
 
If you don’t degree in the camshaft, then it’s simply pot luck on where the camshaft is actually installed.  If there are tuning problems on a freshly built engine and the camshaft has not been degreed in, then this is an area that may have to be revisited.  Only by degreeing in the camshaft can the exact cam timing be determined and corrected if necessary.
 
Here are some links that cover camshaft degreeing in more detail.
http://www.eatonbalancing.com/blog/2015/09/24/degreeing-in-the-camshaft-part-i-finding-tdc/
http://www.eatonbalancing.com/blog/2015/09/24/degreeing-in-the-camshaft-part-ii-phasing-the-camshaft/
http://www.eatonbalancing.com/blog/2015/09/24/degreeing-in-the-camshaft-part-iii-its-twelve-pins-between-the-marks-for-the-ford-y/

Lorena, Texas (South of Waco)

Refer to the instructions to understand how to use the timing light.  If you leave it at 0, then it should work like a regular light.

I would expect that cam to be a slightly lopey at idle.


Lawrenceville, GA