Cam Timing

Ericv · 08-23-2010, 04:26 PM

I completed my first top end refresh on a 2.0L 69E with solex cams and "S" pistons and cylinders a few months ago. I think I made a slight assembly error with the cam timing. I marked what I thought was TDC with white paint. I set the timing to TDC but it was actually 30 degrees before TDC. When I timed the engine, the spot with white paint would advance to the case halves when the engine was at 6,000 rpms. The engine runs and I can actually get it to idle smoothly. But, 2,500 rpms and lower, it's a dog. Over 2500 rpms and it pulls very nicely. Is this something that can be rectified in the car? Or, would it be easier to pull it and adjust the timing out of the car? The range on the timing was 4.2 to 4.6 with the ideal setting at 4.3. Please let me know your thoughts. Thank you.

Flat6pac · 08-23-2010, 05:06 PM

Its a tossup between pulling the engine and removing the bumper and lowering the engine low enough to be able to dial guage from the rear. I would call it a Saturday afternoon job and remove the bumper and muffler, repin the cams, do it all at once so you dont make a mistake.
Tail of the car in the air, engine lowered to horizontal..
Bruce

Ericv · 08-23-2010, 05:47 PM

Thanks for the response. I'm hoping this will take car of my low-mid range loss of power issues.

Eagledriver · 08-23-2010, 09:44 PM

I'm suprised you didn't have interferance between the intake valves and pistons with the timing that far off. Are you sure about the marks on the pulley? There are TDC marks every 120 degrees. Make sure you've found the correct one for #1/#4.

-Andy

Ericv · 08-24-2010, 03:01 AM

Quote:

Originally Posted by Eagledriver

I'm suprised you didn't have interferance between the intake valves and pistons with the timing that far off. Are you sure about the marks on the pulley? There are TDC marks every 120 degrees. Make sure you've found the correct one for #1/#4.

-Andy

Me too. I'm fairly sure about the pulley marks. I had the correct marks for #1 and #4. Upon reassembly, I made sure the valves had no lash and then turned them in 2 full turns or 2mm as a final check of the piston to valve clearance and I had no issues. Then, I adjust the valves and completed the long block. I'm surprised I can get it to idle smoothly and even have good torque and power above 2500 rpms.
Just to be clear, the engine rotates in a clockwise position and the two marks that I'm looking for is roughly 3/4 to an inch apart from one another. The first mark of those two marks is 30 degrees BTDC and the second is actually TDC correct? Thanks for your help in getting this straightened out. By the way, the car will sit until I can get this rectified. I don't want to risk internal damage now I know there's a big problem.

356RS · 356RS's Garage

The Z1 mark on the pulley is TDC. The two marks to the right of that, about an inch and a half, are 30 degrees BTDC and 35 degrees BTDC.

Ericv · 08-24-2010, 10:52 AM

Quote:

Originally Posted by 356RS

The Z1 mark on the pulley is TDC. The two marks to the right of that, about an inch and a half, are 25 degrees BTDC and 30 degrees BTDC.

I didn't see a Z1 on the pulley when I initially set the timing. I did see the 120 degree marks for valve adjustment. What I described before is the only spot on the pully where two marks are close together. After those two marks, it appears they are spaced 120 degrees apart.

356RS · 356RS's Garage

I posted this picture so you can see if your pulley is correct. This is from a early MFI engine.

Ericv · 08-24-2010, 01:44 PM

Quote:

Originally Posted by 356RS

I posted this picture so you can see if your pulley is correct. This is from a early MFI engine.

Thanks for the picture. I spent some time on it today. It appears I did make an error but it wasn't as bad as I thought. There was a Z1 mark and that is the mark that I painted white. I'm a newbie at this and still learning how to read a timing light with advance. I did find that the dizzy was one tooth off because when at TDC, the rotor did not line up. I pulled the dizzy and reinstalled while at TDC, retimed, and there's a noticeable improvement on the bottom end. I still have a little hesitation but but I think that's more from my carbs than the ignition system. There a little rich right now because the idle adjustment screws are at the initial settings of 2 and 1/2 turns out. The idle is stonger as well as overall performance through the RPM range.