[Six7390GT]

I've got the timing chain and valve covers off of the 1968 289. I'm trying to determine the firing order of the camshaft by rotating the crankshaft (clockwise from the front of the engine) and watching the intake valves opening. The intakes are the front valve of each pair of valves, correct? Am I doing this correctly?

 

[rhutt]

How can the valves be opening with the timing chain removed? Are you referring to the timing chain cover? 1-5-4-2-6-3-7-8 is the common firing order found on 289s and the intake valves are only the forward valve on the passenger side. They are the rear valves on the drivers side.

If you haven't yet purchased a shop manual for your model year, I would highly recommend it. It will provide you with the answers to nearly all of your questions.

 

[dobrostang]

Assuming you meant the timing chain cover is off but the timing chain is on, the valves trace easily to the intake or exhaust runners. The intake valve lines up with the intake runner, the exhaust lines up with the header. That is the right way to figure it out, they are not always the front or rear.



Good luck

 

[Six7390GT]

Thanks for the reply and the info regarding the drivers side/passenger intake valve locations. I've got the timing chain cover removed. The timing chain is still attached to the cam. I've installed the Edelbrock top end engine kit https://www.summitracing.com/parts/edl-2027, but could not get the engine to run properly. I had the distributor in and out many times to try to get it to go - indexing it 180 and trying a tooth advanced and retarded - several times. No go - I would still get some carb backfiring no matter where I set it. I reluctantly tore the front of the engine back off so I could check the timing chain setting, but it is correct. I've checked the plug wires in the cap for correct firing order many times - I even had my wife doulbe check it, lol.
I should have re-wired the cap for a 351 before I tore it down, but didn't. At this point, I just need to verify the camshaft firing order is correct and go from there.

 

[rhutt]

Do you actually believe that your cam has the 351 firing order or are you just ruling it out? The kit you purchased is for the 289 and 302 engines. Did you verify that the cam and crank timing gears are indexed correctly with #1 at TDC? Is it possible that you installed the timing chain with the gears 1 tooth off. Easy to check with the timing cover removed.

 

[Six7390GT]

OK, thanks again for the replies. I rotated the engine and checked the cam firing order - it's the 289 firing order 1-5-4-2-6-3-7-8.
I know with the engine sputtering and backfiring when I attempted to start it, the plugs won't tell me much, but the front 6 look great, the back two are pretty dark. The valves are all adjusted properly.
It's possible that with all of my attempts that I never got the distributor timed correctly, but IMHO it's unlikely. I rebuilt my first V8 in 1971, and have been rebuilding engines as a hobby since. I'm not wanting to re-assemble this engine before finding a problem, but there's not much else to check. Now I wish I would have done a compression check on this one before tearing it back apart. With the coolant fully drained from the top end it would be relatively easy to pull the new intake back off as well, but what a PITA.
Any suggestions on how to diagnos this?

 

[TheRktmn]

Assuming you have the 2122 Performer cam it uses the original 289/302 firing order:
1 - 5 - 4 - 2 - 6 - 3 - 7 - 8
https://edelbrock-instructions-v1.s3.amazonaws.com/edelbrock/2122.pdf

 

[kenash]

"I should have re-wired the cap for a 351 before I tore it down, but didn't."

Am assuming you are referring to the firing order? However, did not this kit ship with a cam that follows the 289/302 firing order? Please explain your reference to "351?
1. If #1 piston is at TDC and the cam is installed "dot to dot" with the chain in-place. Then, this relationship is correct.
2. Your firing order should be for a 289/302 (assuming you installed the cam that shipped with your kit) and is noted in the image.
3. With the crank at TDC, both #1 valves closed, insert the distributor, orienting the rotor in vicinity of #1 on the cap. Keep in mind the rotor will rotate as the helical gears mesh.

If all is as it should be above and the valves pre-load, have been correctly adjusted, the engine should fire, May not run perfectly, as timing adjustments may be needed and the valve preload tweaked. Also know to follow proper break-in practices for the cam an lifters.

 

[my289]

When you installed the cam did you verify you where on the compression stroke for #1 cylinder, or just line up the timing chain dot to dot? Simple check: Bump the engine and put your hand over #1 spark plug hole, with spark plug removed, till it blows air out of the hole and then see if the timing chain is dot to dot or 180deg off?

 

[Six7390GT]

Thanks for the replies folks - much appreciated. Yes, #1 is on compression stroke at this setting - thanks for asking. I've attached some photos - I hope.
I think I'll skip pulling the intake and start re-assembling this old sweetheart - which we purchased from the original owners in 1987.
This is a first for me - I'm normally pretty lucky at firing up rebuilt/freshened up motors. Guess it's time to pay some dues, lol.

 

[rhutt]

We all have to pay our dues! I'd button the front end up and stab the distributor one more time ensuring the rotor is pointing in the general direction of the diagram that kenash posted and then verify the plug wires are run consistent with the 289 firing order. Put a timing light on it and see where you're at.

 

[my289]

Is it still carb? Since its hard to tell but is that cam pin sticking out far enough for your 1 piece eccentric? Or are you using a electric fuel pump? I think most cams come with both pins, and you use the longer one for a 1 piece eccentric. Just trying to eliminate possible issues.

 

[macstang]

If it was hitting ok on 6 and those 2 were the only ones that were backfiring I would make sure the spark plugs are in the right plugs and the timing is set right. It could also be that the exhaust valve lash on those 2 is too tight. Actually it depends if it is blowing back through the carb or out the exhaust. It would be best to check the lash on the intake and exhaust on any cylinders you suspect.

 

[kenash]

Yes, "My289" raises an important point regarding the concentric pin.