Originally Posted by ChuckNTruck

Something is still not correct with the timing in that engine. It should crank nice and smooth. when you hear it crank then slow then crank fast again that usually means something is incorrect with the timing. I have seen vehicles actually blow the plugs out of the heads because of this. Is it possible the distributor is off by 1 or 2 teeth? You need to make sure you are at top dead center and on the compression stroke. This means that the #1 piston has to be all the way at the top of the cylinder and both valves have to be closed. That is true Top Dead Center for the engine. Then make sure that the rotor inside the distributor lines up with the #1 plug on the distributor cap when the distributor is fully seated. You need to make sure the rotor is aligned to the #1 plug on the inside of the distributor cap. not the plugwire on the outside. Use a test light or multi meter to find which on is the #1 point You cant just like the rotor up with the plug wire like the old engines.

I say all of this because I have done it in the past. I installed the distributor 180 degrees off on the first Performance V8 engine I put together for my old S10 and almost destroyed a brand new cam shaft. the piston was at the top of the cyl and I didnt know about the valves at the time. so I installed the distributor and aligned with #1 plug the first few times I cranked it she was popping through the carb like yours is coming through the throttle body. Once I installed the dist correctly it cranked right up and ran like a dream.

Would you be able to get the engine at TDC and take a picture of the distributor with the cap off so we can see where the rotor is sitting?
If you still have the timing mark on the harmonic balancer and the timing tab on the block or timing cover line those up.

Also I am still curious how you checked the bearing in the bottom end? did you pull main caps off to see the inner surface of the bearings?

Originally Posted by ChuckNTruck

Sorry I missed those pictures on post 74. that all looks correct if the engine is on the compression stroke. However because of the size of the timing gears and how these engines work the crankshaft will spin 2 times for every 1 turn of the camshaft. This means that the timing marks can be aligned and the distributor will be 180 degrees off. This is what I did in my past.


Basically the engine uses one rotation to compress the air/fuel and ignite it then the piston goes down. Then on the next rotation the exhaust valve opens and the piston pushes all exhaust gases out of the cyl. When the piston gets to the top the exhaust valve closes and the intake valve opens and the piston going down pulls the air/fuel into the cyl and the cycle starts over again.


I hope this is not confusing and if you want more explanation I would be happy to.


Pull the drivers valve cover and align the timing marks on the harmonic balance and timing cover like you have them in the picture. Then take a look at the rocker arms for the #1 cyl. both rocker arms should be flat and both valves should be closed. That is the compression stroke. If one of the rocker arms is pivoting and opening the valve you need to spin the cranks 1 rotation and realign the timing marks to get to true TDC.

Originally Posted by Tynan Tha Real Dill

ok, so when you say "both rockers arms flat", that means the intake and exhaust rocker arm rods need to be down all the way, timing marks aligned ?

Originally Posted by ChuckNTruck

When you look at the rocker arm the part toward the intake is the pushrod end and the part toward the exhaust manifold is the valve end. for the valves to be closed you want both of the valve ends of the rocker arms to be all the way up. When the cam spins it pushes up on the pushrod which pushes up on that side of the rocker arm. This pushes down on the valve side and opens the valve.


If you pull the valve cover and rotate the engine you will see what I am talking about.
you should be able to spin the engine and see the rocker arms pivot one at a time then they will not move for awhile. when they are not moving that's when you want to align the timing marks on the balancer and timing cover.

Originally Posted by ChuckNTruck

I was also just reading and some of these engines have 2 timing marks spaced 90 degrees apart on the balancer. If yours is like this, You want to use the 2nd timing mark to line up with the timing cover. The first mark aligns with anther timing mark on the drivers side of the block
When you are looking at the engine from the front of the truck you want to spin the engine clockwise (I usually use the balancer bolt). Go past the first timing mark and align the timing cover with the second mark.

Originally Posted by Tynan Tha Real Dill

Yea I have those, I understand everything but the difference between exhaust stroke and compression stroke...until now. Exhaust stroke is with the pushrods all the way up and valve down/pressed, is cylinder open. Thats how I've been doing it, on exhaust stroke (pusrods up, valve end down) ! Which means I'm 180 degrees off or a couple of teeth off !!