I've got a question that I've been unable to tackle so far.

I've decided to put some new cylinder heads, cam (it was the Edelbrock top end kit) and exhaust headers on my L-48, and everything seemed to go well during the process. I also decided to re hone the piston chambers, and replace all of the piston rod bearings when I was down there as well.

Now that it's all back together, it's having trouble starting. I'm as certain as I can be that the valve timing is correct. I was very meticulous with that and double and triple checked it before I reassembled it. Everything was done by the book, so I'm hoping that I can rule that out as a possibility (but due to my inexperience I'm not completely ruling it out).

What's happening with the engine is that with the distributor on one way it's causing very loud thunking in the headers (I don't have any other piping on it at the moment). I've never really heard an engine with open headers, so I'm not sure if it's detonating in the tubes or not. There were little plumes of fire coming out every now and then, but again, I'm not sure if that's because it's so close to the block or not.
When I flipped the distributor gear around it would just pop inside of the intake manifold and spit gasoline out, but this would happen very infrequently. I assumed that this wasn't the way it needed to be on, so I went back to the first configuration.
The plug wires are definitely on all of the correct plugs (again, double, and triple checked this).
I tried to turn it over for some time, and used starting fluid as well. It just doesn't seem to want to crank over, and I'm not sure if it just needs more coaxing because of the work that I did to it, or whether I was one notch off on the cam or something incredibly annoying like that.

What does this sound like to you guys?
Thanks,

--Sean

 

Open headers are pretty loud and little flames could appear that close to the block.

Could it be cam alignment? Were the timing mark of both crank and cam pointing up and #1 at TDC?

 

Well, it is probably just something else to tripple check. If you set up the engine correctly it WILL start on the first turn of the key.
Start with the valve timing, bump the motor around until you see the #1 Intake valve close, the timing mark SHOULD be approching the marker plate on the timing cover. Put the timing mark exactly on 8* BTDC. Then adjust the distributor until the rotor contact is exactlu on the contact for the #1 plug.
Make sure there is gas in the carb, I use ru the vent in the air horn on the carb.
Pump the excelerator 2 times and hit the key.
This is the recipe I have always used and it works.

 

Yeah, I figured it'd be really loud, but they're not really little flames...which it seeming more and more like a valve timing issue.

When I put it back together, I made sure that the #1 piston was all the way up (TDC) and that the cam peg was facing the 9 O-clock position and that the marking dot on the cam sprocket was lined up with the one on the crank. All like the directions stated. I'm about 99% confident that I did this right, but would having it one tooth off in either direction cause this kind of issue?

And, yeah, I'll check it again, Sixfooter. I'll pop off the vave cover and see what's going on in there.

I'm not looking forward to having to take the oil pan off again I hope its not the valves.

 

A couple of things come to mind here.

Did the timing set that you used have multiple keyways on the crank gear? Using the wrong keyway has tripped up lots of people.
If it was a single keyway set, you are probably OK if you were careful.

What I would bet is the most likely issue is the valve adjustment.
If you havent done this much, it is likely that you have the valves adjusted too tight.
This is especially true if you tried to adjust them using the "spinning the pushrod until you feel resistance" method.
With a new cam & lifters you may not feel resistance on the pushrod until the plunger in the lifter has bottomed out.
Then you add an extra quarter turn or so and your valves now never close.

 

There were 3 notches in the crank gear, and a dot in one of the teeth to tell you which way it's supposed to face, so it would seem like that's set correctly.

But what you said about the valve adjustment might be right on the dot. That's exactly what I did. What's the correct way to do it with a new setup?

 

I agree! And even lifters that have been run can bleed down and you will never feel resistance until they're bottomed out. Sometimes it's best to watch the push rod and see if/when it starts to move down and start compressing the lifter! I feel that "poly locks" make adjusting valves much easier than when using regular rocker arm lock nuts,,,,,,,
I think that you will find that you have some valves too tight!

 

What I do is use my fingertips to jiggle the pushrod up and down while I am adjusting the rocker nuts.
It is easier for me (and most other people) to tell when I run out of free air space than it is to feel spinning resistance.

 

put some exhaust on it, open hedders are so loud you can not hear whats going on with the motor. and you really want to hear whats happening wih a new motor starting .

 

When you are setting the static timing on the distributor, what is the degree mark on the harmonic damper and the position of the distributor rotor?

For example, my standard timing is approx 12 degrees BTDC (Before Top Dead Center) on the harmonic damper and the rotor 'contact' is position at or just before the #1 spark plug wire where it would be with the distributor cap clamped to the distributor base. If your static timing is not at this point (or if it is 180 degrees off which is a 50/50 chance when you are setting the static timing when you are dropping the distributor into the engine) then you will get either backfires out of the carb or flames from the raw fuel that is building up in the combustion chambers from the fuel that is flowing through the carb when you are cranking and pumping the gas pedal.

Jake Cameron authored the following white paper on setting distributor timing:

https://www.corvetteforum.com/techti...=275&TopicID=5

And Lars' paper:
https://www.corvetteforum.com/techti...=107&TopicID=3

And, from Lars also, if you want to set your distributor timing for top performance:
https://www.corvetteforum.com/techti...=109&TopicID=3

 

I'd really like to be able to do that...but that's been a whole different fiasco. After hours of driving, and countless muffler places, the best I've gotten so far is "Drive it up here!".

I'm going to try readjusting the rockers today. Thanks for the tip, Driveshaft. I'll post the results later.

 

Well, I loosened up the rockers which were indeed all over tightened. Unfortunately, this didn't actually help the problem. I got the same results as before, but now the noise was about twice as loud. So, I'm not sure where to go from here.

 

Go back and read the timing gear instructions again. That has to be right, not close. Multi-keyways can be confusing. Be SURE that the dot with the dot, or diamond with diamond, whatever. If you are sure that is right, turn the engine to just before TDC. Pull the #1 plug and put a piece of tissue in the hole (not inside the engine). If you rotate the engine and it spits it out, turn it back to TDC and put the distributor in pointing to #1. If not, turn the engine 1 revolution and repeat. When you go past #1 TDC it should spit out the tissue. If it doesn't, you have a timing gear or valves too tight or too loose issue. With engine timed as above it should at least start assuming you have fuel and spark.

 

Note that this standard position for assembly (as shown in all the overhaul books) is actually TDC compression #6. 1 and 6 are "companion" cylinders - they're both at TDC at the same time, but on different strokes. This is a very common issue with distributors being installed 180 degrees off.

Set the engine to TDC COMPRESSION #1, pre-oil again and reinstall the distributor. Set the initial timing to 16 degrees BTDC as you want an immediate start.

 

When I TDC'ed the engine I went off of the #1 piston on compression. I'll try reinstalling the distributor at TDC again tomorrow (at 12-16 degrees BTDC as has been suggested) and if that still yields the same result I suppose I'm gonna have to pull the timing cover and set the sprockets right.

Thanks for the help, everyone. I'll likely have an update tomorrow.

 

Any luck?

 

Maybe try to pull the distributor and turn it 180 degrees, See if it fires

 

Not sure how they want you to install your timing chain but this is how I did it.

 

It's not just about lining up the dots - the crank key should be at "2:00" and the cam pin should be at "3:00" when the dots are aligned.

 

Well, I checked the TDC markings against the distributor, and it looks like the cam was actually installed improperly. When it should be firing on #1, it's on #2, and #6 is on #3. So it's retarded by one piston across the board.

I installed the crank gear at the 2:00 position, but the cam pin was at the 9:00 position as the instructions described...looks like I musta been reading them upside down

So, it looks like I'll have to re-time the cam. Is it possible to get the timing cover off without removing the oil pan?