Big Block Timing Issues

[Rat72]

I am working my way through issues on a 454 with HEI ingnition. It did not run well when I picked it up even though the engine is pretty fresh. I figured I should look at the timing but it's been awhile since I did timing with a timing light rather than a computer.

The first thing that happened is that I got shocked when I grabbed the distributor? I've never had this happen before and looking for a cause? Seems like bad grounding but I'm just guessing.

Next I noticed that the timing was around 12 degrees. I bumped it up to about 16 degrees and it ran better. I believe the stock timing should be around 8 degrees and it would not idle when I put it down to 8. It does have a cam which the previous owner said was one step up from an RV cam. I know, that's not much info. Could the distributor be off a notch? What is a reasonable guess on intitial timing, 16 sounds like a lot.

Thanks,
Whit

Thanks,
Whit

[dwaite72lnghrn]

I would say you have bad wires from distrib to plugs. That would cause a you to get a jolt if you touch the distrib. Could also be a cracked cap. Without knowing what cam you have you are guessing but 12* on the timing with vacuum disconnected should be good unless it is a really wild cam. If you run to much advance you will start to have a heat problem and run on when you shut it off. What idle speed do you have? Big cam might need a little more maybe 750-850rpm. What carb do you have?

[Rat72]

Originally Posted by dwaite72lnghrn

I would say you have bad wires from distrib to plugs. That would cause a you to get a jolt if you touch the distrib. Could also be a cracked cap. Without knowing what cam you have you are guessing but 12* on the timing with vacuum disconnected should be good unless it is a really wild cam. If you run to much advance you will start to have a heat problem and run on when you shut it off. What idle speed do you have? Big cam might need a little more maybe 750-850rpm. What carb do you have?

I'm pretty sure this is not a wild cam. It idles poorly at 12 degrees even up to 1000 rpm but at 16 it idles pretty nice at 700 rpm. The other issue that is tied into this problem is low vacuum, which I understand can be cause by retarded timing. It was about 14 in. at 12 degrees. I did not check it when I advanced the timing but I would bet that it was higher.

Thanks,
Whit

[dwaite72lnghrn]

I would check and make sure you are TDC when #1 is firing and again check the plug wires. How long since it has been rebuilt? I got mine back from a rebuilder and it had a rough idle and they said it was from my big cam (crane hmv272=272i/284e), I adjusted the rockers and it smoothed right out. I had 20" on the old 402 with both a qjet and a edelbrock 1411 at 750RPM timing @12*.

[Rat72]

Originally Posted by dwaite72lnghrn

I would check and make sure you are TDC when #1 is firing and again check the plug wires. How long since it has been rebuilt? I got mine back from a rebuilder and it had a rough idle and they said it was from my big cam (crane hmv272=272i/284e), I adjusted the rockers and it smoothed right out. I had 20" on the old 402 with both a qjet and a edelbrock 1411 at 750RPM timing @12*.

The rockers have been on my mind because that is a usual suspect for low vacuum. You've just motivated me to push it up on my list of things to do. But I don't think that would explain why the timing wants to be sooo far off, it wants to go to 20* before it is happy. Maybe the timing gears aren't aligned or maybe the distributor isn't in the right slot. Something is very wrong.

Thanks,
Whit

[jhow66]

Did you check your timing with the vacuum advance hose off and pluged?

[Rat72]

Originally Posted by jhow66

Did you check your timing with the vacuum advance hose off and pluged?

Yes, that was about the only thing I remembered from that era distributor. I think I just learned something new, the distributor can fit into several slots and still work fine as long as as you can rotate the diz to the right place. So the only real potential for screw up is having the timing gears mis-aligned. I doubt if that happened so I need to look for other issues. And when I pulled the distributor apart I found some ugliness. I am hopefull that a new tuneup kit, wires, and plugs will make a difference. I also picked up some roller rockers which will force me to adjust the valves so hopefully things will come together.

Thanks,
Whit