Thread: newb timing question/issue

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New here, but my issue is more pressing than greetings. I've got a crate 350 referred to as 'rocket block' it has a flat tappet cam(only thing I think you need to know as far as my issue is concerned) so the ultimate issue is my timing. I was driving around and the truck began running different. It was running higher rpm and pinging when id hit the throttle a litl bit. Too far advanced as far as I understand. I shut it down and hook up the timing light. Check it and it was at about 15 degrees above. My paperwork says it should be at ten. So I set it. Pull out of the driveway. Sounded normal, hit the throttle as I normally would. Pinging like mad. Back in the driveway, back to 15. I repeated the process. Didn't work. Is there anything that could be doing this aside from the fork that holds the dist in place? Or perhaps that bolt stretched out? I've had to readjust my timing every 5 or so months to keep it where it should be. Any suggestions? I'm having an off day and it could be as simple as anything. All advice is appreciated.

How about some real info??? Like year, make, model??? Is it computer controlled? A lot of them are nowadays.. Need some data to offer an opinion.

Bet ya the hold down bracket is junk or a chinese 1.
Get a stocker and your problem is solved.

I agree with you on his one.Computer controlled dizzies can be a factor.

Originally Posted by 34_40

How about some real info??? Like year, make, model??? Is it computer controlled? A lot of them are nowadays.. Need some data to offer an opinion.

Sorry,I'm not too knowledgeable on the engine. It is in an 84 gmc fullsize and it has a box under the dash with only one wire going to the hei dist. It did have more wires, but all of the emissions were removed and they were cut. Not sure what else to share. Its just a cast iron block with 1.94 heads. Flat tappet cam, alum. Pistons, 4 bolt main, edelbrock perf carb n intake. If you need to know more ill dig out the paperwork on the engine. Thanks for the help so far. I'm going to buy a hold down and bolt for it today and see what happens.

Well when you tighten down the bolt/clamp-can you move the dizzy??.

No I cannot. Not by hand.

OK, you said GMC. Does it have Electronic Spark Control (ESC)? It will have a badge usually on the back of the truck. Anyway, you can tell if it has ESC by the fact it has TWO connectors coming out of the metal distributor housing (not the cap). The ESC is intended to alter the timing under load but sometimes it gets a mind of its own. You can easily remove the ESC from the function.

First thing to do is unhook the spark control computer lead from the pink wire and hook the pink wire directly to the dist. cap. Make sure you plug it into the cap at the BAT terminal. The second thing is to locate the 4 wire connector that feeds into the ignition module. There's a brown (D), green (C), white (B), and black (A) wire there. The letters in () are on the black clip that the wires come out of. You jumper the green (C) and black (A) wires together by adding a short wire stuffed temporarily into the back side of the connector.....just use a short piece of wire and strip each end and stick it into the connector. IF you have a problem, pull the jumper out and you are back to normal setup. IF this jumper works (after testing for a few days), you can permanently make a jumper by cutting the wires and soldering them. You could also replace the 7 pin module with a 4 pin module to elimnate the ESC feature.

So I just tried everything again. Got the engine warm. Set timing to ten degrees. Rev the engine once, check timing right after revving it. Its up to 13. I can't explain it. I cannot turn the dist even right after checking it again and it being higher. The dist didn't move, but my timing advanced 3 degrees. I don't understand it. I didn't buy a new clamp or bolt since I couldn't move the dist so figured that won't change it. Could it be anything in the dist itself?

If it is slipping as you describe, it is either the balancer is broken OR the timing chain is jumping. Either is a mystery since a jumping timing chain will quickly get you a cam that is seriously out. A slipping balancer will get you a problem because, if you line up the timing to the correct amount, the timing will be off (because the mark slipped).

Check list: vacuum advance disconnected...right?
Does the timing ever "slip" the other way? It seems like you have described it slipping at least several times.....Do you notice if it is ALWAYS advanced too far?

Sorry, I missed your post robot. No esc on this rig. It has one 3 wire plug coming from the dist body to the c- grd b+ on the cap. The only remaining wire from the box under the dash is pink and goes straight to bat+ on the cap along with a larger pink wire(ignition source) that's all. The box has a brown wire going to ground, but I don't think that's an issue.

The vac advance is disconnected and plugged. The timing has retarded itself aswell. Once down to 4 once to 6. But it tends to advance more often than not. The rig sounds pretty good when I have it set to ten and just let it idle, but as soon as I rev it even a litl it starts to advance. And when I rev it a few times it can jump as much as a degree at a time. Not hard revs mind you but more than a quick blip.

The advance mech in the dist is seizing onto the lower dist shaft--

you might be able to work some lube into the shaft but easiest way to fix, remove dist, remove drive gear, then with shaft out of dist housing, separate the top advance meckism and lube the inside till it moves freely and then reinstall every thing--this was common back in late 70s early 80s--

Thanks to jerry and robot. Ill try lubing the dist shaft first and see what happens. I'm almost.positive the installer of the engine (dealership) used the original dist(84) when they did the work. So that would be commonplace to what jerry stated. Thanks again. Any other advice will be heard. Thanks again fellas.

first off what fuel are ya running in it? 87-90-92-or 94 octane.....the lower the octane, the lower the advance. Lower octane= shorter burn. On 87 octane......advance 4-6.....on mid grade 6-9 and 92 octane 10-13, on 94 octane advance 13 to 15......this is based on stock or close to stock horse power.