TIMING FOR A STOCK 350

Can anyone tell me what the ideal timing should be for a stock 350 with a very new 4 barrel Edlebrock carb? I've got some help figuring out my running/backfiring issues and would love to get this corrected this weekend.

Thanks!

Idle is pretty rough and timing was adjusted with no appreciable difference. When the vac lines are plugged or removed, there is stil no difference in idle.

Vac advance is working properly.

Distributor seems to be working properly as each cylinder spark plug wire detects a timing light.


Any suggestions on next moves?

I assume that you have electronic ignition? If so you might want to remove the distributor cap and take the control module out of the distributor to a parts store & have them check it out for you. I have had them go bad and cause a miss before. Also you might want to check all of your wires to make sure they are not causing the miss. You can check them best at night when its dark. Just crank it up and look to see if the wires are arcing fire. The next thing to check would be that all of your wires are wired in the correct firing order. The correct firing order is 1-8-4-3-6-5-7-2 the rotation will be clock wise. You will want to pull the #1 spark plug and bump over the engine until you get the #1 cylinder on top dead center. Then once the piston is on top take your distributor cap off and look at the front of the rotor button to see if it is pointing at the #1 wire. If it is just trace down all of your wires to make sure it is wired correctly. Now if it has just recently started missing and you haven't removed the wires or anything it is probably not the firing order. My brother's truck just started missing a few weeks ago & it turned out to be bad plug wires so maybe that could be your problem.

tru 8 degrees BTDC!! if points dist - change all to new .

Update. Yes, HEI.

My father-in-law, airplane mechanic and British car nut (fool!)helped me with the van. We checked timing, cleaned the carb, checked the plug wires (one on the underside was loose) and headed down the road. Timing seemed to be right at 10. She was running pretty good. Then, I smelled burning rubber smell. Then I felt a light mist. Then I noticed the temp gauge was pegged! The belt had blown.

Long and short, I drove it the next day and day after and she was humming. Never ran that good. Then, started running like crap. Discovered plug wire hanging completely off the next day. It's back in place, but van is still missing (but not as bad), so I'm guessing it needs replacement.

Any suggestions for bang for buck wires and plugs? I have a feeling these are cheap wires anyhow. I've also run it rich for months before figuring out the issue, so I figure new plugs are in order. Not looking for racing wires but something that will get me a solid connection.

I can't remember if you are running headers or not Laz. If stock manifolds just some plug n play wires from Napa(for an HEI) should be okay. The after market ones usually require some assembly and that can be a bit of a pain. Don't overlook the distributor cap if the wires don't solve the problem, they can get micro cracks in them and start tracking the spark all over the place. Might not hurt to replace the fuel filter either if the problem seems more in the higher RPM range. What did you do for the running rich problem? Edelbrock? Mine runs a little on the rich side and really haven't been able to tune that out.

Change the plugs!! also look inside the dist cap for a broken/ pieces missing form the top of cap where the rotor metal part rotates on?? Carbon tracking inside the dist cap also?? also dont forget you has a water leak & some fluid could have entered some where unknown?? (electrical)

Digz wrote:I can't remember if you are running headers or not Laz. If stock manifolds just some plug n play wires from Napa(for an HEI) should be okay. The after market ones usually require some assembly and that can be a bit of a pain. Don't overlook the distributor cap if the wires don't solve the problem, they can get micro cracks in them and start tracking the spark all over the place. Might not hurt to replace the fuel filter either if the problem seems more in the higher RPM range. What did you do for the running rich problem? Edelbrock? Mine runs a little on the rich side and really haven't been able to tune that out.

Stock, no headers. Edlebrock 4 barrel. I am saying running rich due to crappier than normal fuel efficiency. Might have been mental, but it seemed to be better on gas when she was runnng right. And, I was heavy in the foot since it was like a lead weight had been removed.

The carb was replaced recently and has very low miles on it. Probably not 1,000. I did notice that I am getting some fuel seepage but it might be from heat soak. Are you seeing that on yours?

I am going to re-check everything. Fuel filter was on the list but after the initial timing check and reset and pushing the plug in place, she was humming. And I had a full tank of gas when we thought of it...

When it went back to missing, that is when I discovered the dangling plug wire. Replacing it improved the situation, but not fully. Since that seems to be an obvious issue, I am going to start there and do the plugs at the same time.

Father-in-law played with distributor when adjusting timing, but not sure if he checked cap. Vac advance removal never solved my initial driving backfire problem months ago, so that is not the culprit. Also confirmed diaphram is working properly. I'm learning, but everything I'm learning has come from here.

One more question: Should we hear any "rumble" in the exhaust when giving it heavy gas and then letting it coast? I still feel I have some rumble. Father-in-law said that didn't concern him as it might be a product of the exhaust setup I chose for this van? Does that make sense?

Only at a fifth grade car repair level...

Hey Laz- from great experiences in engines & having problems as you in wat past -id suggest this 1st - do what i said above- ur looking for things . Next dont look @ plugs / or even clean them -install a new set!!this eliminates a bad plug or problems to begin with!! Plug wires also if any part is cracked or burned - even wires have been pulled on removing!! change them!! now explain in detail as to the new carb?? with 1000??miles use ? used ?? why did u get that ? old one working good?? Thanx

I get some seepage showing up (also a used carb), but it isn't consistent so I'm thinking occasional heat build up on that. FIL is probably right on the exhaust. That would just depend on whats there. If it was me I'd just do the wires first then move to the plugs. plug wires running out of place can burn themselves up kinda, even the plug with enough time. Eliminate 1 thing at a a time that way you have a better idea what the problem was when or if it happens again.

When an engine gets too hot sometimes funny things happen. sometimes wires break inside, connections get a little melty, etc. And sometimes this stuff happens in places and ways you cant see it. Ditch the wires, LOOK AT your old plugs, mark which cylinders they came out of, and KEEP THEM. Next time you change plugs you can look at the last and current ones for tuning refrences. CHECK all your ignition gear. loose vaccuum hoses or maybe pinholes, etc. I had a wire pinched under my distributor cap for a month. It created a really minor starting issue but ran fine otherwise. never even knew it was there. random little things can affect great things.

Also check the exhaust heat riser valve. On my '67 with the stock 283 V8, it's on the RH side of the motor (looking forward). These heat riser valves will crud up and lock in some less than desirable position at the drop of a hat. If it doesn't move freely by hand, get some heat riser luv (I use a Mopar brand) and work it free. Make sure the return spring is functioning properly to close the valve when the engine is cool. When the engine is warm, the bimetal return spring should relax fully to allow the counterweight (and engine exhaust ) to open the valve fully. Anything else will cause either poor idling (valve stuck open) or poor high speed performance (valve stuck partially closed).

Good luck.

I will add -in past =a lifetime ago!! i have actually taken the heat riser butterfly out of the riser!! never did have any problems in the old texas heat then too!

Yep, after I posted that I checked the heat riser on my '67, and sure enough it was frozen in the closed position. In the process of freeing I managed to break off the end of the stop rod that the spring grabs onto. I managed to press on a bit of stainless rod drilled out to .173 (#17 drill) and that seems to be holding. But anyway, now I'm looking for a replacement... I found a few on the internet but damned if I can figure out which one is exact (although there's one that looks like this one). I'll have to take it out and measure everything before I order. It's a stock 283 but of course none of the catalogs discuss Chevy van V8's so it's a bit of mix and match.

Another question I had was timing related as well, which is how I wound up here in the first place. Right now the timing is only very slightly advanced over spec: 6deg BTDC intead of 4. A friend (who knows his small blocks) says I can get away with advancing it to 15 no problem, and I'll see better power and gas mileage. I'm a little dubious and don't want it to ping, but maybe I'll try bumping it up to 10 or 12 for starters.

There was another problem besides the heat riser: someone put in a replacement master brake cylinder before I got the van, and it's a bit longer than stock, apparently. Normally no problem but with forward control the throttle rod winds up hanging slightly on the rear of the brake master cylinder, which prevents a full return to idle. There's so much slop in the linkage I found I was able to lengthen the linkage at the carb quite a bit which brings the pedal to be almost able to be WOT when floored. Still could be better, though. But now it's actually got some power on the freeway for a change.

Later