whats timing

[tim21391]

i got a 402.. and i heard it was suppose to be at 8 btdc and so we hooked a light on it since i couldnt go past 70 on highway.. it ran swell in town.. never shook or nothing good acceleration.. everything good in town but sucked on highway.. and the light said it was like at 26 or so.. we backed it down to 12 and ran like crap no acceleration nothing.. had it floored and couldnt spin the wheels at stop.. then we took it to 18 and seemed better but it shook like crazy.. then took it to like 22 and it was a little better.. now that seems way to high in my opinion is it? it has to be a fuel problem i have.. like the 4 barrels arnt opening up.. fuel pump is new fuel filters are new.. and im sure the lines arnt plugged up.. what could be the problem? any of your guys opinions are wanted/appreciated

[GASoline71]

What condition is the harmonic balancer in? The outer inertia ring could have spun on the hub... which will not let you time the engine right.

Gary

[tim21391]

it looked to be all in tact but im not sure i can check when i go back home this weekend

[Jacfourteen]

Originally Posted by GASoline71

What condition is the harmonic balancer in? The outer inertia ring could have spun on the hub... which will not let you time the engine right.

Gary

I was thinking the same thing.

[tim21391]

is there anything else to check if its not the timing?

[tim21391]

im thinking the coil might of went bad

[GASoline71]

Well the coil really isn't going to affect the timimg... if the rubber between the inertia ring and the hub on your balancer is shot... it will let that ring spin ever so slightly. Over time it will leave the timing marks way off...

Gary

[tim21391]

ya i know what ya mean but if it was timed ok before i messed with it could it be the coil not letting me go over 70 if in town driving was ok

[Dingfodgy]

Originally Posted by tim21391

i got a 402.. and i heard it was suppose to be at 8 btdc and so we hooked a light on it since i couldnt go past 70 on highway.. it ran swell in town.. never shook or nothing good acceleration.. everything good in town but sucked on highway.. and the light said it was like at 26 or so.. we backed it down to 12 and ran like crap no acceleration nothing.. had it floored and couldnt spin the wheels at stop.. then we took it to 18 and seemed better but it shook like crazy.. then took it to like 22 and it was a little better.. now that seems way to high in my opinion is it? it has to be a fuel problem i have.. like the 4 barrels arnt opening up.. fuel pump is new fuel filters are new.. and im sure the lines arnt plugged up.. what could be the problem? any of your guys opinions are wanted/appreciated

OK. Before you start pullin' your hair out- did you disconnet the vacuum advance hoze to the dizzy before you put a light on it? How are your points? Is the dwell set correctly? Check all that again. I'm not familiar with BBC but on my SBC, I set the initial timing @ 14 BTDC and total timing to 34 @ 3000 RPM. She runs like a champ!

[Leviticus]

Dingfodgy beat me to it, be sure you pull the vac advance line while timing it. And I would let the plugs talk to you a little. Pull them and remember which cylinders they came from and read them.

And I set my 350 at around 11-12 BTDC initial timing, its all personal preference but I would keep it between 8-14 BTDC, anything over 16 and you might be pushing it.

Pull those plugs, check to make sure you don't have any bad plug wires arcing to the manifold etc.

Good luck!

[cdowns]

if you have points have you cleaned and set them? have you cleaned your plugs and set gap? do you have lazymans rubber fuel line from the pump to carb they can collapse. have you checked your gas cap? a big wooshing noise from the cap on removal means you have a tank venting problem. are you sure the timing mark pointer is the right one for that balancer? finding TDC with a piston stop will tell you if the balancer and pointer match

[Shyguy]

What every one said, but make sure you plug the hose you take off the vacuum advance.

Danny

[Indyuke]

If everything looks in place and you can't find a problem, you can always rough time it to within a few degrees of where it NEEDS to be with a vacuum guage. Time it to the best vacuum at the idle rpm you want. Every motor, based on how worn out it is, has a spot where volumetric efficiency is the greatest based on when the ignition event takes place in relation to when the valves are opening and closing, compression ratio, etc.

You can tweek the timing, valve lash, idle mixture for best efficiency at idle, which except for the idle mixture setting should result in good efficiency at all power settings. That's assuming the engine has the stock ignition and fuel systems.

Ironically, on a fresh engine, doing this will most likely result in you arriving at the recommended settings set down in the manual. Woohoo!

[Newtz67]

Originally Posted by Leviticus

Dingfodgy beat me to it, be sure you pull the vac advance line while timing it. And I would let the plugs talk to you a little. Pull them and remember which cylinders they came from and read them.

And I set my 350 at around 11-12 BTDC initial timing, its all personal preference but I would keep it between 8-14 BTDC, anything over 16 and you might be pushing it.

Pull those plugs, check to make sure you don't have any bad plug wires arcing to the manifold etc.

Good luck!

What he said.

[tim21391]

im running hei and i pulled the vacuum advance off with it plugged and i still had bizzare readings.. im thinking it could be the thing where they state the balancer spun on the hub or something in that nature.. ill go under the hood this weekend and check things out.. i have a locking gas cap and havent paid attention when i fill up so ill check that next

[Jacfourteen]

Like stated above to find out if the balencer is good, pull the #1 plug then turn the engine over (by hand, in the normal direction) until the plug hole blows air out, keep turning until it stops blowing then put something like a screwdriver or something down the hole (put tape on so you don't scratch the top of the piston) and turn the crank back and forth until the screwdriver is at the highest point it will go, This is top dead center. Now look at the mark on the balancer and see if it is lined up with the pointer, if not get a white paint pen or some finger nail polish and mark a line that lines up with the pointer. Then check the timing again and get a new balencer soon. Hope this helps, I know there are more accurate ways to do this but this will get you within a couple of degrees with out having to buy any tools.

[rbagley]

@cdowns- Hypothetically speaking, if a person did have a wooshing sound when they removed the gas cap, how would they go about fixing it. Hypothetically.

[El Jay]

They could hypothetically put on a vented gas cap; hypothetically speaking.

[LONGHAIR]

Originally Posted by Jacfourteen

put something like a screwdriver or something down the hole (put tape on so you don't scratch the top of the piston) and turn the crank back and forth until the screwdriver is at the highest point it will go, This is top dead center.

That is not really TDC, it could be off by several degrees (either way)
There is a "lag" at the top of the rotation where the piston does not move. This is when the lower part of the rod is crossing over-center.

It may be able to show you that the outer ring has moved, if the move is significant enough. But I wouldn't trust it enough to mark it and use that mark for timing.
A balancer that has moved needs to be replaced anyway. It will just get worse and the potential for disaster is there.

[Jacfourteen]

Originally Posted by LONGHAIR

That is not really TDC, it could be off by several degrees (either way)
There is a "lag" at the top of the rotation where the piston does not move. This is when the lower part of the rod is crossing over-center.

It may be able to show you that the outer ring has moved, if the move is significant enough. But I wouldn't trust it enough to mark it and use that mark for timing.
A balancer that has moved needs to be replaced anyway. It will just get worse and the potential for disaster is there.

Yeah that's true, if you go back and forth a couple times you can get an idea of where the center of the "lag" area is. A degree wheel and piston stop is much better, but I was just giving him the shadetree mechanic version so he could find out if it was causing the problem. And I agree if it is out of line then it needs a new balancer that's why I said change it soon if it has moved, I just said to remark it so he could check his timing and do more dianosis in the meantime before he changes the balancer.

[tim21391]

thanks guys apprecitate it.. thinkin of goin to work on it tomorrow