sbc runs better retarded than advanced?

Hi guys and gals. I have a question that i think i know the answer to, but just want to make sure. The Sbc im running in the nash (.030 over 350 ) seems like it doesnt want to run as well if i advance the timing - ie turn the distributor counter clockwise. The spark is delivered via a mallory dual point. It seems that the more i retard the timing (clockwise) even to the point of it starting to sputter, it runs well. I mean if i put my foot to it in first gear, it'll spin em loose while rolling, but the more advanced i go, the kick fades till it runs like a dog.

Am i getting the advance/retard wrong?

Iv tried setting it with a vaccum gauge, and it runs worse

Im thinkin that the distributor may have so much advance its advancing straight to the sweet spot in the timing, and running retarded prior to that.


Any advice?

I dont have a timing tag on the motor, so im not quite sure where im at for inital.

 

Ive had motors that seemed to run better (power and cooling wise) with retarded timing as well, couldnt always figure out why.. How much compression are you running? Octane?

 

i suggest get your timing marks figured out and properly marked first before you do anything

 

Do you have and 8" balancer? If so is it 3" thick or is it the 1 1/2"?

 

After market timing tags are available from lots of places from cheap steel to polished show pieces. Buy one, mount it then run the #1 piston to top dead center and mark the balancer to align with "0" on the pointer. Now make sure the distributor is in correctly and the rotor is pointing to #1 plug wire. Set the timing with a good light and see if you still have a problem. If the problem still exists have the distributor checked out on a machine.

There is usually a reason that distributors show up by the box full at swap meets. It's hard to beat a HEI unit for all around street use.

 

does it have a vaccumn advance? if so, where do you have it hooked to?

-danny

 

Does your distributor have a vacume advance? If it does what do you have it plumbed to. Is the advance locked in the distributor? What dwell are you running?
Get a timing pointer on the motor, setting the timing by ear is for lames.
Like someone said, it's hard to beat a HEI. I know they're ugly but aftermarket Mallory or Accel are cheap and already have a performance curve in them from the factory. Plus they come with extra springs to let you tune them to your engine.
You can throw all the high dollar parts you want at your motor, but if you're not timing it right you're just shooting yourself in the foot. Plus you can damage your motor.

 

A small block Chevy likes 16-18 degrees initial timing and 34-38 in by 3000 or so. Timing marks, pointers, and lights are all part of getting all you can out of your motor.

 

YES! Unless you want to always want to be working in the dark and do all your tuning by ear.

YES! But with the addition of making sure the #1 cylinder is at TDC on THE COMPRESSION STROKE, not the exhaust stroke. You may need a dial indicator or a piston stop and a degree wheel to do this accurately.

More info on the distributor would be helpful. Does it have a vacuum advance, does it work and how much advance does it provide? Is it connected to ported or manifold vacuum? Does it have a centrifugal advance, does it work and how much advance does it provide? At what RPM does it begin to advance?

All these things contribute to the total timing advance (static timing plus centrifugal advance plus vacuum advance). Your engine may want a total of 36 degrees at cruising speeds but there may be times when it's trying to run with considerably more. Or the total timing may be OK but it could be too advanced at idle or lower engine speeds.

Once all this is sorted out, then you can experiment with the vacuum gauge (which I highly recommend) and tuning by ear.

 

In my opinion most people who run s.b.c. are retarded.

 

This has been gone over many times,there are at least 3 different balancers and timing covers.

 

Tell us how you really feel Rusty

 

1st You need to have a good start point. The Harmonic needs to be checked for correct markings. If you run a disributor that was not engineered to the car. You will need to check it for overall advance and retard capibility. All engines need a exact amount of timing at a specific RPM to run properly. You would be way ahead to have it set up by someone who can curve the distributor correctly. $200 at the most. Or you can always wonder what it really could run like and guess. UGOTPK

 

Not as retarded as people who don't like small block Chevy's and click on a small block Chevy thread. Especially when it's in the title. Thanks for the help dork.

 

Some of us are very advanced.

 

haha nice.

 

Somebody mantioned about the different timing covers and different balancers. You will never know where your at until you accurately find TDC and make sure it corresponds to 0 on the timing tab. After that it's just a matter of knowing how much advance you have in the distributer (easy enough to do if you have a timing tape on the balancer), setting the correct initial according to the degrees in the distributer and referenceing the vacuum advance if you run one. BTW, a street driven car will yield a couple of miles per gallon better fuel economy if a vacuum advance is incorporated.

Frank

 

As a couple of the guys said, it is hard to get a Mallory dual point adjusted correctly without having someone set it up in a distributor machine. And if you bought it used, there is a good chance that it is some circle track racers throwaway.

For now I'd be heading down to the local parts house that has a chrome goodie rack and picking up a timing tab (get the correct one for the diameter of the dampener). Install it, bring the engine up on #1 compression and make sure that it is at tdc and either verify the mark or put your own mark on the dampener to match 0 on the tab.

A lot of 350's and probably other small blocks in the late 70's and later have the stock timing mark straight up and you check the timing by sighting down behind the waterpump (long). I have that on my ot truck and it is a pain in the butt to check the timing.

If you have a stock distributor in good shape (point or hei) I think I would pull the Mallory and swap it in and get the engine dialed in and running right and make sure that the issue is with or not with the Mallory. Sometimes the cost of having "cool" parts isn't just the price you paid for said part.

 

I think if you go back and read that individual's posts about half of them are similar posts. Little or no help on a situation and always ready to bad mouth certain things. That's after reading about five pages of posts on his profile.

He does claim to cook good hot dogs though.

There seems to be a collective group on here who's main purpose for being here appears to be spout off the wall comments on other peoples threads. One of those " I have to make my anti sbc comment so I can be known as one of the "cool" guys.

 

Wow, this thread really fell off a cliff in a hurry...

 

Sorry about that Zookeeper, but when we are trying to help a guy get his rig squared away and the off the same old off the wall crap gets thrown out it gets tiresome.

 

If someone knocks on your door and identifies himself as a Mr. William T. Jenkins, please open the door and welcome him into your home with open arms.

 

no surprise here because FOREST GUMP was retarded and he ran just fine!

 

You need to find TRUE tdc(top dead center) on your engine with whatever timing tab you use. It is easy to do. Buy or make a screw in type piston stop. Remove all spark plugs to make engine easier to turn by hand and also to have a better feel for hitting the piston stop. Now bump the engine around with the starter with a finger in #1 untill you begin to feel compression. That means #1 is comming up on the compression stroke. Your existing timing mark should be comming up, but not past your timing tab. (Unless it is way, way off) If you go past , go around again and stop before you go past the tab. Now install your screw in piston stop and carefully continue rotating the engine by hand untill the piston hits the stop firmly, but gently. Now make a mark on your balancer corrosponding to the 0 mark on you timing tab or pointer. Now rotate the engine counter clockwise by hand untill you contact the piston stop, again mark your balancer at the 0 mark on your balancer. True TDC will be 1/2 way between the two marks on your balancer. If you are lucky the actual timing mark on the balancer will line up with 0 on your timning tab. If not, you can use the new mark on your balancer for TDC , or you can move the timing tab around, or get one with an adjustable pointer. Now you know that tdc is actually tdc. Different balancers and timing indicators can be way off, or the outter ring on the balancer can turn and throw the alignment off. This procedeure will let you know for sure where your timing is set. After all this if the engine still wants to run retarded, I would suspect cam timing is off.

 

It's probably the GAS being used; it ain't what it used to be. Butch/56sedandelivery.

 

William T. Jenkins I can go to him I don't work so I have the time. Give me his address

 

I have to disagree your one statement "THE COMPRESSION STROKE". The relationship of the timing mark and TDC of the piston has nothing to do with what stroke the otto cycle is on. You do have to know what stroke the cycle is on for setting the distributor in, but not the timing mark.

lg
no neat sig line

 

To complete the four cycles of a four cycle engine requires two revolutions of the crankshaft. Intake cycle (piston moving downward), compression cycle (piston moving upward), ignition or power cycle (piston moving downward) and exhaust cycle (piston moving upward).

The camshaft and distributor rotate at half the speed of the crankshaft. For every two revolutions of the crank, the cam and distributor make one revolution. So for each revolution of the cam and distributor the crank turns twice and the pistons reach TDC twice, once for the compression stroke and again for the exhaust stroke.

Here's a link that clearly shows the process.

Four Cycle Engine Animation

If you set the timing mark on the damper at TDC on the exhaust stroke and install the distributor to the manufactures specs you'll end up with the plug firing at the end of the exhaust stroke instead of the compression stroke. And this obviously isn't going to get the engine running. You can randomly reset the distributor and rephase the plug wires in the cap and maybe get it running, but it's not pretty and it's usually worth putting things back to OEM specs as much as possible.

 

The motor fires on each cylinder on the second time it reaches top dead center or the second revolution of the crank in theroy. Advancing the timing is just what it says.. in other words the firing is just before the piston reaches top dead center on the compression stroke. With naturally asparated ( carb) motors this allows the fuel burn process to start early to give more time to burn all the fuel applied. Normally excessively retarded timing is less efficient and produces less power because the fuel does not have as much time to burn.