Chevy 5.7L Harmonic Balancer quandary

[Panoguy]

Hi: Just fired-up my Mercruiser (Chevy) shortblock rebuild today, it fired right up! Once I had it warmed-up, I tried to set timing, but the timing mark was right off of the scale - at about 10-o-clock, instead of the normal 2-o-clock position by the scale. Rotating the distributor to where I could get the mark anywhere near the timing scale results in sputtering/stalling.

I decided to look at the old harmonic balancer, and discovered when lining-up the keyways, that the timing mark on the new balancer isn't in the same position as the old rusty & deteriorating balancer.. it looks like it's off by the amount I see when hitting it with the timing light. My engine rotates clockwise looking from the front, counter-clockwise when looking at the flywheel - this is normal rotation, right?

It feels to me like I received a balancer marked for a reverse rotation engine. I'm thinking about putting a mark on the new balancer where it needs to be, & calling it a day... I really don't want to pull/replace it. Is this a terrible idea?

Thanks in-advance!

 

[alldodge]

My engine rotates clockwise looking from the front, counter-clockwise when looking at the flywheel - this is normal rotation, right?

This is standard rotation, which is called left hand

My guess is you just bought the wrong balancer. Which one did you buy and get? Have a part number?

 

[wellcraft-classic210]

I had that issue many years ago on a build with a variety of parts from various years. I set the timing by ear advancing it until the valves started to ping and than backing it off to where it ran well. Once I had that dial in I painted a new mark.


Just a thought if you cannot find matching parts

 

[Panoguy]

Thanks for the replies!

I purchased a Dorman594-009 Balancer from Amazon - comes-up as compatible with Chevy 5.7L.

Another question: I guess I'm supposed to put the engine in "base timing mode", by shorting a purple/white to ground... problem is, I can't find a purple/white wire anywhere.

This is a rebuild from an engine that I picked-up for the heads, starter, alternator, tin... etc, so I don't have past reference to go by. Ignition is Thunderbolt IV, module is mounted on a trapezoidal metal plate, which in-turn is mounted on the exhaust header.

Thoughts?

 

[Alumarine]

Can you just grind a notch in the correct place on the new one?

 

[Scott Danforth]

I wouldnt buy dorman parts

 

[Panoguy]

Can you just grind a notch in the correct place on the new one?

This is probably what I'm going to do!

 

[Bt Doctur]

Do it the correct way. Get a piston stop tool , locate TDC and match the balancer mark with the timing tab.. Makes no difference if std or rev, the TDC timing mark is in the same place.

 

[Panoguy]

About this Base Timing Mode wire (Purple/White) that I can't find on my engine... From what I've read, that is a thunderbolt V thing, not a Thunderbolt IV thing, can anyone verify?

Ordered Piston TDC tool & Labels Bt Doctur - thanks for the suggestion!

 

[Bt Doctur]

if the module is mounted on the port riser, that a TB IV so point and shoot. If mounted at the dist, thats a TB V

 

[Scott Danforth]

wouldnt a GM balancer from a GM dealer be less expensive and less headache than the chinese dorman balancer and a bunch of stuff to find that the balancer is simply made wrong

at least get a dayco powerbond balancer (available at oreilies, advanced auto, napa, etc)

 

[alldodge]

Ignition is Thunderbolt IV

As Bt mentioned the TB-IV is point and shout, no base timing mode

Also as Bt mentioned pick up a stop bolt, rotate the crank until FWD/REV then mark the spot. Can also get some timing tape to set

 

[Panoguy]

wouldnt a GM balancer from a GM dealer be less expensive and less headache than the chinese dorman balancer and a bunch of stuff to find that the balancer is simply made wrong

at least get a dayco powerbond balancer (available at oreilies, advanced auto, napa, etc)

I guess I didn't know that till now - Live & learn, right Scott??

 

[Bt Doctur]

For any other builders out there one of the first things you do is:
TRUST NO ONE, NOT EVEN YOU
correctly index the cam to the crank
locate TDC and verify the timing line on the balancer is 0 on the timing tab
use a degree wheel if installing a new camshaft

 

[Scott Danforth]

For any other builders out there one of the first things you do is:
TRUST NO ONE, NOT EVEN YOU
correctly index the cam to the crank
locate TDC and verify the timing line on the balancer is 0 on the timing tab
use a degree wheel if installing a new camshaft

Exactly. in addition, dont buy cheep off-shore sourced parts