Engine 90 gt timing at idle

Bburns25 said:

408w vic Jr. Heads and intake, speed demon 750, cam specs not sure of. I have finally got the car fired up. TDC on balancer shows 36* that's with piston stop and on compression stroke and rotor button is between 1 and 3. I cranked the car it runs good but timing light shows 62* BTDC at idle. And another thing is the distributor has stake Mark and they are lined up. If I RIP on the throttle it revs nice and clean after tuning the carb but if you hold the throttle say 1500 to 2k rpm it feels like a dead miss. Any suggestions?

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jrichker said:

Harmonic balancer check to see if it has spun or moved the timing marks

Before you waste time and money replacing a balancer, make sure that it needs replacing....
Spend 30 minutes and $7.50 to save you $60. You can't get a better deal than that anywhere...

Prep step:
Joe R’s note: Timing tape (strip of adhesive backed paper with timing marks printed on it) is available from Summit Racing https://www.summitracing.com/parts/sum-163594/overview/ use it instead of a degree wheel. The cost is about $5 plus shipping

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Clean the balancer rim up real good with acetone or paint thinner. Try not to get the acetone or paint thinner on anything but the balancer rim; it could damage the rubber mounting ring. Some cotton balls or a wadded up ball of paper towel may be the best application tools. Let whatever solvent you used dry completely and then apply the timing tape.
Line the TDC mark up on the tape with the TDC make on the balancer; make sure it is stuck down good.


TDC location process courtesy of Michael Yount
If you're trying to find ACTUAL TDC for cam installation/degreeing, follow the steps below:

Positive stop – obtain an old spark plug for the Ford engine – most of us have at least one laying around. Put it in your vice, and with a tool of destruction you deem appropriate – cut off the ground tip and bust up the ceramic around the center electrode. Keep pounding to get the ceramic and center electrode removed so you’ve got a good ¾” or so of hollow space inside what used to be the ‘business’ end of the spark plug. If you happen to break the ceramic on the other end of the spark plug, don’t worry about it. Once you’ve got a nice hollow space in the tip of the plug, take a 5/16” tap, and cut threads inside that end of the plug. I found that diameter to go right in without any drilling required. Once you’ve cut threads, screw in a 5/16" bolt about 1.5” to 2” long. Then take your hack saw and cut the head off the bolt. Wouldn’t hurt to take your file/grinder and dress up the freshly cut surface so no sharp edges or shrapnel enter the combustion chamber. Also clean up the threads on the plug so that it easily screws into and out of the plug hole.

Determining TDC – remove the passenger side valve cover. Rotate the engine (socket on crank bolt) until the #1 piston is down the cylinder on the intake stroke. Unscrew the spark plug in that cylinder, and replace it with the positive stop you just made. Only screw the positive stop in hand tight. Install your cam degree wheel and pointer (no easy task in some cases as harmonic balancer and other accessories will have to be removed). You may want to remove all spark plugs at this point because it will make it easier to smoothly turn the engine over in small increments. GENTLY rotate the engine clockwise until the piston comes to rest against the stop. Note the degree wheel reading. GENTLY rotate the engine in the opposite direction until the piston comes to rest against the stop. Note the degree wheel reading. TDC is exactly half way between these readings. Calculate where that position is on the degree wheel, remove the piston stop from the cylinder, and rotate the engine to TDC as you calculated it. You are now at true TDC.

After you have done that, make sure the TDC mark on the balancer now lines up with the timing pointer. If it doesn't line up then replace the balancer.
If it does line up, you need to look elsewhere for your problem.

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