How to Check TOP DEAD CENTER???

quick89gt · 01-17-2001, 01:39 PM

Ok, here is the deal. My friend and I replaced the TFI module on his '90 5.0 notchback, and we forgot to mark where the rotor was in relationsihp to the dist. cap. However, we did mark where the distributor was in relationship to the block. It wanted to fire, but I assumed was firing on the wrong cylinders when we tried to start it, b/c the rotor had moved when we pulled the distributor up. I told him the best way to check T.D.C. so we could reset the distributor was to put my thumb over the spark plug hole, have him crank the engine over by hand....when it blows my finger out, it is on the compression stroke where we want it. then, take a screwdriver and feel the piston while he cranks by hand...and feel when the piston is all the way at the top....then, put the distributor back in, and put the roto on cylinder number 1. Does anyone else have any other ways to check T.D.C. that are better???? josh

------------------
*************************
'89 GT, T-5,
Bored .030 Over, GT-40P heads, MAC 1 5/8" headers, MAC Off-Road H-Pipe, 2 1/2" Flowmasters, Edelbrock 65mm T.B., Trick Flow Intakes, Crane 2031 cam, 1.7 Roller Rockers, Keith Black hyp. flat top Pistons, Screamin' Deamon Coil, Champion Plugs, March Underdrive Pulleys, 255lph Fuel Pump, SVO Motorsport Clutch, Adjustable Fuel Pressure Regulator, Formula GP Suspension, MAC Upper & Lower Control Arms, FMS 3.73 Gears.
*************************

Tom351 · 01-17-2001, 02:21 PM

The way you used will work, but the must accurate way would be using a piston stop. You can find a bolt with the same threads as your spark plugs, and thread it into the combustion chamber (while the piston is down) so that about 1"-1.5" is in the chamber. BY HAND (obviously) by hand, turn the engine over until the bolt stops the piston. Mark the balancer at this point. Turn the engine by hand backwards now so that the piston goes down, then back up and is stopped by the bolt again. Mark this position on the balancer. Remove the bolt and turn the engine so you can see both marks. Measure the distance between the two marks. Exactly halfway between the marks will be TDC.

This work because you are marking a certain degrees before TDC, then marking the same degrees after TDC, so TDC is right in the middle.

------------------
67 Fastback - Arctic White Pearl paint
351W ,Trick Flow Aluminum Heads, Edelbrock TorkerII, Comp. Cam, Performance Automatic C-4 Trans, 3.55 gears, Front Disc Brakes, 1-1/8" Fr. 3/4" rear sway bars.

My 351W Fastback

over 40 five oh driver · 01-17-2001, 02:59 PM

Tom351 has the best solution if you have the TDC tool. If not, simply rotate engine by hand to get the balancer and timing mark at TDC or zero, reinstall distributor using the marks you did make on what I assume was distributor body to the block where it slides in? Make sure the rotor is indexed at the #1 position and mark the inner part of the distributor along with where the rotor points to on the upper intake. If it fails to start, you were off a full turn on the crank/balancer marks for TDC. Pull the cap and rotate engine by hand to get the balancer TDC mark and previous marks lined back up as before. Now, pull distributor out far enough to rotate engine by hand to get the crank/balancer around a full 360 degrees and place it back on TDC mark. Put distributor back in lining up the marks on the rotor to the #1 position again along with relative position marks on the inner part of distributor and upper intake, and, using the marks you had already made on the distributor to block. Should fire up as the crank will turn the balancer 720 degrees while the distributor only turns a full 360. If you have a TDC tool, go with Tom351 method as it will get you right on it. Good luck...

------------------
*92' GT, Keith Craft Racing 306 (10.25:1 CR), PRO-M 80mm MAF,65MM TB, Edelbrock U/L intake,
TFS-TW heads milled .056" (52cc chambers), CompCams XE274HR (.555/.565" lift w/1.6 rockers), A-351 adjustable roller rockers, 30# injectors,
Kirban FPR w/external pump, FRPP ceramic coated headers, Bassani X-pipe w/cats, Bassani cat back, Centerforce DF clutch/T.O. bearing...MSD 6AL w/MSD distributor, Steeda Tri axe, aluminum D/S, 3.73's, w/Factory Five U/L control arms. Lakewood 50/50 shocks. Stee

[This message has been edited by over 40 five oh driver (edited 01-17-2001).]

Tom351 · 01-17-2001, 04:26 PM

over 40 had the obvious solution (look at the balancer) I assumed that you had no timing marks on it. His answer would be my first suggestion if your balancer has marks on it (I can't think of why it would not). If you dont have marks, you can use my idea with no special tools, just use a bolt of the right size for the piston stop.

------------------
67 Fastback - Arctic White Pearl paint
351W ,Trick Flow Aluminum Heads, Edelbrock TorkerII, Comp. Cam, Performance Automatic C-4 Trans, 3.55 gears, Front Disc Brakes, 1-1/8" Fr. 3/4" rear sway bars.

My 351W Fastback

quick89gt · 01-17-2001, 09:30 PM

i'm sure his has marks on it. i know he had it advanced to 15 degrees b.t.d.c. i assume if you put his balancer on 0, and align it with the metal bracket coming off the motor that it will be at t.d.c. also, do you look at the edge of the metal bracket, or through the circle on the end of it to determine t.d.c.???

------------------
*************************
'89 GT, T-5,
Bored .030 Over, GT-40P heads, MAC 1 5/8" headers, MAC Off-Road H-Pipe, 2 1/2" Flowmasters, Edelbrock 65mm T.B., Trick Flow Intakes, Crane 2031 cam, 1.7 Roller Rockers, Keith Black hyp. flat top Pistons, Screamin' Deamon Coil, Champion Plugs, March Underdrive Pulleys, 255lph Fuel Pump, SVO Motorsport Clutch, Adjustable Fuel Pressure Regulator, Formula GP Suspension, MAC Upper & Lower Control Arms, FMS 3.73 Gears.
*************************

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01-17-2001, 01:39 PM	#1
quick89gt Registered Member Join Date: Apr 2000 Location: O'Fallon, IL Posts: 243	How to Check TOP DEAD CENTER??? Ok, here is the deal. My friend and I replaced the TFI module on his '90 5.0 notchback, and we forgot to mark where the rotor was in relationsihp to the dist. cap. However, we did mark where the distributor was in relationship to the block. It wanted to fire, but I assumed was firing on the wrong cylinders when we tried to start it, b/c the rotor had moved when we pulled the distributor up. I told him the best way to check T.D.C. so we could reset the distributor was to put my thumb over the spark plug hole, have him crank the engine over by hand....when it blows my finger out, it is on the compression stroke where we want it. then, take a screwdriver and feel the piston while he cranks by hand...and feel when the piston is all the way at the top....then, put the distributor back in, and put the roto on cylinder number 1. Does anyone else have any other ways to check T.D.C. that are better???? josh ------------------ *********************** '89 GT, T-5, Bored .030 Over, GT-40P heads, MAC 1 5/8" headers, MAC Off-Road H-Pipe, 2 1/2" Flowmasters, Edelbrock 65mm T.B., Trick Flow Intakes, Crane 2031 cam, 1.7 Roller Rockers, Keith Black hyp. flat top Pistons, Screamin' Deamon Coil, Champion Plugs, March Underdrive Pulleys, 255lph Fuel Pump, SVO Motorsport Clutch, Adjustable Fuel Pressure Regulator, Formula GP Suspension, MAC Upper & Lower Control Arms, FMS 3.73 Gears. ***********************

01-17-2001, 02:21 PM	#2
Tom351 Registered Member Join Date: Oct 2000 Location: Atlanta,GA,USA Posts: 278	The way you used will work, but the must accurate way would be using a piston stop. You can find a bolt with the same threads as your spark plugs, and thread it into the combustion chamber (while the piston is down) so that about 1"-1.5" is in the chamber. BY HAND (obviously) by hand, turn the engine over until the bolt stops the piston. Mark the balancer at this point. Turn the engine by hand backwards now so that the piston goes down, then back up and is stopped by the bolt again. Mark this position on the balancer. Remove the bolt and turn the engine so you can see both marks. Measure the distance between the two marks. Exactly halfway between the marks will be TDC. This work because you are marking a certain degrees before TDC, then marking the same degrees after TDC, so TDC is right in the middle. ------------------ 67 Fastback - Arctic White Pearl paint 351W ,Trick Flow Aluminum Heads, Edelbrock TorkerII, Comp. Cam, Performance Automatic C-4 Trans, 3.55 gears, Front Disc Brakes, 1-1/8" Fr. 3/4" rear sway bars. My 351W Fastback

01-17-2001, 02:59 PM	#3
over 40 five oh driver Registered Member Join Date: Sep 1998 Location: Oklahoma City Posts: 278	Tom351 has the best solution if you have the TDC tool. If not, simply rotate engine by hand to get the balancer and timing mark at TDC or zero, reinstall distributor using the marks you did make on what I assume was distributor body to the block where it slides in? Make sure the rotor is indexed at the #1 position and mark the inner part of the distributor along with where the rotor points to on the upper intake. If it fails to start, you were off a full turn on the crank/balancer marks for TDC. Pull the cap and rotate engine by hand to get the balancer TDC mark and previous marks lined back up as before. Now, pull distributor out far enough to rotate engine by hand to get the crank/balancer around a full 360 degrees and place it back on TDC mark. Put distributor back in lining up the marks on the rotor to the #1 position again along with relative position marks on the inner part of distributor and upper intake, and, using the marks you had already made on the distributor to block. Should fire up as the crank will turn the balancer 720 degrees while the distributor only turns a full 360. If you have a TDC tool, go with Tom351 method as it will get you right on it. Good luck... ------------------ *92' GT, Keith Craft Racing 306 (10.25:1 CR), PRO-M 80mm MAF,65MM TB, Edelbrock U/L intake, TFS-TW heads milled .056" (52cc chambers), CompCams XE274HR (.555/.565" lift w/1.6 rockers), A-351 adjustable roller rockers, 30# injectors, Kirban FPR w/external pump, FRPP ceramic coated headers, Bassani X-pipe w/cats, Bassani cat back, Centerforce DF clutch/T.O. bearing...MSD 6AL w/MSD distributor, Steeda Tri axe, aluminum D/S, 3.73's, w/Factory Five U/L control arms. Lakewood 50/50 shocks. Stee [This message has been edited by over 40 five oh driver (edited 01-17-2001).]

01-17-2001, 04:26 PM	#4
Tom351 Registered Member Join Date: Oct 2000 Location: Atlanta,GA,USA Posts: 278	over 40 had the obvious solution (look at the balancer) I assumed that you had no timing marks on it. His answer would be my first suggestion if your balancer has marks on it (I can't think of why it would not). If you dont have marks, you can use my idea with no special tools, just use a bolt of the right size for the piston stop. ------------------ 67 Fastback - Arctic White Pearl paint 351W ,Trick Flow Aluminum Heads, Edelbrock TorkerII, Comp. Cam, Performance Automatic C-4 Trans, 3.55 gears, Front Disc Brakes, 1-1/8" Fr. 3/4" rear sway bars. My 351W Fastback

01-17-2001, 09:30 PM	#5
quick89gt Registered Member Join Date: Apr 2000 Location: O'Fallon, IL Posts: 243	i'm sure his has marks on it. i know he had it advanced to 15 degrees b.t.d.c. i assume if you put his balancer on 0, and align it with the metal bracket coming off the motor that it will be at t.d.c. also, do you look at the edge of the metal bracket, or through the circle on the end of it to determine t.d.c.??? ------------------ *********************** '89 GT, T-5, Bored .030 Over, GT-40P heads, MAC 1 5/8" headers, MAC Off-Road H-Pipe, 2 1/2" Flowmasters, Edelbrock 65mm T.B., Trick Flow Intakes, Crane 2031 cam, 1.7 Roller Rockers, Keith Black hyp. flat top Pistons, Screamin' Deamon Coil, Champion Plugs, March Underdrive Pulleys, 255lph Fuel Pump, SVO Motorsport Clutch, Adjustable Fuel Pressure Regulator, Formula GP Suspension, MAC Upper & Lower Control Arms, FMS 3.73 Gears. ***********************