The piston is at TDC twice during two of its four strokes....#1 piston. On one such stroke, the crank key is on the bottom of crank. During second such stroke, the crank key is on top of the crank. I can’t remember which key position indicates tdc of power stroke ! Anyone refresh my memory. This engine is being assembled stage.
The crank and its key will be in the same position with #1 piston at TDC whether on the firing or exhausting stroke. Actual location depends on what engine. One example: At TDC, a small block Ford's key is not vertical, which seems kind of odd.
I’m working a ford B engine block. I want to establish #1 TDC , firing/power stroke, then match up cam/crank gear marks. I guess I’m over thing this. I’ll just match gear marks and check for TDC thereafter. I’m remembering something like....most accurate to check TDC and then indicate on crank pulley....when Head is off, that is too split difference after piston rotated BOTH ways ?
It takes two crankshaft rotations for all cylinders to complete their 4 cycles and for the cam to make one revolution. Just line up the timing marks & cam will be timed to the crank. Sent from my iPhone using H.A.M.B.
If you want to degree the cam you will need to find Exact 0 deg TDC with a piston stop & degree wheel Sent from my iPhone using H.A.M.B.
The piston doesn’t know if it’s on power or exhaust stroke! The cam tells it which one it’s on. As long as the timing marks are right.... you are right. Bones
Just understood what you were talking about. Make a positive stop and bolt it to the block so that the piston positively stops a little before it gets to the top. Exactly where is not important. Rotate the piston to this stop. Mark your flywheel/ damper, or where ever you time your engine. Reverse the rotation till the piston stops again. Make a mark. Exactly 1/2 between the marks is top dead center. Sorry Triumph, this was supposed to be for” Hardtimesaintit”. Bones
This is something I recommend to peeps who pick up a "new" old piece of iron, before they start troubleshooting or throwing parts at it or especially ignitiontiming etc. make sure the damper is right! Saves lots of time and aggravation.
An easy tip I learned some time ago- if you remove the spark plug on #1 and rotate the engine with your finger over the hole- if you are in the power stroke, the exhaust valve will be closed and you will feel a major pressure build against your finger. If no pressure, then you are on the exhaust stroke. I rotatw until i feel the pressure build, then keep turning it a little more until the balancer mark lines up with the timing pointer.
Exactly how I did it when I worked on piston-popper aircraft performing compression checks. Sent from my iPhone using The H.A.M.B. mobile app
I also have used this procedure, for 60 yrs, on any engine that has the HEAD installed. As stated, this ‘32 B (style) block is in the assembly stage, with pistons in. At this stage it is time to get a pretty accurate initial timing setup. I’ve been in ‘for repairs’ for months now. Just getting back into action is a step forward. Meds don’t help the memory, eh. I appreciate you guys taking time to help ! ALL of you.
Not to hijack but I'm having difficulty with TDC on Ford 351. Had to pull dist to replace intake mainifold gasket. My "helper" started to screw around with the crank pulley after I pulled the dist. Almost brained him. Anyway did the thumb over the hole routine but the engine doesn't run well and the timing marks are off. So... can I get TDC by pulling all plugs and removing valve cover then cranking engine by hand until the #1 exhaust valve is closed and the intake is just, almost, darn near closed?
NO! You want both valves completely closed at TDC for ignition timing/distributor installation set -up purposes. Intake valve will have been closed at that point for something like 60° of crank rotation, and exhaust valve is at least 50° away from starting to open. When the Exhaust valve is just closing, and the Intake valve is just starting to open you are at TDC but it is TDC overlap for cylinder #1 (exhaust was just pushed out, intake charge is now going to be drawn in as piston goes down).... and not TDC firing #1 plug.
Everyone should build one of these before they reach puberty or senility. Whith the piston on the bottom and the exhaust valve closing - this is the beginning of the compression stroke. Once the position reaches the very top of this stroke with both valves closed that is WHEN you'll find TDC.
Well, if it runs as good as it looks it is going to be a screamer. Nice Sent from my XT1254 using The H.A.M.B. mobile app
Rick, Just picked up one of Yapp's small crank pulleys. The timing mark for TDC is inline with the crank notch. So I would think you want the notch up.
How are you my friend ! Good to hear from you and thanks for this input. It answers my original inquiry ! I have one of those pulleys, old without mark, so I make marks when assembling via #1 piston , as discussed above. Although this assembly is balanced out, I’m going to run a balancer with pulley, and will mark it also. Just getting over cancer bs, and haven’t had time/energy to work this project. But that is changing ! Last several days too much wind, smoke and ash to breathe, let alone work. Ah, life is good though. Things can be worse ! Be safe.
Your right , if done correctly. The more correctly, the more $$$$$, to do so... make a screamer. Short blk form now with stock 200.5 cubes, but capable of handling....LOTS of hp, if done correctly, I. E. - full OHV crossflow head; blower or some such. It is with 5 -4 bolt mains and 5 cam support bearings so very sturdy indeed ! If you think that it costs LOTS to build a stocker, this one is worse / more $. I’m just present custodian. May not even go good with my low buck home made roadster.. now if I had a show boat build that needed some giddy up..look out !! A little known fact, there were only thirty (30) ever made ! Interesting history here.
Thanks for the reply. Again this all started with my "ASSistant" . A fellow on another site suggested that method and and I thought WTF. Didn't make sense to me so I though I'd turn to th empower of the HAMB. I really do not want to pull the head so I'll try the best I can to do as you described. I would think that if I kept an eye on the harmonic balancer and the timing marks I should get it pretty darn close as figuring 60* and 50* by eye could be tough. Hopefully the timing chain isn't stretched.
TDC is TDC as far as the crank and number 1 piston go. Simply because the piston is at top dead center of the stroke. As the others said, then you time the cam to the crank. As many engines as I have done over the past 56 years I still have to get the book out most of the time and check to see where the timing marks are supposed to be on specific engines. I had to laugh a bit at that because I got to the point where I never even mark where the rotor was pointing when I pull a distributor. Bring it up on compression, line up the marks and drop it in and on I go as it ends up being simpler than trying to remember if the rotor points to this side or that side of the chalk mark.
So what if he moved the crank??? This is something every gear head should be able to do. Pulling the head to find TDC and set a distributor is not how it's done. Squirrel can get TDC and set a dizzy without opening the hood.
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