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Old 02-05-2004, 05:53 PM
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Question engine timing chain,..positions and such....

ok so this may come of sounding a bit dumb....but ive got to ask anyhow.

im currently installing the camshaft into my short block.
ive read in the repair manual(haynes) that its simply a matter of lining the dot on the cam sprocket to 6'oclock position and the dot on the crank sprocket to the 12 position with the number one piston at TDC.

ok i know that part have done it before many a time....

however i was also told by various people it needs to be at top dead center on the compression stroke...
the manual says to find TDC on compression stroke line up ur marks and look at the distributor and if its pointing at #1 plug then there ya go its TDC on compression....

however im installing this with out the dist. in it ,how do you tell if your at TDC on compression with out dist being in?

and reguardless of that what is the position of the lifters for number one piston with the 2 dots of the timing chain at 6 and 12 as described above?
are they both down in the bore? intake up in bore and exhaust down in lifter bore,or both up?

and if its supposed to be installed on the compression stroke does that mean both valves are closed on the head and therefore it would mean that both lifters should be down in bore, correct?

so exactly how does this all work?
lobe lifts intake lifter which inturn opens intake valve while piston is traveling in which direction?down? id assume to suck air in right?
then both valves close so lifters are down ,while the piston travles up to compress the mixture.
the explosion then pushes the piston down,again with valves closed and lifters down.
then the exhaust lifter raises in bore to open exhaust valve ,while piston travels up to expell the leftovers.....

so thats a total of 4 operations...

im going to assume i can install 2 lifters into the #1 cylinder and rotate the assembly and count piston movements and watch the lifter positions and deduce from that which is compression stroke..

ive likely answered my own question here,but was needing to have confirmation of my theory before i commit myself.
bare in mind im self taught on this and this is only my second engine build up,im goin on instinct and simple logical reasoning figuring this out my self...and of course a haynes manual now and again.and the expect advice i get from gurus on the net.

and ive a strange suspicion(sp?) that none of that matters at this point as i dont have the dist in....just line up marks then put in dist with it set to number 1 plug wire....

and if youve read this far....thanks

--Jason
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Old 02-05-2004, 06:04 PM
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Default 2 minute editing time limit.......

yea thats a good idea 2 minutes given to edit something....what if ya dont proof read it right away...or catch ur F' up in the two minutes alotted?...

anydamways...its a 360 if it matters.....
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Old 02-05-2004, 09:41 PM
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hedgehog hedgehog is offline
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After the chain is on, rotate the engine till both #1 lifters are down. Usually you will find that in this position the crank dot will be at 12 o'clock and the cam dot will be at 12 o'clock so they will still be inline but not opposing each other as when you installed the chain. Then drop the oil pump drive in so that the slot is parallel with the cam line or faces front to back of the engine.
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Old 02-05-2004, 10:39 PM
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pishta pishta is offline
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Doesnt matter, does it? your crank doesnt know if it is on the compression stroke or exhaust stroke, and the cam turns at 1/2 speed so you could theoretically line the thing up 12-12. because in one crank revolution youll be at 12-6. the cam will only index in one position, and the cam is what moves the valves. Easiest to get it in at 12-6 because the dots are close together, and consequently the cam 6 position is always close to TDC (what cycle?). Y block fords were 12-12.
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Old 02-05-2004, 10:49 PM
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Yep, if you're putting a short block together, it doesn't matter (read: doesn't care). Just line the marks up like the book says. It's when you get the distributor back in that you'll have to find TDC on the compression stroke. For now, just line up the dots.
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Old 02-05-2004, 11:34 PM
Steve Barracuda Steve Barracuda is offline
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Dots at 6 & 12 o-clock = overlap on #1 , Dots at 12 & 12 o-clock = TDC #1
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Old 02-06-2004, 12:24 AM
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thanks hedge...tht pump shaft part i didnt know.

and thanks everyone else aswell...as i assumed i was worried over nothing at this point in assembly.
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