How do I find TDC?
 

Okay, so I'm getting ready for my first tune up on my project truck: '75 F250 4wd w/ 352FE.

I got a matching Pertronix HEI distributor, HEI wires, plugs, PCV, vacuum hose 12 ga. wire, and extra tools to match: timing light, vacuum gauge, under-hood tach.

Problem is, I'm a little iffy on how to find Top Dead Center. Between Haynes and the factory manual, I've figured out where the #1 cylinder lives.

I heard a rumor I can drop a screwdriver into the #1 plug hole and crank the shaft by hand until it goes to its topmost position. Sounds a lot easier than removing alternator, steering pump, fuel pump, fan, coolant hoses, water pump vibration reduction system, and timing cap just to crank it a couple degrees and put it all back together again.

I'd be happy to not meet my timing belt just yet if I can save a whole weekend day's worth of labor.

Any suggestions?

PLEASE don't stick a screwdriver or anything hard in the hole. The most basic way I know how to get the cylinder on TDC is to pull the spark plug out of cly#1 and stick your finger over the hole. have someone turn the engine with a breaker bar till you feel compression. Then stick something straight though the hole like a straw or a chop stick and keep turning the engine till the straw is stuck out the furthest. Go back and forth if you have too, whatever it takes to make sure the piston is as close to TDC as possible. You must fell the compression to be on TDC or you will be on the exhaust stroke and 180 off. There are two top dead centers one compression stroke (what you want) and also a top dead center on the exhaust stroke.

Quick and easy. Find the number 1 wire on the distributor cap. Pull the cap and turn the engine by hand until the rotor is pointed close to that position. The bolt on the snout of the crank takes a 15/16" socket. Then look at the timing marks on the balancer. Line up the 0 with the pointer. It may even say TDC on the balancer. Number 1 is now at top dead on the compression stroke.

FYI your engine has a timing chain, not a belt and the engine is probably a 360 rather than a 352, though they are in the same family and very similar.

Thanks for the reply.

Unfortunately, I pulled the original distributor before making a note of the position. So, I'm hoping on "straw or chopstick trick" at this point.

As to the engine: The intake manifold says C6AE..., but the VIN means 6.9L diesel, so I'm assuming someone in the past swapped in a 352. Until I pull the manifold or measure the bore stroke, I'll probably not know for sure.

Diesels weren't available until the 80's so something going on with the VIN or the interpretation thereof. The 360 would've been original to that truck, but like you said, that doesn't mean it wasn't swapped at some point.

Like 1977F250 said, don't stick anthing in the hole while you are turning the engine. Use the mark on the balancer. Pull the plug (front passenger side) the set the mark to 0. Look in the plug hole to see if the piston is at the top. You should be able to shine a light in and see it. If its not at the top, rotate the crank one turn and set it to 0 and check it again.

Interesting about the engine. The VIN interpretation I got from the Ford shop manual. The only VIN I've got came on the registration - there's none left in the usual places (door jamb, windshield - don't think they put 'em there back then - etc.)

I understand that intake manifolds are somewhat interchangeable from FE to FE (352 donor to 360 doesn't seem like much of a stretch), but the C6AE .... on there supposedly means 352. Do you suppose someone would've dropped the manifold on there to accommodate an Edelbrock 1406?

Most definately. The manifolds are interchangable between FEs untill you get into some of the high performance models with specialty heads, mostly 427's. My 390 may very well have the same one that you have but I can't remember the number on it.

As far as the VIN goes it sounds like there's been some messing around with the paperwork or a cab swap. The factory tag is an adhesive label below the door striker on the driver's side door jam. Are you sure it wasn't painted over? It is also stamped on the top flange of the right framerail either along side the engine or under the cab in which case you might be able to find it with a mirror.

I went looking for the VIN under the paint on the door. The cab is yellow, but used to be red. Same with the rest of the body. The vin plate wasn't there. Thanks for the tip about the framerail. I'll take a looksee for that.

Based on my impression of the guy who sold me the truck, I'd saying messing with the VIN was a distinct possibility. I bought it on ebay, gave him the cash at his house when I picked it up. As soon as he had the cash in hand, his buddies and him loaded up a duffel full of long guns and ammo into the back of a car and took off.

After the truck broke down about a half mile down the road, I had a conversation with the local constable and mentioned it. He just smirked. :rolleyes:

Sounds like quality folks you're dealing with there. :-X14

Neighbor came over tonight. Cranking with a 15/16" and the thumb trick + a straw in the 1 hole did the trick. I think.