timing chain replacement

I need to replace the timing chain in my 71 350. I have a general idea of what I am doing but have never done a timing chain replacement before. Can anyone give me the proper procedure just so I dont have to worry about screwing something up.

thanx

 

First thing is first...turn the crank so the rotor on the distribuitor lines up with the #1 plug wire (this is approx TDC)mark the dist. for the #1 plug wire on the base, then take it out. Then take all the excessories (dist., fuel pump, brackets, etc) off. Then take off the waterpump, crank balancer, pulleys, and belts. Then take off the timing cover...the chain is behind the cover. Make sure that the 2 dots line up on the crank gear and cam gear, its illustrated in the new timing chain set directions. Use a puller to remove the crank gear, then unbolt the cam gear. Use the correct presser to put the crank gear back on (DO NOT SMACK WITH A HAMMER!!! WILL DAMAGE BEARINGS AND SEALS ON CRANK!) and cam gear with the new chain. Make sure the crank gear is on all the way and that the chain is in perfect alignment(dots as well as the chain when looking from the side)...then reassemble in the reverse order. It's alot of work, I know I'd rather pay someone to do this kind of a job...just my $0.02. :TU:

Larry

 

Cant line up the rotor at #1 because everything is already apart. I have the dist out, timing cover , accesories etc all off to replace oil pump. What do I do in this situation?

 

just did this

here is what i did when i just did this about 1 week ago and its not to hard (for me never doing this before it took me about 3 hrs to fully install)

Take the 2 timiming gears and install them without the chain (should just slide on) try to align them so the marks line up

(the larger gear on the cam the mark should be strieght down (use your old gear set to turn it)

the smaller gear you want the mark streight up. (again use the old gears) you may need to put the nut back on the crank to rotate it.

you should now be able to remove both of the gears (careful when remoivng the bolt from the crank it will want to turn the crank)

place the new gears inside the chain with the marks aligned (the smaller gear should be able to balance in the chain. )

if i rember correctly the shaft coming out of the engine that is longer is the cam so you would install this gear partially first and go back and forth sliding the gears on.

in my case i did not need to strike any part of my gears to get them to install.


when the 2 dots are aligned piston one should be very close to being at TDC.

verify that the dots are right inline with another and the centers of the cam and crank. (streight edge would work nicely)

acording to my motor''s repair manual they say that the bolt in the cam just needs a swift jerk to tighen it as not to disrupt the current alignment

now you should be able to install the timing cover. (dont forget to use all new gaskets.) I had a problem when installing my new gasket between the pan and the timing cover to align on the lower pin since the new thicker (non compressed gasket) is in there I had to remove the front half of the oil pan bolts to loosen the pan enough to pry a pair of screwdrivers in the edges of the pan near the front corner most bolt holes. and then sliped the cork gasket in (had to trim some of the edges off of it too)

with the timing cover mostly bolted on (you may or may not reinstall the water pump at this point)
now the distributor.
this was to me the trickyist part.

hopefully you packed your oil pump up with vasline so it can start some suction. and if you have the attatchment for a drill you would use it now to prime the oil pump before starting the engine (oil is ofcourse in the engine at this point if using the drill attatchment). you put it down into where the distributor would drop into.

ok that part was easy. the pain comes in aligning tab on the bottom of the distributor to the slot in the oil pump. while having the rotor pointing at the number one wire inside the distributor.

if i rember correctly the number one wire should be lined up pretty close to where the altenator bracket attaches into the water pump/timing cover assy. so this is where you want the rotor to point to. (i believe the large lower radiator hose connects just below this also)

rember the rotor is going to turn about 15 degrees from where you started inserting it from because of the gear.

IMPORTANT!!
again the tab slot problem when inserting the attatching bolt to tighten down the distributor. if your distributor assembly does not want to seat itself (the seal will fall below the top of the timing cover with a little pressure) if that does not happen the tab of the distributor and the slot of the oil pump are not lined up.

also to line them up you shoulden't turn the crank to move the position of piston one TDC incase you need to remove the distributor again. just insert a long big screwdriver into the timing cover to rotate the oil pump just a few degrees and try again. untill it drops into the cover.


now you should be able to reinstall the distributor and rotate the vacuum advance so that the number one wire attatching point is basicly on top of the contact of the rotor. (the vacuum advance diaphram should point near the passengers side most part of the radiator or just to the drivers side of the battery) if this is not the case you may wish to pull the rotor assembly and move it over a tooth or two. and realign the oil pump
then reinstall the distributor again lineing up the wire connection with the rotor contact.

next step is to install all the belts and accessories and install all the fluids.
the main pully bolt (the big bolt) needs at least 150 foot lbs of torque acording to buick spec.

don't worry if the electrical timing is a lil off you don't need to drain the fluids. just pull the distributor shaft again.

now hopefully you have a dwell meter and a strobe light.

for the dwell you want 30 degrees and you want the timing at idle to be at 6 degrees

doing it the way i spelled out i think the timing was about 10 degrees when i first started the engine. and was able to slowly set it correctly.
when setting the timing do not have the vacuum advance tube in the port of the distributor but have the end closed off somehow. (a plug or vice grip?)

if you have any other questions feel free to hollar


Nate

 

Why is this? Should you do that all the time when you adjust the timing?

Adam

 

Nate, cool on the instructions.. Maybe mine won't be so bad when I get to it.. :TU:

Adam, always adjust the timing with the vac advance disconnected, otherwise when you set it @ 6-12deg you'll be retarding at least 8-10deg from where you think it is. ie. set at 6, really -2 or lower. Because the vac advance raises timing based on vacuum. hth

 

water pump

I thought you could leave the water pump on the timing cover? Do you need to take it off?

o No:

- Bill

 

I don't know why not....it should all come off at once. Good Question.

Adam

CyberBuick - thanks for the info

 

You remove the water pump so the anitfreeze in the block can drain fully, if you dont remove it the anitfreeze will drain into the oil pan when you diss-assemble the entire unit. Also, it's cheap insurance to replace it while your in there to avoid taking it apart again to do so.

Just something to think about :TU:

Larry

 

a good answer to a good question:grin:

 

That is correct. even with taking the water pump off first i had some coolant drain into the oil pan. (I also had my car jacked up about a foot off the ground in the front so it may have not been able to drain fully)

I had a full gasket kit also and i needed to clean all the oil off of mine.

orginal reason to remove the timing cover was to replace my main seal that was no longer there. (darn 30 year old rope seals)
i have 4000 miles of oil leaving the main seal area all over everything.

when i removed my water pump i also broke 3 bolts off in the timing cover. some quick work on the dirll press and a run to a hardware store with a good supply with stainless steel hardware and we were back in business.
I also chased the threads with a tap as to remove all the calcium and rust build up from the coolant.

the other nice thing is if your doing this on an engine that was recently running you shoulden't need to rotate the cam in relation to crank much. When starting the removal line up the existing 2 dots (they should be pretty close even with a loose timing chain.) using your old timing gear set.

and they are correct in saying that the vacuum will pull the advance some when setting the timing.



OH!!!!! ONE MORE THING!!!!

IMPORTANT!

if your doing this while the engine is in the car put a piece of cardboard over your radiator on the engine side so a stray tool or arm or something doesn't find its way thru your radiator.

just some cheap insurance.


Nate