optimal valve timing

[lwasson]

Hi all

Getting the '83 slowly put back together and was wondering what would be the optimal valve timing? My cams have no colored dots but they do have punch marks.

Before removing the cam housing I set the crank to TDC then rotated 90degrees before I removed the housings. Cams are back on and was just wondering if there were any tips on performance besides the specs in the manual.

On another note ... the PO had put on a new timing belt and I ordered a new one to replace it as is always suggested to start things off fresh. I didn't notice at the time that someone had put on 104 cam pullys. Removed motor and it hit me that some PO had put on the wrong belt and I had ordered the wrong one too. So I have two new square tooth belts if anyone would like them. No charge...I save enough by reading and applying what I read on the forum. My way of saying thanks. To go on with the story ... one of the many PO's welded a rigged timing belt tensioner to one of the brackets because they couldn't get enough tension on the square toothed belt because it didn't fit properly on any of the pullys. Engine is damn lucky its still around. So, when you read 'Professionally Maintained' you had better go over the car with a fine toothed comb.


Thanks!
louis

'83 Turbo

[Dr.Hess]

Hey Louis,
I think you are lucky there. Yeah, 'Professionally Maintained' means nothing to me. I have had too many friends that were professional mechanics and I have seen what they do. They need to make a living, so sometimes it goes out the door working for today and probably this month, but maybe not for five years. I have even seen a Harley dealer weld the flywheels onto the crank pin and send it out the door because he didn't have the parts to fix it right in stock. He told the customer "Well, I can fix it a different way, but the factory doesn't recommend it." Yeah, right.
I am at the point that I don't let anyone touch my vehicles but me. And I don't trust any rebuilt motors that I did not personally do.

Dr.Hess

[lotusguy]

lwasson said:

Hi all Getting the '83 slowly put back together and was wondering what would be the optimal valve timing? My cams have no colored dots but they do have punch marks. Before removing the cam housing I set the crank to TDC then rotated 90degrees before I removed the housings. Cams are back on and was just wondering if there were any tips on performance besides the specs in the manual. On another note ... the PO had put on a new timing belt and I ordered a new one to replace it as is always suggested to start things off fresh. I didn't notice at the time that someone had put on 104 cam pullys. Removed motor and it hit me that some PO had put on the wrong belt and I had ordered the wrong one too. So I have two new square tooth belts if anyone would like them. No charge...I save enough by reading and applying what I read on the forum. My way of saying thanks. To go on with the story ... one of the many PO's welded a rigged timing belt tensioner to one of the brackets because they couldn't get enough tension on the square toothed belt because it didn't fit properly on any of the pullys. Engine is damn lucky its still around. So, when you read 'Professionally Maintained' you had better go over the car with a fine toothed comb. Thanks! louis '83 Turbo

Louis,

All the timing pulleys have colored dots as their identifiers, but yours may well have faded or worn off in the 21 or years they've been around. Unfortunately, these marks are really the only way to identify them. All the pulleys are cast the same, they differ only as to where the keyway is cut into them and the variation between these is very small. If you had a 'known' pulley, you could match them up against it and determine whether it was the same or not, but this still would leave a couple other possibilities if the keyways didn't match. Assuming that your car has retained it's stock pulleys over the years, you should have a 110° Pulley on the Intake cam while the 104° was used on the Exhaust with another 104° pulley used on the Aux. Shaft. Swapping the Aux. shaft pulley with the Intake one will give you the Euro valve timing. If you match them up, you will have two the same and one different.

It's good you rotated the engine back 90° before fitting the cam towers, I assume you rotated it back 90° to TDC when you were done (I say assume, because you don't mention it here).

So far as the timing belt tooth profile, this is somewhat disconcerting. As you are aware, there are two profiles the trapezoidal used on the earlier cars and the 'HTD' profile used on all cars '86>. These belts are used in accord with the pulley tooth profiles, including the crank pulley. Please be sure that all your pulleys have the same profile and that a PO didn't replace a couple pulleys with the wrong ones. With a '86> car, you need to purchase an additional 104° pulley to establish the 104°/104° Euro timing. This is because the car come stock with a 110° pulley on the Intake cam, a 100° Pulley on the exhaust cam and a 104° pulley on the Aux shaft instead of the two 104° Pulleys and one 110° pulley on the <'86 cars.

Your story of the Jerry-rigged tensioner is amazing, and you're right, it is lucky that a major catastrophe didn't ensure. I hope you can reverse this and get it corrected.

So far as other performance tricks, you can consider increasing the idle jets in the carbs to say 58's, increase the wastegate pressure to produce 10PSI, this latter is suggested only if you installed forged pistons. A staic timing increase from 1°BTDC to somewhere in the neighborhood of 12°-14° will also make the car better. Finally, you can recurve the distributor to have all the advance (16°) come in earlier than the stock 4,000RPM (Mine is all in at 2,300RPM. These are free/inexpensive upgrades to consider. Increases aren't gargantuan, but worth it I believe. Happy Motoring! ...Jim'85TE

[lwasson]

As always ... many thanks.

No, I haven't set the crank back or put the belt back on. Was waiting for everyone's comments. All the pullys are the same round toothed gear. After your comments I will closely look at the other pullys. I too had a fear that the pullys were different considering the mysteries the car has presented during its restoration.

Another question...this on handling. All bushings have been replaced and new components if we couldn't bring the originals back to spec. I have never really driven a car like this at speed around a corner. I do I know its right?? I have already been looking at driving schools and will invest in attending one to learn what it is suppossed to feel like in the seat of my pants. Just wondering...


Thanks!!
louis

'83 Turbo

[bojangles]

lotus guy.. i see you may not be an engineer..hehe...

need to get the < and > less confusing

car < 86 would be car "less than" 86
car > 86 is car "greater than " 86
car 86 > is very hard to understand..
need to put the comparitor ( < or > between the thing beging compared, ideally with the car first..

86 < car would be 86 less than the car.. but harder to figure out..

all that being said what do you think my 95S4s has?
104-104-110?

Bruce