Setting ignition timing on 97 Silverado

[rel3rd]

Truck is a 1997 Silverado with 5.0 litre Vortec engine and I need some info on setting the ignition timing.

I can't seem to find any info on how to do this. My intake manifold sprung a coolant leak today and I need to fix it asap...I found that everyone say to use the updated, or revised, GM gaskets so that's a non-issue. The only concern (so far) is timing the engine after the intake is re-installed. Once the distributor is dropped back in, how do you set the timing? I saw somewhere about having to use a "scan tool"? Is this the only option? If so, what scan tool do you guys recommend?

Also, should I erase the Hypertech program until I get the truck back up and running again?

Thanks for any tips or tricks.

[king44]

Can't help you on the hypertech question, but I am familiar with the timing issues.
It is possible to sset the base ignition timing without a scan tool, but you would need to know where the distributor was before you took it out(like drawing marks before removing it). Your best bet is to find a shop that has a tech 2 scan tool to set the base ignition timing. These scanners can cost hundreds or thousands of dollars so it might be worth looking into to let a shop do it if you do not have access to one.

[hondariderar]

its easiest just to mark it..u have a 10 degree window.

[IH8FORD]

i tell you what i marked mine and i still had to time it with a tech 2 granted i work at a chevy dealer so it wasnt hard to get ahold of one. I would say your best bet is to just take it to a dealer and have them set it. they shouldnt charge u too much and will be alot cheaper then buying a scaner.

[hondariderar]

we (me and my dad) just did an intake manifold gasket on a 97 express van (same motor as his) last weekend. we marked the timing, when we put it back together all was well...

[rel3rd]

I think to be safe and take one variable out of the equation, I'm going to go ahead and re-flash the stock program back into the truck before touching a wrench.

I talked to a friend who has his own shop today who suggested simply marking the distributor housing and the intake, as well as making sure I have a good reference point regarding the rotor position. He claims the worse case scenario is a CEL, but said if that happens to bring it to him and he'll help me dial it in properly. He's a Snap-On "nut" and seems to collect tools and testers, scanners, etc...I would assume that if a 2 or 3 hundred dollar scan tool can help me set the timing that his $3K Snap-ON scanner can do it as well?

I am a heavy equipment mechanic by trade so I'm not going in totally blind, just going into unchartered waters, lol...WTF ever happened to dropping a distributor back in, setting the timing with a timing light, or back in the day, "by EAR", lol???

Anyway, I used an old trick today and dumped a small can of PEPPER into the radiator, which all but sealed the leak completely, and have 6 gallons of water for the drive into work tomorrow (16 miles or so). I figure I'd rather do the job there, in the heated garage, instead of my driveway with no heat, plus I have all the cleaners, parts washer, etc...to help the job go smooth....hopefully.

BTW, I did get the new upgraded GM intake gasket set, instead of the Fel-Pro design, which from what I have read, is prone to failure...

These Vortec engines must have a very poor design. The aluminum VS. cast iron heat expansion and contraction differences theory is BS IMO...How many of us have been running cars, trucks, whatever with iron heads and aluminum intakes for several years without EVER having a gasket just blow out?

Thanks for the replies...Wish me luck.

[HegsZ-71]

BTW, I did get the new upgraded GM intake gasket set, instead of the Fel-Pro design, which from what I have read, is prone to failure...

Thanks for the replies...Wish me luck.

Where did you pick up the new upgraded gm gaskets? I'm going to be doing this to my esclalade this new week and was wonder where and how much you go yours? and what makes them so special?

[rel3rd]

I picked them up at my local dealership, since I wanted to get my truck back in service asap... www.gmpartsdirect.com has them (part# 89017465) for about $33.00 if you can wait for shipping. I paid almost double that.
The "upgraded" version has steel inserts to keep you from overtightening the manifold bolts. When I was searching around yesterday, the FelPro versions looked like they had some issues, to put it nicely...

[rel3rd]

Fixed it today...all in all not a bad job. Took me longer to tag all of the sensors and connectors than it did to do the actual R&R, lol...

Took me about 5 hours total, with a few coffee breaks and an egg sandwich mixed in....Probably 4 hours or so with no stopping...I was being extra careful and thorough since I definitely didn't want a do-over...
I read somewhere a guy claiming he can do it in 2 hours...I'd have to see that to believe it...Heck, it's a half hour wasted near the end of the job refilling (and bleeding air out of) the radiator...

BTW, as far as the timing, I scribed alignment marks on the distributor cap, intake, and firewall, as well as marked the rotor postion on the firewall as well...fired right up and no CEL...not yet anyway.

[Pauly]

I think to be safe and take one variable out of the equation, I'm going to go ahead and re-flash the stock program back into the truck before touching a wrench.

I talked to a friend who has his own shop today who suggested simply marking the distributor housing and the intake, as well as making sure I have a good reference point regarding the rotor position. He claims the worse case scenario is a CEL, but said if that happens to bring it to him and he'll help me dial it in properly. He's a Snap-On "nut" and seems to collect tools and testers, scanners, etc...I would assume that if a 2 or 3 hundred dollar scan tool can help me set the timing that his $3K Snap-ON scanner can do it as well?

I am a heavy equipment mechanic by trade so I'm not going in totally blind, just going into unchartered waters, lol...WTF ever happened to dropping a distributor back in, setting the timing with a timing light, or back in the day, "by EAR", lol???

Anyway, I used an old trick today and dumped a small can of PEPPER into the radiator, which all but sealed the leak completely, and have 6 gallons of water for the drive into work tomorrow (16 miles or so). I figure I'd rather do the job there, in the heated garage, instead of my driveway with no heat, plus I have all the cleaners, parts washer, etc...to help the job go smooth....hopefully.

BTW, I did get the new upgraded GM intake gasket set, instead of the Fel-Pro design, which from what I have read, is prone to failure...

These Vortec engines must have a very poor design. The aluminum VS. cast iron heat expansion and contraction differences theory is BS IMO...How many of us have been running cars, trucks, whatever with iron heads and aluminum intakes for several years without EVER having a gasket just blow out?

Thanks for the replies...Wish me luck.

How many people only torque their aluminum cylinder heads to their cast iron blocks with only 11 lb/ft of torque? The Vortec intakes are head on with 8 bolts at 11 lb/ft of torque. Cylinder heads have MANY more bolts and at least 65 lb/ft of torque.

Why would you think the dis-similar theory is BS, its a proven fact, has been for years. Aluminum and iron contract and expand at very different rates. this movement coupled with a poor gasket design, is what makes the L31 FACTORY sealing so horrible.

the new GM BLACK gaskets are MUCH better than the stock blue gaskets, you can tell just by looking at them.


Marking the distributer and the rotor will get you close, but it wont get you 100% dead on, a scan tool is needed. You want it to read 0 or ZERO. Just because you dont have a light, doenst mean its perfect.

i hope it all stays leak free.

peace
PAuly

[rel3rd]

How many people only torque their aluminum cylinder heads to their cast iron blocks with only 11 lb/ft of torque? The Vortec intakes are head on with 8 bolts at 11 lb/ft of torque. Cylinder heads have MANY more bolts and at least 65 lb/ft of torque.

Why would you think the dis-similar theory is BS, its a proven fact, has been for years. Aluminum and iron contract and expand at very different rates. this movement coupled with a poor gasket design, is what makes the L31 FACTORY sealing so horrible.

I didn't mean you (or your theories) are incorrect about heat properties in dissimilar metals, as that is a no-brainer. I mean for GM to take a step backwards is a joke. The expansion differences are not the problem. Like you said above, it's just a part of the problem, but I'd bet anyone that if there was four more bolts holding it down (like there always used to be), we'd never have a problem. I didn't realize until today that there was only eight bolts total holding the intake to the heads...that's crazy and solves the mystery of why people are replacing their manifold gaskets multiple times...it's a stupid setup and a piss-poor engineering design.

FWIW, I've owned and tuned several supercharged Fords, and they only have 10 head bolts, and 12 intake bolts...I've personally ran 18psi of boost through one for well over 100 dragstrip passes, and 6 years worth of "spirited" street driving, and I have never, ever seen, heard of, or had, an intake manifold gasket blowout driving down the road at 1800 rpm's...it simply does NOT happen...at any rpm, with any intake, with any cylinder head. I've also owned quite a few older Chevrolet cars with nitrous and also have never seen a failure of an intake gasket on one of those before.

I doubt very highly that the expansion/contraction theory has much, if anything, to do with the problem on our trucks...The only reason the torque specs are so low is because of the "missing" intake bolts. If there was a proven gasket, like Fel-Pro or whomevers, and the intake's TWELVE bolts could be actually tightened up to a more normal setting of 20-25lb/ft of torque, we'd never have a problem. Common sense dictates that with an area roughly a foot long that cannot possibly be evenly torqued (since there are no bolts there), would easily warp if the end bolts were tightened up more than the ridiculously low 11lb/ft that's required.

Small block Fords have been running iron heads and aluminum intake manifolds REGULARLY for 25 years and they have ZERO intake gasket issues...Several GM products have done the same.

I didn't intend to start a debate, but like I already said, and now given some examples that even a blind man could see, the Vortec engine has a design flaw and it has nothing to do with thermal expansion and contraction...That MAY "add" to the poor design, but it isn't THE problem...That's why I said that theory is BS...strictly in this example.

Regardless...the intake manifold to cylinder head attachment design is a joke...period.

BTW, thanks for the tip about the scanner. My buddy has the high dollar Snap-On version, so I'd hope he can help me verify and/or correct my distributor phasing...

[Pauly]

Aaahhh I understand what you mean now, cool.

I agree that there is a problem in the Vortec design for sure, the original gaskets are to blame, the gaskets combined with the dis-similar metals are also to blame, and the lack of torque/attachment points are to blame.

The dis-similar metals is what causes the gaskets to roll and causes shear stresses, gaskets arent designed to seal under shear. The older gaskets were encapsulates silicone gaskets which roll under the expansion and contraction ofthe aluminum and iron. Its what causes this, simple low torque could not cause this. http://www.pacificp.com/forum/viewto...intake+gaskets

We will have too wait and see if the new black GM gaskets which are flat and wont roll like the originals. This will prove if its the gaskets or not.

With more and more marine intakes being used which have iron lowers (like the 1 I have installed currently) we will see if the dis-similar contraction is at least part of the problem, since I have installled new the new GM gaskets, we will see if the 11 lb/ft and 8 gaskets can provide a leakfree durable seal or not. So far so good. I really hope it holds, since you used the new GM gaskets, you will be able to see if they work better than the old blue gaskets on your stock aluminum lower intake and iron heads.

peace
Pauly

[rel3rd]

You know what I can't help but wonder...is if the Dex-Cool antifreeze plays/played any part in these problems? Just a thought.

Every picture I have seen so far, the gaskets look the same....distorted, sometimes severely.

Mine looked worse than most I have seen so far and I wish I had saved them and taken a few pics to show you guys. On the port that leaked the worst, the waterfall one, the orange bead looked like oil soaked RTV...you know, when it gets into that stringy, spongy form? I actually had two distorted, and a third looking like it was ready to go.

Another mystery, to me anyway, is why the failures happen on the ends, where the mounting bolts actually are, and the intake ports where there is nothing holding them, looked fine with no signs of failure. I did have some signs of oil in the cylinder head ports, which would lead me to believe that they were possibly "sucking oil" out of the lifter valley, but the intake itself also had the same oil film, so I don't know where that's coming from, lol...I don't think it's possible for a failed gasket to allow oil upstream of the vacuum, but who knows?

I guess that's the next project...for another day. ;)

HOPEFULLY...this "revised and improved" intake gasket set solves the issue for both of us. Time will tell. I know I was as meticulous as I could be on the job, since I know there are issues, so whatever the results...I did my part with what I had.

[Pauly]

Yeah I wonder about that Dexcool, if it is exposed to any air, acidic globules are formed, these globules can etch cast iron.
here are some more gasket carnage and a picture of Dexcool etching of a Vortec cast iron head. 3rd picture down

http://www.pacificp.com/forum/viewto...excool+etching


I really wish you the best, I also hope these GM wonder gaskets are the fix, but only time will tell. I do know that I am well practiced at the Vortec gasket change procedure.

By you being meticulous and using the correct torque, you have removed the installation as a possible problem, lets see if the parts hold.

Good work

peace
pauly

[rel3rd]

I had some very slight etching similar to that one picture, but I don't use the Dex-Cool. I have no idea how long my truck has had "green" antifreeze in it, but I'd assume that it's been in there at least as long as the gaskets that recently failed, have been there...If the factory gaskets have grey "beads" surrounding the ports, then my truck had a different brand...I'm 99% sure mine were orange...Without searching for pics again, I believe they would be the Fel-Pros?

FWIW, I used generic bulk anti-freeze from my work 500 gallon surplus. It's pink colored, but not Dex-Cool and it seems to work well in everything I've used it in so far...(in the last 8 years anyway)...

BTW, by me working in a heavy duty industrial type shop, it's harder than I thought to find a torque wrench that even goes that low...lol.

Thanks for the new word too...
GLOBULE...I don't know what it means, but it's fun to say...hahaha....

[Pauly]

HAHAHA

GLOBULE- small spherical, or GLOBE shaped thingy, Kinda like the round balls in Tapioca pudding.

I have been using green coolant for 4 or 5 yeras now, I make sure I change it every year now.

I am pretty sure the orange gaskets are Felpro.

peace
Pauly