How to Diagnose & Replace Any Chevy 350 / 5.7L Timing Chain Pt2 Timing Chain Inspection and Removal
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- เผยแพร่เมื่อ 26 ส.ค. 2024
- Part 2 we will continue the timing chain tear down for this 350. We show you how an after market camshaft will lines up different then a stock 350 camshaft. In this video we will also show you how much timing chain stretch this hi performance 350 really had. The timing chain stretch was worse then we had both thought!
Hi guys, '95 Silverardo 350, 191 000 miles. This winter was getting 6 miles to gal. (last summer/fall about 12-14 Mi./G) , last fall it started making a slight ticking sound (but not lifter clack) that is constant in its sound level and time - sounds like the ticking that you were showing just louder and consistent in time. Truck has rough start and rough idle, sometimes it would smoke on those really rough starts. Recently, it started stalling at stops signs when under load, seemed to hold while in N - I limped it home. So, I checked the timing and found that the previous set of hands had left the distributor a bit loose. So, I timed it to an acceptable btdc range (I can't read the markings on mine but from looking at others it looks like 6 btdc or so). But it isn't staying in the exact same place timing wise, sometimes it'll be a bit before and sometimes a bit after. It seems to have some play. I haven't taken the time to check if it moves forward when its cold or hot - or if there is a noticeable pattern... So I think I know that the chain has slop but I'd like to hear it from guys that have seen this before. Thanks
You need to re time it. You need to find the ECU / DIST interrupt wire so you can run in base timing mode. On a 1995 I believe its under the glove box, You will know your in the base timing mode because the SES light will be on. The base timing needs to set at 0 on the balancers because the computer control the timing advance. Also the fuel injection TBI is timed as well of the dist timing. Over the years we have seen people try to move the dist to fix an issue to make it worse. Before you can do any diag you need to get that timing back to zero. When the dist shaft is bad you will get a clicking sound as the bearing in the shaft go bad. I have only seen it a few times but it does happen.
/K&K
@@KNKRNR I found the wire under the glove compartment, it is tan with black line and has its own connection for a quick disconnect. So, unplug, time to ZERO, plug the wire back in and check timing to see what the computer is doing. Easy. Thanks for your help.
@@muchgreatness7497 Yup pretty much. GM built the TBI computer / dist to be time by disconnecting the "DIST BYPASS" wire. After you plug the ECU/DIST bypass wire back in after you re time the engine you need to restart the engine and make the SES light is off. Then you will see the computer advancing the idle timing from 8 to12 Degrees BTDC. Its a simple system but there are people who try to treat the LO5 5.0/5.7 TBI like the old days if the engine had a carb. Once this engine gets too much base timing then add the computer advancement these engines will run bad if they even start at all. Let me know how it goes with re-timing the engine.
/K&K
@@KNKRNR Alright, got it timed to ZERO in bypass. Shut off. Plugged the bypass wire back in. She starts but it isn't the smoothest that I've ever seen her. I can't read how many degrees advance that I have but I'll describe it. You have the TDC Zero mark on the metallic tab, then moving leftwards you have the large triangle marking, then you have 2 smaller triangle indents. Then at the end you have half a triangle indent, that has only the right side of its triangle. My timing mark is where the top point would be if that marking were a complete triangle. So, I don't know if that is 12 degrees BTDC but it certainly is early. Any earlier and I could not read it on the tab marker. I hope that make sense. She doen't have full power, when I went up a small hill she seemed to be working harder. I dropped a few bucks of gas and when I restarted it took 3 tries and had to floor the pedal and she puffed some smoke. I'll keep looking around to see if I can find anything wrongly adjusted or broken. Thank you.
When I run it with bypass un-plugged (timed at ZERO - TDC), the idle is better but not 100%. When I plug the bypass back in, the engine is 90% good but there's a little something missing. As said earlier, I have a loud enough ticking sound that is coming from the aftermarket muffler and I was wondering if the knock sensors could be picking that up, thinking its a knock and advancing timing by as much as they can? My next option is either to run it without the muffler (to confirm its actually from there) and see what happens to timing...Or, pull the bypass plug, time it to 6 btdc and run it without the plug and see how that goes.
Hello, correct me if I am wrong.... but I believe the camshaft dot should be at the bottom (6 o'clock), and the crankshaft dot at the top (12 o'clock), so that the two points are very close together and point at each other is the correct TDC on the compression stroke.
Yes I may have have miss spoke on that one correct orientation is as follows. Crankshaft at 12 O'clock / Camshaft At 6 O'clock both dots should line up for correct TDC. You can verify correct orientation after the chain is installed by spinning the crank over till you feel compression on number 1 cylinder or if you have not removed the dist check to see if the rotor is pointed at number 1 cylinder when the dots are lined up at the correct position.
/K&K
(My dad bought his 98 silverado new.) Last year he decided to replace the original timing chain set before giving the old truck to my son and the dots on the original were not lined up quite correctly from the factory. He could not get the new or old distributor to fall down in place like it should by aligning the marks like they should be. The only way to get it all back together was to align it off just like he found it. He has revisited this 3 times now, and now he believes it has the wrong cam from the factory in it. He has spoken to countless mechanics and all of them have never seen this before. He is at a loss on getting it just right. My nissan frontier V6 has more power than the 98 Silverado because we think the timing is off too much to develop the gas mileage or power it should have had all these years.
Did he use an aftermarket timing chain by chance? Those Vortec's 1996-1999 you want to use an OEM GM timing chain only. The problem with that engine is it needs to sync cam and crank to start and run properly. If you say its low on power I would bet the compression is low because the valve timing is off to start with. If your timing dots were off for any reason this will make the valve timing late and that effects the basic operation. That engine should be putting 255 HP/330Ft Lbs Tq. Other note anytime you change the Optispark distributor unit you must have the Dealership sync the ECU to the distributor or the ECU can't advance the timing as needed to get the full power it has. The Vortec engine takes the basic 350 operating principles and adds a computer nightmare to it. No matter what those timing dots should line up or that engine will not run right period.
/K&K
@@KNKRNR Like I said in my comment above....the timing chain had never been uncovered from the factory assembly before my dad decided to change it. When he took the cover off to expose the chain, the timing marks were off as if they were off a tooth from the factory to begin with. Replacing the chain and gears it is impossible to align the marks and fit the distributor into place and still have range for adjustment. It HAD to go back together misaligned just like it was from the factory as if it has the wrong cam maybe from day one. Hard for me to believe you must take the vehicle to the dealer to "sinc" anything just because you replace the distributor. It's still an old school distributor engine. The computer can only calculate and control spark timing unlike a newer VVT engine that controls timing of spark AND cam timing.
Please check out the link below for further information on the re-timing procedure "CMP Retard Offset data" for Vortec's made from 1996 to early 2000. Some automotive repair shops might be able to do this procedure as well if they have the GM Tech II scan tool.
www.gmtruckcentral.com/articles/distributor.html
/K&K
How did u get the oil pan out to clean everything and make sure the new gaskets sit right and seal ?
We had already installed a Fel-Pro "Reusable Oil Pan Gasket" when we installed this used engine. All we had to do is drop the pan just enough to remove clear & install the front cover after the repair. If you have the factory or non reusable oil pan gasket, you can still seal the pan back up with a new front lip oil pan seal and little bit of RTV to meet the old gasket on both sides before you reinstall the front cover. If you are this far I would recommend installing the one piece reusable Fel-Pro Oil Pan Gasket in the link below. Be sure to verify your year and application because GM changed the dipstick location on these engines.
www.summitracing.com/parts/fel-os34510t/overview/make/chevrolet
/K&K
@@KNKRNR I want to see more.
I have bought a Chevrolet caprice built 1992 5.0 V8 question has it a timing belt or chain
That's going be a chain both use the same part number for the timing set.
/K&K
Moving the timing chain so the gears are dot to dot is it alright to turn it with the harmonic balancer to do this? Mine are not lined up and I need to move them dot to dot
You can or use the Harmonic balancer bolt instead installed in the crank to turn the crank back dot to dot.
/K&K
So if chain that loses will here it knock well driving
Then can make noise while running, but when there really bad you will hear it clank when you shut the the engine off. Normally you will have drivability issues before they make noise.
/K&K
Oh ok makes sense
That much chain slop will definitely throw timing off.
How u doin sir i got a quick question. Will a timing chain thats goin bad cause valves too rattle somtimes
Not likely, If its intermittent I would say more likely weak lifters as the lifter tolerance is dependent on oil pressure. A weak lifter would cause the push rod to tap rocker arm then tap on the valve and make an odd noise. I would pull the valve cover(s) and check the rocker arms and see if there is any excessive play. Might be a simple valve adjustment that's needed. Bad chains tend have problems with cold / hot starts, lack of power, and base timing that bounces around while idling.
/K&K
Thank you very much for responding. Have a blessed day sir.
My van did that but it was the timing that was off.. could be the knock sensor too
I want to see more!
Please answer me!!! I have a 91 z71 5.7 tbi it has a misfire cold and hot no check engine fuel pressure is 12psi with load I check Egr and for any vacuum leaks the truck runs ok on the highway but has no power going up a slope the truck turns on always right away can it be timing chain I have 160 and 150 psi on all cylinders
Do you know if the disturber was ever adjusted or moved for any reason? We had this 1994 TBI 350 1500 in once that would start too quick and miss like crazy. The timing was too advanced as the owner thought he just turn the disturber tell it ran right like the old days which is not the case with the TBI 350's. You will need a timing light to test the timing. The timing at idle should 8 to 12 degrees BTDC in the computer control mode, if you see 15 to 30 degrees BTDC in the computer controlled mode at idle the engine will miss like crazy. There should be a black connector joining a single tan and black wire that breaks out of the wiring harness under the battery-junction block in the rear center of the engine compartment. Once disconnected, the electronic spark timing will go into bypass mode / timing set mode. The base timing needs to be 0. In these trucks if the timing chain is bad you will have late starts and sluggish performance. I would suggest before you go any further make sure your timing is dead on as these truck will run like crap tell your base timing is set at O BTDC in the bypass mode. and once the timing connector is plugged back in computer controlled timing curve is running 8-12 degrees BTDC at idle. Please let me know what you find out after checking your timing before I have you check other items in this engine.
/K&K
@@KNKRNR yeah I set my timing too like 5 days ago I disconnected the wire and set to 0 I forgot to say it has a small misfire cold but gets worse once warmed tomorrow ima set the truck to 0 tdc and remove the distributor cap and check how many degrees I can move the crank before my rotor moves I want to fix my truck so bad I’ve had this problem for 9 years I don’t really drive it tho only put 25k miles in those years but the misfire just got worse, like maybe it jumped a tooth, but like I said my truck turns on right away on the freeway you can’t really tell it’s misfiring but I have to power going up hills
@@KNKRNR so I lined up the timing mark to tdc right at 0 and yeah my timing chain has a lot of play when I turn counter clock wise the mark on the harmonic balancer doesn’t even stay on the timing cover readings when my dizzy starts to move, I’ll let you know how it goes I my symptoms are misfire at idle , no power going uphills it’s a 91 k1500 5.7 TBI I get no check engine light not even a knock sensor miss
@@miguelplascencia6093 . When you unplug the timing bypass connector does the engine still miss at idle?
/K&K
@@KNKRNR yeah it does I remember like 5 years ago me and some friends that are mechanics set the timing because the distributor gave out and when we where trying to set the timing it kept jumping all over the place with their snap on timing gun it was difficult for them little adjustment on the dizzy will move the mark a lot I bought a timing gun brand sunpro and it hasn’t jumped and I checked timing like 4 times with this gun and timing is steady maybe my chain is so stretched it jumped a tooth I’ve been really busy I sold my car trying to buy a Harley at the moment to get around but today ima try to remove the timing cover
1999 5.7 cam 2 degee out where marks at
What brand of timing chain did you buy? I looked up a few chains today and it looks like they all label their dots differently.
/K&K
I have a 1995 Pontiac Firebird with a 5.7 L and the bearings to the Pistons that go on the crankshaft are all scratched up what do I do
You have a few options you can do,
1. Swap in a good used engine (Cheapest way to go, but roll on the dice on the health of the engine)
2. Remove the engine and have it rebuilt (Expensive but you know what you have).
3. Order a Crate LT1 from Jegs swap over your parts as needed
4. LS swap as they have kits today to make it a plug and play install for the Firebirds / Camaro's.
This is what we recommend to our customers when they have bottom end damage such as yours.
/K&K
@@KNKRNR thanks I really appreciate it
So I went with a big cam and dot 6 on the cam and 12 on the crank Is that right? I can’t get a fire and when it does try I get fire out the carb
Cam changes can change the compression stroke time on the disturber. First check and make sure your plug wires are correct firing ordering. If so move on and take the #1 spark plug out and turn the engine by hand till you get a compression stroke on #1 cylinder. At this point take your dist cap off and see if your pointed at #1 cylinder or not. If your blowing flame up the carb chances are you may be 180 degrees out on your disturber or your disturber could be one or two tooth off and your timing is off. There's a curve gear on the disturber and its real easy to be off one or two tooth off and blow flame up the carb. The video link below shows how we time most V8's after installation.
th-cam.com/video/um4ldtUyXz4/w-d-xo.html
/K&K
This is the problem I'm having
Can’t you just wiggle the cap? If there’s more than a degree then you can assume the timing chain is sloppy. I’m pretty sure mines sloppy at 270k but it runs great with quite a bit of power
Nope, the cam is a solid connection to the Disturber. If you try to move the rotor / cap to test for stretch you can break the shear pin at the bottom of the Disturber shaft assembly. Stretch effects the cam / crank timing, If your running a stock cam chain stretch doesn't effect much beside cold starts and flat spots in throttle response. Normally you wouldn't change the timing chain until you have driveability issues which we had with this engine.
/K&K.
See that? Sloppy chain.