Thread: messed up timming and fiiring order

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I own a 1990 Chevy Suburban (350, 5.7L V8) (not rellay a Hot Rod, but I have always had a thing for the tank)

anyway, the truck has stated to backfire. It "was" doing it just after startup and continues unitl it is put into grear. After about a mile down the road, it backfres off and on ( no pattern) The backfires sound like they are comming out of the exhaust.

I spoke to a loacl mechinic and he sugested a change of the plugs, wires, and cap and rotor. I just now finshed the sugested "repairs" and as i was replacing the plugs noticed the the plug in cly #8 was loose and had oil on the nut.

after replacing the cap and rotor, i atempted to start the truck. No go.

I am prety sure that i put the wires back in the correct positions. so I am stuck not knowing whats wrong.

The engine wont even spin now, and i know the battery is good

All I hear when i try to start it is a fast ticking that sounds like the starter is not getting enough juice. the battery conections are tight.

could it be compresion related? IE: too much

If I have messed up the wires, how can i get them back in the right positions?

And why would a missplaced wire casue the the engine not to start?



This is a "daily driver" and i need to get it back on the road asap.

Any ideas or sugestions would be greatly appretiated

thanks

Charles

Ok just replaced the battery and bought #2 size custom cables and instaled them.

Engine now cranks.

It sitll wont start though

I really did mees up the plug wires on the cap. my sequence is 1,8,4,3,6,5,7,2. double checked this morning.

The problem is the cap is mounted so that ther are two posts facing forward.

here is a picture of the old one in it's original oreintation on the engine.

http://img264.imageshack.us/img264/4...itorcappk1.jpg

Well, I hope that gives an idea anyhow.

I have numbered the posts with the current cyl. assignments. The red shading is the posts i have questions about.

Which post is going to be #1?

Thanks

Charles

So, #1 can be anywhere on the cap?

to get TDC, i have to pull the plugs back out and put the tool ( that I don't have ) in cly. 1? right?

I just spoke with Chevy, and they say that # one is the white post on you diagram.

I am gonig to try to get the wires in the right order (again) can i find TDC with a compression gage?

ok off i go....( trembeling with fear)

" (Make sure you do not have any power to the coil !!!! )"

you mean dissconect the power lead and not the short wire to the cap right?

If you don't have a compression tester stick a rag in the #1 plug hole with your finger. When she comes up on the compression stroke it will blow the rag out, then adjust the balancer to 0 per Denny. You can also plug the hole with your finger and feel the compression stroke. Disconnect the coil first!


Kitz

All done and she's purring like a kitten

Thanks for the help !

I had to put littel pieces of tape on the wires to indicate what cyl. was what.

BTW, is 60 psi good compression for a 350 V8?

Charles

"IF" that 60 psi is accurate, you have some digging to do. Valve train or valve issues are at stake when this happens usually.

Originally Posted by loadrunner5@hot

All done and she's purring like a kitten

Thanks for the help !

I had to put littel pieces of tape on the wires to indicate what cyl. was what.

BTW, is 60 psi good compression for a 350 V8?

Charles

Crank the engine six revolutions so as to get a good compression reading.
You'll be able to count the revolutions as you crank and you'll also see the compresson gauge come up to the max and additional cranking won't raise it any higher.

60 is good for the first stroke about 70 is optimal on a 350, but yes... you want 6 revolutions or 3 compression strokes to get a full compression reading

So if it is purring like a kitten......me thinks that the test wasn't accurate or properly done.

hey denny... 4 is good.... but ASE specifies 3 should make it reach maximum compression..... but then again i swear ASE doesn't ever actually work on cars, they just do everything on paper

Wow, lots of info. Thanks I just cranked her once to find the TDC. I might do the full test this weekend. The #1 post truned out to be right where the diagram indicated.

I am still getting a little backfire if the throttle is opened fast and then closed. Any thoughts?

Also, should I retighten the plugs?

thnaks.

After you do a full compression test,pull the cap and do 1 more. turn engine clockwise up to timing mark using a socket on the balancer bolt. Now turn backward until the rotor just starts to turn. This will show how much slop is in your timing chain. You don't want a lot. Hank