car won't run and Backfires - NJFBOA - Home of New Jersey's Camaros and Firebirds

Saitin · 08-01-2009, 04:05 PM

it will start but not run, and occasionally would backfire out of the intake. like a small pop and a lil puff of smoke would come out.

-LS6 243 heads, i bought these heads and then had them cleaned up and a valve job done, with dual titanium patriot gold springs and ti retainers and new seals
-comp cams custom 234,236 11+4 lsa .580 lift cam
-7.400 hardened trickflow pushrods
-LS2 Timing chain
-Ls6 intake
-ls6 oil pump

Would the timing of the cam and crank being reversed cause this the happen?
The book calls for the pins for crank to be at 12 O'clock and the cam at 6 O'clock basically having them close to each other.
I think when I did this part I had the motor upside down and can't recall if I corrected for that and they might be reversed facing away from each other.

Here is a pic of the proper way

S.J.SLEEPER · 08-01-2009, 04:34 PM

You are probably 180 degrees out on the timing. Crank turns twice before the cam turns once. When you set you timing you want #1 & #6 cylinder @ top dead center. If you 180 out i believe #6 will not
if timing is correct than if you didn't take the cam sensor out before install of cam (located on back of engine below intake) then cam sensor maybe broke/damaged

Saitin · 08-01-2009, 04:42 PM

Quote:

Originally Posted by S.J.SLEEPER

You are probably 180 degrees out on the timing. Crank turns twice before the cam turns once. When you set you timing you want #1 & #6 cylinder @ top dead center. If you 180 out i believe #6 will not
if timing is correct than if you didn't take the cam sensor out before install of cam (located on back of engine below intake) then cam sensor maybe broke/damaged

the block it went into had no sensors on it before we put them on so I doubt that it got broke.
I am fairly sure the timing is off but I was wanting to get some input from a couple others on here.
Thid was a complete rebuild on a new shortblock.

S.J.SLEEPER · 08-01-2009, 04:51 PM

Besides being 180 out the only other thing i can think off is if yhou put some rediculously big injectors like 60lb or better, likely to flood/wash out the motor which would cause to initial start but not run.
Best of luck

Saitin · 08-01-2009, 05:13 PM

i did upgrade to 42lb greentop ford injectors
was planing to get them tuned down a bit.
I thought that the stock ones wouldn't do it with the new intake and heads/cam setup.

S.J.SLEEPER · 08-01-2009, 05:47 PM

36lb. inj. would be enough, when tune they will just lower the duty cycle. 42lb. inj. shouldnt cause it. did you try start the car @ w.o.t. if fuel in the cylinder already when you w.o.t. it the computer doesn't allow injector to spray on ignition.

HeadlessNorseman · 08-01-2009, 05:50 PM

the backfire is pretty much a dead giveaway of timing or cam being off.

S.J.SLEEPER · 08-01-2009, 05:52 PM

Yeah that was my answer the first time !!!!

Saitin · 08-01-2009, 06:06 PM

Quote:

Originally Posted by J.Reed

the backfire is pretty much a dead giveaway of timing or cam being off.

Yeah that was my first guess, I was just wanting to get some other opinions in here.
I'll be taking the front end apart weds to see if it was lined up correctly.

S.J.SLEEPER · 08-01-2009, 08:43 PM

don't forget to take 1 & 6 plug out so you can stick a straw in there to see if both are at top dead center

NJ Torque · 08-01-2009, 08:46 PM

...you did retune for the 42# injectors, right?

Saitin · 08-02-2009, 07:48 AM

Quote:

Originally Posted by NJ Torque

...you did retune for the 42# injectors, right?

haven't got tot he tune yet need it running first.

NJ Torque · 08-02-2009, 11:22 AM

Quote:

Originally Posted by Saitin

haven't got tot he tune yet need it running first.

Thats your problem right there. When I did my 42# injectors on a stock injector tune, the car would not run and spitted and sputtered.

sweetbmxrider · 08-02-2009, 11:37 AM

yeah and i can't see you installing the gears incorrectly. if the pins are supposed to face each other, it really doesn't matter what way you look at the block.

Saitin · 08-02-2009, 01:55 PM

Quote:

Originally Posted by NJ Torque

Thats your problem right there. When I did my 42# injectors on a stock injector tune, the car would not run and spitted and sputtered.

I've been talking around the 42's wouldn't cause it to not run they would jsut spit and sputter and backfire until tuned.
The car just turns over and back fires at the moment,If the timing is correct then I'll put the stock injectors back in and see if that changes anything.

Saitin · 08-02-2009, 01:56 PM

Quote:

Originally Posted by sweetbmxrider

yeah and i can't see you installing the gears incorrectly. if the pins are supposed to face each other, it really doesn't matter what way you look at the block.

The gears can be installed one way,but the position of the cam can be incorrect quite easily, I installed them as the book said unfortunately the motor was upside down at the time the the positions would have been different.
I am almost 100% that the 2 dots where not close to each other as in the picture.
I'll post what I find when I take the front cover off.

Syzygy · 08-02-2009, 03:22 PM

the markings are the same if the engine is upside down. just have to face each other.

Saitin · 08-02-2009, 03:56 PM

Quote:

Originally Posted by Syzygy

the markings are the same if the engine is upside down. just have to face each other.

yep I'm like 99% sure they are facing apart =(

BobonaStick · 08-02-2009, 05:11 PM

Ehh... Don't beat urself up over it... Just pull the cover off that will be the best way to tell without having to worry about the injectors.

Saitin · 08-02-2009, 06:01 PM

Quote:

Originally Posted by BobonaStick

Ehh... Don't beat urself up over it... Just pull the cover off that will be the best way to tell without having to worry about the injectors.

yeah I'm going to pull the cover weds and see whats going on.

foff667 · 08-03-2009, 02:04 PM

Put your stock injectors back in until you get it running, swapping injectors takes about an hour if you have a second set of hands with you so isn't a big deal to do if that turns out to be the issue.

The fewer variables the better IMO when setting up a new engine/heads/cam especially if you can't tune for the injectors.

You've got to remember most 42lb injectors are rated at only 43.5psi effectively making them 48lb injectors by GM's fuel pressure std of 58psi. Since your stock injectors are likely either 24 or 28lb depending on what year vehicle you have your pcm is trying to trim 50% of your fuel, the stock pcm can only trim 25% so 25% of your extra fuel is not being trimmed out. if your commanding 11:1 afr at startup idle multiply that by 75% and thats probably the rough afr your engine is seeing. Bad idea.

Stock tune+48lb injectors

Batman · 08-03-2009, 04:22 PM

Quote:

Originally Posted by J.Reed

the backfire is pretty much a dead giveaway of timing or cam being off.

yup, I'd say you are 180 out

crainholio · 08-04-2009, 04:47 PM

Quote:

Originally Posted by Batman

yup, I'd say you are 180 out

Just for ha-ha's, visualize a properly installed cam & crank gear with the chain attached. Zero dots are lined up facing each other perfectly.

Then rotate the crank one turn.

It's a 4-stroke engine, cam turns at half the speed of the crank. Next time the crank has #1 piston at TDC, the cam gear dot is "180 out" according to your belief system.

Historically all that "180 out" stuff happened when the shop chimp installed the distributor pointing to #1 plug tower, but the cam was on #6 firing. If it's possible to install the cam 180 out of phase on a distributorless LS1, I'd love to hear about it.

Saitin · 08-05-2009, 09:36 PM

opened it up this after noon and the timing was out.
almost got it all back together today except when it started to get dark I dropped the pick up tube bolt in the oil pan so I said F'it and I'll finish it up tomorrow.
4 months 1 week down time can't wait to get it back up and running.

BobonaStick · 08-06-2009, 01:27 AM

Damn what luck you seem to be having. Hopefully it all turns around for you tomorrow