Stewie5409

hello, ive recently installed a new comp cams cam into my Camaro and have run into an issue while trying to start it. I lined up the timing marks during the install but when you try to start it, it backfires through the intake almost immediately and pretty badly. any ideas of why it would be doing this?? is it possible I timed it 180' off?? any insight is appreciated, thank you.

Mercier

iTrader: (15)

Sounds like you are on the right track. My father always warned me of this exact situation so likely worth checking. Maybe check your cam and/or crank position sensor(s). There is a crank position re-learn procedure but I don't think it would help such an extreme issue.

Did you change anything else? Did you get your pushrods and all set up properly? Backfire like that could be caused by pushrods too long and intake valve(s) not closing all the way.

How possible is it that you set the cam wrong?

nzgreenfox

cam timing gear should be 6 o clock and crank timing gear should be 12 o clock, and in this position cyl 6 is at TDC on the compression/power stroke and cyl 1 is at TDC of the exhaust /intake stroke. In other words cylinder 6 is ready to fire. The cam sensor tells the computer which stroke the engine is on. so if you installed the cam 180 degrees out the computer will identify the problem the engine will run. So I agree with Mercier check your pushrod length or maybe the cam is installed totally incorrectly.

Stewie5409

ill check the sensors, I did put on an intake, valve springs, pushrods, and longtubes. the pushrods are just factory length so I don't think they would be too long. my friend installed the cam and hes a mechanic for a dealership so id hope it was installed right. lol

LLLosingit

iTrader: (4)

Did he/you check piston to valve clearance?

Mercier

iTrader: (15)

Depending on the cam and your setup, factory length could be too long. Ideally you measure for this when installing a new cam, springs, etc.

svede1212

iTrader: (3)

I had a similar thing happen once putting on heads. After pulling the heads again thinking I did something wrong I noticed on my log that my IAT was way, way off. Turns out I forgot to plug in the IAT sensor and it was fueling like it was -40* out. Plugged it in, no more bad backfire.

LilJayV10

iTrader: (39)

Did you check pushrod length? What size cam?

2002kirk

iTrader: (3)

are you sure you timed it correctly? it sounds like you have one gear completely backwards.