sbc 305 need help!

[oakshade_racer]

Hey guys ive got a major problem I believe and need some ideas on the cause. I have a sbc 305. nothing fancy, mild lift hydrolic cam. ive ran this cam and top end on a 355 with no problems. What I am down to now is I have to be at about 50degrees advance for the engine to run. sounds awesome, idles great, revs good without load but severe lack of power on track. ive never ran a 305 before so I wrote it off to that. But if I crank back the timing to about 40 the idle goes south and I get a backfire thru the carb. we rebuilt the carb, I know my distributor is good, plugs good, proper fireing order all the basics have been checked and double checked and correct. is it possible I have the cam itself off a notch and still be able to make it run despite not setup correctly?? any ideas iam lost.. thanks in advance.. nick

[Egoracing]

Sounds like the cam is installed incorrectly.

[Racer Roy]

Which timing cover and balancer are you using? The 305 cover and balancer have the timing marks at 12 o clock if you use a 350 cover and the small 305 balancer, the timing will be at least 45 degrees out.

[9modified]

What type heads are you running might be lacking compression. You said 355 top end what CCS heads? What piston?

[StuckInReverse]

Like Racer Roy said, the timing lines are in different places 305 vs 350. A lot of 305 balancers have the timing mark 10 degrees before the keyway on the crank. This may account for your timing issues, assuming that the cam is installed correctly.