Timing issues and spark knock

[spooky1]

I just installed my new vac advance on my car.I timed the engine to 10 before top dead center.Took he car own the road and it ran ok.I noticed though when i had the hood popped and was reving the engine about 1/2 throttle it started spark knockng.Sounded like a friggin diesel truck.When i pulled the vac advance hose off it went away.What am i doing wrong? It has new accel wires,msd blaster 2 coil,new cap,new rotor.Its running a small 16g with non jet head,225 walbro,and fuel pressure at 38-40lbs.The motor has less than 1000 miles on it.

[Indiana]

Was it fully warmed up when you timed it?

Sure you had the right mark on the crank pulley and not a scratch or nick?

Sure you used the #1 plug wire?

 

I'd check that timing again, don't drive it like that.

[spooky1]

I just checked it again waiting till the car was completely warmed up.When i checked it it was not at 10 but clser to top dead so i reset it.When i rev up the car it revs nice with no sounds. Its oly when i slowely rev up the car that it gets to a knock sound.Timing mark on the crank is correct because i used a metallic silver pen to higligt the notch,The tester was on the #1 wire. Dont know what else to do.When the advance is unhooked theres no noise when sowely reving so its def in te timing.

[TainterRacing]

Rev the motor and have the timming gun on and watch and see what the timming is at.

[Starwolf]

idk if it could be this...but the grease inside the distributors gets pretty bad after 20 years if it hasnt been done already. I would take the cap and rotor off and check to see if the weights are still moving freely. Again im not very smart with the whole timing bit...but i know i had problems with this in my car recently.

[Shelby]

check to make sure the vac signal hose is on the 1st of the 3 in a row vac ports

 

and that is is not seeing any vac at idle

Edited June 27, 2010 by Shelby