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I'm new here and was told this is the place to ask my questions. Here it goes... I have a 68 xr7 gt, she's got a 390 "stock & rebuilt", and new Holly Street Dominator intake, Hooker Headers, 3 1/4 Flowmaster exhaust, Holly 750, Mallory Coil + Ignition + Distributor, and all the other goodies are new also (alt,voltage reg, ect)
So here's my question if you bring up #1 cylinder on compression stroke & the timing mark is @ tdc and you set the dizzy so the rotor points to #1 on the cap, why would she start & drive like a bat outa hell but apon slowing down to the legal speed limit backfire through the exhaust? It's not dumping fuel, it's like a late detonation and will backfire "exhaust" in the shop when I bring it up to cruising rpm to set the timing.
I have NO vacume leaks or exhaust leaks either my plugs are new + wires & I'm running premium fuel.
Help?
So here's my question if you bring up #1 cylinder on compression stroke & the timing mark is @ tdc and you set the dizzy so the rotor points to #1 on the cap, why would she start & drive like a bat outa hell but apon slowing down to the legal speed limit backfire through the exhaust? It's not dumping fuel, it's like a late detonation and will backfire "exhaust" in the shop when I bring it up to cruising rpm to set the timing.
I have NO vacume leaks or exhaust leaks either my plugs are new + wires & I'm running premium fuel.
Help?