Over the winter and through the spring I have performed some suspension and performance upgrades to this '67 Camaro convertible. It has an unknown year 396 with Quadrajet 4-barrel (carb is from a 1975 Chevy truck) with a new 4L60 transmission and a new 3.55 geared 12-bolt rear.
A couple of months ago during acceleration the engine would stall like it was starving for fuel. I had noted earlier when installing a new fuel tank and fuel sending unit the fuel filter on the old sending unit had disintegrated with some strands remaining. This car had an inline fuel filter before the mechanical pump so I figured it was probably full of residue from the old pickup unit filter.
I replaced the fuel pump, removed the inline fuel filter and installed a fuel filter in the carburetor. My recent driving did not display any hesitation tendencies. I felt the hesitation problem was solved.
Today the brother of the car's owner came by to check things out. The owner lives out of town and due to distance he cannot visit. He drove the car for about 10 miles, sometimes aggressively, with no hesitation. We then we stopped to fill up with gas. During the fill up the car sat in the sun.
After re-fueling he began experiencing hesitation during spirited driving. Not super aggressive driving but feeling the pull of the engine.
It is 95 degrees today with no clouds and the humidity is low Really too hot for a convertible with top down but it was fun nonetheless. Could this car be experiencing vapor lock? Another thing I noted as I replaced the fuel pump this car has 5/16" fuel line from the fuel tank to the fuel pump. Should a 396 have 3/8" line? This 396 seems pretty stock with no thumpy cam and as stated the Quadrajet 4-barrel on a cast iron intake. Pretty basic for a big block, but for all I know it might be a 454 engine. There are no stampings on top by #2 piston, they may have been cut off when decking the block. I didn't concern myself with the 5/16" line because this is not a high performance engine. Are there some casting numbers somewhere on the block that might identify it?
Please school me on Quadrajets and how I might rectify this concern. If it were a Holly I would be checking float levels and maybe changing out the jets. I know very little about the workings of a Quadrajet.
I may drive the car again in cooler morning climate to see if I can repeat the hesitation. What do you Camaro experts think? If it is vapor lock how do I rectify it?
I am sorry for this wall of text but hope I clearly represented the concern.