I have 3 issues to fix: 1. My BBB 455 back-fires through the carb occasionally when reving from idle in park. Is this a timing issue? I have a 870 Holley Street Avenger carb. New! 2. When it's cold and I start it. It seems like it is missing on a cylinder until I warm it up at about 2,000 rpm for a few moments then it smooths out and runs fine. 3. When the car is warmed up and I park it, I smell antifreeze. I have no leaks and a new radiator, hoses, everything. It comes from the engine bay and can be a little embarassing at times. What's up with that? Should I try Bar's Leak? I also need to know how to properly time an engine. (Any books on this for a Buick?) Tools needed and so-on. Thank's for your time and any help will be greatly appreciated. Mike
1. If the carb is set up lean - which may be possible with the Holley Street Avenger, but I doubt it. They're set up a bit rich (5% or a little less in most cases) from the factory assuming the carb goes on the engine size the factory thinks it will. Anyhoo . . . if it's lean, the carb will pop back a little bit until the engine is fully warm. You could have a vacuum leak as well. 2. Sounds fairly typical on startup. I've run three different electric choke carbs on my 462" mildly built BBB and they all needed to run for a few seconds until the engine settled down and smoothed out. 2000 rpm strikes me as a bit much on a dead cold engine. Mine will clear out when run up to 1000 rpm or so. Once it does clear out, you can drive off with no problems. 3. Are you sure the anti-freeze smell is coming from the engine bay? Heater cores leak and the smell inside can fool you. Perhaps you've spilled a little anti-freeze on the engine - it can pool up in the external manifold pockets next to the carb. If you used the stock tin intake gaskets it's common for those to leak. I run a thin ring of Permatex copper RTV around the water passages to the thermostat. Both on the head side and the intake manifold side. That seals them off pretty well, but don't get carried away with the stuff. You don't want RTV floating around inside the engine. Get a Motors Manual and follow the timing figures for the stock engines until you get to the point where you want to make changes. The big basic on timing is to disconnect the vac advance line at the distributor and plug it - golf tees work great. Shoot the timing, adjust if necessary. Raise the rpms to see if the centrifugal advance is operating properly. Stay out of the plane of the fan blades. Connect the vac advance, see if it has advanced the timing (about 16 degrees if I remember right) Wing the throttle and see if the vac advance backs the timing off. The above comments are with the vac advance line connected to full-time vacuum. Needed for cool running in traffic on hot days.
Mike, My best advice; Give Holley a call if you suspect you may have carb problems. I have a 770cfm on my Buick 350 with 10.25:1 compression and was told that the high compression of my engine and my low gears in back were much too taxing on the stock carb. I was also under the impression that these common carbs are set up rich to safely run on many cars, but this was not the case with mine. The Holley guy told me their carbs are set up for much lower compression engines and lighter cars with taller gears. He advissed going up 2-3 jets and 1-2 sizes on my discharge nozzle; it worked great for me.
Thanks for all the ideas. I know my heater core is not leaking because I don't have a heater hooked up. It's by-passed. I am leaning towards that my distributor is faulty. It's an HEI unit. Does MSD make a kit with everything a guy needs to set up an engine? I am also going to richen up the jets on the carb also. Thank you... and if there are anymore ideas send them my way. Mike
