1972 Chevy 4wd Longhorn Project: Never Ending Changes

[burnin oil]

Kjones, what what the pump off of? There are mods that can be made to the AFC to alow more travel out of it along with modding the diaphragm. My guess is that your fuel plate is pulled back and limiting full fuel or the AFC is to far back and not letting it fuel enough. The AFC housing is the only emissions equipment I ever liked. Set it up for a ton of fuel then dial it back till boost rises. Another thought is to ensure that you don't have a leak in the AFCs boost reference line or a faulty overflow valve (pressure valve in the return line). My 175hp pump and stock injectors would black out a lane of traffic when it had a stock turbo. 500HP has been hit with pump mods and a HX35 even though it was hot and smokey. You may want to reduce the timing a little. I ran 18-19* but always had head gasket issues even with studs and orings. 17* seemed pretty safe and spooled up a little better but power also dropped off earlier.