Here's what I have, 69' GS 400 stock engine with 68,000 miles. freshly rebuilt carb, dwell & timing set to Fact. specs and I get low Vacuum reading . When I advance the timing to I'm guessing 15-20 deg. I get 16" of vac but hard starting and spark knock. I can find no Vac. leaks anywhere. Vac. guage was slightly jittery. I did a compression check and here's what I found. DRY DRY wet 150 150 145 125 155 140 130 170 180 155 F I only wet checked the two lowest cyl. which happen to be next to each other. I know this indicates poor ring seal. Is there anything I can do to make this last the season before I do a rebuild in the fall ? The car idles great, no smoke but has no power. When I step on it it dosen't bog but seem to lack any power. Any ideas on whats up with this engine. It ran good last season except for stalling when I stopped after about 2 or more hours of driving. Didn't stall till it was good and hot. Thanks Jay