Close-i just looked in the 620 file and NOTHING.WHich means the machine shop has the specs.IF they held onto them.THe search will continue next week.
Feel free to harass me off line at Cobrabill@earthlink.net
I can spill some of the powerband secrets.Anyone care to guess as to port work & manifold?
OK-Board Gashole here.This is what you need to do:
It obviously has a vent...so vent it.(a-DUH)
Take the cover off and get the brightest light possible up inside the firebox and check for cracks.
Check the Down draft divertor for cracks also.
Then verify what the valve/regualtor and orifice is sized for NG or propane.
Clean out the burner.Spiders love these things.
Adjust the airshutter to give an ENTIRELY blue flame.The flame should not impinge on ANY part of the firebox or be "lifting" off the burner
Something is failing.(duh)And with an aluminum radiator you should be able to "refridgerate" you motor this time of year even in Flori-duh.Test the T-stat as i had 6 bad in a row including name brands.Right now i have a factory 3-row that i have to block half of it off to get up heat if it's below 50 here.Other than that it sits right on the 180 mark.Aluminum extracts/rejects heat better than brass by 30%,so the behavior of your motor(heat-wise)indicates you have an issue that is putting abunch of heat into the motor.
Are you getting full timing advance?
Have you tested for exhaust in the coolant?
Your sympton of hotter in city indicates an airflow issue.Fan clutch good?