Join Date: Jan 2015
Location: Injun Territory, 'Merica!
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No truth to running hotter as a rule.
having noted the engine has a temp sending unit in a cyl head, what engine is in the Cat? What casting number cyl heads? have helped many locals sove their cooling issues over the years. Nearly everyone of them had cooling issues due to one on the following:
-engine rebuilt and block not decked. the absolute worst offenders are engines rebuilt with the multi valve relief cast pistons, often used in cheap engineoverhauls. These pistons will be down in the hole, then add the thickness of the head gasket. Result: NO quench. Have examined quite a few such builds, often the carburetion and ignition were thrown together years ago with a POS 1850 Holley or an Edelbrock 1406 or 1407 and either we're combined with a lazy advance curve smog era HEi or a Mallory or Accel Distrib from the '70's. Short timing and rich, long timing and lean, either will create heat problems. Just because Gratiot, or Stupid Shoppes sold it in the 80's and 90's, or Summit has sold it in their catalogue, CHEAP, for the last 25 years does not not make such cheap carbs a good fit.
-Wrong ratio pulleys. AC application PULLEYS when combined as a set, will give optimum cooling ratio. The factory engineers were not STUPID. With factory non AC applicationpulleys onthe engine, one cant just swap one pulley:
- if a '71+ pulley and PS bracket setup is being used, run the common 481038 and 481040 pulleys. PS pulley will be the same,mfactory AC or not. Can't find them priced right, drop me a PM. Have two sealed 55 gal barrels full of '71+ pulleys, do ship outs every week.
- If running an 11 bolt timing cover and tall 11 bolt pump, and the '67-70 PS set-up, run a "128" or "130" wp pulley and a "842" crank pulley. don't have AC with this height 11 bolt pump and with '67-70 PS set-up, can run an extra crank pulley rein ring behind the "842" crank pulley. Make sure, if running this setup, that the PS pump pulley is the large diam '67-70 pulley, not the smaller 5.5" diam non AC version.
Fan clutch...get the engine to operating temperature and warm, the fan clutch should lock up. With the engine warmed up and shutoff, grab the 19" factory 7 blade AC fan and see if it spins slightly. The fan shouldn't, the clutch should be locked up tight. If it spins, on a rel hot engine, need a new clutch. if factory non AC engine and it has a factory 5 blade flex fan, consider swapping on a 19" clutch style factory fan. Not that hard to find, I've personally seen a 25 degree improvement in cooling with just this mod!
In a thread i just read, Jim mentioned yesterday, running full manifold vacuum for the Distrib vac advance. Good advice, need a properly curved distributor utilizing vac advance. Lot of mpg goes out the window, as well as tune ability with straight advance and no vac advance.