UPDATE: yes indeed folks, putting the thermostat back in seems to have done the trick. I did add an extra hose clamp to the middle of the 5/8 fitting, lightly tightened just to help the hose adaptor keep it's shape under pressure...
I only ran it long enough to have the efans cycle on once .. and I can tell you I was pretty jumpy keeping a wary eye on that damned 5/8 hose fitting, while wearing a face shield and full welding leathers...
I'm very happy it did not blow off...I spent a hard earned $90 cdn on those damned flexible hoses ... to me it's not like I cheaped out... for that price those hoses should be idiot and bullet proof !!! then again, I'm over the hill, and still think a loaf of bread, container of milk, and a stick of butter should cost under $5...
I will however take a closer look at making my own 5/8 - 90 degree elbow pipe fitting, or perhaps, if its possible, to change how the heater core is mounted in it's box there, so that instead of it's fittings sticking up, they would stick downward, through new holes cut towards the engine rather than away from it... if I do go that route I'll post up a how to of such butchery...
thanks again all for your expertise!!!
and oh ya this truck is far from stock...she is a mishmash of chev parts, for sure...
the p.o. did all kinds of things to it. most notably, the entire front body (hood/fenders/grille etc) is a fiberglass flip front, that has a 63 grille and headlight assy...
-several body parts modified to seal up the wiper/firewall/drainage area I think
-radiator core support is from a 71 chev according to the stickers n stamps
-front frame hacked up to support the flip front fiberglass hinges...
-fishplated driver front frame standard for power steering gearbox upgrade
-radiator I installed out of a 93 suburban, recored from 4 core hi efficiency down to a 4 core, several years ago...
-efans are out of a 6cyl 99 contour (boo! ford parts on a chevy! but those fans draw less than 15 amps together, and are reliable. but when they do fail, I'll grab some dual efan setups from late model impalas or something chevy related)
-brake master cylinder I upgraded a few years back after the stock closed knuckle gave up the ghost. front axle is now a dana 44 with disc brakes.
-wiper washer pump and resovoir I installed from an 80's chev
-engine of course is not stock, as mentioned, its a freshly built 70's gen 1 block, hei ignition, vortec heads 383 stroker...
bucket seats are out of a 99 tahoe...
inner fenders are probably from a 67-72...
tires are 33x15x12 mud country
frame/engine mounts/trans/tcase/rear end/steering column are all stock... I'm pretty sure I've posted the specs on this truck on this site before ... but if you are really bored, here's my inital build post on my buds local forum:
http://www.bomp-bomp.com/forum/viewtopic.php?f=4&t=604