hi guys, i have been off the site for a while working on my chevelle...{ first let me say, i did a search here and i can never find what i ask for, never seem too}...now that i have that finished that, i have been driving the 65 roadster more and its not happy! i took it into town yesterday, {90' day} about a 15 mile run one way all nice country roads with open air and no stop and go stuff cruzzin about 50 mph.. and by the time i got there it was hot! i have installed a stat controlled electric fan as a pusher and when i stopped at the light in town i could tell it was running. the stat comes on at 185'...the trip in was fine the trip home not so much... i should give you car back round so you can all think it over:
65 roadster
L78 396 425 hp .030 over bore 11.1 comp
good 112 octane fuel
TI ign with new replacement board in the box and new bobbin and magnet in dist with FACTORY TI coil 36' timing total
4.56 gear
factory 3007436 L88 radiator
factory clutch fan
after market high flow 165 stat
factory front license plate in place, but not needed in mich
13lbs rad cap with a anode, i do have a catch can hooked up to the vent.. and it has gotten hot enough too dump into it in the past..
so, as i was returning home the car started bucking, i had run into this before with a faulty aftermarket TI coil so i replaced it with a original TI coil last yr..with all the shields and factory wires in place it tough too keep those parts cool under there. so i just babied it along coughing and missing...until it stalled about a mile from home, i dumped my soda on the coil and that help too fire it back up and limp it home.the temp gage was at 235-240 if its reading properly....i know the IGN issue is heat related, i get that...but the engine heat is causing my IGN failures in my thinking.....to eliminate my IGN issues i am gonna remove the factory TI peices from the motor {CAREFULLY} and install a pertronix set up, i have had good luck with this on other cars..but i still need to figure out why this runs so damn hot... the radiator looks clean with no damage any where.. would a water pump impellar up grade help{factory original pump}? i hate too have too buy a 1200$ dewitt repalcement radiator ! if i missed anything here please ask, i would like too drive it more but cannot trust the ign or the over heating..thanks guys please give me your thoughts on this....troy

 

Is your factory fan on the right way?
Is the factory fan clutch working, what’s its story?
4:56 is pretty deep for a BB engine, what is the rpm you are cruising at?
Have you verified your balancer mark is true to TDC?

 

Quoting John Hinckley's Corvette Cooling article:

"Most low speed cooling problems are related to air flow management and/or ignition timing, and most high speed cooling problems are related to the radiator or restricted air or coolant flow."

Read this article and follow John's guidance and you WILL solve your overheating problem.
http://www.camaros.org/pdf/corv_cooling2.pdf

 

yes the fan is on properly, but I question how well the clutch works?
50mph is around 2300-2500? Not real high, but enough that it should move air.
ballancer is perfect on zero when I put the motor together. Thanks troy

 

thank you! I will read it

 

Had similar problems with my L76.
The following actions correctd the overheating problem:
1) Sealed up all openings around the fan shroud, and radiator, so as to concentrate cooling effect of fan.
2) Adjusted the Static Timng (10 BTDC)
3) Adjusted Total Timing to 34.

Steep three is critical. Your values will be obviously different for your engine.
However, it solved the overheat problem, and has made driving more enjoyable.
Good Luck and keep us posted.

 

pressure check the coolant jacket to make sure you don’t have a blown head gasket.

I’ve tried 3 fan clutches and all three did not lock up until 210/215 compared to my stock unit at 185/190. With modern gasoline the carburetor is more sensitive to temp swings of 45*. I cruise down the road at 180-185 and in idle traffic it goes to 220. My timing is dead on, and I know it’s the fan clutch.

in your case you have an issue at cruise and idle. Ditch the electric fan and the flupty doo T-Stat and install a stock 180* T-Stat. Next verify and Map out your distributor and vacuum advance functions. Search for “Duke Williams Timming” and read the article until it is understood, then get your car dialed in or verified.

If it still overheats, swap in the Hayden 2747 fan clutch.

 

Very helpful info!

 

Get yourself one of these bad boys...fully engaged at 165*. A bit spendy, but they work!

https://www.parts123.com/parts123/yb...Z5Z5Z50000370a

 

2300-2500 with a 4.56 rear? Doesn’t sound right to me!

 

I’d start with making sure you remove the front license plate mount. Made a big difference for me and my L78, though I’m running 3.70 rear

 

thank you leif, i am going thru that artical peice by peice...troy

 

have you used one of these leif?

 

i am prob off there, too be honest, i do not remember looking real close at the tach? but i will get you exact number....thanks troy

 

thanks i did do that...i have not driven it since too see if there is a difference...this is what i have done so far:

I REMOVED THE FRONT PLATE
INSTALLED ONE STEP COLDER PLUGS {ORIGINAL LOOKED A LITTLE HOT UNDER THE SCOPE}
REMOVED PORTED VACUUM ADVANCE LINE AND HAVE IT TOO FULL MANIFOLD VACUUM NOW.
i have new wires,coil, pertronix lll module to install now..

my only other thought now is if i should leave my shield off the dist and coil for cooling ? any thoughts there guys?

 

i did remove my fan, and test my clutch? now, all i did there was heat the coil with a small solder torch.. it seemed too tighten up a little but no full tight in my opinion? this was a CC replacement clutch, has anyone tried the LONG ISLAND CORVETTE clutch posted above? let me know! thanks troy

 

I have one on my current '67 with factory A/C. It was the final piece to a long puzzle to fix my overheating issues years ago.

 

With a 4.56 gear and a 26.5" tall tire, the rpm in 4th gear at 50 mph would be 2,891. Car would run much cooler with a 3.55 gear, all else being equal.

 

i put the lower gear in it too play at the strip with donny. it is not and never will be a highway cruiser. the factory original rear is 4.10 and that is sitting on the shelf. 2900-3000 rpm sounds about right { F70 goodyear bias ply}. even with the 4.10s in it all i and my wife ever do with it is run the country roads along lake mich watching the sunset and out too dinner locally. so i figured the 4.56 was not going too hurt our drives.. but its a blast stop sign too stop light! anyway, as i said i tested my clutch and it seemed just a bit tighter after heating but not much? how tight should they really get? i thought of trying too rig up a tension/resistance of some type with a inch/pound torque wrench? but i dont think it would go that low...i think i am going too just buy the LIC clutch.all my original TI parts will sit on the shelf with the rear end until someone wants too buy the car someday..
so far i have removed my front plate, installed a pertronix complete kit wires and all..i removed my metal braid from my factory wires and installed that on the new wires. the ohm resistance on the original wires was stupid high !! no wonder everyone kept telling me too get rid of the wires at the track and the car would run better...i am setting up my curve and the advance line will go direct too manifold vacuum.. any other ideas guys?

 

On my 67 that had a fairly rowdy 383, 11:1, Healthy cam, and I was having cooling issues so I swapped the clutch fan and went with the Dewitts radiator and the electric fan and harness/relay setup. Took a day or so to get it installed and wired up but it was totally worth the $1500 or so bucks and a my time. I took the fan and shroud out completely. I know some folks don’t like the look but...it stayed cool not matter the temp, idling, traffic, etc.