Indy heads single water crossover /single plane manifold.
512 Stroker said ..........Gett'n hot at highway speeds is a coolant flow issue for sure, as you have all the air you want at higher speeds.
You need to take a serious look at your water pump drive ratio.
Let me guess you have an overdrive transmission?
Stroker......No over drive trans......Sportsman 727 ....5 clutches, aluminum billet drum built by Dave Smith at Pro trans in Waco TX. Trans cooler out front of radiator.. Hughes performance 2500 RPM stall converter, Hughes flex plate, ARP Bolts.....
turned out that the distributor hold down clamp was not tightened up and timing had moved. Got timing back to 10 to 12 degrees initial..... and car is responding much better.... temperatures much better......... I have done give away ALL my spare water pump pulleys, crank pulleys.......... But that does not surprise me.
TIMING IS EVERYTHING! Yes I screwed up on the centrifugal springs.....2 light silver springs will replace the heavy ones....... Timing needs to be all (Locked out for race engines) in for race engines..... But my car is a street car and consulting MSD I can plot my own curves on my 6AL2. I will be choosing all in at 2500 RPM..... to start with. Its a shot in the dark without a distributor machine when you make changes anyway......but that should put the timing all in about 2500 to 2800 RPM...... After looking at the timing curves I understand now where I screwed up.... I will fix it...that info is welded in ......
I have built bunches of cars through the years even working for a shop that produced pavement and dirt car chassis .......but when it came to the engine compartment and all the MSDs, Holley carbs, engine tuning, changes etc.....I was always pushed back to the welding end...... install this rear end housing .....no go do this over here....
No I will be the first to tell any of you that this high level car (no expense spared) has been built solely by me and will be tuned by me ....I reference to my Larry Sheppard books and the books he has written in the past as Larry was one of the very best to ever start an engine. His race records speak for themselves.
What is the correct water pump ratio for a LA engine? Then there is the fact that some water pumps have 6 blade rotors, some have 8 blade rotors, Some have a backing plate on the rotor...... Yes I realize its my job to understand what I have and I will get to the bottom of it and solve the puzzle.... Got a 63 MM Stant USA Made gutted thermostat in the water neck now as I am still testing some things trying to make what I have work.
Did I mention that this whole brand new build has a whopping 250 miles on it! Things are coming together... I am going to Snapka's drive in tonight for car night.
Signed....Constantly learning........ constantly taking in what info I have coming at me, constantly thankful for all the years of experience being poured at me, forever thankful for everyone's input, part numbers, ideas. I promise it is NOT taken lightly.......
Have a blessed weekend
Rome was built in a day and It would not have been finished if you were running that job either .... NO it would have not......LOL