Team please read and provide input if you have any.
I have a 71 442 clone that heats up a lot more than I would like all the way 240-250 degrees.
I’ll start with the engine, 71 block .040 with 21cc dished pistons, bearings and crank are .010, new cam bearings, line honed, balanced. Engine isn’t tight has about 10k on it and can spin find by hand without plugs in. Cam is a comp 284h with .558/.558 lift and double roller timing chain installed and degreed straight up. Heads are # 5 W31 big valve from a 69 olds, the heat passages have been blocked off with metal etc. Minor port and bowl cleanup. 5 angle valve job good seals and Springs that are installed at the right height and seat open/close pressures to match the cam. Heads are angle milled to 60.4 cc’s static compression is about 9:1 max based on the calculations we ran. Screw in studs, guide-plates, moly pushrods, and comp roller rockers. Headers are Hooker Super Comps ceramic coated. Edelbrock Performer RPM port matched to the heads and headers. Water pump is a Mondello aluminum unit, with mondello pulleys. 100 AMP 1 wire alternator, Twin Flex-a-Lite electrics w shroud and with adjustable stat. (set at 180). 4 Row factory radiator (new as of Saturday) Custom fabricated a skid plate that seals from under the bumper to the bottom of the core support to force all the air through the radiator at speed and prevent hot air from being re-circulated back into the fans. Trans cooler is an 11x11 plate and fin type mounted in front, currently bypassed the factory radiator cooler to remove that heat load from it, 2800 stall, 3.73 gears with Eaton posi. Timing is set at 34 degrees all in by 2450, ran it both ways with and without vac advance which is connected to ported vacuum on the Holley 670 street avenger. Tried retarding timing to 30 (car ran slow and hot vs. quick and hot) I am now running plugs that are 2 heat ranges colder than stock R43S vs. R45S AC Delco. I went up 5 jet sizes from #65 to # 70’s on the primary Ignition is an Accell blueprint HEI with Super Coil and MSD digital 6 controller. Car sounds great and runs strong, just keeps getting warmer and warmer the longer you drive it. Tried multiple stat configurations, 160-180-195 and even a modified (gutted) for just a restrictor, end result is the same it just heats up to op temp faster with a stat in place as expected. Flow across the core looks great, and heater works REALLY WELL… you can cook with it L. I tried running a 17” Hayden and a 12” Hayden together mounted as pullers (same configuration as flex-a-lites) same result just runs hotter and hotter the longer it’s on.

So I have read that I should have 4000cfm of airflow to cool this size/config of engine and I think my current setup is only rated at 2500, so ordered a set of SPAL 4000’s today. Also ordered an oil filter relocation kit (filter sits really close to headers now) and an 11x11 oil cooler that I will mount with it to cool the engine oil down. One would think that a 4 row radiator wouldn’t let this thing heat up so easily at 50-70 on the hwy that should be enough airflow to cool this motor even without fans!?!?!?! When I built this motor 5 years ago I used felpro head gaskets with a compressed thickness of .040 I used the same again as cometic .020 were on backorder via Jegs. The thing I noticed is there are not full size holes around the center 2 cylinders, but rather puny steam holes in the gaskets. Could they somehow be wrong for the 71 motor? The #5 heads have the same configuration as the #7’s I pulled. Open to suggestions guys, other than relocating to drive my convertible on the ice roads of Canada.

 

Not trying to be a smart-***, but is your gage accurate?

My next thought is the waterpump may have the wrong impeller or may be spinning too fast or slow for proper heat transfer thru the block and radiator. I know the Mondello piece set you back some, but try an A/C water pump for 66-70 Toronado. Those things were notorious for running on-the-edge hot even with their overkill cooling systems.

What is the lower rad hose doing? Any possibilty it's collapsing and restricting flow back to the engine? All radiator seals in place to duct full airflow thru it?

Most overbored blocks will run a little hot til they're well seasoned, but seems like 40 over shouldn't cause all this grief.

 

Good thought on guage, i tested that as well using the mechanical one off my stingray and the electronic laser one with the wired probe. Guages are spot on plus once she breaks 220-230 it really starts run funky and the plugs show bright white indicating overheat. I wondered about the pump i bought it because the new oriely replacement supposedly didnt have close enough impeller tolerances etc...that was per joe himself many years ago when i first built thr car. He was a really nice guy, anyhow whats different about a toro pump? Higher flow impeller?

 

Oh yeah i checked the lower hose at 3500 rpm stays round...supposedly they dont put springs in them anymore???

 

Who did the engine machine work? Was it someone truly familiar with Olds engines?
I know you say the engine isn't tight, but the reason I ask is because inadequate internal clearances are the common cause of hot-running Olds high performance engines. No cooling system will keep it cool if internal friction is making the heat. You shouldn't need extraordinary cooling measures to keep the temp under 240.

 

South Austin machine did the work on the bottom end, I wish I had gone someplace elese but I had just moved back into town and didnt know anyone. I was thinking the same thing about the short block. The heads were done by one of the best guys in Austin. Would it be piston to wall, main or rod bearing or all the above?

 

Typical problems are piston-to-pin and piston-to-wall. Overly tight bearing clearances usually don't show up till it's too late.
Exhaust valve guide clearance is a common problem, too.

 

I did have the shop change the pistons, if the piston pin clearances are good, but the piston to wall is too tight, is that a function of a rebore/hone or ring end gap being too tight? I have a bad feeling this engine is coming out and going to a more reputable machine shop... sad because it runs strong.

 

I just went thru this with mine, .....check the fan, should be 3/4 '' from shroud, with a blade pitch of at least 2'', it has to pull a lot of air

 

If piston-to-wall is too tight, it'll usually scuff the piston skirts all up. Unlikely that ring ends are butting unless they were file to fit rings and someone forgot.
What pistons are in it? The piston to pin issue is usually with TRW/Speed Pro forged pistons with pressed pins.
I'd suggest reading Bill Trovato's book "How to Build Max Performance Oldsmobile V8's". You can buy it on Amazon.com or direct from Bill at BTRPerformance.com

 

I had the short block built 5 years ago (approx 15k miles) and just had the heads off 3 wks ago doing the head/cam swap. The walls looked great still crosshatched all the way up and down the bores. The pistons have matched rings that (not file fit) they are Sealed Power Cast Z332AP40 21cc dog dish units. Unfortunately they were the only .040 over I could find as the block was already .030 when I got the car. The mains and cam bearings looked perfect and oil pressure is 70 cold at idle holds 50 at cruise 2k or above until she heats up too much of course then it drops below 25 at idle. No knocks no death noises, engine sounds really solid and runs every bit as strong as my 06 LS2 Z-51 Vette, I have only spun it up to 5,500 but it showed no signs of peaking out I am confident it will pull strong to 6,500 but with cast pistons and stock rods... uh... rather keep them inside the pan. I do have all ARP bolts throughout the motor. New fans arrive this weekend and remote mount filter kit/oil cooler come in today. I will keep you guys posted. From everything I have read if your going with electric fans you must have a min of 3300-3500 CFM to cool a decent V8. Now I see why so many are beleivers in the large factory fan/clutch setup.

 

Rocketraider... you mentioned trying a pump from a 66-70 Toro is it just a larger impeller? Supposedly the Mondello piece has closer tolerances and it does have a covered backing on the impeller itself... which I found to be grinding against the timing cover, (i fixed this with a grinder while it was apart a few wks ago) it was actually the impeller not being smooth it was warped and had a high spot on one 1/2 of it. Pretty crappy for the $$$ paid for the product. The big question is this.... is increasing water flow going to increase cooling capacity by increasing the flow across the radiator core? I know more flow through the block is good but too much rad flow = bad?

 

It's not the cooling system,the carb tune,or the timing.It could the the tolerances,or the block itself.Don't rule-out the heads either.I had something similar to this a long time ago,with a mild-built 71 455.That thing ran great,but ran hot,and it seemed to take forever to cool off.I swapped heads,and it ran much better for 3 more years.The heads had cracks between the valves.A few more years later,I had the block cleaned & checked to do another build,and it had tiny cracks coming from the steam holes on each deck.One caused the other,but just not sure if it was the heads or the block that went first.The previous owner might have also overheated it as well.The engine ran great,but in the end,the block & heads were scrap.

 

Installed the Derale 4700 CFM dual electrics, problem solved! She runs 180 which is where the fans are set at. They are fully sealed to the radiator via the shroud etc. I also switched out the Joe Gibbs Driven break in oil for the Redline Synthetic. My oil cooler adapters didnt fit, so the correct one will arrive this week still would like to see the oil temps lowered to keep the back sides of the pistons cooler.

 

Oil cooler and remote mount filter = awesome. Oil temps never broke 180 water remained about the same. Prior to installing this unit the oil temp would break 250+ after only a 25m drive. Pressure stays up at idle now around 40 vs 20psi hot. Engine feels much happier.