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Overheating big block - could use some suggestions...?

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Overheating big block - could use some suggestions...?

 
Old 05-19-2019, 05:10 PM
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BigBill94
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Originally Posted by PAmotorman View Post
go to the auto parts and buy a brass cup type expansion plug that is a snug slip fit in the hose and drill a 1/8" hole in the center. https://www.clipsandfasteners.com/7-...gs-p/a3952.htm. not the correct size just to show what to buy
I'll do this for sure, thank you for the tip.
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Old 05-19-2019, 07:55 PM
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Originally Posted by BigBill94 View Post
Interesting. For a street motor you definitely want the bypass to eliminate steam pockets. Restricting it though would still allow for the function without all the bypass flow.

Not sure I've seen a bypass hose restrictor however..... I suppose you could use a 1/2 NPT -> -3 or -4 AN, sort of an exotic way around it however.... Any suggestions?
- AN fittings for water cooled exhaust for boat headers use restrictors in the water lines to adjust the amount of water flowing through the header primary tubes.
West marine, Bassett Racing Headers and Earl’s sell them.
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Old 05-22-2019, 09:15 PM
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Rather than check the cooling system to hold pressure, I did a compression check. I have no oil in the water and no water in the oil

Readings:

#1 210.5
#2 214.5
#3 (tool won't fit due to borgeson box, gave up after about 45 mins)
#4 191.5
#5 184.5
#6 191
#7 186
#8 211.5

I'd surmise with the 184.5 reading in #5 and 186 in #7 that the driver's side head gasket is the source of my cooling problem. BBC with flat tops and 100CC chamber heads.
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Old 05-22-2019, 09:25 PM
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I'm surprised on one mentioned head gasket to block coolant port missmatch. One of my Big blocks behaved the same way. We tore it down to find Siamese flow gaskets on a series flow block..

Pm or email if you would like to learn more.
Best,
Milan
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Old 05-23-2019, 07:44 PM
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Default Here's the engine / gaskets - these don't look like the correct gaskets...? Thoughts?

Here's what I have...

The front and rear coolant holes on the head gaskets don't match the head / block.... These head gaskets don't look right to me.

Thoughts?


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Old 05-23-2019, 08:32 PM
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Old 05-23-2019, 08:42 PM
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get a copy of "Chevrolet power" edition 7 as it has a chapter on what head gaskets block and heads are compatible
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Old 05-23-2019, 09:19 PM
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Originally Posted by derekderek View Post
Yep - it's a Gen VI big block. It's Chevrolet P/N: 12498778.

According to this, the gaskets are correct for the block, or look to be.

The heads were hard to find, they're Edelbrock 60499 Performer TBI heads, 100cc chamber. The only number cast into them is 6045 which has nothing to do with the p/n of the heads.

The front of the head says "Performer TBI and has an EO#" They look to be compatible with the block according to the edelbrock instructions. I'll pull the passenger head tomorrow.

They're covered in soot / carbon, the carb is clearly too big and jetted to big as well. I picked up an 850 cfm for it.



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Old 05-23-2019, 09:59 PM
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if they are edelbrock heads I would call them and aske what head gaskets to use with your block
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Old 05-23-2019, 11:26 PM
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You can ask Edelbrock for sure but I think the 6045 number on your heads is the casting number for their Performer series heads and the true part number tells which head it actually is ie TBI, RPM, 100cc or 110cc etc...
They call out the specific head gasket set for my RPM 110cc heads with my Mark IV block in the detailed instructions sheet.

Last edited by OldCarBum; 05-23-2019 at 11:28 PM.
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Old 05-24-2019, 11:09 AM
  #51  
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You should measure your lift on the cam before you call them, a friend of mine has edelbrock heads on his gen vi 454 and hyd roller cam and the stops pulling at 4800, goes pig rich and makes no power. It appears the heads cant flow enough or the 502 lifters in the car are collapsing.
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Old 05-24-2019, 11:11 AM
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Originally Posted by Kacyc3 View Post
You should measure your lift on the cam before you call them, a friend of mine has edelbrock heads on his gen vi 454 and hyd roller cam and the stops pulling at 4800, goes pig rich and makes no power. It appears the heads cant flow enough or the 502 lifters in the car are collapsing.
This one has some sort of Luanti hydraulic roller cam in it, the short block ships from GM without a timing set, cam or lifters.

My biggest concern is the 100cc chambers and those pistons have a small dome on them. It wouldn't surprise me if the static compression ratio is north of 11:1.
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Old 05-24-2019, 11:41 AM
  #53  
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I have not read this entire thread, but over the last many years I have noticed the flow passage in thermostats have all been narrowed/restricted to the 195f temp size opening, it has nothing to do with the opening of the valve....BUT so it opens at say 160-180 if the flow is restricted, the engine will work it's way up and overheat due to bad/inadequate flow......

so lately I have taken snips to the skirt of the stat in my '72, opening up bypass, engine takes longer to warm up but being in FLORIDA....hoo cares....??? on a 100f day, I can run the freeway at ~190f or so, then to get off freeway into congested street traffic dual spals howling, and it may reach 210 or so.....where the assfault streets are at least 160f in temp....so can't bitch too loud....

OP, try that trick, easy do.....and cheap....
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Old 05-25-2019, 08:36 AM
  #54  
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update?
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Old 05-25-2019, 08:38 AM
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the pistons are allegedly 13.8 cc domes. get a piece of plexiglass 6 inches square. drill a 3/8ths hole near one side. get some grease. now go to Walmart cooking aisle and get a flavor shooter. 30cc syringe for squirting gravy into meat. roasts, turkeys, etc. or auto parts store and get a syringe for mixing 2-stroke oil into gas. lay head flat with chambers up. grease up plexi and stick it to the head with the hole on the high side. start filling with water. now you know how many cc's your chambers really are. you can do the same with piston domes bu putting a thread of grease around piston and running piston up to seal rings. now have the flat part of the piston exactly 1/4 inch down in the hole. grease plexi and fill bore with water. now you have to calculate how many cc's 1/4 inch by 4.25 inch diameter is and subtract what you just measured to get dome volume. do it many times to see if you get the same result. i also double check the measuring device by filling several different known volumes with the syringe. (you could also spring for a real burette.) but using summit's CR calculator and .039 head gasket thickness i got 10.3:1, assuming your pistons are .020 down in the hole at TDC. (another dimension you have to measure.)

Last edited by derekderek; 05-25-2019 at 08:41 AM.
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Old 05-25-2019, 10:33 AM
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Originally Posted by derekderek View Post
the pistons are allegedly 13.8 cc domes. get a piece of plexiglass 6 inches square. drill a 3/8ths hole near one side. get some grease. now go to Walmart cooking aisle and get a flavor shooter. 30cc syringe for squirting gravy into meat. roasts, turkeys, etc. or auto parts store and get a syringe for mixing 2-stroke oil into gas. lay head flat with chambers up. grease up plexi and stick it to the head with the hole on the high side. start filling with water. now you know how many cc's your chambers really are. you can do the same with piston domes bu putting a thread of grease around piston and running piston up to seal rings. now have the flat part of the piston exactly 1/4 inch down in the hole. grease plexi and fill bore with water. now you have to calculate how many cc's 1/4 inch by 4.25 inch diameter is and subtract what you just measured to get dome volume. do it many times to see if you get the same result. i also double check the measuring device by filling several different known volumes with the syringe. (you could also spring for a real burette.) but using summit's CR calculator and .039 head gasket thickness i got 10.3:1, assuming your pistons are .020 down in the hole at TDC. (another dimension you have to measure.)
The engine documentation says 9.8:1 with 110cc heads, dropping 10cc out should raise ~1 point. or 10.8:1 give or take.

I called Edelbrock yesetrday. The unknown quantity left is the camshaft, and I've been arguing with myself over the past 24 hours or so on pulling the AC condenser (have to evacuate it), taking the front running gear, harmonic balancer off and and seeing what cam is in it - and looking at changing it.

The nice thing with the C3 corvette March serpentine accessories, you do NOT have to touch them to pull the heads off.
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Old 05-25-2019, 09:38 PM
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Just tried another calculator. 10.27 to 1.
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Old 05-26-2019, 11:30 AM
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Originally Posted by 97C5 View Post
update?
I've pulled the radiator, both cylinder heads, all of the accessories. Heads are going to a shop to get checked.

I'm going to sell the BeCool radiator/fans/overflow tank that were on it, I ordered a DeWitts HP series kit for my 1970. I picked up a Mighty Demon 850 CFM to replace the 950 ProForm that was on it.

What I've learned so far:

- Water pump is correct, it's a standard rotation Edelbrock Victor, P/N 8850, which is correct for my serpentine set up, it looks fine, spins freely
- Unrelated, all 4 tie rod ends were missing cotter pins!!
- The cylinder head bolt torque was all over the place, some were just past snugged down, others took a 2' piece of pipe on a 18" breaker bar to get loose. They're ARP head bolts
- The pistons (and heads) were caked with soot from an overly large carburetor not jetted properly, heads LOOK to be in great shape, wiped down the pistons with carb cleaner, worked pretty well. (Subsequently wiped them down with oil)
- The passenger side head / pistons were noticeably cleaner than the driver's side for whatever reason (Coolant getting into the cylinder?)
- It has high end steel full roller rockers on it, a Lunati hydraulic roller cam most likely as that's what's on the roller lifter crossbar.

I am going to pull the harmonic balancer and see what camshaft is in the damn thing while I'm at it. In for an ounce, in for a pound.

Guessing it will take me a couple of weeks to come back out the other side of the tear down....
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Old 05-26-2019, 09:53 PM
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Best of luck sir.
Subscribing to learn more.
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Old 05-27-2019, 06:29 AM
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Check valve lift and check those dog bone lifters for how much lift they will take. If I recall, mine looked like they would do .610 max. Which would be around .560 or so with .050 wiggle room.
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