Now What
Thread Starter
Instructor
Joined: Jun 2003
Posts: 143
Likes: 1
From: New Fairfield CT
Now What
This weekend spent most of it tracking down timing problems on the new engine in the 71. Now I have a high heat issue. Using a xe 268 comp cam, old style rebuilt chevy iron 2.02 heads, high volume stewart alum. water pump, brand new summit alum. radiator, all new foam radiator seals, high rpm flex fan, removed fan clutch, replaced with spacer, moved fan mounting point closer to radiator, great airflow across radiator. Installed remote Auto trans cooler. timing is at 20 BTDC at 800 rpm idle. New 180 stat. Engine will run up to 250 and past if I don`t shut down. Checked temp with laser unit. radiator side tanks temp hitting 250 also, so I know temps are correct unfortunatly.
Now the carburator I am using is a edlebrock 600 CFM preformer with a preformer intake. I am at a loss at this point. It is running hotter than it was with the old engine and pos radiator. I have went thur a lot of serching on the archives here, but can`t seem one that fits here. I am really getting to the end of my rope on this engine.
Now the carburator I am using is a edlebrock 600 CFM preformer with a preformer intake. I am at a loss at this point. It is running hotter than it was with the old engine and pos radiator. I have went thur a lot of serching on the archives here, but can`t seem one that fits here. I am really getting to the end of my rope on this engine.
Last edited by 71stockray; May 31, 2005 at 10:54 AM.
Drifting
Joined: Nov 2002
Posts: 1,665
Likes: 1
From: Ontario
Sounds frustrating, with that awesome setup it sounds like your engine should be cooler than the Fonz... Maybe your thermostat is not opening all the way? Can you somehow verify the rate of coolant flow through the engine?
Thread Starter
Instructor
Joined: Jun 2003
Posts: 143
Likes: 1
From: New Fairfield CT
Pulled thermostat at the end of a high temp run, it was opened as far as it whould go. Even tried swapping out other temp rated stats, same outcome. Can a lean condition cause this much excess heat?
Burning Brakes
Joined: Nov 2003
Posts: 990
Likes: 0
From: North Texas
Some thing is very wrong.
Double check your gun versus a thermometer - just in case.
You need to re-check you thermostat in a pot of water.
Do you have a front air dam?
Does it climb to that temperature sitting idling or when driving?
Have you pulled the radiator cap to verify flow?
What pressure cap are you running?
Double check your gun versus a thermometer - just in case.
You need to re-check you thermostat in a pot of water.
Do you have a front air dam?
Does it climb to that temperature sitting idling or when driving?
Have you pulled the radiator cap to verify flow?
What pressure cap are you running?
Drifting
Joined: Nov 2002
Posts: 1,665
Likes: 1
From: Ontario
Originally Posted by 71stockray
Can a lean condition cause this much excess heat?
Pro
Joined: Sep 2004
Posts: 595
Likes: 0
From: Boston MA
air in the radiator
I had a similar problem. I checked the radiator and it was air bound. Try taking off the radiator cap while cool and letting it run with no cap. When the thermostat opens, you will see the coolant flow through the radiator. See if the level goes down and if it does, then fill it up. Make sure you have an expansion take with fluid in it. It will suck the fluid back in when it cools.
As for the lean condition, it is hard to tell. I knew I had a carb tuning/ timing issue because the header would heat up to 900 degrees in 2 minutes, no lie…. I changed my 600 carb for a 750, advanced the timing and now the headers run at about 400/500 after several minutes. The header temp is NOT a good way to tell if it is lean, but I knew something was wrong because my headers would glow red after a 5 minute drive.
I would start with the radiator and then go from there. You might want to come to the Lars New England tour on this Friday or Saturday and learn about carb tuning!!! He does not work on Edelbrock carbs, but you will get a good idea of how to tune that puppy!! What do you say?? Fairfeild is not that far….
Thanks,
Joe
As for the lean condition, it is hard to tell. I knew I had a carb tuning/ timing issue because the header would heat up to 900 degrees in 2 minutes, no lie…. I changed my 600 carb for a 750, advanced the timing and now the headers run at about 400/500 after several minutes. The header temp is NOT a good way to tell if it is lean, but I knew something was wrong because my headers would glow red after a 5 minute drive.
I would start with the radiator and then go from there. You might want to come to the Lars New England tour on this Friday or Saturday and learn about carb tuning!!! He does not work on Edelbrock carbs, but you will get a good idea of how to tune that puppy!! What do you say?? Fairfeild is not that far….
Thanks,
Joe
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
interesting..have you tried it with no thermostat just to rule that out of the equation. if you have the old fan clutch and old fan put those back on and see what happens?.... my engine set up is similar to yours and i have no heat problems....have you tried purging air from the system in case some is caught there?
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Pro
Joined: Sep 2004
Posts: 595
Likes: 0
From: Boston MA
overflow tank
Another problem I had was the stock overflow tank. I was told that they can some times cause problems, so I temporarily eliminated it using a piece of cooper tubing. That brought my temps way down. I eventually took it out and replaced it with a vented expansion tank.
Where is the cap on radiator or on the expansion tank? Do you have on cap on the radiator and one on the expansion tank?
What type of top radiator hose are you using?? Stock or custom flex hose? If the hose is higher than the radiator cap, it will be air bound……
Thanks,
Joe
Where is the cap on radiator or on the expansion tank? Do you have on cap on the radiator and one on the expansion tank?
What type of top radiator hose are you using?? Stock or custom flex hose? If the hose is higher than the radiator cap, it will be air bound……
Thanks,
Joe
Thread Starter
Instructor
Joined: Jun 2003
Posts: 143
Likes: 1
From: New Fairfield CT
Sorry no overflow tank on my 71. No old clutch is gone. Observed a good flow thur radiator the other day. I tried it with thermostat out one day last week, took a lot longer to heat up, but it did. like I said in the opening post, I`m pretty much out of ideas on this one. What I might do tonight is just start from square one, all over again and go over everthing one more time. I might try swapping the 750 holly of my 75 camaro tonight, see if that helps.
Burning Brakes
Joined: Nov 2003
Posts: 990
Likes: 0
From: North Texas
Does your lower radiator hose have the spring in it to keep it from collapsing?
I've heard of too much flow which doesn't allow the fluid to transfer the heat but I would think of this as a last resort.
I've heard of too much flow which doesn't allow the fluid to transfer the heat but I would think of this as a last resort.
Melting Slicks
Joined: Jul 2002
Posts: 3,128
Likes: 3
From: Deltona (son of Deland and DAYTONA) FL
if you're flowing as much water and air as that it should be cool as long as timing (20 sounds good) and fuel are right.
The ONLY time my 383 would do that was if I accidentally left a vacuum hose off the carb.
Check for vacuum leaks.
I'm fighting a A/C-on-while-not-moving cooling issue, otherwise the currently-installed L48 is fine.
The ONLY time my 383 would do that was if I accidentally left a vacuum hose off the carb.
Check for vacuum leaks.
I'm fighting a A/C-on-while-not-moving cooling issue, otherwise the currently-installed L48 is fine.
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
i can't see how its your carburetor.....i'd look at the water pump and cooling system, and flush the cooloing passages in the block.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Is it heating up idling just sitting there ? How loong does it take ? I never let mine idle for more than a few minutes it will heat up too, gotta keep it moving 
Melting Slicks
Joined: Sep 2004
Posts: 2,655
Likes: 19
Could be carb, in part. With new intake, 4 hole spacer, recurved distributor, I'm running much hotter. My vacuum secondary 650 holley was jetted with 64s in the primaries. I'm up to 71s and still not too rich and the cruise temp has dropped almost 10 degrees with jet change.
