Hey guys, I have been lurking around here for a couple years now and never posted anything but today I thought maybe some one could give me some ideas on an issue with my car.
So it's a 383 sbc and for years the engine has always run at 180 degrees, didn't matter what the outside temp was, always 180 on an autometer gauge. Over the winter I made some changes and have now seen temps as high as 220 coming back home from an autocross last month. It seems fine at idle but at speed is when it runs hot.
Heres what I changed;
Added cowl induction hood
Changed intake manifold
Conveted holley carb from 4160 to 4150
Converted from v belts to serpentine from 92 caprice ( including new reverse rotation water pump)
Changed to 92 caprice ac condenser
Added electric cooling fans from 00 camaro
Replaced all radiator and heater hoses.
Today I pulled the electric fans off and put a mechanical clutched reverse rotation fan on, but on a short drive I was already seeing 195 on the temp gauge.
So I'm looking for ideas on how to get this back to cooling like it used to.
Is your hood scoop sealed to the air cleaner?
Running hot at speed screams airflow problem. As a quickie test you can tape off the scoop and see if it improves.
I have seen clutch fans disengage at speed because there wasn't enough airflow through the radiator to engage the fan's thermostatic magic jelly, so don't assume it's not an airflow problem just because you have a mechanical fan.
Did you do anything to the rear ride height?
I'm going with the cowl induction hood. "They Say" that it is much easier to get air to "fall out" of something than to "push into." With your new hood pushing air in, you might have messed up the pressure differential between the outside (in front of the radiator) and the inside (behind the radiator) such that air no longer "falls out."
Also make sure your fans are turning the correct way.
When are the fans set to come on? On 90s GMs I think they kicked in at a fairly high temp for emissions reasons. 220 doesn’t sound too out there.
Another vote for the cowl induction being part of the problem.
The_Jed
PowerDork
7/28/19 2:40 p.m.
I have nothing to add but I love that Crammit is still a thing!
LOL
When you put a mechanical fan back on did you also use the stock fan shroud?
I've seen the cowl hoods cause problems if the hood isn't sealed to the air filter/carb AND the cowl. If it isn't sealed to the cowl at all the air pressure under hood increases and you don't have as much of a pressure difference between the front/back of the radiator at speed.
How old is radiator?
Was thermostat changed when new hoses etc. installed?
Were any under drive pulleys used in the serp swap?
In reply to The_Jed :
I was sure I would make some grammatical errors so I thought crammit might prove I'm a real person and not a canoe.
Air cleaner is not sealed to the hood
I kind of suspect the hood is a problem but its needed for carb clearance with this intake. I have an idea on how to seal it but haven't made it happen yet. On the 2nd gen it might be hard to block the cowl scoop to test because it's also where the hvac system picks up air. I'll see what I can do with some tape and cardboard.
Both the mechanical fan and electrical were spinning in the direction to pull air through radiator.
Electrical fans have flexalite adjustable controller #31165. I had them set to come on at 180
I did put the stock shroud back on with the mechanical fan
I did put on hotchkis rear lowering springs last year to match the front springs. And come to think of it probably only drove it twice last year since the springs were installed. I've never heard of rear ride height affecting cooling. Maybe it was running hotter last year after the springs but I'm not sure.
I'm going to go out to the garage and see if I can block the cowl off and test drive. I'll report back
Thanks for the help everyone
In reply to BionicTigerShark :
Oh yea
Radiator is about 5 years old -aluminium
Thermostat was reused from old intake, when it seemed to run hot I replaced with another 180 t stat
All pulleys are stock for a 92 caprice (they are the same as late 80s early 90s camaro or the gmpp conversion, it was just alot cheaper to buy used and I never see any Camaro or firebird in junkyards around here)
In reply to BionicTigerShark :
Rear ride height absolutely can affect cooling, it can reduce the low pressure area in the front if there is a wedge of higher pressure air behind it.
Have played with this for years on my RX-7. Cooling turned out to be really sensitive to the car's rake. Higher nose OR lower rear from where I am at right now makes for higher temps.
But it sounds more like the hood is more likely your issue.
BionicTigerShark said:
In reply to The_Jed :
I was sure I would make some grammatical errors so I thought crammit might prove I'm a real person and not a canoe.
Air cleaner is not sealed to the hood
I kind of suspect the hood is a problem but its needed for carb clearance with this intake. I have an idea on how to seal it but haven't made it happen yet. On the 2nd gen it might be hard to block the cowl scoop to test because it's also where the hvac system picks up air. I'll see what I can do with some tape and cardboard.
Can you stuff a pool noodle in the opening, or near the opening to close it off?
otherwise, you might look around for 'silicone baffle sealing' which aircraft use to seal airflow into the cooling fins with their cowl. You could do the same thing between the aircleaner and the hood... and perhaps someone will chime in with "GRM equivalent" material
Ok I taped off the hood and test drove then stopped removed the tape and drove the same route again.
With the hood sealed it ran about 195 maybe 200 up a long hill.
With out the seal it hits 210 before I even got to the hill
Inm fine wit it running around 195 so looks like I'll be finding some way to seal the air cleaner to the hood then trying the electric fans again.
Till I get the air cleaner built I'll try some pool noodles to seal it off so I can keep driving it.
In reply to BionicTigerShark :
I was suggesting that mainly to plug up the back of the hood for the test. Pool noodle around the engine is probably a recipe for a giant sticky mess all over the engine... assuming it doesn’t catch on fire.
