Started to figure out why my bird over heats.

I have a 4 core rad. Water seems to flow thru (garden hose). Will call my radiator guy later for a cleaning.

Cast iron impellers on pump.

Will install new upper and lower hoses, 160F thermostat.
Stat will be tested before install.

Past post here, seems like my diffuser plate does sit to high off the impeller ~ 3/16"
I have not, but will tap it down to within 1/16".

I can tell, a prior owner, might have had a problem installing diff plates. There is a small ridge on the
engine casting(timing cover?). Not to worried about the ridge.

Diff plates might need a small amount of grinding on the outer edges to sit flat within the cavity.

Question... My 2 piece diff-plates do not sit flat to one another. Is this normal?
I can provide a pic if needed.

Question... One of the 3 studs, threads are buggered.
I have a tape/die set, will try to fix, but what If I can't?
Are the studs pressed or screwed in?
Any tips for removal appreciated.

Question.... Is Duplicolor DE1616 the correct paint for a 68 bird engine?
I'd like to paint the water pump before install.

Hoping to get everything I need, getter back on the road this holiday weekend.

Appreciate your time.
Thanks much.....don t. .....

Yes on the Duplicolor 1616.

Only thing I would do different is use a 180-190 thermostat. 160 will never close to allow the radiator to do its job.
Make sure you have a good fan shroud. Make sure using correct fan and if you have a fan clutch make sure it is working. There were some rubber mastic pieces covering the open space between radiator core and radiator to insure air wen through radiator, make sure they are in place.

If you have a 400, make sure all the baffles in place, upper and lower.

There are other things that causes over heating such as Timing and engine specifications..

Duplicolor DE1616 Will work if you want to use Duplicolor paints.

Studs are screwed in. If it is stripped you can heli-coil it.

If the plates are all corroded or other issues, they make new stainless plates which may be better.

So what temperatures are you observing to make you say the engine is "overheating"?

"Only thing I would do different is use a 180-190 thermostat. ".....
Initial thought was to install 160 stat, to see about coolant flow thru radiator.
Plan to swap (IIRC) a 185F stat long term.
Yes, a slight pita to go back in, but no big deal.

"Make sure using correct fan and if you have a fan clutch"....
I have a 5 blade fan. Blades are not evenly space as a sbc would be.
No clutch on fan.
Shroud is installed. Fan sits ~ 2" inside shroud.

"There were some rubber mastic pieces"....
I will need to investigate.

I have a 350

"There are other things that causes over heating such as Timing and engine specifications.."....
Once I have verified coolant flow, this is next on the list.
I can smell gas out the exhaust, seems rich, stumble here and there on occasion.

"If the plates are all corroded or other issues, ".....
Plates look fine, still stainless looking. The plate that goes in first, does not sit flat in the cavity.
When placed on a piece of glass (only true flat surface I have), you can tell its not totally flat near
the lower radiator hose area of the pump.


"So what temperatures are you observing to make you say the engine is "overheating"?".....
It's peaked at 250-260F, which I know is not good(duh-grin).
If you care, click... https://firstgenfirebird.org/forums...;Main=36899&Number=307203#Post307203
or click... https://firstgenfirebird.org/forums...;Main=36906&Number=307250#Post307250
Since those posts, I did remove the electric fan which did not seem to help much.
Due to other projects, never dug into it much, drove it locally and watched the gauge religiously.

Thanks much.....don t. .....

Here is the recipe for success to your problem:

1) get a big box
2) pull off all non-stock parts off engine/compartment DROP IN BOX
3) remove water pump DROP IN BOX
4) remove thermostat DROP IN BOX
5) Purchase new parts: water pump, thermostat (160), plates
6) Purchase/acquire: factory clutch fan or flex fan, stock radiator shroud

This is a min configuration that should solve the problem.
BTW: you can leave the t-stat out for max cooling if you like.
T-stats stuck shut will over heat your car; stuck open
don't hurt the system from an overheating issue.

Love da blue

Good luck!

1st off... Thanks for the tips, tricks, things that work to help out a newbie. Learned a lot.

Did quite a bit of tapping on the divider plates. Clearance is now ~ 1/16".
The tapping also kinda flattened the 2 plates, better than what it was.
Did a bit of grinding, esp around the lower rad hose area.
Seemed like the back plate sat a bit proud in this area.
Ended up installing a 180F stat(tested ok), new upper/lower hoses.
Gotter all back together yesterday, 50/50 mix on a-freeze.
In garage, gotter up to temp, saw flow thru radiator. After market gauge shows 185-190F.
Had 1 leaker...forgot to tighten a bolt(embarrassed-grin).
Wife and I took ~ 100 mile cruise, mostly open country roads. Gauge showed 190F.
The little traffic we did have, peaked just short of 200F, dropped back to 190F once we started moving.

While I believe it's a good fix, I'll still be watching the temp gauge.

Thanks again. Appreciate the help.

Had fun.....don t. .....

I'm not an expert and this is just my opinion.

I'd use a 160 degree thermostat not a 180. A 180 thermostat will have the radiator cooling procedure start at 180, can only go up from there. A gasoline engine does not need to be that hot, it's not a diesel. A 160 degree will get you up to operating temp quickly then start the cooling system to maintain what it can above that temp. The radiator works to cool things when fluid is flowing through it, with the thermostat closed it's only cooling what is in the rad itself. With a 180 degree thermostat you are choosing to never have your engine run below 180 degrees once it's warmed up.

I use a 160 degree thermostat and the cooling system, the pump, hoses, radiator, 10 pound radiator cap, fan, shroud, etc, keep the temperature around 185 degrees while running. If the cooling system was a bit more efficient it may keep the coolant a bit cooler, if it was less efficient it would run hotter.

Our engines produce a lot of heat, it takes a good cooling system and a properly tuned engine to maintain that heat.

X2, Bluebird428. I have used a 160 degree thermostat for many years. Much of that time in Arizona, and found that my 400 likes it. I run higher compression with lots of octane and find hot starts and preignition less of a problem with lower temps.

My 461 had a 160f thermostat. I went to a 180f and the engine liked it better. Then I went to a FlowKooler waterpump and I'm at a 195f thermostat now. Engine likes that even more. These engines do not like to be cold, they will only waste fuel and carbon up when colder. I also have full forged internals so the hotter the better for expansion.

I also ditched the factory mechanical fan and went with an electric with it's own full fan shroud, NEVER gets how now, even idleing with heat soak and the A/C on. The engine reevs WAY better and is generally MUCH happier without the drag of the mehanical fan.

Thanks for sharing that info as I was wondering what stat to put in my 461. I am using pretty much the same set up with elec fans and shroud and A/C but I have edelbrock alum heads so hoping a 195 stat works good for me as that is what the engine builder is telling me.

The thing about a 160 thermostat is that once the car hits 190 it doesn't matter if you have a 160 or 180 because they are both wide open at this point. So if your car runs hot the 160 does you no good. The flip side is that on a cool day the motor will stay at 160 which isn't optimal.

Waking up an old thread I started, update, question.

Car has been running very good since the fix of my spark and carb issue.
According to my after market gauges, 180F t-stat opening like it should.
Temp around 190F in 30-65mph traffic. Stop-n-go temp around 200-210F

What bothered me the most, was the temp creeps up to 230-240F about 5 minutes after shut down.

Installed 160F t-stat. Gauge says it's opening when it should.
For all intents, same temps as with the 180F t-stat.

I had my 4-core radiator re cored, left the 160F t-stat installed.
Temps are much, much better overall.
170F in 30-65 .... 180-185 in stop-n-go.

But I still have a +40F temperature rise about 5 minutes after shut down.
Question .... Is the temp rise normal?

After waiting for the temp to rise, I start the car.
Engine cranks as it should, but is a little slow in firing/starting.
Ultimately, it does start, water pumps coolant, temp drops once coolant moves.
Question .... Is this a sign of vapor lock?
E-brock 1406 has a 1/2" spacer currently installed.

Thanks much...don t.

I have the exact same problem with the heat creep after shutdown, always have. I have the cast iron 670 heads and I was thinking that may have something to do with it.