TBucket Engine Project (Dart SHP)

Brian tested several Robert Shaw/Mr Gasket racing thermostats. He has 2 160F & 180F. They all open at the correct temps on his stove in a pot of water heated up, but they all opened at different sized areas. 1/4" to 1/2" difference. He tested to 212F boiling water. Brian says thermostats are not reliable in taxed cooling systems, but Moroso water restrictors are. Brian tells me he is using the blue one with a 3/4" hole on his 63 Grand Prix giving warmup water temps of 140-160F. 1/2 hour idling temps of 190-195F abd down the road driving temps of 160F. Yellow Bullet Drag Forum has reliable data for the Moroso water restrictors, blue plate cools 700 hp 496 BBC fine. Red plate with 1.00" hole gives 120-140F temps typically, and cools off 2000 hp engines. All this info per Brian by text message :)
 
Also, Brian says there is no substitute for mechanical racing flex fans and clutch fans, they are best on GM cars like his TA, move around 10,000 cfm of air. Semi truck fans move around 100,000 to 200,000 cfm of air.

Brian and I were discussing this the other day, I had electric fans on my Vette and went back to the clutch fan with electric auxiliary fan set up from the factory. The electric fan set up couldn't handle south Georgia heat in traffic at stop lights with the A/C running. Mech. fan keeps the temps around 180F highway (with a 180 thermostat) and under 200 stop and go stoplight traffic in town with the A/C running.
 
First, i dont think this is a water pump/heat issue.. that would show up on the temperature gauge...(unless its defective..)
Id check the ignition timing and advance curve and fuel delivery(follow grumpy's advice)... before going too far.
Am surprized no one mentionned a leaking intake gasket.. this seem to be a common place for oil(and vacuum) leak on sbc..
I run about the same 8.3:! DCR and a much higher effective/Boost CR (11.5:1) on 91 octane... i can guarantee you there is NO detonation(pulled the heads 2 week ago).. i do run a rich fuel mixture right from the idle and heavy pump shot and slighly less total ignition advance with cold plugs ;).
Steady knock sound like too much ignition advance or too lean A/F ratio(unless something else is causing it like deposit/hot spot).
For your case here is what am thinking:

First give us more info(while am not very experienced am sure it will help others)
Is the oil consumtion all the time or only when its knocking/detonating?..(probably sound stupid,, let's reformulate below)
Did it reduce its oil consumption since you increased the octane/stopped the detonation problem?
Do it look to be happening(the detonation and oil consumption) to every cylinder or just one or a few of them? (how do the spark plug look?)
Was the engine (re-)tuned on a dyno?(i think you said it was going to a few week ago) maby they did a bad job..

Stupid question again..
How do the exhaust smell?(any smell of burning oil?) No blue smoke at all? (get someone to follow you in another car behind)
what about the 400 steam holes? did you need them and forgot?

Are you sure you have the correct spark plug heat range? from the past picture, they seem hot a little to me for a race engine(and a bit on the lean side too..).. maby its just me..
Is your spark plug reach the correct lenght?.. often an overlooked item... if i remember, you did check that clearance.

Do you know that fuel pump octane can have huge octane variation? they don't guarantee 91 octane on the 91 pump....(maby try a different gas station.)

As for other tests beside ignition and fuel delivery... there's not many test that will tell the oil ring and valve seal sealing condition(that i know of)...

As for detonation sometime it can show as black spec only, .. the aluminum ones are when heavy detonation occur. in that case, you should really fix the problem before running it again.(any any case, you should never run an engine that has detonation..)

EDIT:
My previous 350 before the 383/blower rebuild had the exact same problem.. it was knocking under a certain load at a certain rpm on the highway in 4th gear. it ended fucking up all the crank/rod/cam bearing, then oil pressure dropped to 4 psi and started knocking at idle because of that. (Dont want to scare you, just be cautious..)
The problem was too much ignition advance on 87 octane.. or lack of experience from my part, call it whatever you want haha ;).
 
Last edited:
I appreciate all the input guys!

At this time I'm not going to be able to do any tests for a couple of weeks. But my
timing curve as tested last time is the blue line. Maybe I need to go back to the red
line timing and retard timing to 33°. The balancer was checked for TDC when the
engine was built. With only 5000 miles it not likely to haved slipped, but certainly
is possible. I do think the balancer is one placed where I cut corners.

Also clean out the combustion chambers with Grumpy mix of 33% water, 33%
Seafoam, 33% Methanol to reduce compression and hot spots.

To answer Mathieu's questions about detonation and oil consumption. The detonation
happens only on the highway with the torque converter locked up, RPM is about 1800
to 2100. As soon and I unlock the TC, the detonation goes away. Around town I never
hear any detonation. Since I don't spend alot of time on the highway, I would think that
oil consumption is all the time.



Ignition-Timing-Curve_2014-05-30.jpg
 
I also wanted to address the possibility that I might be overheating, excluding pinpoint spots
on the combustion chamber wall. I've had both 180°F and 195°F thermostats and the car
will not reach the thermostat designed temperature. With the 195°F thermostat that is
installed presently, the car only runs in the 180°F range while in a cruise mode. If I have
to idle for a long period, then it will reach 195-200°F, the fan comes on and it maintains
designed temperature. The cap is rated at 15 psi. Ambient temperature are in the 90-100°F.

One other minor detail .....during assembly of the valves I used the plastic sleeve that goes
over the valve stem.
 
Indycars said:
The balancer was checked for TDC when the
engine was built. With only 5000 miles it not likely to have slipped, but certainly
is possible. I do think the balancer is one placed where I cut corners.
Click to expand...

A co-worker had the outer ring come off his new balancer within 300 miles.
It was a Profreesional Products 383 balancer.

Rick, are you using vacuum advance? If so, then along with your rapid advance curve
you are adding in additional timing, in the hot weather, under load. Maybe too much.
Quick test - disconnect vacuum advance and see what happens.
 
Indycars said:
I've had both 180°F and 195°F thermostats and the car
will not reach the thermostat designed temperature. With the 195°F thermostat that is
installed presently, the car only runs in the 180°F range while in a cruise mode. If I have
to idle for a long period, then it will reach 195-200°F, the fan comes on and it maintains
designed temperature.
Click to expand...

I have had some intake manifolds, where the pocket for the thermostat was machined too deep,
causing the thermostat to flop around in its pocket. This causes the coolant to bypass the thermostat,
the same as drilling the extra holes. It does not take that much of a bypass to render the thermostat
almost useless. You should hold it up to a light to see that it completely seals, as well as testing it on
the stove in a pot of boiling water.
 
mathd said:
Am surprized no one mentionned a leaking intake gasket.. this seem to be a common place for oil(and vacuum) leak on sbc..
Click to expand...

Now that the engine has had more than a few heating/cooling cycles, things have moved, or are still moving
(expanding & contracting) including your gaskets. You located your intake gaskets with those roll pins. If
the gaskets have compressed and the pins are now holding the intake up, then you might be sucking in oil
there, as Mathieu said.
I can't remember if you drilled corresponding holes in the intake flanges so this would not happen.
 
obviously boosting your fuels octane helps so thats the first part of the equation, retarding the cam timing reduces effective compression,
retarding the ignition curve will reduce cylinder heat and effective pressure,
all factors should reduce detonation,
keep in mind the main function of a T-stat is to RESTRICT coolant flow UNTIL the coolant temperature reaches and very slightly exceeds its designed temp level, at which point it opens to un-restrict the coolant flow,
now drilling a couple 3/32" holes in the flange INSURES that the t-states fully engulfed in coolant , where a t-stat without the holes may and in many cases will delay the t-stat opening because only static/ stationary mass of coolant temporarily trapped behind it can trigger its temp sensitive function.
RICK! ID also try modifying that ignition advance so your curve
is a bit slower, reaching full advance near 3200 rpm, rather than near 2600 rpm- 2700 rpm like your posted graph posted below, indicates,it might cost you a bit of mid rpm, power but Id bet it reduces the heat the engine generates, and coolant deals with thus potentially reducing the engines tendency to get into detonation.
index.php


chart3e1.jpg


READ THE LINKS INFO
http://garage.grumpysperformance.com/index.php?threads/correct-thermostat.5607/#post-17121

http://garage.grumpysperformance.com/index.php?threads/verifying-your-real-advance-curve.4683/
 
Last edited:
Loves302Chevy said:
Rick, are you using vacuum advance? If so, then along with your rapid advance curve
you are adding in additional timing, in the hot weather, under load. Maybe too much.
Quick test - disconnect vacuum advance and see what happens.
Click to expand...
Yes I am running vacuum advance. Will be a couple of weeks before I'm back in the
garage again to make the change.


Loves302Chevy said:
How much does your rpm drop when you lock the converter?
Click to expand...
About 250-300 rpm drop when TC locks up.

Loves302Chevy said:
You located your intake gaskets with those roll pins. If
the gaskets have compressed and the pins are now holding the intake up, then you might be sucking in oil
there, as Mathieu said.
I can't remember if you drilled corresponding holes in the intake flanges so this would not happen.
Click to expand...
Yes I have holes thru the intake manifold, the roll pins cannot hold the intake up from
seating on the gaskets.

IntakeRollPinAlignment_2555_2557.jpg
 
Grumpy said:
now drilling a couple 3/32" holes in the flange INSURES that the t-states fully engulfed in coolant , where a t-stat without the holes may and in many cases will delay the t-stat opening because only static/ stationary mass of coolant temporarily trapped behind it can trigger its temp sensitive function.
Click to expand...
I have a Stewart Components high flow thermostat, there is not room for drilling holes.

StewartThermostat.jpg

If I run a regular thermostat without holes, then it sucks the top radiator hose
flat when it cools off. I keep adding water, but after 4-5 times adding water it
still flattens the hose. When I put in the Stewart thermostat I don't have this
problem and I don't have to keep adding water.
 
Loves302Chevy said: ↑
"You located your intake gaskets with those roll pins. If
the gaskets have compressed and the pins are now holding the intake up, then you might be sucking in oil
there, as Mathieu said.
I can't remember if you drilled corresponding holes in the intake flanges so this would not happen."


yeah! thats a NON-STARTER as a problem... RICK did the index pins install and manifold mods ,correctly,

RICK said:
I have a Stewart Components high flow thermostat, there is not room for drilling holes.
Click to expand...


you don,t need to drill the holes in that style T-stat the factory already does it for you!
 
Rick, what did you do about the water pump bypass channel? Did you block it with a 1/8" NPT plug in the block?
Chevrolet built in this bypass so that some coolant would flow while the engine is cold during warmup.
This, combined with your additional holes in the thermostat bypasses quite a bit of coolant. And since you have no
closed engine compartment, you don't have trapped underhood heat to deal with. As Grumpy said:
Grumpy said:
now drilling a couple 3/32" holes in the flange INSURES that the t-states fully engulfed in coolant , where a t-stat without the holes may and in many cases will delay the t-stat opening because only static/ stationary mass of coolant temporarily trapped behind it can trigger its temp sensitive function.
Click to expand...
That is what that bypass channel does. Except it makes cylinder #2 run colder than the rest. You might want to block
this channel, because you are already doing this with the holes in the thermostat. Is this passage drilled open on your Dart block?

0408sc_pump_04_z.jpg 0408sc_pump_08_z.jpg CoolantBypass.jpg frontofmotorserntinebeltsystem.jpg
 
Brian's advice is to go for a drive on a safe 2 lane test road where it's safe to get up to 80 mph. Fill up with your 95 octane brew, drive up to 80 part throttle, hold for 10 seconds, then let off throttle and coast down to 40 not touching brakes. Speed back up using part throttle to 80 mph, coast down to 60, speed back up to 80, coast down to 70. Then cruise at 55-70 for 5 minutes and drive home. Pull all 8 plugs, almost guarantee they will be dry and oil free, piston rings fully seated. A top end blast to 100-140 would be best but don't want to get caught in the daytime. Midnight run only to 140, Brian said so :)
 
I would use 11.5 gal of 91, then 4 gal of 110, I figure that will give you 95.90 octane. If I remember right the beer keg is 15.5 gallons right?
 
I have almost Zero Blowby with the Moroso water restrictor plate in place now Rick.
Checked by pulling the PCV Valve out after cold start till water temps are 140-160 F.
Before and after results .
Pretty amazing for me because the Olds 425 is 51 years old now.
Never been rebuilt.

You have to experiment.
As I did.

It hasn't been this Hot steady since 2012 here
I am upgrading to a Mechanical Flex Fan.
Found a Good one rated to 8,000 rpms.
Come fall remove water restrictor plate. And reinstall the 180 F T-stat.
 
Using 91octane Ethanol free here too.
Cranking compession on mine is 180-185 psi with factory cast iron heads.
 
You must log in or register to reply here.
Back
Top