383 Stroker Cooling Woes
07-16-2002, 12:24 PM
#1
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383 Stroker Cooling Woes
I recently built a small-block Chevy 383 I/O engine for our 1990 Larson Senza 210LX. The engine is rollerized (rockers and lifters), has a .528"/ .509" lift Crane cam (112 LSA), and runs 9.2:1 compression thru Torquer heads, exhausting through a GIL Marine Magnum Choice. The engine Dyno'd at 380 HP and 450 ft lbs of Torque. The new engine really woke up the boat and we are pleased. I know that I am on borrowed time with the outdrive, as it is a 1989 Alpha I, but after investing $8,500 in the engine, the wife got excited and put a hold on replacing the drive until this winter.
My first concern is that the engine temp is running high at ~ 190- 200F. After seeing the high temp, I replaced the thermostat again, and rebuilt the water pump in the Alpha I (recirc. pump was already new), but the temp continues to run high. I understand that the 350 Magnum and Big-Blocks use the belt-driven water pump.
Are there any other options left before converting to the belt-driven pump?
How much of a difference in water flow does the belt-driven pump make?
What needs to be done to convert from the Alpha I pump to the belt-driven pump (strip out Alpha I pump guts?)?
The engine has the "Old-Style" thermostat housing w/ check valves in it. What are these for and are they necessary?
The GIL Exhaust instructions had me add "Y" pipes to bring the old manifold & riser cooling hoses together so that the elbows were cooled full-time (not affected by thermostat opening & closing).
I am running a 140 degree thermostat w/ the brass insert.
Alpha I Gen I
My first concern is that the engine temp is running high at ~ 190- 200F. After seeing the high temp, I replaced the thermostat again, and rebuilt the water pump in the Alpha I (recirc. pump was already new), but the temp continues to run high. I understand that the 350 Magnum and Big-Blocks use the belt-driven water pump.
Are there any other options left before converting to the belt-driven pump?
How much of a difference in water flow does the belt-driven pump make?
What needs to be done to convert from the Alpha I pump to the belt-driven pump (strip out Alpha I pump guts?)?
The engine has the "Old-Style" thermostat housing w/ check valves in it. What are these for and are they necessary?
The GIL Exhaust instructions had me add "Y" pipes to bring the old manifold & riser cooling hoses together so that the elbows were cooled full-time (not affected by thermostat opening & closing).
I am running a 140 degree thermostat w/ the brass insert.
Alpha I Gen I
Last edited by 21_senza_383_2; 07-16-2002 at 05:33 PM.
07-16-2002, 12:44 PM
#2
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Your motor sounds almost like mine.. 383 I ended up with the vortec heads, 9.8:1, air gap intake, 750 holley, fuller roller valvetrain with the same cam, but went to 1.6 ratio rockers... for a lift of .543/.563.. and EMI exhaust and a very pissed off alpha LOL! ... Its nice to know what kinda HP your motor makes..
No matter what the engine a alpha always has the impeller in the drive and the bravo drive has the motor drivin pump . I have not had a problem with cooling... mine always runs around 130-140.. almost to cold... I put in a new impeller this winter too...
Could you have a plugged up hose? A hose hooked up wrong?
I know weeds can plug my oil cooler and not let water through, see it on my cousins boat too..
Do you have alot of water coming out of the exhaust? If you don't it might be telling you there might be a restriction some place.
No matter what the engine a alpha always has the impeller in the drive and the bravo drive has the motor drivin pump . I have not had a problem with cooling... mine always runs around 130-140.. almost to cold... I put in a new impeller this winter too...
Could you have a plugged up hose? A hose hooked up wrong?
I know weeds can plug my oil cooler and not let water through, see it on my cousins boat too..
Do you have alot of water coming out of the exhaust? If you don't it might be telling you there might be a restriction some place.
Last edited by traviss; 07-16-2002 at 12:49 PM.
07-16-2002, 01:52 PM
#3
BEACH PARTY / HOLLOWPOINT
Platinum Member
Mine is basically the same setup as Traviss's and I have yet to have any cooling woes and that is with an Alpha. I would look at a blockage somewhere. What temp thermostat are you running in there?
Now, if I may ask... how did you end up spending over $8500 on a small block? I'd love to know what's in there.
Now, if I may ask... how did you end up spending over $8500 on a small block? I'd love to know what's in there.
07-16-2002, 02:20 PM
#4
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I'm running 160 with the 409's. The only difference is my water pickups on the alphas don't have to suck they are pressurized from the remote mount pickups on the bottom. Maybe I lucked out with out knowing it but they still will only be able to move x amount of water.
What thermostat are you running. I have a 140 in mine. My temps are a solid 160 at most speeds. I was missing the brass insert in the thermo housing and my stat wasn't doing anything. I was hard pressed to get about 100. So I know my gauges are accurate. I got 160 after installing the inserts.
A 160 degree stat doesn't fully open until 175-180. Try a 140 if you don't already have one.
What thermostat are you running. I have a 140 in mine. My temps are a solid 160 at most speeds. I was missing the brass insert in the thermo housing and my stat wasn't doing anything. I was hard pressed to get about 100. So I know my gauges are accurate. I got 160 after installing the inserts.
A 160 degree stat doesn't fully open until 175-180. Try a 140 if you don't already have one.
07-16-2002, 05:11 PM
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21 sena 383 2,
Do you have a alpha I or an alpha i gen 2. The alpha i gen 2 has a low pressure high flow design. The gen 2 requires the exhaust to suck the water out of the block. Your gill exhaust may not be the right setup for a gen 2. The water needs to be sucked through the engine. I think a couple of these guys are running the older alpha I with stock exhaust which is a different design. The bravo is a postive pressure pump and very different from the alpha setup.
I was having cooling problems with my alpha i gen 2 and added a bravo pump. I went to full fresh water cooling and i have lots of cooling capacity. I wanted full freshwater because these engines rot so quickly even in fresh water.
If you strip the guts out of your outdrive you need to add a drive shower to cool your outdrive.
The inlet line from the outdrive to the engine is 3/4 with the alpha and 1 1/4 for the bravo. I don't know if the bravo pump will suck enough water in from an alpha drive.
I converted over with a thru fitting. A 1 1/4 Pertco strainer basket that runs through a 1 1/4 shut off vavle with a 1 1/4 hose that runs directly to the bravo pump. The down side to this design is that the boat can sink if the hose comes off going to the bravo pump and you may have too much pressure at speed. Over 30 knts my raw water pressure will run over 30 psi but the heat exchanger is rated for 60 psi so it is not an issue. I don't like over 14 psi in my motor. The vortex intake seals would be easy to overpressurize and fill you motor with water. The advantage to this system is lots of water. My bravo pump is pretty close to water level so the pump doesn't have to run dry to suck the water into it. It also doesn't suck sand because it is not near the prop. At speed the water just flows thru the system and my pump is really just necessary for low speed. I also have tried a 140 and a 160 t-stat and my engine runs better with the 160.
I wish I could give you a bravo drive but if I had one it would be on my boat. Until I get a bravo I am very happy with what I have.
I would put a water pressure guage on your block and start there. I think that water is bypassing your motor and going to your exhaust rather than thru your engine. That y sounds like a bravo setup to me.
Good Luck
Do you have a alpha I or an alpha i gen 2. The alpha i gen 2 has a low pressure high flow design. The gen 2 requires the exhaust to suck the water out of the block. Your gill exhaust may not be the right setup for a gen 2. The water needs to be sucked through the engine. I think a couple of these guys are running the older alpha I with stock exhaust which is a different design. The bravo is a postive pressure pump and very different from the alpha setup.
I was having cooling problems with my alpha i gen 2 and added a bravo pump. I went to full fresh water cooling and i have lots of cooling capacity. I wanted full freshwater because these engines rot so quickly even in fresh water.
If you strip the guts out of your outdrive you need to add a drive shower to cool your outdrive.
The inlet line from the outdrive to the engine is 3/4 with the alpha and 1 1/4 for the bravo. I don't know if the bravo pump will suck enough water in from an alpha drive.
I converted over with a thru fitting. A 1 1/4 Pertco strainer basket that runs through a 1 1/4 shut off vavle with a 1 1/4 hose that runs directly to the bravo pump. The down side to this design is that the boat can sink if the hose comes off going to the bravo pump and you may have too much pressure at speed. Over 30 knts my raw water pressure will run over 30 psi but the heat exchanger is rated for 60 psi so it is not an issue. I don't like over 14 psi in my motor. The vortex intake seals would be easy to overpressurize and fill you motor with water. The advantage to this system is lots of water. My bravo pump is pretty close to water level so the pump doesn't have to run dry to suck the water into it. It also doesn't suck sand because it is not near the prop. At speed the water just flows thru the system and my pump is really just necessary for low speed. I also have tried a 140 and a 160 t-stat and my engine runs better with the 160.
I wish I could give you a bravo drive but if I had one it would be on my boat. Until I get a bravo I am very happy with what I have.
I would put a water pressure guage on your block and start there. I think that water is bypassing your motor and going to your exhaust rather than thru your engine. That y sounds like a bravo setup to me.
Good Luck
07-16-2002, 05:19 PM
#7
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I'm running a 406 with an alpha 1, and I go to 150 and stay there. No cooling issues. I agree with Tom I think you've got a blockage somewhere. I replaced that old style stat housing with an in-expensive stainless unit that I got from boatfix.com. I think it was made by aquapower. It's simple, effective, and looks good.
07-16-2002, 05:36 PM
#8
Toxic FORMULA
Platinum Member
A friend of mine has a 406/alpha and Gil exhaust with the old style thermostat housing with a "y" connection to the exhaust and was running to cold. He had a 120 stat and went to a 140.He does have a Canton 10 qt.pan and BB combo oil & ps cooler , but that shouldn't make that much difference in water temp. only oil temp. The combo you have should work fine, just check for any blockages. I just went through the same thing with one of my BB's (200-210) checked everything from the drive in... found rust in the old thermostat housing. Now I'm back to 150...think I'll do the other to be safe.
Good Luck
Good Luck
07-16-2002, 06:31 PM
#9
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I'm running a 421" with GIL exhaust and a alpha1 gen 2 drive. 140 stat and never get over 160. Stainless Marine stat housing. On your stock housing do not take those little ball shaped diverters out. You'll overheat. Been there, done that with an old motor. How is your temp at idle?
