HOT exhaust

[maddad]

With all the other motors in my boat, as I would flush the motor on the trailer, you could wash your hands with the water from the exhaust and it would feel like very warm tap water. Now it is at uncomfortably hot.
My cranking compression is 188-190 lbs.,timing is 14*+18* for 32* total.
Is there a way to cool my exhaust temps without retarding the cam?
Motor is 413ci SBC, cam is Comp X4270H set straight up.
Would fattening the carb or moving the timing help?
I have a 140* thermostat and removing it did not change anything.
:confused::boggled:

[mrfixxall]

With all the other motors in my boat, as I would flush the motor on the trailer, you could wash your hands with the water from the exhaust and it would feel like very warm tap water. Now it is at uncomfortably hot.
My cranking compression is 188-190 lbs.,timing is 14*+18* for 32* total.
Is there a way to cool my exhaust temps without retarding the cam?
Motor is 413ci SBC, cam is Comp X4270H set straight up.
Would fattening the carb or moving the timing help?
I have a 140* thermostat and removing it did not change anything.
:confused::boggled:


whos block are you running? i dont have a t-stat in mine,,i run a restrictor plate in my 355,,more timing and 165-175 cranking compression and 36 deg of total timing....been running for 7 yrs now like that and the old engine with just a restrictor for 14 yrs and probably would ave still been if i didnt want more power...moroso make them or you can knock the center out of a old t-stat..

Permimum fuel will lower cyl temps and advancing the timing can too along with fatting up the mixture..

[MOP]

Mike what risers are you running, may need to open up the outlets to let a little more water through.

Phil

[glashole]

does the motor run hot??
or are you just concerned about the exhaust water temp?

[maddad]

mrfixall, I use premium fuel already. Someone told me that a bit more advance would leave the heat in the motor, and not in the exhaust, thats why I asked. I like the idea of a thermostat for quicker warm ups and more stable temps in the block. Do you think 34* would make a difference?
Phil, I have a Stainless Marine set up and outflow does not seem to be a problem. This set up includes a crossover with bypass and thermostat housing.
Glashole, the motor temps are steady 145* until it's over 4500, then it gets to 150-155*, but settles back down fast with less throttle. It's just the water out the back is very hot and steamy, vs. all the other motors I've had.
The water out the back is hot at idle on the hose, at idle in the water, and at 3500 rpm underway.(thanks Fred, for checking that)
I'm concerned that this had something to do with melting the plastic fittings on my exhaust manifolds earlier this summer.

[MOP]

Not sure about the timing thing but I am running 34 using 89 with 9.125, the move from 32 to 34 did not seem to make any difference.

Phil

[maddad]

Phil, on the dyno the motor was set at 34 and all was good, but with the ultra 24" I'm using, I don't need max output. When I did a compression test and came up with such high numbers(8-10 lbs. higher than on the dyno),I felt I was to close to a problem zone. That's when I backed off the timing and wanted to go richer. By this weekend, I'll have a Solas prop and don't want to have more of a heat issue because of the extra load.

[mrfixxall]

mrfixall, I use premium fuel already. Someone told me that a bit more advance would leave the heat in the motor, and not in the exhaust, thats why I asked. I like the idea of a thermostat for quicker warm ups and more stable temps in the block. Do you think 34* would make a difference?
Phil, I have a Stainless Marine set up and outflow does not seem to be a problem. This set up includes a crossover with bypass and thermostat housing.
Glashole, the motor temps are steady 145* until it's over 4500, then it gets to 150-155*, but settles back down fast with less throttle. It's just the water out the back is very hot and steamy, vs. all the other motors I've had.
The water out the back is hot at idle on the hose, at idle in the water, and at 3500 rpm underway.(thanks Fred, for checking that)
I'm concerned that this had something to do with melting the plastic fittings on my exhaust manifolds earlier this summer.

First thing you should have brass fittings in on your exhaust hoses,,the ones your running are probably for fresh water so get rid of the plastic fittings or they will melt again and get the brass ones..

are you running alunimum heads? you shave one point of compression,,in other words they disapate the heat faster then a cast iron head and you can run more timing...i have mine at 36 deg but my temps run around 120 at idle and 130 at 6200 rpm (the motor likes rpms)

try running a little more timing your motor is not like some others motors on here and they all react differant do to the mods we have done..

[maddad]

mrfixxall, I have cast iron heads. I use the plastic because Allan Brown at Stainless said using bronze fittings in an aluminium manifold with warm salt water would make quick work of the female aluminium threads.
I tried running the motor with no thermostat and got temps between 110-130*. It made no change in the exhaust water temp.
I will try adding some timing this weekend.
Will a jet change also help?
Let me add that after running a while, the manifolds and risers are not cool enough to leave your hand on for more than a few seconds.

[glashole]

have you considered washing your hands in the sink rather than with the exhaust? :confused:

:)

[mrfixxall]

[QUOTE=maddad;421997]mrfixxall, I have cast iron heads. I use the plastic because Allan Brown at Stainless said using bronze fittings in an aluminium manifold with warm salt water would make quick work of the female aluminium threads.
I tried running the motor with no thermostat and got temps between 110-130*. It made no change in the exhaust water temp.
I will try adding some timing this weekend.
Will a jet change also help?
Let me add that after running a while, the manifolds and risers are not cool enough to leave your hand on for more than a few seconds.[/QUOT


are they white plastic fittings? 90 deg or straight?mercruiser casts alunimum and bronze together in all their intake manifolds for that reason(so salt water doesnt corrode the crossover where the t-stat goes) and ive never seen a problem..

jetting up will make a engine run cooler but not at idle..

Running without a t-stat is not good at leaste a restrictor is required.

steam usually indicates your getting air bubbles from some where..

try using the 90deg black plastic fittings that merc sells for their late model stuff if you dont have them already..

[MOP]

Mike i wonder if some plastic got into where it should not be! Another thing that I myself ran into, my fitting on one riser screwed in to far and slowed the flow. It looked Ok but was not enough to cool the one side, I ground the fitting down length wise and fixed it. Give the site below a shot they have almost any conceivable S/S item you can dream of and are quite reasonable. I got all my ARP S/S engine hardware from them and am very pleased. The S/S is happy with the aluminum!!!

http://www.totallystainless.com/

[maddad]

All the fittings are black plastic, some straight, some 90* and some plugs. Phil, I shook, flushed and blew out the risers and manifolds before I pressure tested them and reinstalled them. The water was hot even before the overheat event. Because the impeller broke up, I even took the crossover off and flushed the block out through the thermostat housing.
I had put a new lower on the 280 leg I'm using at the moment. Could it somehow be letting air in at idle or underway? The water passage through it was pretty straight forward and I didn't have any parts or seals left over. In my sea strainer, there is a bit of air at the top under way, but no bubbles swirling around with the intake flow.

[MOP]

Mike the answer is yes, Volvos will suck air past the O rings on the water transfer tube. Easy test put a clear hose on one side going to the exhaust, you will see no bubble trail until the mid section clears the water as you go on plane. If you have no bubble trail then that is not the problem.

Phil