Blown head gasket
08-26-2014, 02:19 PM
#21
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Hey MT, Tried to call you a few days ago, went to your vm. I upped the primary to 91/92 and 95 on the rear and I still have pv's. Ran in on the water this morning running my 3 blade 27, bumped the timing back to 26 total, ran 72 at 5000 at 5 1/2 lbs of boost on FLAT water. I am wondering if it would live with the smaller pulley and the larger jets/timing. If I put on my 24 on that is double cupped I can get 6000 out of her and get 80/82mph depending on chop..
With the smaller pulley I was getting 7 1/2 lbs and spinning the 27 5300/5400 and that was about 80/82 depending on chop.
The motor sounds happy so I might just leave it alone at this point. Like you have said about 10 TIMES, I'm at the end of the rope with this set up. My best was 83 gps with the smaller pulley in good chop.
With the smaller pulley I was getting 7 1/2 lbs and spinning the 27 5300/5400 and that was about 80/82 depending on chop.
The motor sounds happy so I might just leave it alone at this point. Like you have said about 10 TIMES, I'm at the end of the rope with this set up. My best was 83 gps with the smaller pulley in good chop.
08-26-2014, 03:35 PM
#23
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I was running 28 total. My motor has 9:1 maybe a bit more. I was told by Dean Nickerson {builder/carb guy} lwith an 8:5 to1 @ 5lbs that would push comp to 13:5/14:1. On premium fuel I'm past the limit. I was running 7.5lbs at 28 and took out intake valves. Granted that was with 92 with pv's on secondary and I now have 95's with pv's. Would that jet change been enough to cool the cylinders? I don't know......
08-26-2014, 03:56 PM
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Timing and jet will only crutch you so much. The hot air will eventually lead to detonation no matter how rich or how lazy the timing. Unless you want to up the octane of your fuel of course, but you will still be leaving power on the table. Engines don't make power off of boost, they make it off of airflow, and hot air brings your airflow down and your combustion temps up no matter how you cut it.
08-26-2014, 04:18 PM
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Seems like a few guys that have by-pass tube for the water pump have put dumps on the rear intake water jackets to help water flow in the back on the block and cool 7 and 8. One guy I spoke to told me his buddy had a BIG problem with 7/8 on four builds. Installed the dumps and problem solved. Something to think about ........
08-26-2014, 08:39 PM
#26
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+1
Seems like a few guys that have by-pass tube for the water pump have put dumps on the rear intake water jackets to help water flow in the back on the block and cool 7 and 8. One guy I spoke to told me his buddy had a BIG problem with 7/8 on four builds. Installed the dumps and problem solved. Something to think about ........
08-30-2014, 08:43 AM
#27
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Sorry I missed your call, its been a crazy week here.
Ok, theres a few things we need to look at here, for the big picture of what you have there.
Boost pressure in the manifold, is NOT the end all answer. I say this, because many tend to look at things like 8.5:1, with 5lbs of boost max. Its not that simple.
Not all blowers are created equal. A small blower, like you have, is going to generate a TON more hot air, than if you had, say an 8-71 on it. So, a 174 spinning like crazy, is gonna cause detonation much sooner than a 8-71 that may be underdriven at that point. The larger blower, may be able to run 8lbs of boost on your setup, on pump gas, and not hurt the engine, where as the 174 blower, may cause issues at 6lbs of boost. This is why with modern whipples, centrifugals, you can run more boost. The air is simply cooler.
Aside from the fact the 174 is struggling to make boost on a 489ci engine, (especially anything over 5psi), the fuel distribution is horrible, and even more with a superchiller. Retarding the timing to 26*, is a pretty good way to start tuliping exhaust valves. Retarded timing, is not the answer.
As far as the rear water dumps go. I agree they do not hurt, and I think they are a great help on a siamese cylinder block, like a 502. A 454 based block, doesnt have siamese cylinder walls, and cool a little better around the cylinder. Main thing they do is help prevent steam pockets from forming.As far as mercury's supercharged engines, like the 525sc, 600sc, 800sc, 575sci, those did not have rear water dumps, and also didnt melt #7/#8 pistons.
My advice would be this. IF you must keep that blower/carb combo, simply back the boost down to 5lbs, timing at 30*, and throw some big jets in there. Especially in the secondary side. Alot of people get scared of running it too rich on the big end, as for washing the rings out of it, and diluting the oil. My theory is though, at 5500RPM, you're not washing anything down past the rings. The extra fuel is being blown out the tail pipes. Now, you dont want a super rich idle, or low speed AFR, but a bit extra fuel on the big end, may prevent you from ripping this thing apart every season.
Now, if you are serious about keeping the engine healthy, being able to make some good honest power, I'd ditch the blower combo you have. I understand everyone is on a budget, as am I. But a great bang for the buck blower, is a 420 B&M. You can find them very reasonable. Sometimes complete with carbs and intakes for 2500 bucks. By going to that blower, which is close in size to a 8-71, you not only will dramatically lower your intake temps, but you're fuel distribution will be MUCH better. Your engine will pick up a bunch of power, pound for pound of boost. 6lbs with what you have, will not make as much power as the 420 at 6lbs.
Roots blown stuff likes big carbs. Perfect example. Last weekend, I was running my boat. I noticed my starboard engine, was only hitting 5lbs. (always at 6lbs). I starting thinking the blower was tired or hurt. I got back to the dock, and started looking around. Turned out while I changed jets prior to the weekend, I had pinched the secondary accelerator pump linkage on one carb, and it was keeping the secondarys on one carb from opening (twin 850's). So, my one engine, was really working of 6 barrels instead of all 8, or lets say instead of 1700CFM, I had 1275cfm of airflow. That was enough to make my engine down on power from 3500-5500RPM. These are 468 engines, not 598's either. Theres also proven theories that on roots blowers, if you undercarb them, the air temp in the manifold will go up.
Back in the day, your typical 250 blower, single dominator carb, was pretty much maxed out at 700HP, regardless of what engine was under it. A 489, with the right cam, heads, blower, is fully capable of 750-800hp on pump fuel. But, in your case, you have a blower, and carb, probably capable of no more, than about 600-625hp on pump. A 420 blower with a pair of big carbs, can do 900-1000HP, but thats about it on pump fuel.
Ok, theres a few things we need to look at here, for the big picture of what you have there.
Boost pressure in the manifold, is NOT the end all answer. I say this, because many tend to look at things like 8.5:1, with 5lbs of boost max. Its not that simple.
Not all blowers are created equal. A small blower, like you have, is going to generate a TON more hot air, than if you had, say an 8-71 on it. So, a 174 spinning like crazy, is gonna cause detonation much sooner than a 8-71 that may be underdriven at that point. The larger blower, may be able to run 8lbs of boost on your setup, on pump gas, and not hurt the engine, where as the 174 blower, may cause issues at 6lbs of boost. This is why with modern whipples, centrifugals, you can run more boost. The air is simply cooler.
Aside from the fact the 174 is struggling to make boost on a 489ci engine, (especially anything over 5psi), the fuel distribution is horrible, and even more with a superchiller. Retarding the timing to 26*, is a pretty good way to start tuliping exhaust valves. Retarded timing, is not the answer.
As far as the rear water dumps go. I agree they do not hurt, and I think they are a great help on a siamese cylinder block, like a 502. A 454 based block, doesnt have siamese cylinder walls, and cool a little better around the cylinder. Main thing they do is help prevent steam pockets from forming.As far as mercury's supercharged engines, like the 525sc, 600sc, 800sc, 575sci, those did not have rear water dumps, and also didnt melt #7/#8 pistons.
My advice would be this. IF you must keep that blower/carb combo, simply back the boost down to 5lbs, timing at 30*, and throw some big jets in there. Especially in the secondary side. Alot of people get scared of running it too rich on the big end, as for washing the rings out of it, and diluting the oil. My theory is though, at 5500RPM, you're not washing anything down past the rings. The extra fuel is being blown out the tail pipes. Now, you dont want a super rich idle, or low speed AFR, but a bit extra fuel on the big end, may prevent you from ripping this thing apart every season.
Now, if you are serious about keeping the engine healthy, being able to make some good honest power, I'd ditch the blower combo you have. I understand everyone is on a budget, as am I. But a great bang for the buck blower, is a 420 B&M. You can find them very reasonable. Sometimes complete with carbs and intakes for 2500 bucks. By going to that blower, which is close in size to a 8-71, you not only will dramatically lower your intake temps, but you're fuel distribution will be MUCH better. Your engine will pick up a bunch of power, pound for pound of boost. 6lbs with what you have, will not make as much power as the 420 at 6lbs.
Roots blown stuff likes big carbs. Perfect example. Last weekend, I was running my boat. I noticed my starboard engine, was only hitting 5lbs. (always at 6lbs). I starting thinking the blower was tired or hurt. I got back to the dock, and started looking around. Turned out while I changed jets prior to the weekend, I had pinched the secondary accelerator pump linkage on one carb, and it was keeping the secondarys on one carb from opening (twin 850's). So, my one engine, was really working of 6 barrels instead of all 8, or lets say instead of 1700CFM, I had 1275cfm of airflow. That was enough to make my engine down on power from 3500-5500RPM. These are 468 engines, not 598's either. Theres also proven theories that on roots blowers, if you undercarb them, the air temp in the manifold will go up.
Back in the day, your typical 250 blower, single dominator carb, was pretty much maxed out at 700HP, regardless of what engine was under it. A 489, with the right cam, heads, blower, is fully capable of 750-800hp on pump fuel. But, in your case, you have a blower, and carb, probably capable of no more, than about 600-625hp on pump. A 420 blower with a pair of big carbs, can do 900-1000HP, but thats about it on pump fuel.
08-30-2014, 11:41 AM
#28
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Sorry I missed your call, its been a crazy week here.
Ok, theres a few things we need to look at here, for the big picture of what you have there.
Boost pressure in the manifold, is NOT the end all answer. I say this, because many tend to look at things like 8.5:1, with 5lbs of boost max. Its not that simple.
Not all blowers are created equal. A small blower, like you have, is going to generate a TON more hot air, than if you had, say an 8-71 on it. So, a 174 spinning like crazy, is gonna cause detonation much sooner than a 8-71 that may be underdriven at that point. The larger blower, may be able to run 8lbs of boost on your setup, on pump gas, and not hurt the engine, where as the 174 blower, may cause issues at 6lbs of boost. This is why with modern whipples, centrifugals, you can run more boost. The air is simply cooler.
Aside from the fact the 174 is struggling to make boost on a 489ci engine, (especially anything over 5psi), the fuel distribution is horrible, and even more with a superchiller. Retarding the timing to 26*, is a pretty good way to start tuliping exhaust valves. Retarded timing, is not the answer.
As far as the rear water dumps go. I agree they do not hurt, and I think they are a great help on a siamese cylinder block, like a 502. A 454 based block, doesnt have siamese cylinder walls, and cool a little better around the cylinder. Main thing they do is help prevent steam pockets from forming.As far as mercury's supercharged engines, like the 525sc, 600sc, 800sc, 575sci, those did not have rear water dumps, and also didnt melt #7/#8 pistons.
My advice would be this. IF you must keep that blower/carb combo, simply back the boost down to 5lbs, timing at 30*, and throw some big jets in there. Especially in the secondary side. Alot of people get scared of running it too rich on the big end, as for washing the rings out of it, and diluting the oil. My theory is though, at 5500RPM, you're not washing anything down past the rings. The extra fuel is being blown out the tail pipes. Now, you dont want a super rich idle, or low speed AFR, but a bit extra fuel on the big end, may prevent you from ripping this thing apart every season.
Now, if you are serious about keeping the engine healthy, being able to make some good honest power, I'd ditch the blower combo you have. I understand everyone is on a budget, as am I. But a great bang for the buck blower, is a 420 B&M. You can find them very reasonable. Sometimes complete with carbs and intakes for 2500 bucks. By going to that blower, which is close in size to a 8-71, you not only will dramatically lower your intake temps, but you're fuel distribution will be MUCH better. Your engine will pick up a bunch of power, pound for pound of boost. 6lbs with what you have, will not make as much power as the 420 at 6lbs.
Roots blown stuff likes big carbs. Perfect example. Last weekend, I was running my boat. I noticed my starboard engine, was only hitting 5lbs. (always at 6lbs). I starting thinking the blower was tired or hurt. I got back to the dock, and started looking around. Turned out while I changed jets prior to the weekend, I had pinched the secondary accelerator pump linkage on one carb, and it was keeping the secondarys on one carb from opening (twin 850's). So, my one engine, was really working of 6 barrels instead of all 8, or lets say instead of 1700CFM, I had 1275cfm of airflow. That was enough to make my engine down on power from 3500-5500RPM. These are 468 engines, not 598's either. Theres also proven theories that on roots blowers, if you undercarb them, the air temp in the manifold will go up.
Back in the day, your typical 250 blower, single dominator carb, was pretty much maxed out at 700HP, regardless of what engine was under it. A 489, with the right cam, heads, blower, is fully capable of 750-800hp on pump fuel. But, in your case, you have a blower, and carb, probably capable of no more, than about 600-625hp on pump. A 420 blower with a pair of big carbs, can do 900-1000HP, but thats about it on pump fuel.
Ok, theres a few things we need to look at here, for the big picture of what you have there.
Boost pressure in the manifold, is NOT the end all answer. I say this, because many tend to look at things like 8.5:1, with 5lbs of boost max. Its not that simple.
Not all blowers are created equal. A small blower, like you have, is going to generate a TON more hot air, than if you had, say an 8-71 on it. So, a 174 spinning like crazy, is gonna cause detonation much sooner than a 8-71 that may be underdriven at that point. The larger blower, may be able to run 8lbs of boost on your setup, on pump gas, and not hurt the engine, where as the 174 blower, may cause issues at 6lbs of boost. This is why with modern whipples, centrifugals, you can run more boost. The air is simply cooler.
Aside from the fact the 174 is struggling to make boost on a 489ci engine, (especially anything over 5psi), the fuel distribution is horrible, and even more with a superchiller. Retarding the timing to 26*, is a pretty good way to start tuliping exhaust valves. Retarded timing, is not the answer.
As far as the rear water dumps go. I agree they do not hurt, and I think they are a great help on a siamese cylinder block, like a 502. A 454 based block, doesnt have siamese cylinder walls, and cool a little better around the cylinder. Main thing they do is help prevent steam pockets from forming.As far as mercury's supercharged engines, like the 525sc, 600sc, 800sc, 575sci, those did not have rear water dumps, and also didnt melt #7/#8 pistons.
My advice would be this. IF you must keep that blower/carb combo, simply back the boost down to 5lbs, timing at 30*, and throw some big jets in there. Especially in the secondary side. Alot of people get scared of running it too rich on the big end, as for washing the rings out of it, and diluting the oil. My theory is though, at 5500RPM, you're not washing anything down past the rings. The extra fuel is being blown out the tail pipes. Now, you dont want a super rich idle, or low speed AFR, but a bit extra fuel on the big end, may prevent you from ripping this thing apart every season.
Now, if you are serious about keeping the engine healthy, being able to make some good honest power, I'd ditch the blower combo you have. I understand everyone is on a budget, as am I. But a great bang for the buck blower, is a 420 B&M. You can find them very reasonable. Sometimes complete with carbs and intakes for 2500 bucks. By going to that blower, which is close in size to a 8-71, you not only will dramatically lower your intake temps, but you're fuel distribution will be MUCH better. Your engine will pick up a bunch of power, pound for pound of boost. 6lbs with what you have, will not make as much power as the 420 at 6lbs.
Roots blown stuff likes big carbs. Perfect example. Last weekend, I was running my boat. I noticed my starboard engine, was only hitting 5lbs. (always at 6lbs). I starting thinking the blower was tired or hurt. I got back to the dock, and started looking around. Turned out while I changed jets prior to the weekend, I had pinched the secondary accelerator pump linkage on one carb, and it was keeping the secondarys on one carb from opening (twin 850's). So, my one engine, was really working of 6 barrels instead of all 8, or lets say instead of 1700CFM, I had 1275cfm of airflow. That was enough to make my engine down on power from 3500-5500RPM. These are 468 engines, not 598's either. Theres also proven theories that on roots blowers, if you undercarb them, the air temp in the manifold will go up.
Back in the day, your typical 250 blower, single dominator carb, was pretty much maxed out at 700HP, regardless of what engine was under it. A 489, with the right cam, heads, blower, is fully capable of 750-800hp on pump fuel. But, in your case, you have a blower, and carb, probably capable of no more, than about 600-625hp on pump. A 420 blower with a pair of big carbs, can do 900-1000HP, but thats about it on pump fuel.
A+ post right there!
09-01-2014, 12:49 PM
#29
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Thanks MT for the info and hope you had a good weekend! You are a BIG help! Will bump the timing back up to 30. Changed jets on Thursday to 92/91 on the frt and 95 on the rear. Ran all weekend and kept an eye on the plugs. a bit dark but way better then hurting something. Pulled hard and was low 70's @ 5000rpm. I'll keep you posted.
09-01-2014, 04:06 PM
#30
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Also, be careful with plug readings. They can be deceiving, especially with the gas we get today.
http://www.dragstuff.com/techarticle...ead-plugs.html
http://www.dragstuff.com/techarticle...ead-plugs.html
