Cylinder Head Temperatures, Calling on the Brain Trust and they Win! |
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Cylinder Head Temperatures, Calling on the Brain Trust and they Win! |
Mblizzard |
Aug 30 2016, 12:49 PM
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#1
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Advanced Member Group: Members Posts: 3,033 Joined: 28-January 13 From: Knoxville Tn Member No.: 15,438 Region Association: South East States |
OK so I have reviewed the information by Jake regarding cylinder head temperatures http://www.914world.com/specs/JakeRabyHeadTemps.php.
A bit of background. Engine 2056 based on 74 2.0 engine # GA 014782, stock cam, stock FI, fuel pressure at 31 psi, recently added big valve heads, external oil cooler, valves adjusted correctly with engine install, 150+ compression on all cylinders, stock Trans, Evo Muffler, all stock cooling items in place (flaps and tins), running 123 electronic distributor set to the curve for the 0 231 174 011 dizzy which is correct for the 74. Timing seems to be correct using the marks as indicated in the photo below. Likely at about 25 BTDC. At cruise I see temps in the 350-375F range with it being pushed to the higher end and above. On hill climbs it will go quickly to the 400F range and run at that for the duration of the climb. Most I have seen is about 405F. Letting off the throttle quickly brings the temp back down so I have to think the cooling system is working. I would expect a 2056 to run some warmer but not to be consistently in the upper end of the range I am not sure what is causing this. I have seen lower temps on cruise by richening up the mixture. But overall based on the guidance it seems to be running too hot. I have suspicion my AF meter is reading too rich so that might be part of it showing an acceptable AF range but could be going lean under load. Changing out the sensor and will recheck. So given all of that what do I check or where do I start changing things to bring the temps down? Taking a few degrees out of the timing helped but not significantly. Anyone? (IMG:style_emoticons/default/headbang.gif) |
HAM Inc |
Sep 14 2016, 09:20 AM
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#2
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Senior Member Group: Members Posts: 846 Joined: 24-July 06 From: Watkinsville,GA Member No.: 6,499 Region Association: None |
You may have more than one problem causing these temp issues.
Insufficient piston to cylinder clearance will cause oil temps to rise very rapidly. Jugs that aren't normal to the crank axis due to case warpage can cause this issue too. Same effect as insufficient piston clearance. Were these things checked carefully prior to assembly? |
Mblizzard |
Sep 14 2016, 10:11 AM
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#3
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Advanced Member Group: Members Posts: 3,033 Joined: 28-January 13 From: Knoxville Tn Member No.: 15,438 Region Association: South East States |
You may have more than one problem causing these temp issues. Insufficient piston to cylinder clearance will cause oil temps to rise very rapidly. Jugs that aren't normal to the crank axis due to case warpage can cause this issue too. Same effect as insufficient piston clearance. Were these things checked carefully prior to assembly? This engine was dome by Original customs. Essentially a new top end (taken to a 2056) to a good running bottom half. I am sure Mark checked the pistons and such before assembling the top half using the new AA 96 mm cylinders. This engine has always seemed to run hotter than expected but the external oil cooler seemed to address the oil temps. When running on a 95 F day with the external oil cooler fan running, the temp will go up to the upper end of the M on the gauge but never towards overheating or pinging. But I have always thought I hear an odd sound in the engine at times like a knock but no one else has ever been able to hear it. Could be a problem in the bottom? My level of expertize in the recent head replacement was essentially to swap them out and make sure I had no parts left over. |
914_teener |
Sep 14 2016, 01:48 PM
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#4
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914 Guru Group: Members Posts: 5,202 Joined: 31-August 08 From: So. Cal Member No.: 9,489 Region Association: Southern California |
You may have more than one problem causing these temp issues. Insufficient piston to cylinder clearance will cause oil temps to rise very rapidly. Jugs that aren't normal to the crank axis due to case warpage can cause this issue too. Same effect as insufficient piston clearance. Were these things checked carefully prior to assembly? This engine was dome by Original customs. Essentially a new top end (taken to a 2056) to a good running bottom half. I am sure Mark checked the pistons and such before assembling the top half using the new AA 96 mm cylinders. This engine has always seemed to run hotter than expected but the external oil cooler seemed to address the oil temps. When running on a 95 F day with the external oil cooler fan running, the temp will go up to the upper end of the M on the gauge but never towards overheating or pinging. But I have always thought I hear an odd sound in the engine at times like a knock but no one else has ever been able to hear it. Could be a problem in the bottom? My level of expertize in the recent head replacement was essentially to swap them out and make sure I had no parts left over. So...you recently swapped out the heads? Did you set the deck height? |
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