Side Seal Gap?
06-13-2005, 08:34 AM
#2
Super Moderator
Join Date: Jul 2002
Location: My BIG ol TURBO-DIESEL
Posts: 5,181
Read the FAQ Section, lots of good info there.
https://www.nopistons.com/forums/ind...howtopic=15468
https://www.nopistons.com/forums/ind...howtopic=15468
06-13-2005, 08:37 AM
#3
Fabricator
Join Date: Jan 2004
Location: Central Ohio (Hebron) Zephyrhills Fla.
Posts: 1,322
[quote name='scottystraub' date='Jun 13 2005, 04:33 AM']what is the gap between the side seal and the corner seal??? my new side seals are long and need to be cut down but i done know what the tolerance is.
[/quote]
You are allowed up to .004" in a rebuild. My opinion is that .004" is a disaster and I actually build to zero clearance.
This is not as tight as it sounds. So long as the oiled corner seals and side seals pop back up when depressed, that is enough clearance.
The ends of the side seals wear pockets into the side of the corner seals very quickly and the actual clearance begins to increase as soon as the engine fires.
The corner seal drives the side seal around the engine. So you get the pocket on only one side of the corner seal.
If you used old corner seals, the feeler gage cannot account for the existing pocket depth, and there will be excess clearance very shortly after start up.
If you are not comfortable with zero, use .001"
The loaded seal moves tight to the inside of the groove. The unloaded seals move tight to the outside of the grooves. So the measured zero is acually a bit more than it sounds.
The clearance at high RPM is of small concern, because the time available for gasses to leak passed the clearance gap is so short. At low speed (where most driving is done) this is not the case.
Clean the grooves and corner seal pockets completely. Spend a lot of time getting the seal ends square. Use new springs. Make the first oil dose a straight weight name brand dino oil. No wide open throttle fo 1,000 easy miles. Change oil and filter and go nuts.
In an off the road situation under controlled conditions of course.
Lynn E. Hanover
[snapback]724495[/snapback]
[/quote]
You are allowed up to .004" in a rebuild. My opinion is that .004" is a disaster and I actually build to zero clearance.
This is not as tight as it sounds. So long as the oiled corner seals and side seals pop back up when depressed, that is enough clearance.
The ends of the side seals wear pockets into the side of the corner seals very quickly and the actual clearance begins to increase as soon as the engine fires.
The corner seal drives the side seal around the engine. So you get the pocket on only one side of the corner seal.
If you used old corner seals, the feeler gage cannot account for the existing pocket depth, and there will be excess clearance very shortly after start up.
If you are not comfortable with zero, use .001"
The loaded seal moves tight to the inside of the groove. The unloaded seals move tight to the outside of the grooves. So the measured zero is acually a bit more than it sounds.
The clearance at high RPM is of small concern, because the time available for gasses to leak passed the clearance gap is so short. At low speed (where most driving is done) this is not the case.
Clean the grooves and corner seal pockets completely. Spend a lot of time getting the seal ends square. Use new springs. Make the first oil dose a straight weight name brand dino oil. No wide open throttle fo 1,000 easy miles. Change oil and filter and go nuts.
In an off the road situation under controlled conditions of course.
Lynn E. Hanover
06-13-2005, 11:24 AM
#5
Senior Member
Join Date: Nov 2002
Location: Honolulu, Hawaii USA
Posts: 925
I personally try to shoot for 0.002" to 0.003" - tighter the better.
0.004" is too much, and causes a lot of blowby and headaches.
I find anything under 0.001" tends to bind too much for my tastes.
0.0015" is about as tight I would go.
-Ted
0.004" is too much, and causes a lot of blowby and headaches.
I find anything under 0.001" tends to bind too much for my tastes.
0.0015" is about as tight I would go.
-Ted
06-14-2005, 01:22 AM
#8
Senior Member
Join Date: Jun 2003
Location: Grand Prairie, TX
Posts: 917
[quote name='scottystraub' date='Jun 13 2005, 04:33 AM']what is the gap between the side seal and the corner seal??? my new side seals are long and need to be cut down but i done know what the tolerance is.
[/quote]
Some people recommend 0.0025" to 0.003", Mazda's is no more than 0.006".
B
[snapback]724495[/snapback]
[/quote]
Some people recommend 0.0025" to 0.003", Mazda's is no more than 0.006".
B
06-14-2005, 01:23 AM
#9
Senior Member
Join Date: Jun 2003
Location: Grand Prairie, TX
Posts: 917
[quote name='scottystraub' date='Jun 13 2005, 10:49 AM']do you measure the gap on both sides, or slide the seal to one side and then measure? .003 on both sides would be .006 overall? i will shoot for .001, can you get a .001 feeler gauge? thanks for the info guys
[/quote]
Measure just one side.
B
[snapback]724699[/snapback]
[/quote]
Measure just one side.
B
06-14-2005, 10:22 AM
#10
Fabricator
Join Date: Jan 2004
Location: Central Ohio (Hebron) Zephyrhills Fla.
Posts: 1,322
[quote name='banzaitoyota' date='Jun 13 2005, 05:58 AM']Lynn, What about someting like this to get the equivlent of a true "zero gap"??
[attachment=31763:attachment]
[/quote]
Yes, this is the ideal situation. The specs need not be too close as the leakdown time is so short. I thought of this years ago, for another reason.
Suppose that the notch in the corner seal were only half the thickness of the side seal. The the end of the side seal were to be notched half way through so it could sit in the notch on the side of the corner seal so that when unsupported by the iron on the short side of a giant street port, the side seal could not extend into the port.
Then just support about 1/3 of the corner seal and still have the reliable long lasting GIANT street port.
So once in the Florida shop I will acquire the mini mill I have been wanting for so long. And give it a try.
I apperantly was not the first to think of this, because the SCCA just published photos of a legal street port for E production and if the junction of the side seal and corner seal is visible through the intake port, the port is illegal.
So it was being done by others before I thought of it.
Need I suggest pinning the corner seal in its hole with a loose fitting roll pin and supporting the side seals as above so that there would be no need to support the corner seal at all? How big could the port be then?
I've got a million of them.....
Lynn E. Hanover
[attachment=31763:attachment]
[snapback]724521[/snapback]
[/quote]
Yes, this is the ideal situation. The specs need not be too close as the leakdown time is so short. I thought of this years ago, for another reason.
Suppose that the notch in the corner seal were only half the thickness of the side seal. The the end of the side seal were to be notched half way through so it could sit in the notch on the side of the corner seal so that when unsupported by the iron on the short side of a giant street port, the side seal could not extend into the port.
Then just support about 1/3 of the corner seal and still have the reliable long lasting GIANT street port.
So once in the Florida shop I will acquire the mini mill I have been wanting for so long. And give it a try.
I apperantly was not the first to think of this, because the SCCA just published photos of a legal street port for E production and if the junction of the side seal and corner seal is visible through the intake port, the port is illegal.
So it was being done by others before I thought of it.
Need I suggest pinning the corner seal in its hole with a loose fitting roll pin and supporting the side seals as above so that there would be no need to support the corner seal at all? How big could the port be then?
I've got a million of them.....
Lynn E. Hanover