S&S Strker compression questions
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Joined: Nov 2009
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From: Farmington ,MS
I don't think they make "low compression" pistons for a 98" motor. Lowest I can find is 8.9...most of the 98 kits came with 9.7...what compression do you have now? Still say a spyke starter will fire it right up...completely different gear reduction than stock type starter.
http://www.jpcycles.com/product/380-832
Displacement: 98"
- Stroke: 4-3/4"
- Flywheel Diameter: 8-1/4"
- Compression Ratio: 8.9:1
- Cylinder Length (SH and P series engines): 5.530"
Last edited by Tom84FXST; Oct 30, 2013 at 05:40 AM.
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5th Gear
Joined: Oct 2013
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From: Leipsic, OH
I had a good conversation with Al at S&S tech support yesterday. Great guy and very helpful. We decoded my serial number (it was a factory built long block).
They pistons are the cast, lower compression units. The cam is an S&S 560S which already has pretty good overlap. In our conversation, Al was suspect of the Comp Cams era Velva Touch lifters. He commented that at that time there were some quality control issues and there is a problem with excessive leak down that could result ill timed valve opening until they pump up resulting in high static compression on start up. He suggested getting the lifters to zero lash with the plungers bottomed and trying that to see whether or not that was the culprit. He mentioned that he had built a 98" very similar to mine and a stock Prestolite with XL fields coils rolled it right over.
I guess I need to check that out. Hydro lifters drive me nuts. About ready to try solids. I can put up with a little clatter if things are running like they should...
They pistons are the cast, lower compression units. The cam is an S&S 560S which already has pretty good overlap. In our conversation, Al was suspect of the Comp Cams era Velva Touch lifters. He commented that at that time there were some quality control issues and there is a problem with excessive leak down that could result ill timed valve opening until they pump up resulting in high static compression on start up. He suggested getting the lifters to zero lash with the plungers bottomed and trying that to see whether or not that was the culprit. He mentioned that he had built a 98" very similar to mine and a stock Prestolite with XL fields coils rolled it right over.
I guess I need to check that out. Hydro lifters drive me nuts. About ready to try solids. I can put up with a little clatter if things are running like they should...
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Joined: Mar 2009
Posts: 66,131
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From: Niles Canyon Ca.
I don't think they make "low compression" pistons for a 98" motor. Lowest I can find is 8.9...most of the 98 kits came with 9.7...what compression do you have now? Still say a spyke starter will fire it right up...completely different gear reduction than stock type starter.
http://www.jpcycles.com/product/380-832
Displacement: 98"
http://www.jpcycles.com/product/380-832
Displacement: 98"
- Stroke: 4-3/4"
- Flywheel Diameter: 8-1/4"
- Compression Ratio: 8.9:1
- Cylinder Length (SH and P series engines): 5.530"
The Spyke is still a 1.4KV starter just like the Ultima ( which I tried with no love )and the All ***** OEM style which is in mine now and a 600CCA Lithium battery from Antigravity also and it struggles to turn it over cold , other times spins it like the plugs are out .
Mines only a 93" but my cold static compression is 195 a hole which works out the ratio to be about 11-1 . on a shovel this ****'s hard on the starting system , the kicker and my 230lbs on the hoof is what fires her cold after that the button works fine .
OP consider compression releases , It's the route I'm going later this winter . I'm going to drop one of the dual plugs in mine and install them . We are fighting the same battle and I have been a while now , looked at all the options and it's the best compromise all round .
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Ben E
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Nov 25, 2011 06:19 AM
