Spark Plug Heat ranges, what gains have you made?

[MoJo Risen]

I also forgot to mention the colder plugs vs the standard plugs give me a full CC less combustion chamber volume.
This increases static combustion ratio, almost always positive.

I feel like stockers should be able to submit their own spark plugs to compliment the shape of their combustion chambers, just like people submitting their own piston variations in Stock.

Btw...
Has anybody been caught moving their piston pin offset/location in Stock yet?

[Stan Weiss]

A wrist pin offset normally is 0.060" to 0.080". When people reverse the wrist pin offset (do people still do this in stock?) this moves the pin center line 0.120" to 0.160" they may see a very small difference. Lets look at a 0.060" reverse and we a talking a little under 1 degree change in Piston TDC to crank journal TDC

Bore = 4.0 Stroke = 3.25 Rod Length = 5.7
Actual Piston Stroke 3.25019600382
Cylinder Volume 40.843168 CI 669.299602 cc
Engine Size 326.745340 CI 5354.396814 cc

Wrist Pin Offset = 0.06
Crank Angle Piston TDC -0.46932221356 Piston BDC 179.15635067565

Wrist Pin Offset = -0.06
Crank Angle Piston TDC 0.46932221356 Piston BDC 180.84364932435

Where you can really see a difference is with an inline motorcycle engine where the crank line has been moved 10 mm.

Stan

[MoJo Risen]

Originally Posted by Stan Weiss

A wrist pin offset normally is 0.060" to 0.080". When people reverse the wrist pin offset (do people still do this in stock?) this moves the pin center line 0.120" to 0.160" they may see a very small difference. Lets look at a 0.060" reverse and we a talking a little under 1 degree change in Piston TDC to crank journal TDC

Bore = 4.0 Stroke = 3.25 Rod Length = 5.7
Actual Piston Stroke 3.25019600382
Cylinder Volume 40.843168 CI 669.299602 cc
Engine Size 326.745340 CI 5354.396814 cc

Wrist Pin Offset = 0.06
Crank Angle Piston TDC -0.46932221356 Piston BDC 179.15635067565

Wrist Pin Offset = -0.06
Crank Angle Piston TDC 0.46932221356 Piston BDC 180.84364932435

Where you can really see a difference is with an inline motorcycle engine where the crank line has been moved 10 mm.

Stan

I honestly don't think NHRA ever checks wrist pin offset in Stock or any other class. It's a gray area. Maybe that's why nobody has ever been bounced for it.

Thank you for your math on the v8 engine offset.

The initial wrist pin offset was to make engines quieter in early days, that particilar offset was the opposite of centerline direction that the offset used to gain leverage and ultimately Horsepower.

It's always been a gray area and until someone comes forward with "they've been bounced for this, then anything goes in my opinion.

[Terry Cain]

Originally Posted by MoJo Risen

I honestly don't think NHRA ever checks wrist pin offset in Stock or any other class. It's a gray area. Maybe that's why nobody has ever been bounced for it.

Thank you for your math on the v8 engine offset.

The initial wrist pin offset was to make engines quieter in early days, that particilar offset was the opposite of centerline direction that the offset used to gain leverage and ultimately Horsepower.

It's always been a gray area and until someone comes forward with "they've been bounced for this, then anything goes in my opinion.

NHRA DOES check wrist pin location. Ask David Walther or Tom West. 1972 winners of div race at Muncie, IN until getting tossed for have stocker pistons in backwards. It's all been tried. Nothing new.

[MoJo Risen]

Originally Posted by Terry Cain

NHRA DOES check wrist pin location. Ask David Walther or Tom West. 1972 winners of div race at Muncie, IN until getting tossed for have stocker pistons in backwards. It's all been tried. Nothing new.

Thank you for some clarity.

Why isn't the stock offset listest in accepted pistion?

[Terry Cain]

Originally Posted by MoJo Risen

Thank you for some clarity.

Why isn't the stock offset listest in accepted pistion?

Probably because it might not be a checking point now. Not sure. Need to ask Tech. Back in 1972 you couldn't run replacment pistons. Had to run OEM.

[MoJo Risen]

Originally Posted by Terry Cain

NHRA DOES check wrist pin location. Ask David Walther or Tom West. 1972 winners of div race at Muncie, IN until getting tossed for have stocker pistons in backwards. It's all been tried. Nothing new.

Thank you for some clarity.

Why isn't the stock offset listed in accepted pistons?

[GTX JOHN]

Pin offset is no longer an issue that Tech is concerned.

[CMcAllister]

It ain't 1972 anymore.

[GTOMayhem]

Originally Posted by Stan Weiss

A wrist pin offset normally is 0.060" to 0.080". When people reverse the wrist pin offset (do people still do this in stock?) this moves the pin center line 0.120" to 0.160" they may see a very small difference. Lets look at a 0.060" reverse and we a talking a little under 1 degree change in Piston TDC to crank journal TDC

Bore = 4.0 Stroke = 3.25 Rod Length = 5.7
Actual Piston Stroke 3.25019600382
Cylinder Volume 40.843168 CI 669.299602 cc
Engine Size 326.745340 CI 5354.396814 cc

Wrist Pin Offset = 0.06
Crank Angle Piston TDC -0.46932221356 Piston BDC 179.15635067565

Wrist Pin Offset = -0.06
Crank Angle Piston TDC 0.46932221356 Piston BDC 180.84364932435

Where you can really see a difference is with an inline motorcycle engine where the crank line has been moved 10 mm.

Stan

Help us slow ones out a little bit. What exactly am I looking at and how would it affect power?


Rick Thomason
GTOMayhem