Previous Thread
Next Thread
Print Thread
WHAT ROD LENGTH? #882271
12/17/10 05:20 AM
12/17/10 05:20 AM
Joined: Nov 2006
Posts: 370
Queensland Australia
M
moparmacka Offline OP
enthusiast
moparmacka  Offline OP
enthusiast
M

Joined: Nov 2006
Posts: 370
Queensland Australia
I know there has been a lot of discussions lately in relation to rod ratio, but I'm after what seems to be the most common rod length/ piston combo when using a stock height SB (340 Resto) with a 4.00 stroke crank using Chev journals? Remembering this will see a fair bit of street time too?

Re: WHAT ROD LENGTH? [Re: moparmacka] #882272
12/17/10 05:40 AM
12/17/10 05:40 AM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
I'm using a 6.125 chevy H-beam for my street/strip
engine with a Diamond piston

Re: WHAT ROD LENGTH? [Re: MR_P_BODY] #882273
12/17/10 09:00 AM
12/17/10 09:00 AM
Joined: Nov 2006
Posts: 370
Queensland Australia
M
moparmacka Offline OP
enthusiast
moparmacka  Offline OP
enthusiast
M

Joined: Nov 2006
Posts: 370
Queensland Australia
Is that around 1.460 comp height for the pistons?

A friend has a set of 6.250 Chev large journal rods at the right price and I figured I need to get custom pistons anyway......

Re: WHAT ROD LENGTH? [Re: moparmacka] #882274
12/17/10 09:10 AM
12/17/10 09:10 AM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
Quote:

Is that around 1.460 comp height for the pistons?

A friend has a set of 6.250 Chev large journal rods at the right price and I figured I need to get custom pistons anyway......




With a stock deck and the 6.125 Diamond has a 1.459
CH for a 4" crank... my block is decked and mine has
a CH 1.383 (I think it is)

Re: WHAT ROD LENGTH? [Re: moparmacka] #882275
12/17/10 02:16 PM
12/17/10 02:16 PM
Joined: Aug 2003
Posts: 43,141
Bend,OR USA
C
Cab_Burge Offline
I Win
Cab_Burge  Offline
I Win
C

Joined: Aug 2003
Posts: 43,141
Bend,OR USA
Quote:

Is that around 1.460 comp height for the pistons?

A friend has a set of 6.250 Chev large journal rods at the right price and I figured I need to get custom pistons anyway......


Like many things in a mans life, longer(especailly on engine connecting rods ) is always way better than shorter using the 6.25 long rod with a 4 inch stroke ends up with a 1.56 rod ratio


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: WHAT ROD LENGTH? [Re: Cab_Burge] #882276
12/17/10 05:41 PM
12/17/10 05:41 PM
Joined: Nov 2006
Posts: 370
Queensland Australia
M
moparmacka Offline OP
enthusiast
moparmacka  Offline OP
enthusiast
M

Joined: Nov 2006
Posts: 370
Queensland Australia
Yes, I was also thinking of the loading of the cyinder walls with a shorter rod with the longer stroke.

Re: WHAT ROD LENGTH? [Re: moparmacka] #882277
12/17/10 05:50 PM
12/17/10 05:50 PM
Joined: Jan 2003
Posts: 6,137
Melbourne , Australia
LA360 Offline
master
LA360  Offline
master

Joined: Jan 2003
Posts: 6,137
Melbourne , Australia
The decrease in piston speed between using a 6.125" and a 6.25" rod would be negligible. If the 6.25" are the right price, that would be reason enough for me.


Alan Jones
Re: WHAT ROD LENGTH? [Re: LA360] #882278
12/17/10 06:02 PM
12/17/10 06:02 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
Quote:

The decrease in piston speed between using a 6.125" and a 6.25" rod would be negligible. If the 6.25" are the right price, that would be reason enough for me.




BUT... can you get a off the shelf piston... you might
be spending more money for pistons VS buying a set of
rods...I had to look at both for my build... I had the
chevy rods and could have bought a off the shelf
piston BUT my block was cut to much so I ended up
having the pin moved for $30 extra... but he MAY be
able to do the same... just got to look at all the
angles

Re: WHAT ROD LENGTH? [Re: moparmacka] #882279
12/17/10 06:17 PM
12/17/10 06:17 PM
Joined: Jul 2010
Posts: 3,502
SOUTH JERSEY
HEMIFRED Offline
master
HEMIFRED  Offline
master

Joined: Jul 2010
Posts: 3,502
SOUTH JERSEY
Quote:

Yes, I was also thinking of the loading of the cyinder walls with a shorter rod with the longer stroke.




for user as a streeter I would stick with combo that does not require any special order pistons or extra machine work.
the returns of juggling rods lengths are not worth the extra money . you can find more per dollar power power returns in head work or other areas


home of the
Sox and Martin Hemi Duster


Re: WHAT ROD LENGTH? [Re: HEMIFRED] #882280
12/17/10 06:22 PM
12/17/10 06:22 PM
Joined: Nov 2006
Posts: 370
Queensland Australia
M
moparmacka Offline OP
enthusiast
moparmacka  Offline OP
enthusiast
M

Joined: Nov 2006
Posts: 370
Queensland Australia
Sorry didn't mention the reason for custom pistons is the heads have 55cc chamber and I will need a custom piston with a larger dish to suit our 98 pump premium and still not not affect the .040" quench, hence me considering the 6.250 rod......if that makes some sense.

Re: WHAT ROD LENGTH? [Re: moparmacka] #882281
12/17/10 06:39 PM
12/17/10 06:39 PM
Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY Offline
Master
MR_P_BODY  Offline
Master

Joined: Jun 2003
Posts: 52,972
Romeo MI
Quote:

Sorry didn't mention the reason for custom pistons is the heads have 55cc chamber and I will need a custom piston with a larger dish to suit our 98 pump premium and still not not affect the .040" quench, hence me considering the 6.250 rod......if that makes some sense.




Just talk to Diamond... I had them reduce the dish
volume, move the pin height and open the valve relief
on a shelf piston... I have a 59cc chamber

Re: WHAT ROD LENGTH? [Re: LA360] #882282
12/17/10 08:01 PM
12/17/10 08:01 PM
Joined: Nov 2006
Posts: 370
Queensland Australia
M
moparmacka Offline OP
enthusiast
moparmacka  Offline OP
enthusiast
M

Joined: Nov 2006
Posts: 370
Queensland Australia
Quote:

The decrease in piston speed between using a 6.125" and a 6.25" rod would be negligible. If the 6.25" are the right price, that would be reason enough for me.




Exactly what I what I was thinking.........

Re: WHAT ROD LENGTH? [Re: MR_P_BODY] #882283
12/17/10 08:04 PM
12/17/10 08:04 PM
Joined: Nov 2006
Posts: 370
Queensland Australia
M
moparmacka Offline OP
enthusiast
moparmacka  Offline OP
enthusiast
M

Joined: Nov 2006
Posts: 370
Queensland Australia
Quote:

Quote:

Sorry didn't mention the reason for custom pistons is the heads have 55cc chamber and I will need a custom piston with a larger dish to suit our 98 pump premium and still not not affect the .040" quench, hence me considering the 6.250 rod......if that makes some sense.




Just talk to Diamond... I had them reduce the dish
volume, move the pin height and open the valve relief
on a shelf piston... I have a 59cc chamber





I was thinking of using an off the shelf Chev forging and having it modfied...........most piston manufactures tell me it is sill a custom piston price though.

Re: WHAT ROD LENGTH? [Re: moparmacka] #882284
12/18/10 12:21 AM
12/18/10 12:21 AM
Joined: Aug 2003
Posts: 43,141
Bend,OR USA
C
Cab_Burge Offline
I Win
Cab_Burge  Offline
I Win
C

Joined: Aug 2003
Posts: 43,141
Bend,OR USA
Quote:

Quote:

Quote:

Sorry didn't mention the reason for custom pistons is the heads have 55cc chamber and I will need a custom piston with a larger dish to suit our 98 pump premium and still not not affect the .040" quench, hence me considering the 6.250 rod......if that makes some sense.




Just talk to Diamond... I had them reduce the dish
volume, move the pin height and open the valve relief
on a shelf piston... I have a 59cc chamber





I was thinking of using an off the shelf Chev forging and having it modfied...........most piston manufactures tell me it is sill a custom piston price though.


But being it will be for a "Chevy" it will be cheaper, correct

Last edited by Cab_Burge; 12/18/10 10:50 PM.
Re: WHAT ROD LENGTH? [Re: Cab_Burge] #882285
12/18/10 07:09 PM
12/18/10 07:09 PM
Joined: Nov 2006
Posts: 370
Queensland Australia
M
moparmacka Offline OP
enthusiast
moparmacka  Offline OP
enthusiast
M

Joined: Nov 2006
Posts: 370
Queensland Australia
That is the main reason and also the smaller .927 pin diamter.







Powered by UBB.threads™ PHP Forum Software 7.7.1