B Rod spec..

[hardtimes]

Anyone have a B rod handy to measure the small end WIDTH size/spec ?


And, do A/B rods have same small end width ??


Thanks !

[ursus]

I measured six and the small end width is 1.600 - 1.604 inches, same as the Model A, to my knowledge.

[hardtimes]

Originally Posted by ursus

I measured six and the small end width is 1.600 - 1.604 inches, same as the Model A, to my knowledge.

THANKS much , ursus !
I've got to modify some Ross pistons and your help / info is appreciated !

[Jim Brierley]

It may be easier to narrow the rods, I have done this in the past.

[hardtimes]

Originally Posted by Jim Brierley

It may be easier to narrow the rods, I have done this in the past.

Hey Jim,
Thanks much for your input !
Yes I've thought about that, but do not have rod end to figure with. I'm thinking of using crower rods again. And, I think that the WIDTH of the small end of a crower for an A/B should be same as an A/B original rod small end, eh ??


Anyway, where I'm at, is that with the 1.600 (stock small end width) that ursus gave me, that will work. The Ross pistons now have only a 1.187 space between bosses. Not being a machinist, I still recognize that this machining of a piston , is serious undertaking to get it 'right' ! I'll most likely send them to Ross for needed alteration.


The old timer who ordered them back in '04, was a racer. He was also a machinist and was going to do finish work himself (didn't mention that...ha !). They are built like a brick out-house, so hopefully Ross can also lighten them some. If I were to have an OHV head that needed these piston heads to be 'carved' to fit combustion chamber....I'd be in TALL cotton !
I will definitely keep your great suggestion in mind for final solution !

[harryc]

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Did I sell you those Pontiac rods I had? ( I can't remember) If I did why not use them if you don't want to use B rods?

[johnneilson]

a word of caution, the "B" rods were 1.000 pins, usually when the pistons are made for narrow rods the pins are .927

make sure to check this.

reciprocating weight (piston) increases the load logarithmically so if trying to run some RPMs keep that in mind. the lighter the better, and the con rod bolts are what take all the abuse. there is a reason that ARP gets $50 per rod bolt for the Carrillo rods.

J

[Ronnie Lawson]

[attach][attach]Model B Rod Connecting Cap.jpg[/attach][/attach]

[Jim Brierley]

A hacksaw will narrow the rods any amount you need. There is no strength in the outer portion of the rod, so no worries about that. Balance the rods before installing them. Piston weight is important too, lighter is better.

[hardtimes]

Originally Posted by harryc

Did I sell you those Pontiac rods I had? ( I can't remember) If I did why not use them if you don't want to use B rods?

Hey harry,
No, that's one thing that we never looked at or discussed. Would have liked to examine those when you had them. Maybe tooo heavy, don't know. I've seen some really weird and very heavy home brewed rods that were raced back when.

[hardtimes]

Originally Posted by johnneilson

a word of caution, the "B" rods were 1.000 pins, usually when the pistons are made for narrow rods the pins are .927

make sure to check this.

reciprocating weight (piston) increases the load logarithmically so if trying to run some RPMs keep that in mind. the lighter the better, and the con rod bolts are what take all the abuse. there is a reason that ARP gets $50 per rod bolt for the Carrillo rods.

J

Hey John,
Yup, 1" pins in these Ross. For 4" bore. Modern ring pack.
I hear what you are saying regarding reciprocating weight. I'm in a bad way with these pistons, as they have .680 dome thickness ! .500 over stock thickness !! Maybe wait till I get a head that will run better with carved dome ? Can remove .032 to bring comp height down to even with deck....but that ain't much compared to what's there. Not sure that Ross will have a 'solution' for this situation ? Heck, maybe further ahead to hang these on the wall and get a super light set, eh ?

[hardtimes]

Originally Posted by Ronnie Lawson

[attach][attach]Attachment 360572[/attach][/attach]

Hey Ronnie,
Wow, very nice of you to share these drawings with us , thanks !
ursus' measurement of 1.600 was/is right on with drawing numbers !

[hardtimes]

Originally Posted by Jim Brierley

A hacksaw will narrow the rods any amount you need. There is no strength in the outer portion of the rod, so no worries about that. Balance the rods before installing them. Piston weight is important too, lighter is better.

Hey Jim,
So, taking say 1/8" off on both sides would be OK , in you view ?


'lighter is better'...now you sound like my doctor who keeps taking a little off/out ..here/there ! Now he wants to take something really important out !!


'hacksaw'...now you are talking my language...most technical tool within my toolbox.

[johnneilson]

Originally Posted by hardtimes

Hey John,
Yup, 1" pins in these Ross. For 4" bore. Modern ring pack.
I hear what you are saying regarding reciprocating weight. I'm in a bad way with these pistons, as they have .680 dome thickness ! .500 over stock thickness !! Maybe wait till I get a head that will run better with carved dome ? Can remove .032 to bring comp height down to even with deck....but that ain't much compared to what's there. Not sure that Ross will have a 'solution' for this situation ? Heck, maybe further ahead to hang these on the wall and get a super light set, eh ?

Ross usually supplies a spec sheet for the set, how much do they weigh?
have to be over 800 grams. also what is comp height? dome height? sounds like someone missed a dimension.
J

[hardtimes]

Originally Posted by johnneilson

Ross usually supplies a spec sheet for the set, how much do they weigh?
have to be over 800 grams. also what is comp height? dome height? sounds like someone missed a dimension.
J

Spec sheet says: 'C.H. 1.400'.
Dome height says: 0.500.
Net dome cc's- SPL


Piston weight says: 938 grams.


Note: The way designed, these Ross are same .032 popup (now) as stock . When placed side by side with STOCK model A piston, pins on both sit exactly opposite each other. The RINGS on the Ross are way down the dome compared to stock.


Hm, just realized that the old dude must have been going to use a LONGER rod to bring dome on Ross up.....if it were to be available to carve, eh ?

[johnneilson]

Originally Posted by hardtimes

Spec sheet says: 'C.H. 1.400'.
Dome height says: 0.500.
Net dome cc's- SPL


Piston weight says: 938 grams.


Note: The way designed, these Ross are same .032 popup (now) as stock . When placed side by side with STOCK model A piston, pins on both sit exactly opposite each other. The RINGS on the Ross are way down the dome compared to stock.


Hm, just realized that the old dude must have been going to use a LONGER rod to bring dome on Ross up.....if it were to be available to carve, eh ?

Or any combination of stroked crank with longer rods.

J

[Pete]

Those pistons could be lightened a whole bunch.
The average 1 inch pins can be lightened considerably also.
It would still be heavier than a lightweight .927 pin.
My guess is you could probably lose 400 grams from the
combo.
HOWEVER, this is going to be expensive unless you can do the work yourself.
It may be cheaper to order a new set of lightweight racing pistons from Ross.
If you are going for really light, a significant amount can be taken off of Carrillo or any H beam rod and still be within safe limits for 6000 rpm.
If this is going to be a really high performance engine you might also consider doing a bob weight balance job at 70% on it. Also consider dry sump oiling. It is good for 30 hp alone.

[hardtimes]

Originally Posted by johnneilson

Or any combination of stroked crank with longer rods.

J

I'm going to call him, to see what the heck on these !
I think that you most likely are correct, in that he did his own machine work and talked of exotic building, when a racer. Hope he is kicking yet !

[hardtimes]

Originally Posted by Pete

Those pistons could be lightened a whole bunch.
The average 1 inch pins can be lightened considerably also.
It would still be heavier than a lightweight .927 pin.
My guess is you could probably lose 400 grams from the
combo.
HOWEVER, this is going to be expensive unless you can do the work yourself.
It may be cheaper to order a new set of lightweight racing pistons from Ross.
If you are going for really light, a significant amount can be taken off of Carrillo or any H beam rod and still be within safe limits for 6000 rpm.
If this is going to be a really high performance engine you might also consider doing a bob weight balance job at 70% on it. Also consider dry sump oiling. It is good for 30 hp alone.

Thanks Pete for your input. I might just go the lightweight route from Ross. Will have to talk with them..again.

[Jim Brierley]

With a pin half way into your pistons and half into a stock piston, compare distances to the top of the piston, not the bottom as pictured. I believe the stock height is 1.906". If my measurement is right, your pistons are for a stroker crank. Double check everything. Cutting the rods as I mentioned will not affect rod strength as there is nothing out there connected to the beam section.