1st Stroker questions.

[Brian Rogers]

Acquiring parts for a 2165. Have the 78mm forged crank, Empi. AA 94B p&c kit. The question being con rods, 5.4” or 5.5”? Will I have to shim for the deck or clearance the skirts with either rod? I know I’ll need to shim with the 5.5”s.
For heads I’m thinking CB’s Panchetoes. I’m limited by my carbs, 40 Dellortos. I’m not anticipating any racing but hiway cruising and stop light Grand Prix. Cam wise I was thinking a 120ish cam. Exhaust will be 1 1/2” mergered running w/o thermostat but flaps and doghouse tin, sump and filter.
Again, this is a healthy (for Utah) street, freeway engine.
Any advice is appreciated.

[Martin S.]

Rod length topic comes up regularly. The longer stroke the better EXCEPT if your motor is limited in rpm for whatever reason. Then a short stroke fills in the shorter rpm range with quicker snappier power. Ultimately though, if your engine is designed to maximize power in all aspects, the longer rod helps make more power thru to the end of its rpm range.
When I asked what rod length to order, I got "the longest you can get, look what BMW and everyone else uses" so I got 5.7" for my 82mm stroker engine.

[Mike]

Hi Martin,
Do you use "C" Pistons with these long rods?
Otherwise your engine will be quite wide?
Regards
Mike

[Martin S.]

We used B slipper skirt AA pistons. It made the motor about 10mm or so wider each side. Since this motor was for my runner, and cooling is important, Steve extended the upper tin by welding in donor pieces from another set of tin, and as well moving the outer ends of the shroud out to meet the upper tin. The header almost could be stretched to fit, but ultimately he had to cut and put a slip joint in to extend the pipe. He felt that this extra work was worth it and the engine has been in and out of the 68 a couple times without a problem and didn't need any butchering to fit in the car. In these pics you can see what was done to keep this hot engine cool.
In the pic without the cooling system on, you can see the custom spacers he made to extend the cylinders. You could buy longer cylinders as an alternative. Also note the custom heat spreaders he inserted between the cylinders to break up the air flow. Always a fan of turbulence, hence the drilled heads with burrs intact.

[Mike]

Hi , thanks for the info.
With 10mm spacers, are the cylinders still "centered" in the case hole.

[Martin S.]

I didn’t build the motor but Steve had a penchant for being a perfectionist when it came to machining. You should buy longer cylinders. Same thing for the C pistons, how much difference would that make to the width? We probably weren’t aware of some options available at the time.
The whole point I’m making here is how important long rods were to this builder, and how an engine can be built around that, rather than decide to take the easy way out and use short rods. The results speak for themselves 

[richie]

The whole point I’m making here is how important long rods were to this builder, and how an engine can be built around that, rather than decide to take the easy way out and use short rods. The results speak for themselves 

 

[Martin S.]

The whole point I’m making here is how important long rods were to this builder, and how an engine can be built around that, rather than decide to take the easy way out and use short rods. The results speak for themselves 

 

 

[Brian Rogers]

My question is do I need the longer rod to clear the skirts and crank or can I use the stoke length rod?

[richie]

My question is do I need the longer rod to clear the skirts and crank or can I use the stoke length rod?

I think with a 5.4 rod and B pistons the cylinders will be to long and need shortening but this is dependant on if case is decked and by how much, each one is different. I think with AA pistons they will clear crank ok but been a while since i built that combo

cheers Richie

[richie]

Also most likely head studs will be to long & you won't be able to use regular pushrod tubes, you will need 1200 tubes or collapsible type to fit in there

[Martin S.]

My question is do I need the longer rod to clear the skirts and crank or can I use the stoke length rod?

The 78 was a super popular combo back before 82-84 cranks became cheaper, and someone has to remember this?
John recommends a 5.5" rod even with a 76 stroke crank with his bus/T3 engine combo. https://www.aircooled.net/2054cc-engine-parts-list-busses-type-3s/

[richie]

The 78 was a super popular combo back before 82-84 cranks became cheaper, and someone has to remember this?

But they used A pistons not B pistons like Brian here has got so different set up

[Martin S.]

From what I remember most guys were and are advised to use B pistons on 78 and up 'stroker' cranks so he has the right parts.
Was there a time when there was no B available

From John C. :
"Almost all piston and cylinder sets are available in two versions: short stroke (these are considered “A” pistons), and long stroke (these are considered “B” pistons). A pistons are used on up to 76mm stroke engines and B are used on 78 and longer stroke engines."

[Brian Rogers]

Thank you. The kit should be here tomorrow. I plan on doing a mock up as soon as my schedule allows.