Pistons-Rods-Cranks-Crankcases.

[1650bullet]

Im going threw a heap of my parts and i am seeing many differences in things. Take the conrods. Which is better out of the two.

[skyetoyman]

From an engineering point , the top rod is better. "H" shape much stronger than "I " and lighter. It means your crank can be lighter too.

[1650bullet]

Thanks for that. I have also noticed a difference in crank case top halfs, The stub looks a bit tall compared to others. Are the bushes bigger

[Collector Inspector]

I tend to favour the single beam rod. Think of both that and H thrashing about with mind's eye.........aye.

Mind you, what do you want a rod to be over stock?

Single beam is far easier to get straight by the way.

No printing on the one I am going to use. Just die marks easily smoothed gently.

No sharp edges and by hand finish always.

Taller top case..........taller bearing.

B[/color]

[Charles uk]

It appears that over the course of time Seagull felt that making the conrod stiffer & stronger was worth the extra cost.

As a lot of their technical feedback came from the distributors via warrenty claims, I think it might be safe to assume that the Seagull 1, 2, 3, & 4 rods got stronger & more suitable for purpose throught out their development.

From memory it seems the oval section rods (Seagull 1 & 2) were only used on the lower powered models & the H section rods on all the higher powered models from the ON & OP in 1936/7 up to the modified Seagull 4 in the Kingfisher.

[1650bullet]

Ive have notoiced that some of the upper crankcases have a larger port area than others. The pic shows the difference in size. Is this the tranfer port.

Ps" The one on the left is a LLs and the right is a W.

[Horsley-Anarak]

I tend to favour the single beam rod. Think of both that and H thrashing about with mind's eye.........aye.

I like this single beam style, shame they a a bit rare

I have just taken my latest Seagull 6 apart, glad conrod is rust free.

H-A

[1650bullet]

So out of the 2 rods ive posted up, The seagull 2 (single beam) would be the best to use. Im after reliability thats all. The taller bearing crankcases would be the best to use then.

[Horsley-Anarak]

I would use the stronger I beam one.

If you want reliability, then strong must be best, it might even survive a swim.

H-A

[skyetoyman]

The I beam is not stronger. H is stronger and lighter.

[Horsley-Anarak]

I beams are H shaped beams.
Same thing, used in their correct orientation, their cross section is like a capital I, hence the name I beam.
H-A

Or should it be I-A.

[Collector Inspector]

B

[skyetoyman]

H agree !!!!! except I cannot type I .. I can only type H.

[Collector Inspector]

My selected rod is from WPCL 1864B1. That makes it 1971 4-4.5 something.

The crank will go with it as when tested it was perfect from the factory, all things are straight and parellel.

The other side of rod just shows injection points. It has no other markings.

It is 6.30mm thick and 17mm wide. It will do what I want it to do very nicely. It had a "Droop" at the small end and was easily corrected. Dry run of motor showed that on the piston rub.

It will handle any torque that I can get out of the HotRod Gull power head most assured. It appears to be made out of really tough stuff..........just ask my pin file in cleaning it up.

Work in progress.


B