Yes, the Chev crank does, in the link provided by Les there is more info from the ebay auction. Cant remember what the Ford Crank weight was, with all the counterweights its probably close to 50lb or more at a guess.Do you mean that the crankshaft in your photo weighs 30 lbs?
The rods & pistons must also be very light to be compatible with the crankshaft and balance factors. The ebay advert states the car had only done ~60k miles, wonder if that is also true for the engine? Need more actual user comments!!Jac;
Wow, a 30 lb Chevy crankshaft? That is really light- my Lunati SBC crankshaft weighs 52 lbs.
Chev or Ford Howard??Jac, I do see your point about rod ratios, however I really like the idea of relative low rpm very high torque with an ability to run through slow corners one gear higher that the high reving smaller motor would require. It's just that much less stress on the rest of the power train and a lot less monkey motion by the driver.
Without race class rules I can't see why to limit CI's and then run the engine to higher revs to make hp. I thing it's really "what you like thing" but we have established elsewhere that you are correct on the rod ratio idea.
For the record what would a 400 CI "Jac Mac" rod ratio motor look like if you were so inclined to select parts to build one. I am thinking a big block would be required to get the required bore size but I'm likely wrong about that.
Interesting you mention the Airplane/boat prop thing, been involved with a couple of those, one was a 2.0 pinto in 3 point hydro direct drive onto 0.75" monel shaft from front pulley single keyway double row chain on two single row sprockets with only lower half of prop in water once up on plane etc. That 0.75" monel shaft developed a 3" whip at full noise ~ 7 to 8k RPM, never hurt the engine or shaft, but made a mess of every bulkhead in hull where it passed thru! All came to a halt once the shaft brg bracket tore out of transom. Lot more about that but it would take to long to type up! Lets just say we are no longer friends!!Lightweight cranks sound good but they sacrifice torsional rigidity. Driving a "flexible load" like an airplane or boat propeller is OK but not a pair of sticky tires. Frequently checking a 30 lb crankshaft for fatigue cracks would be a good idea.
I would go with 6.250" rod & 1.025'' ch piston (1.786/1 rod ratio )to suit for those two combos.Have both, but currently interested in SBC. Been reading and I'm thinking 4.0 bore with 6 inch rod and 3.5 stroke for a 1.75 RR and 351 CI. Unless a aftermarket block was used then the bore can be a 1/8 " bigger for a 377 CI. But what do you think Jac?
In your case with SLC it might,Wow, that's pretty interesting. A 400CI SB with a pretty good rod ratio. Would the 377 with the shorter stroke (3.5) be a better combination as far as being closer to ideal RR and still a fairly large CI engine?
Starting to think you need an auto transaxle Howard Was just thinkin, the reason the hyd roller works so well is the residual oil pressure in lifter maintains roller contact with cam lobe, fit a rev kit with the solid roller & most of your problems will dissappear.Neil, Thanks I have waved that one off already and stayed with a 350 for a variety of reasons at the time. I have my 350 apart right now to clean up and inspect for debris damage having loss a distributor gear. If I find other bad parts, now the time for a change depending what I find is not reusable. At this point I do not think I will find any real damage its more of a clean it out thoroughly exercise. But if I do I find the need to redo the rotating assembly pieces I was just wondering...……………
Jac, Ya I like hyd roller cams and valve train systems that last pretty much as long as the rest of the motor and those two factors pretty much limit revs to about 6500. I guess what I am saying is I would like to take out the number of gear changes by making the same torque but lower on the curve. My engine pulls real hard once it gets to about 3500-6K but if it did the same thing down at around 2800 I could stay out of 2nd quite a lot and run the center of the corners in 3rd. I was thinking that the reduction in the number of gear changes would really improve power train life and not upset the car from the center of the corner to the exit making gear changes. I wrote down the 377 & 400 info Jac, thanks again
I think I have drifted the flat plane crank thread far enough for now thanks guys.