Technical *** October 2015 Banger Meet - Shadows Getting Shorter in Aus and NZ ***

Sorry to say, sad to report, IMHO, the breakage is strictly a function of attempting to transmit too much torque through an inadequate amount of material. While Toms shop builds a nice piece, the "A" rod journals are not large enough, especially when you drill them for oil.

The "A" journal is only about 64% the cross section of the "B" journal. Now, drill a 1/8" hole across that and reduce it another 10%.

Can I ask what head you have on this motor? and CR?

Thanks, John

 

I agree with you John,
This is why I'm wanting the next one to be a model B grind. For now I'm running a drilled C crank.
I'm hoping Scat will honor the request for the B grind and if not, then I'll be upgrading to a Billet 5 main crankshaft with the early Chevy V8 rod journal size.
I did express my concerns but was told the Forged H beam A rods and the Scat would break the 39 box and or the stock Model A rear running gear before the rod or crank would break. (I don't understand why they keep selling these combo's)
It's such an expensive and time consuming mistake!
I've heard a balancer does help though.

Oh, the head is a Cragar 4 port cross flow, set at 10 to 1 CR. The person that sold the parts knew in advance that this was the head and CR I was running and he said not to worry and there was no way I could ever break this crank or rods without first breaking everything else!
He is a world known builder! (not saying any names) He is a good friend and I think he actually didn't think it would break either!
thanks again,
Joe p.s. I would still like to see a picture of a balancer in a stock 30/31 A chassis
maybe it would help me keep from breaking my drilled C crank?

 

Hi Jiminy,

I like this idea and once I see a few options I will make one and take pictures and videos of the install and post them or start a new thread.
I only need to be pointed into the right direction.
Thanks,

Joe

 

I was suspecting the 4 port head, the last broken one I had here was the same combination.
It is really amazing the difference in the 4 port vs the 2 port. Efficiency at its finest.
Those H beam rods are very nice, like I have mentioned, it is just the limitation of design.

When going to the "B" rod journal, an issue will arise, cam clearance. I have seen many rods with the separation line on an angle which rotates the bolts away from the cam. This works well but does have a limitation as to how much piston weigh and rpm they can withstand. This is where ROSS pistons can be very helpful.
The other thing that does work is to machine or grind a flat on the cam where the rod interferes. I like this much better than reducing the diameter of a part already too thin.

As with anything, especially 80+ year old technology, it is all a compromise.
There is no magic bullet, I have seen the motors with dampers fail also.
Make sure that if you go 5 bearing setup you understand all of the angles. About the only usable parts from stock is the block and front cover, maybe the flywheel too.

Best of luck, J

 

So the "lobe" on the right half of the cam (halfway between the center and end bearing surface is for the fuel pump?

 

Thanks John,
I'm running really light Ross pistons because I have 8 inch rods.
I can post pictures if anyone would like to see them?
My cam lobes aren't too tall only 300 lift. My rockers are 2 to 1
so that makes around a 600 lift to the valves.
My front cover is a Kong Jackson with a brass button.
I have a large lathe and just recently purchased Neil Jern's
Milling machine from his wife. The machine has the digital
X and Y axis readout. I'm gonna be making my own billet
flywheel. Do you think a flywheel that is light will make the
crankshaft more prone to break or would it be a benefit?
thanks for any help in advance,
Joe

 

I built a harmonic balancer for my last B motor. I posted some pictures and tech on how I built it in the March 2013 banger meet. The posts start on page 5 about half way down the page. Post 127.
Here is a link to the page:

http://www.jalopyjournal.com/forum/...e-a-hamb-march-2013-banger-meet.781649/page-5


.

 

I may have a 1931 wico jem1509 mag for a banger to sell . has the starting lag . fresh rebuilt . works as it should .........

 

Joe,

Good for you, I too seem to buy machinery and then just make my own stuff.
The flywheel is a good question. To my way of thinking, the larger it is (stock) the more prone to breaking a weak crankshaft design. I am specifically referring to a long skinny journal (rear main).
I like the aluminum flywheels, steel insert for disk and use 8 bolts for crank flange. I too have been thinking about making some, like I need another project in house right now.
My current car does not run a flywheel, only a 6" dia ring gear and a coupling hub (push start car) no problems. I also do not run a damper up front, just oil pump drive and a trigger wheel.

IMHO, the 5 main crank solves more than just the number of bearings, it is a much stiffer (torsional) unit than the 3 bearing layout. Also, the 5 main typically has more counterweights to absorb some of the harmonics closer to the rod journal where the torque is developed. A couple of people have told me that the 5 main feels much smoother than the 3 main and that is a good thing. One guy just kept revving the motor till the rev limiter did its job as he could not feel the motor revving up past 5k (limited at 6500).

4 cylinder motors have a very distinct characteristic in the fact that the power is 180° of crank revolution and the offset acceleration/deceleration of the pistons. You really cannot balance one, you can balance the crank and flywheel assy (with dampener) but the rods and pistons can only be matched to one another. We raced small dis MG's and Miatas with good success but the harmonics just break things.

Show pics of completed parts, John

 

would an automatic behind your motor , maybe the constant equal pressure would stop some of the breaking . just a thought

 

I think the problem comes from multiple issues, but is exacerbated when the crank is drilled for pressure AND the big ends are ground with a small radii...there is naff all metal in the corner of the journal. BUT I also think that the longer rear main gives it a lever point...or should I say a rigid point compared with the shorter center and front mains.Especially with tight clearances and a heavy flywheel.
I think the flex/harmonics ( what ever you want to call it) becomes concentrated in the rear corner of the fourth rod journal .
Think of it like a branch on a tree, if you start to bend it , or twist it at the outer end it will always snap near the base of the branch where the trunk supports it and forms a resistance . AND if there is a node or any other weakness ( like a hole drilled through) it will break there.
Maybe the answer is a counterbalanced two up two down crank, ( ala Winfield) with roller bearing center main and double roller rear main , change the firing order to 1 3 2 4 , move the rocking couple to the center of the engine/crank.
One could maybe use barrel shaped Superblend roller bearings aka Norton Commandos .
Okrasa , SPG and Hirth , (maybe Weber) made roller cranks for VWs in the past, and I believe some Offys had them.. Crower was working on them at one time and Jim Fueling had them down pat before his untimely passing.

 

Hi, Thanks for the valuable info.
That's a lot to take in! Right now we just switched the thrust bearings to the rear instead of the center bearings. Also did a few other things. These are the pistons and rods that will be ran on this temporary build. For some reason they just don't seem to last long!?
I'll be getting better and better at building these experimental engines!$$$
I will be building a 5 main soon,but for now I just want my Roadster back on the road!

 

That's some really nice work!!!!
So tell me please, Did it fit in a stock A chassis?
Has anyone tried it?

 

Here again

 

good morning jimski ..........

 

Sorry, still haven't tried it in a stock A chassis. I've done some measurements and It would work, but the lip of the front cross member would have to be trimmed.

Since I built that unit, I have discussed the unit with the guy that took over Jay steel's balancer production and the SBC balancer that I used is the same one that Jay used too. So, if anyone that has installed one of Jay's units in a stock frame, then this would work too.

.

 

Thanks,
I'm gonna look it over and will most likely be doing it. That and the flywheel will put me a couple weeks back on my engine install but I think it'll be worth the time, money and effort!
I will post pictures of it in the chassis if I choose to try it.
Thanks again,
Joe

 

Just ordered my Harmonic Damper!
I will post pictures, as it's being put together.
Thanks Crazydaddyo for the help!
Joe

 

This should help, you can see the fuel pump looks green for some reason.

 

I run an 11.5 lb flywheel on my A stroker. I have had crank problems but the problem is bending. I guess from the twisting. At the hillclimbs it is wound up to around 3 grand then drop the clutch this is a second gear start. Jay used to slip his foot off of the clutch to start. This is a B crank with welded weights and drilled for pressure. Joe Gemsa once said he would get as many as 10 races with a welded B crank and maybe 3 or 4 with a C. I had 2 welded and drilled A cranks break in the same location. I use J and E pistons.

 

I use a Jay Steel dampener in my 29 RPU. You have to split a 32 style mount till it clears I'll see if i have any photos.

 

This all just confirms that I'll be starting my 5 main project A.S.A.P.!!!!
My engine now will be just for freeway running and reliability runs!
I have had 4 engines in and out in less than one year on this Dangdo 31 Road$ter!
I'm so tired of sinking time and money on engine work! I really miss doing metal fabrications,
like chopping and rust repairs, ect. ect!
I have recently been collecting parts to build a real "RACE" banger car, starting with a set of 32 rails. My roadster was built to have fun and do long trips on the highway and not for actual racing.
If it was, I obviously wouldn't have it up so high. ( I will still do some hill climb racing but will never EVER drop the clutch or side step it!)
Thanks,
Joe

 

Thanks for the photos,
This is definitely going to come in handy when it's time to figure out how to mount the front cover/engine to my crossmember.

 

Dampener motor mount modifications for Jay Steel type SBC Dampener

 

I built this car in less than one year and then spent a year on engines at this very moment the engine is out and being built again!
I usually build one car every year.

 

Sorry but I should've asked on an earlier post, what trans you're running and gear ratio on rear end and overall tire height/circumference? Being you start off in second.
Thanks again,
Joe

 

cant see the car for the fog !

 

You will be happy to know that I ran the same stock crankshaft in my Plymouth banger for years. Ran it in the OHV version until the deck separated from the rest of the block. Then used it in the flathead version for at least 3 or 4 more years. Set a record at Muroc as a OHV and again at El Mirage as a flathead. Went 135 as an OHV at both El Mirage and Bonneville. Used SBC rod bearings on the stock crank pins. Came with thin steel backed mains. Full pressure of course. No damper. Of course the new '26 Dodge engine has five mains so it should be lots better than the 3 main Plymouth was. Just like to help out the Ford guys when I can.

 

Trans is a 38 Lincoln side shift. People today think a column shift is a side shift but a side shift the stick comes out 3" to the right and 3.5 " forward giving a lot of clearance for the throttle foot. With these transmissions the throw is shorter and more positive. The Lincoln stick shifts used Ford gear ratios. Long Lincolns came out in the column shift in 1940. We run (usually) 5.30's in the rear with 6.50 16's car weighs 1500+ pounds has run in the 8's at hill climbs I have a stock model A rear end in the shed with 5.12's in it.

 

Pictures of my front engine mount:

If you look close, you can see where I cut clearance on the bottom to cleat the damper.