Projects '23 Model T Gow Job - AKA: Sand Creek Special

Hang in there, once it fires you'll forget all about the hard times.

 

IMHO ,If you have the original Bob weight calculator card you could just take all the rods out and adjust them all to the same weights end for end. The small amount you have removed will slightly alter the balance factor/percentage but should not materially change what you will experience . When I say that I realise that the balance will change slightly , but as the useful rpm range is relatively low and narrow in a banger it will only move the "perfect" balance point a few hundred rpm, if at all .
If you do not have the balance (bobweight) calculation card ,but have one rod which you have not altered you can weigh that end for end and use those numbers to to recalculate the percentages and then do the same with the lightest rod , From there you can use the two numbers to figure the difference in balance factor. Then modify all the rods to match the lightest rod. From your pictures I would say you have only removed a few grams , of effective bobweight . You can do all of this at home with a home made jig and a 0-2kg digital scale , most are accurate to .5 or less grams.

 

@97 I have the balance sheet on the engine. I talked with my machinist today, We are leaving the pistons, pins, rings, and locks as is and use those numbers. The rods will get rebalanced and a new calculated bobweight added to the crank to rebalance. The trick is balancing the rods, there's just not alot of material to play with like later engines have with balance pads on the rods.

#1 and #4 rods had to have the most remove to clear the exhaust lobes---this is due to the A crank being longer and pushing those rods further out. #2 and #4 actually went in with no interference, but it was so close that I had to grind a little to be safe. Everything now has at least .040" (should be a fair bit more than that, I just cant get an accurate measurement) between the lobes and rods.

 

Bobweights...?!? Aren’t we talking about a flat plane crank in a 4 banger...? The crank should be spun balanced independently, and the rods simply balanced end to end... unless I’ve been doing it wrong all these years...

 

Generally I would agree, that was the universal thinking at one time and that is why I said to check the balance card , and then just rebalance the rods etc . These days some machinist/balancing technicians use bob weights on a flat plane crank, some do not !
The big lumps on the pistons in this case may need them . I dunno there are no full counterweights added , but i see some heavy metal in the pictures.
If the numbers are available the amount that has been removed is easier to calculate.

 

Like everything gentleman, there are many ways to skin a cat to get to the result.
There is no heavy metal added to the crank.
Original balance sheet I posted previously:
'23 Model T Gow Job - Balance sheet

 

AH ha, I forgot you posted that ... I thought there was some "heavy metal" there . My eyes not as good as they once were. For some reason your pics do not enlarge when I right click as most here do? No matter as I said balancing is a black art, a lot of theories are out there and what is fashionable changes with time .
Have you ever seen the Don Terrill "speed talk" forum? Some real "experts" there fail to agree

 

@97, sorry, I was trying to be web considerate on the picture posting size. I will try to make them bigger for you. If your having issues seeing, probably means someone else is too, I just never knew. Thank you for letting me know.

 

Rotating assembly is all rebalanced again. I have alot of other work going on with my machinist so he did it gratis for me. And we went from the original .25 oz imbalance down to .025 oz---near perfect. I ordered new spiral-lox retaining rings as I didn't trust some of them that came out. Better safe than sorry with all the dollars invested. Now maybe I can get the short block back together for good.

 

Perfect, will be a smooth running T . Should make good power too.

 

Had today off from work *cough cough* , and was able to get my short block together finally. This has been a long road to get here. I feel like it has been together and apart a million times already.

 

It has - but this is a unique motor, and is an inspiration to others - I, for one, will no longer reject the idea of building a T engine at some point, and out of that, a T racer. Haven't started gathering parts, not yet, at least... although, I know where... hmm...

 

Looks sharp

 

I am sure that it does seem so, but you are building a custom engine! (and correctly) I have been watching intently, because I will probably run into the same types of problems when I get to putting my Leroi crank into my Chevy 4 banger! Thanks for sharing the info!

 

what kind of pistons are this ?

 

They are custom Ross pistons. They fit a single spark plug Frontenac overhead valve head and have been made to create a 7.5 : 1 compression ratio. Thanks for the questions [emoji2]

 

guitarguy, just curious, What side of $2,000 did they cost?

 

At the time of purchase (there have been two price increases since), they were $850, pistons, pins, rings, and oil ring supports.

 

Please remind me not to buy a Frontenac head for the B-block in my T roadster...

 

The Fronty was the cheap part, LOL. The short block is what ate up a ton of money.

The Fronty can be bolted on a stock engine for significant power change. This short block however is far from stock. These are not required pieces for a Fronty to be functional, this is just the next step to making it even better.

 

Old saying still applies. "How fast do you want to go? How much money do you have?" Bigger and better have always cost more, but the expensive bits usually last longer and do the job better.

 

Thats the plan, one time only. This stuff is far to expensive to keep doing over.

This same combination (except with counterbalanced Scat crank) has been run by the gentleman that sold me the NOS Stipe Roof cam (no longer made). He runs it in a hill climb car. It's a stout combination, I don't plan to ring it out like he does though.

 

850 for what you got is a lot better than I though. You are getting One off, engineered, high quality components. I am getting so tired of looking for a piston (just close enough) to work, and then finding out that it is not available anymore. I think that I may give them a call.

 

And being a forged piston, they will take a fair bit of abuse and survive. They do have alot of wall clearance (.009") but also consider the fact that 2/3 of the cylinder is air cooled.

Give them a call. I was lucky in the fact someone already did the hard work for me. They looked his pistons up, we changed the bore size and deck height, a tiny bit of the dome height, and that was it. It worked out great, I waited a couple of months and got the email they shipped. Very good people to work with. I had just called to get more Spiro-Lox for the piston pins as I didn't trust putting the old ones back in, and they were again great to deal with.

 

Great thread!

 

You may want to reconsider... the only Fronty head for a Model A/B was the “Stagger Valve”. Nothin says awesome like intake and exhaust manifolds on both sides of a twin cam banger!!!

 

Hey Kevin, do you have any more photos of this?
Also, do you have an Instagram where you post progress on your winfield stuff?

 

Here is a great link to the history of the Stagger Valve head. There are a bunch of great pics of the design blueprints... but none of the finished head;

https://www.chevroletbrothers.com/stagger-valve-fronty

There is one on the Speedway museum website, but has been converted to cross flow... still friggin cool... but not quite as cool!

 

Insta... what???

Just the HAMB and the Model T forum are special enough! I haven’t made too much progress lately on the Winfield’s thanks to getting the Covid, children, life, work, and I obligated myself to build a couple sets of Buffalo wire wheels before the end of the year too. I have been putting together the paperwork for the Winfield project, so I can figure out what’s left to build, and what prices to set

 

I’ve always had a thing for the obscure, so when a friend of mine came up with some Gemsa reproduction raw castings a while back... I got a bit excited. He came up with the prints and I started digitizing the design so we could better anticipate the machine work. All that was left to do was the water jackets... now all I have is these screenshots due to a hard drive crash...!