*"Tis the last rose of summer"* The Sept. 2012 Banger Meet

Timing gear? Front pulley?

 

Uses A key, haven't had any problems with the key. Care must be taken with key alignment when fitting to the crank.

 

Time is the delta that we strive to extend, along with increased energy extraction.

John

 

My experience with the A B crank breakage has been, I think, and again this is my opinion based on my limited experience that as long as the driver drove "by the seat of his pants" things went well with many runs but the breakage occurred when trying to run to a specified RPM. In our case 4,000 RPM's. I'm not going to reengineer the design but then this is the ramblings of an old fart. When we last ran the car with the Winfield flathead, the driver, a first timer, said he felt he should shift when the surge was over so I said go for it and we made a few believers that day. Same thing at the Antique nationals that year, grandson said he never looked at the tach.

 

Bill,

There are too many factors involved to make any rational decisions in these discussions. The corner radius is not the cure-all, after all, if it was then there would be no reason to increase the journal diameters from the "A" to the "B".

John

 

My experimental engine ...to try some of my own ideas, which may or may not work.....

I have a "worn out and beyond redemption B crank for my A block. Which will be ground o suit the modified main bearing bores once the bearings are poured and bored.
Block is line bored as far as it will go before the main cap bolts will not clear ....obviously there needs to be room for bearings...I am using babbit, but harder and thinner than normal..... and the crank is to be ground with a larger radii on the mains than stock....
It will be drilled for pressure oiling....
I feel that the rear main breakages in pressurised motors may be in part be attributed to the way the mains are drilled....the hole is awfully close to the fillet radii.
Here is a pic of Artiki's crank from an old Banger meet.

I think a good place to start with strengthening and modifying the block would be on the SCTA- website..... especially the things they say you are NOT allowed to do if you want to run at Bonneville or El Mirage..

http://www.scta-bni.org/pdf/2012_SCTA_V4-V4F_Guide.PDF

 

97,

Is the picture of a 1.62Ø journal? Ouch, that will leave a scar.

If you are to use the "B" crank in the "A" block, try to leave the rod throws as large as possible and use "B" rods. This will leave the the unsupported section of the crank stiffer to resist flexing as much. I did one recently with a "C" crank, std rod throws and 1.85 dia mains in the "A" block. IMHO, this will also help dampen the offset accel/decel influience of the pistons. YMMV.

The SCTA guideline is an accumulation of mods done over the last 50? years. Some of it works, some of it is questionable? I am also experimenting with it.

here is my latest, should be making smoke next month.

J

 

If the Thomas head is new I might agree with Herb and say your piston is hitting the head.

 

From this to this.
Seems to run much stronger.
6.1 head, Home made headers, twin MGB hs4 carbs, ford prefect mech advance dizzy.
Brendan

 

Can I ask what crank you are running? Also who made it, Very nice bottom end.

 

I am trying to do this one in ways it COULD have been done , in the late 30s....I know a cast girdle and even ghost mains could have been done then, and I have that set up on a 8CM flathead .......but I am endeavouring to be a little more grass roots with this one......
I have B rods, but I have some 36 Pontiac rods I intend using for this one.
I am sure he doesn't like being reminded about it even if it was three years ago , but the broken crank belonged ( belongs) to Artiki..
see post 37 here
http://www.jalopyjournal.com/forum/showthread.php?t=403641&highlight=artiki+broken+crank&page=2

If you search broken banger cranks you will find that there are heaps of them here and they nearly all break in the same place. I intend drilling my crank differently, to avoid intersecting with the fillet near the counterweight.......I will take plenty of pics and if it works I will report back. If not I will scrap it and try something else....

 

Artiki's old engine is now in my garage with a B crank in it... It's all assembled but for piece of mind I just need to check through it before buttoning it up and trying it on the tourer.

Brendan - do you have some bigger images and other views of the SU's - I cut a MGB manifold in half the other day and offered it up to see how to work out throttle linkages and all. You seem to have saved me some time...!

 

Ah - just looked at your header thread - sorted...!

 

Our 5 main OHC block goes to get scanned tomorrow

We fed 14 friends last night ...... the party ended at 2AM

 

Is the fuel system under pressure? Or gravity feed

 

Good to hear you are feeling well enough to party.

 

Gravity
I bought a fuel pump however SUs use low fuel pressure, the fuel bowl is at the same height as the ports, so several inchs below the tank. So I did not fit the pump. Drove it 20 miles today no problems. I think I can get away without the pump.
Brendan

 

I don't believe the Best gasket will compress to less than .060 so for the piston to be hitting the head at idle, which is the impression I'm getting from the post, means quite a bit of popup. Most current production pistons are held to industry standards regarding compression height. Compression height being the distance from the center of the piston pin to the top of the piston for those who might wonder what the term means. This said, most "A" blocks have .020 to .030 popup before being surfaced. One fellow on the A barn has done some comparison on many blocks over the years and he wondered if Ford cast the blocks a little short as most were minus on this dimension to save material cost.

 

97,
Using the "B" crank may get you more material at the intersection for the drilling. I have seen a few broken Pontiac rods in the past, would a set of Scat or Eubanks rods be better? I would hate to see a rod failure be the cause of a mishap.

John

 

Good job, 2am is just in time to re-open the bars.........

Keep us informed on the progress of the block.

John

 

Your header came out real nice.
I was looking at some of those carbs last night on eBay last night. Did you need to do any thing with the jets?

 

So far, not really, as with any carb tight shaft are good, some SUs have replaceable bushes, mine were OK. I did buy a kit for them which includes the main jet, needle and seat. The main needles are what controls the mixture very much like a motorcycle carb, these come in various types, I may get a new stock set as someone has scraped mine in the past. SUs seem to sort of self tune depending on the vacuum. If your car is left hand drive you should be able to make the stock linkage work. I had to swap them over so the fuel bowl would not clash with the steering column. So far I am very happy, .
Brendan

 

Yes I agree the B crank will allow a bigger fillet radius and therefore a little more material if I drill it the conventional way.... but I have other ideas.....
Yes new modern rods are probably stronger etc , but they were not available in 1939 .............. this motor owes me nothing except time ...... all the parts have been scavenged or built/machined by me, if it goes bang, I will learn from it.

When I get back on to the all out race motor with 5 main bearings and a full girdle and ghost mains (or fit the block with new webs) I will use a set of custom made rods.... probably Denco to match the crank and pistons , but also possibly either Cunningham or Arrow.

In the mean time I am applying 30s hopup tech to this one..... it will have weld on counterweights, a home made harmonic balancer, and light flywheel.. I still have the B rods as a backup plan. There are 14 Pontiac rods to chose from, so I might just "test" one or two before I go ahead....I wonder why they used them back in the day if they are prone to breaking ?
Were the broken Pontiac rods you have seen from full out race motors or hot street motors?
I don't intend using this motor for serious LSR or drag racing .

 

John

Please remember this is an overhead cam only block with no provision for any in bloc cam, valves pushrods ect.

It is a very ridged block ...lots of iron ....... but useless to almost all folks here.

 

Bluto,

one of the factors that stops me from making the DOHC head is the block strength. I am not sure that adding rods from the head studs down into the lower section will be adequate. Tell us more about the construction.

John

 

Hi John

Easier to show you photos. This block is preHAL the rear main is different

It's NOS but machined beyond it's limits. So we scan and adjust measurments before making casting models.....

This has been here before. I was trying to save it .....no more we'll just make new and machine it correctly

If you have questions please PM me. That way we don't go over and over this for those folks not really interested

 

I was having some tuning issues with the SUs which I think I have resolved, one was opening slightly sooner. While searching for the problem I thought lack of vacuum so I did a compression test 110,110,105,110. Ok I think, tried a search to see what is normal, no luck, anyone have a number?
Brendan

 

Brendan, what is your compression ratio?

I was running @ 120 with a 7.6-1 CR head.

.

 

I have just fitted a snyder 6-1 head.
Regards
Brendan

 

Then your numbers look good.

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