x-flow crank , steel or not ?

[Al Weyman]

I thought George was down in Sussex somewhere past Garwick, has he moved? Always was a fast peddler even came out for a stint with us in ModProds years ago.

[Copperbottom]

Originally Posted by Al Weyman

I thought George was down in Sussex somewhere past Garwick, has he moved? Always was a fast peddler even came out for a stint with us in ModProds years ago.

He moved from Heathfield to near Cambridge about 8 years ago(I think)

[GORDON STREETER]

Yes Al George deserted Heathfield to increase his business by buying a house and premises in Cambridge as the prices were too silly "darn sarf"
I got a phone call from him last year asking if I was in as he was sitting on the beach just down the road to our gaff. No I was working in the p******g rain in the UK

[ian_w]

From my brief experience with X-Flow cranks they only have 4 relatively small counterweights. These look too small to me, i.e. the interia of the big-end pins & rods are more than the interia of the counterbalance weights.

This means that there will be bending loads on the crank due to these rotational forces which could cause a failure of the crank. Secondly, these forces will increase the loads on the main bearings - on a 4 cyl, the centre main takes all the abuse as the loads from cyls 2 & 3 add together. The loads increase with the square of engine speed so small rpm changes can give large changes in force.

The way around the problem is to increase the mass of the counterweights ( possibly by adding tungsten metal inserts ) and/or reducing the mass of the big ends ( drilling the pins and perhaps carefully grinding down the con rods ).

[zefarelly]

or use a twin cam crank which has bigger counterweights anyway, shorter stroke can be offset by bigger bore for capacity, and all assuming regs allow alterned geometry of course.

[stoppodriver]

Thanks Ian , since i posted this originally - i've checked the rules and they are now saying the rule on A6 cams will be for 2010 , so any cam can be used if you're not using all steel lower end , so i'll use one with the power lower down . From a stress point view - I won't be driving anything from the front pulley ( no alternator and no water pump , as I was going to use an electric one ) so i wasn't going to fit a front pulley as such - would that be detremental to the crank ? regards AL.

[Copperbottom]

Originally Posted by ian_w

From my brief experience with X-Flow cranks they only have 4 relatively small counterweights. These look too small to me, i.e. the interia of the big-end pins & rods are more than the interia of the counterbalance weights.

This means that there will be bending loads on the crank due to these rotational forces which could cause a failure of the crank. Secondly, these forces will increase the loads on the main bearings - on a 4 cyl, the centre main takes all the abuse as the loads from cyls 2 & 3 add together. The loads increase with the square of engine speed so small rpm changes can give large changes in force.

The way around the problem is to increase the mass of the counterweights ( possibly by adding tungsten metal inserts ) and/or reducing the mass of the big ends ( drilling the pins and perhaps carefully grinding down the con rods ).

Why make the crank heavier? By using much lighter rods and forged pistons the weight issue is countered. All of the old Spedeworth 1600 hot rods HAD to use a standard crank and cast pistons and they used to rev to 8250 lap after lap,the best engines used machined 1600 pistons (instead of 1300) and decked blocks to bring the CR up to 12:1,by using modified 1600 pistons instead of 1300 (common mod) it reduces the weight of the rod/piston combination so counteracting the lighter counterweights

[zefarelly]

only if you don't fit anything to stop the oil and water coming out!

seriously, less mass = quicker acceleration

I think I'd run a water pump myself, and get the crank assembly balanced

[stoppodriver]

Copperbottom , was that the other way round ? use 1300 pistons instead of 1600 ?
As the cams are free unless you've got an all steel engine , what would anyone suggest , I think i'll stick to what copperbottom said was done with the stock crank and rods and use something like a 262 cam (?) . i'll build the motor myself and if i knacker one i'll review the situation but I don't want to spend £850 to £1500 on a crank , about £175 each rod + forged pistons only to find i'm no good at it or don't enjoy it , they won't make me any faster - just last longer . Besides the car i'm starting with is heavier than the rest ( untill the Mk1 Cortina that's being prepared starts racing ) so i'll prepare an Anglia as a spare car - any all singing all dancing engines can wait till that's ready . Many thanks for all replies so far , regards Al.

[Copperbottom]

Al,1300 pistons are TOO heavy for your purposes,it's worth using accralite or similar forged pistons to end up with 12:1 CR. (cast pistons are the weak link)IF you get stuck when you come to build it pm me and I'll try and give you some pointers.

[stoppodriver]

Cheers , thanks for the offer - i'll let you know later . regards Al.

[phoenix]

Originally Posted by Copperbottom

All of the old Spedeworth 1600 hot rods HAD to use a standard crank and cast pistons and they used to rev to 8250 lap after lap

Reading the further contributions to this thread since my earlier one, I am now thinking that the rev limits I was given by Tim Swadkin, who built my engine, may have been dictated by the cast pistons used in my engine, rather than the crank.

However, to me 8250 rpm does seem extremely high for a combination of cast pistons and a standard cast iron crank. I didn't realise the basic 1600 x-flow was so tough!

[ian_w]

Originally Posted by Copperbottom

Why make the crank heavier? By using much lighter rods and forged pistons the weight issue is countered. All of the old Spedeworth 1600 hot rods HAD to use a standard crank and cast pistons and they used to rev to 8250 lap after lap,the best engines used machined 1600 pistons (instead of 1300) and decked blocks to bring the CR up to 12:1,by using modified 1600 pistons instead of 1300 (common mod) it reduces the weight of the rod/piston combination so counteracting the lighter counterweights

Copperbottom,

If you imagine swinging a weight around attached to a piece of string then you will know that there is a considerable force generated in the string. This is exactly the same thing that happens in the crank due to the the big ends. By putting counterbalance weights on the opposite side of the crank you can reduce/cancel out the force from the big ends and reduce/eliminate the bending forces on the crank.

Lighter rods / pistons won't have much effect on these rotational forces as you need to lower the mass around the big end.

The lighter rods / pistons will however reduce the reciprocating forces on the crank ( the force required to accelerate the piston / rod up and down ), so they are definately a good thing.

I once had a racecar with a 'full race' 1300cc x-flow that revved to 9000rpm using cast crank ( with drilled out big ends ) and lightened/polished std rods. I did miss a gear once and revved it to over 9500 and wiped out the centre main bearing. This is a classic symptom of lack of counterweights on a 4 cyl engine.

[stoppodriver]

Ian , can you elaborate on " drilled out big ends " please . Many thanks , regards Al.

[zefarelly]

crossdrilling to maximise oil feed to all the big end journals . . .the std crank is a bit shy with oil distribution

[ian_w]

Originally Posted by stoppodriver

Ian , can you elaborate on " drilled out big ends " please . Many thanks , regards Al.

It was a good while ago so exact dimensions are a bit sketchy...

Basically, the front and the back side of the big end was drilled a decent diameter ( 20ish mm ) to a depth of maybe 15mm. The drillings were slightly angled relative to the crank axis, to clear the counterbalance weights from the neighbouring cylinders.

The critical part of the job is to set the depth correctly as you don't want to break though into the oil drillings. Alternatively if you are brave you can carve a lot more out but you will then have to come up with a method of plugging your new holes in order to keep the oil in.

[stoppodriver]

So it was just to reduce the mass ? did you crossdrill for better oil feed as well ? I've read that somepeople think it's not needed on crossflows - but it wouldn't do any harm would it ? Thanks for replies so far - regards AL.

[ian_w]

Yes, the mod was purely to reduce the mass of the big end. The crank was already modified when I got it. As I said it was a long time ago and I can't remember about the cross drilling.

I'm sure I'll be shot down but here goes...

I can't really see why cross drilling would improve lubrication. The rotation of the crank will tend to centrifuge oil towards the big ends so there should be plenty of pressure there. Also, the std oil drilling enters the big end at around TDC which is the region of highest load due to the firing pressures.

As I understand it when you cross drill, you drill thro the big end at 90deg to the original drilling ( and intersect it ) and then plug the original hole - what is this really supposed to achieve, is it just old 'folklore'?

[zefarelly]

I've never cross drilled, but steel cranks are as std

[stoppodriver]

That's what i was led to believe ( that it wasn't necessary ) I'm tyring to keep costs down , so I don't want to have anything done if it's of no benefit . What about tuftriding etc ? So the concensus is standard crank / rods , lightened and balanced with forged pistons and reduce the rotating mass where possible = hopefully a crossflow that will rev to 8000 and bit ( obviously running a cam that produces it's power lower than or up to 8000 ) Regards Al.

[jonners]

With regard to standard cast iron cranks don't forget that Ford produced a fully counterbalanced cast iron crank for the Monte Carlo Mk 1 Fiesta XR2 - which ran a cross flow.

These cranks were only available from RS dealers and featured briefly in the RS?AVO catalogue very briefly.

The flywheel flange was a different size but this could be accomodated on a rwd car by using a spacer.

We run one of these cranks in our car - we bought it from Burton who had acquired all remaining stock from Ford. Burton told us that they are safe up to 8500 rpm continuous and we've used it for years now up to 8000

Burton told us they used them for years in Hot Rods and whenever I've heard it said that Hot Rods used standard cranks I've always reckoned they mean they used these cast iron cranks...

I just don't like the idea of the standard crank at such high revs - as Zef mentioned the standard cranks are only counterbalcaned to 4500rpm whereas the twin cam cranks are counterbalanced to 5500 (not sure what all thatr means - just useless info pcked up in the distant past)

Gordon - you must know about these cranks and whether the Hot Rods really used bog standard crannks??

[stoppodriver]

Jonners , thanks for that - that's very interesting and something i'd not heard of before - i'll certainly look into that ( price & availability ) . Many thanks , regards Al.

[jonners]

Al - don't waste your time trying to get hold of one - the one we had was out of Ford's remaining stock which Burton bought as a job lot

The point I was trying to make was that these were cast iron and I blieve Hot Rodders used to get round thr standard crank rule by using this one rather than steel - cliaiming its standard as its cast iron whereas in fact these are very far from standard

I think the legend has grown from this that Hot Rodders had no problems with standard cranks up to huge rev limits...

need a real historian like Gordon who was there at the time (cue Dambusters theme tune )

[GORDON STREETER]

We did use std Ford cranks but I used a "twink" one that has different counterbalance weights and is shorter stroke than the std 1600.
Also don't forget that you are constantly on and off the gas on the ovals, so the crank isn't revving at its maximum for a long time, like it would on the back straight at Snetterton for instance.
And jonners, yes I was there (and like the 60s) I don't remember much about it !
I don't think I could get away with a std crank in the Anglia (have you heard it on youtube ? )
http://uk.youtube.com/watch?v=3JEq7Tf46PE

[Copperbottom]

Originally Posted by jonners

Al - don't waste your time trying to get hold of one - the one we had was out of Ford's remaining stock which Burton bought as a job lot

The point I was trying to make was that these were cast iron and I blieve Hot Rodders used to get round thr standard crank rule by using this one rather than steel - cliaiming its standard as its cast iron whereas in fact these are very far from standard

I think the legend has grown from this that Hot Rodders had no problems with standard cranks up to huge rev limits...

iirc we had to use a certain part numbered crank in the Spedeworth days...I've built loads of hotrod crossflows and only ever used bog standard 711m cranks,WITHOUT any problems,the weakest parts were the standard type cast pistons. I rev my current 1700 to 8+krpm regularily.It IS important to get the crank crack tested regularily though.(I do mine once a season)