Cosworth MkIV engine - Lotus 27

[RogerH]

I am trying to determine what head configuration was used in period (up to 1963) on the Cosworth Ford MkIV Formula Junior engines primarily used in the Lotus 27 FJ.

Was the period Cosworth head a modified standard head or was it a totally new modified casting? Is the current Richardson head used on a number of current FJ cars a copy of a period head or is it a subsequent non-period casting?

[PeterMorley]

Cosworth Mark iv was the 1961 1100cc junior 105E based engine
Cosworth mark xi was the 1963 1100cc junior engine, using a 109E block.

Lotus 27 would more likely have used a mark xi rather than a iv, with the extra 10 or 15 bhp available?

Cosworth mark iv Junior head would have been based on a standard production 105E head (or 109E later) as the rules required (e.g. block & head from production car).

Richardson heads are based on castings made (from the original patterns) by someone like Holbay for F3 use. Quite apart from any possible internal changes they look different since they were made to allow for fitting downdraught manifolds.

[GORDON STREETER]

Like this one ? I have had several pass through my hands over the years.

[tony griffiths]

Have the original Cosworth engine specs but no details of the casting numbers -- Geoff is doing some very good new castings ........

[RogerH]

Thanks for the replies. I think it answers my query in that the last FJ Cosworth head (on the Mk XI engine) would have used a modified standard based head with the Richardson head being a re-make of a subsequent F3 head.

[simon drabble]

I sense someone being quite mischievous...

[RogerH]

Originally Posted by simon drabble

I sense someone being quite mischievous...

If I was in the UK you would probably be right but here in NZ we run under slightly different FJ regulations that allow modifications only if they can be proved they were used in period (I understand the UK FJ regulations specifically allow Richardson heads on some classes of cars). There has been some suggestion here that the last period Cosworth FJ engine (the Mk XI) had a head from which the Richardson head was copied - hence the query.

[zefarelly]

it should have been a std production casting, Ford also produced, for Cosworth, a thick floor casting to help chamber flow/compression, in anglia and 1500 cortina types.

I don't think these have been available for decades, and no one makes anything like it now, why would they when there's far superior alternatives available.

[Marcus Mussa]

Originally Posted by RogerH

I understand the UK FJ regulations specifically allow Richardson heads on some classes of cars

Actually it is FIA Appendix K that allows Richardson heads in class FJ/2

I believe that a "works" Lotus 27 ran once in 1963 with downdraft carburettors, perhaps in the last race at Brands Hatch (which does not mean we can run such equipment in historic FJ!).

[eamonn ledwidge]

As Marcus states, this was probably towards the end of 1963 season and probably not homologated. I suspect that the head mentioned as fitted in the 27 was somehow connected to the development work done by Mike Costin and referred to in MotorSport Jan 2008 interview - Costin on the Cosworth 105E engine development and sales. Details the early problems Duckworth had with cam and valvetrain design: "best engine - one that Brian Hart and I had used in our Lotus 22 - we bored through the top of the cylinder head to the back of the inlet valve and brazed in inlet pipes. We eventually got 123bhp."

Then came 1000cc F3 and the downdraft head became essential on MAE engines.

Originally Posted by Marcus Mussa

Actually it is FIA Appendix K that allows Richardson heads in class FJ/2

I believe that a "works" Lotus 27 ran once in 1963 with downdraft carburettors, perhaps in the last race at Brands Hatch (which does not mean we can run such equipment in historic FJ!).

[Alan Morgan]

Then came 1000cc F3 and the downdraft head became essential on MAE engines.

...but not until 1967 - sidedraught engines were usual until then.

[SJ LAMBERT]

G'day RogerH, we've got a Holbay S65 engine that is equipped with it's original stock modified to down draft head on 5 bearing block with 53.3 mm stroke Laystall crank (it's a 1150cc Sports Race engine) -so it's not a FJ motor, but I reckon the head would have to be the same as Holbay's 3 bearing FJ motor, if that assists at all? Has a gear cam drive and is very much a screamer spec engine..........it was first installed in a car in 1967 after being assembled in 1965...............I think.

[SJ LAMBERT]

The original Holbay downdraft head pictured above is a 105E casting.

[john ruston]

Did FJ stop at end of 63 so assume it's another one of those one off's.

Same thing applies to those ally engines used in Lola 210's.

[RogerH]

Yes, FJ stopped at the end of the 1963 season.

The "discussion" regarding the validity of the recast Richardson heads still remains and is causing a bit of controversy here "down-under". One faction says that the specially cast heads were supplied by Ford to Holbay and Cosworth at the end of the 1963 FJ season and therefore they are allowable as the current Richardson head just replicates the period Holbay/Cosworth head.

The other faction says the period FJ regulations stated that the cylinder head had to belong to an engine from a car classed by the FIA in the touring capacity. As this sounds like it is restricting heads to those from at least a limited production car (I presume there is a list of the FIA classed touring cars), then a one-off or go-faster recast head would not have complied with period FJ regulations in any event.

So I suppose the outstanding issues are :

what is the proof that these "special" heads were used in FJ in period, and
what is the correct interpretation of the period FJ regulations

Any input on these issues would be gratefully appreciated.

[phoenix]

According to this site:

http://www.race-cars.com/utility/coswrthr.htm

And referencing Graham Robson's book "Cosworth - the search for power" The only downdrafted heads appeared on the MK XVII MAE in 1964 - after FJ had come to an end.

[SJ LAMBERT]

Well, I'm pretty sure the Robson book quotes Duckworth or Costin as saying all the castings as standard Ford supplied castings because the rules didn't allow anything else (ie Cosworth made plenty of special non standard items but were restricted to standard castings for blocks and heads), and the Holbay head we have is on a 120E block with a Laystall crank scribed with "1965" on it - and Carl Haas sent it to Australia. I imagine Haas would have specified the grooviest componentry available - yet, it is very definitely a standard Ford 105E casting...........

Originally Posted by RogerH

Yes, FJ stopped at the end of the 1963 season.

The "discussion" regarding the validity of the recast Richardson heads still remains and is causing a bit of controversy here "down-under". One faction says that the specially cast heads were supplied by Ford to Holbay and Cosworth at the end of the 1963 FJ season and therefore they are allowable as the current Richardson head just replicates the period Holbay/Cosworth head.

The other faction says the period FJ regulations stated that the cylinder head had to belong to an engine from a car classed by the FIA in the touring capacity. As this sounds like it is restricting heads to those from at least a limited production car (I presume there is a list of the FIA classed touring cars), then a one-off or go-faster recast head would not have complied with period FJ regulations in any event.

So I suppose the outstanding issues are :

what is the proof that these "special" heads were used in FJ in period, and
what is the correct interpretation of the period FJ regulations

Any input on these issues would be gratefully appreciated.

[zefarelly]

As I said previously, FOrd made a 1500 (116/120E) thick floor casting for bigger engines, Willment used these, as did Cosworth, and it is homologated. These have bigger ports than 105/109 castings and shallow chambers so would be good for smaller capacity highly tuned engines, you won't find one in a hurry now. other than that I believe they where all standard production castings.

I've taken anglia heads out to 30mm ports but its very time consuming, you can take a 1500 head to 32mm, any much more is risky and In my experience counter productive for most tunes.

105/109 heads and blocks are essentially the same, I'm pretty sure 113 head castings are the same as 109e ones chamber aside, which you need to open up anyway.

I 've had several conversations with FJ racers in NZ and AUs in recent months and actually started sifting through castings, 3 x 105 heads only went to 21cc when skimmed roughly, but I got a 113 casting down to 19cc and it still looks good for another 40 thou to fall off before the water jackets start to recede.

the trouble is finiding head castings, the late ones are better but seem to crack more in my experience, lots of them are cracked