cam chain chest spacer on a 711m conversion

[tdafforn]

I am continuing with the 711m conversion of my twink and have got to the satage where I have to install the spacer between the cam chest and the head.
Does any one know of the optimum spacing between the top of the spacer and the bottom of the head (e.g. where the gasket is going to go?)
tim

[types26/36]

Tim, Caterham used to sell the spacer a few years ago and I think Burtons did as well, I just measured one (although its not a Caterham one) and its 0.320" or 8.15mm.
Its easy enough to check, just put the head on with a gasket and measure the gap...allow for head gasket compression but then allow a little for the top cork gasket to be compressed.
PS did you sort out the clutch kit?

[rgh0]

Tim

The spacer should just fill the gap between the top of the standard front cover and the top of the new taller block. The thickness depends on how much the block may have been decked to match pistons and con rods and crank being used. Seal the metal to metal join of the spacer to the top cover with a suitable Loctite anerobic gasket maker. You also need a longer bolt that goes through this spacer to the front cover as the standard bolt only just engages a 1 or 2 threads typically.

Then you just have the standard problem of getting the front cork gasket on top of the spacer to seal properly when the head gasket is torqued down.

In Australia you can get from the Elan Factory 3 thicknesses of of the front cover gasket to suit variations in head gaskets that also exist and can be used to assist in setting the compression ratio you want. I presume in the UK people selling head gaskets of varying thicknesses also sell matching front cover gaskets.

cheers
Rohan

[john.p.clegg]

Tim
If you want the cork gasket to stay put and are not adverse to a little butchery,then with a pillar drill,drill the spacer with 1/4" holes at inch spaces to a minimal depth,this will help the cork gasket stay in place....

John

[kenny]

On a similar note but with the standard 701 block is it right that the top of the timing cover should be within .010" below the head for the cork to do its stuff?

Kenny

[tdafforn]

thanks for the info, looks like it is about right.
As far as the clutch..
I have a few conclusions
1) there is a lot of confusion in terms of size. 8", 81/2", 200mm, 210mm, 216mm. Some of which I think is just a case of metric versus imperial
2) the clutches are expensive
3) best price I got was around 130 pounds
(haven't ordered one yet as I have to save a bit, vernier cam sprockets this month!)
Tim

[iain.hamlton]

I heard recently about a different approach to a 711 conversion.

Deck the block down to standard twincam height; use a 1600 crossflow crank and rods, and (the clever part) ford zetec pistons. Apparently these are shorter than twincam ones between the small end and the crown.

I dont have any information on what machining has to be done to the pistons, but the spacer and longer chain are not needed.

best regards, iain

[rgh0]

Iain

Decking a 1600 tall block down to 1500 block height is very risky as the top deck thickness is reduce to a very thin amount and bore stability is affected. It is not something I would try based on what I understand about it and I would want to see more information that it really works in practice before trying it.

Regards
Rohan

[tdafforn]

The machine shop were concerned enough with the amount I was asking them to take off the block.
So much so it is noted as "at customers risk" on the receipt
Cheers
Tim

[types26/36]

I agree, taking that much of the block (if is possible) would weaken the block.From memory the 1500 block is about 200mm and the 1600 about 212mm and that is a lot to remove, the head bolt threads would have to be redrilled and taped and the amount of metal left from the deck to the internal water jacket casting is anybody's guess.
I just looked up Zetec bores and they all appear to be 3.339" (84.81mm) and although most 711 blocks will take 85mm its getting to a unreliable area, another weakening factor.
Tim, dont know if you know but the oil take off (gauge) is a different thread on the 711 to the T.C. block, not sure what fitting you have on your +2 but the small Elan needs an adapter to use the mechanical guage, if you have not got one and need a fitting I can help you with one.

[iain.hamlton]

Agree. I have written to try to find out more. I will let you know. The car in question was at Goodwood, and certainly goes....

best regards, iain

[tdafforn]

Have checked the threads for the Oil gauge and it goes into the 711m block fine...
were the threads different for the 701m twink blocks compared to the earlier blocks?
Tim

[types26/36]

were the threads different for the 701m twink blocks compared to the earlier blocks?Tim

Could be...not sure but I have had to use these adapters on the 711 block

[kenny]

My 701 block has an angled piece of what looks like industrial bsp air/water pipe coming out with an adapter on the end. As I'm nearing completion of the engine does this sound right, if not what does the proper capillary take off look like for the 701 and are they still available?

Kenny

[types26/36]

Sounds about right for a mechanical gauge, I think my S2 has a right angled fitting but my Sprint has a stright fitting (see pic) with the normal plastic pipe.
Dont know about +2's as I thought they had electrical gauges but reading the +2 threads sounds like they have a multitude of different fittings.
I've also added pic of a 711 with the adapter in.