452 replies to this topic

[ACDodd]

Need the picture of the top face, not the side.

Ac

[JonnyAlpha]

Need the picture of the top face, not the side.

Ac

 

I'll check tomorrow, but I don't believe there is anything stamped on the to face of the block?

[JonnyAlpha]

Need the picture of the top face, not the side.

Ac

 

Ah ha, it's the letter 'B' 

What does this mean?

 

 

[ACDodd]

Good it's a standard block that has not been skimmed. Ok so what cylinder head chamber volume have you got?

Ac

[JonnyAlpha]

Good it's a standard block that has not been skimmed. Ok so what cylinder head chamber volume have you got?

Ac

 

Ah brilliant, I need to clean up the valves and re-fit them with the springs before I can calculate that. 

 

I did measure the thickness of the head though and it is 69.4mm

 

The inlet valves measured 35.77

The exhaust valve measured 29.44

 

But I was advised that the original measurements were: 35.6 mm inlet and 29.5 mm exhausts.

 

The chambers don't look modified and if not according to this info the chamber capacity would be 21.4

 

Here is a thread I started some time ago with some additional info on the head.

 

When measuring the CC what fluid and what tools would you recommend.

[ACDodd]

Use a burette filled with parrafin.

Plenty of YouTube vids on cc'ing heads.

I would go for omega pistons at 10cc dish set at 0.014" deck height. Together with a bk450 head gasket This would give 9.75:1 for the ACD - RS cam with the 21.4cc chamber.

Alternatively you could run a set of cheaper 21253 pistons and machine the dish to 11.4cc and run them optimum at zero deck.


Ac

Edited by ACDodd, 13 March 2019 - 08:18 PM.

[JonnyAlpha]

Yes

 

Use a burette filled with parrafin.

Plenty of YouTube vids on cc'ing heads.

I would go for omega pistons at 10cc dish set at 0.014" deck height. Together with a bk450 head gasket This would give 9.75:1 for the ACD - RS cam with the 21.4cc chamber.

Alternatively you could run a set of cheaper 21253 pistons and machine the dish to 11.4cc and run them optimum at zero deck.


Ac

 

OK thanks AC

I have looked at a couple of videos but the guy used meths not paraffin, but I suppose anything with a low meniscus.  

 

So the standard BK450 head gasket here or the copper PAYEN one here?

 

How much is your AC RS Cam? 

 

As I am on a tight budget I was only looking at the Evo001 Cam to basically ensure the Cam was new as the MG one has done 50K, and the Omega Pistons are £340 as opposed to the 21253s which are £240 (less 7.5%). But the P21253 says it has a possible CR of 10.3:1 how does that effect its use?  

 

What I haven't got my head around yet is the correct combination or Piston / Cam / CR apart from the fact that they all need to be matched to obtain the best performance.

 

What about the Evolution Pistons?

Edited by JonnyAlpha, 17 March 2019 - 06:03 PM.

[ACDodd]

The evo pistons are out as they have 6.5cc dishes.

 

9.75:1 is ok to use with the Evo 1 cam. I would not run higher,

 

Either gaskets will work in your application.

 

I have given you the correct aaplication with 21253 pistons, they need the dish machining out to 11.4cc (from 8.2cc Nominal) to get the cr down to 9.75:1 with the stock head chamber of 21.4cc. Piston machining will set you back another £75 ish. Those omegas now doent look so expensive!

 

 

Unfortunately you budget must cover setting the correct CR. if you can't afford it, wait and save.

 

Ac

Edited by ACDodd, 13 March 2019 - 09:47 PM.

[JonnyAlpha]

The evo pistons are out as they have 6.5cc dishes.

 

9.75:1 is ok to use with the Evo 1 cam. I would not run higher,

 

Either gaskets will work in your application.

 

I have given you the correct aaplication with 21253 pistons, they need the dish machining out to 11.4cc (from 8.2cc Nominal) to get the cr down to 9.75:1 with the stock head chamber of 21.4cc. Piston machining will set you back another £75 ish. Those omegas now doent look so expensive!

 

 

Unfortunately you budget must cover setting the correct CR. if you can't afford it, wait and save.

 

Ac

 

Acknowledged.

 

Without sounding daft, as far as measuring the CC, what size burette, 25 or 50ml?

 

What's the best place to buy 10cc omegas ? 

[ACDodd]

Med for omegas. 50cc burette is perfect.

Ac

[JonnyAlpha]

Living in rural North Devon nothing available locally, apart from a 20ml syringe from a Homebrew Shop :-( 

Anyway, I am going to have a go tomorrow and see how it pans out. I'll have to order a 50ml burette to get a better measurement before making the final decision.

 

Before doing the measurement I am going to have to clean up the valves using some thinners and then wet and dry with the valves in a drill. 

 

 

I may have to lap the valves in to get a good seal, any recommendations on where and what grades of paste and a twizzle stick?

Frost do several different grades and I believe we get a discount with Frost?

 

Eurocarparts (we have a local branch) do this kit.

 

Or on Amazon there is a Chemco two grade here and a Laser Lapping Tool

 here it has 19mm and 22mm heads?

Edited by JonnyAlpha, 16 March 2019 - 11:45 AM.

[JonnyAlpha]

Cleaned up all of the valves with a brass wire brush attachment and then fitted the Exhaust and Inlet Valve into chamber 1. Fitted the valve springs and a small amount of copper grease around the valve seats, also fitted a cleaned up Spark Plug (Had to route through my bin to get them :

 

 

 

Then I drilled through an old CD case and put some Copper Grease around the chamber.

 

 

And using my 20ml syringe proceeded to fill the chamber, this was with about 20ml:

 

 

Didn't get a pic of the finished fill but it most of that air bubble disappeared a small amount ended up on top but there was still a small air bubble. It took about 21.5ml so looks like its completely standard (which is 21.4cc).

 

The valves will get a final polish up and get still need lapping in, so i'll re-check using a burette next time once the head is more or less finished.

[JonnyAlpha]

Use a burette filled with parrafin.

Plenty of YouTube vids on cc'ing heads.

I would go for omega pistons at 10cc dish set at 0.014" deck height. Together with a bk450 head gasket This would give 9.75:1 for the ACD - RS cam with the 21.4cc chamber.

Alternatively you could run a set of cheaper 21253 pistons and machine the dish to 11.4cc and run them optimum at zero deck.


Ac

 

Iv'e done a first chamber volume measure above and it seems that the head is still standard. 

 

Looking at your advice on the OMEGA pistons, they need to be set 0.014" down the block, the current pistons already sit about 0.015 down the block and the block is going to need re-facing. Any idea if the Gudeon Pin to Crown on the OMEGAs is the same as 21268s currently in the engine, can't find any info on the web? 

 

All needs to be re-measured again just to be sure.

[ACDodd]

The omegas usually sit 0.035 to 0.040" down the bore at tdc on a fresh block like yours. You will have no worries achieving the required deck height.

Ac

[JonnyAlpha]

I have been further dismantling the engine ready for machining and have a couple of concerns and questions that I need advice on.

When I removed some of the lower bolts that hold on the aluminium flywheel casing there was a lot of debris in the bolt threads. Will I need to get the bolt holes drilled out and inserts fitted?

 

 

In the gasket face on the lower part of the block that mates with the gear box, there was a hole that was covered by the gasket and filled with silastic? There is, I believe a matching hole in the gearbox? There was no bolt in this hole?

 

 

 

 

Also what is the purpose of the hexagonal threaded object that sits underneath the Oil Pressure Sensor in the pic below? When removed it has a spring on it. Is there anything else inside that needs to be removed?

 

 

What are the two holes to the left of the Core Plugs in the pic below?

 

 

Lastly, I managed to undo the nut on the larger of the two timing gears however the gear itself will not pull off by hand. What would be the best puller or method to get it off?

Edited by JonnyAlpha, 20 September 2019 - 01:26 PM.