You only cheat yourself lol, what pride can you take in winning something via being illegit?

And may not be so intense at events he'll be doing, but certainly at karting our engines were stripped down to every component on a regular basis, components measured, weighed etc.

The ABD block is the same height as a 3F and has the same cambelt

The deck shouldn't be a problem for the AFH internals route then, the ABD has a longer stroke crank than an AFH and the AFH takes a 1.6 crank, so the ABD should be tall enough to allow the 16v piston crown to the requirement of just meeting the top of the deck surface, allowing a metal gasket. Even if it means the deck will need a skim.

If the piston breaches, there's a compound gasket for the 76.5mm bore. If it breaches even that, then you can lower the pistons with 1.6 16v rods and skim the deck to meet the piston then, and use the metal gasket.

The only question then is getting the con rod to clear the crankcase, which i can't see much of an issue with.

For the ABD internals route..

The ABD block is the same height as a 3F and has the same cambelt

..it looks like they share the same block then. An overbore to take the 16v pistons seems quite simple, plus adapting the rods to take them, then the same issue with decking the block to match the crown height. The only problem with that route is it takes you over 1400cc..

Seriously though, what you really need is ABD internals in the 3F to get it to 1391cc numbers matching, skim the ABD piston crowns down to meet the deck and angle pocket them for the 16 valves, use a metal gasket, hide a turbo in the centre box/muffler and disguise the turbo boost input pipes by using two small ones, painting them in rubber paint, then routing them via the heater matrix and saying they're water pipes.

Could you use the internals from the mechanical head engine? They have flat top pistons! Obviously the oil pump from the mechy might be a bit weak but maybe it could be changed for another?

The deck shouldn't be a problem for the AFH internals route then, the ABD has a longer stroke crank than an AFH and the AFH takes a 1.6 crank, so the ABD should be tall enough to allow the 16v piston crown to the requirement of just meeting the top of the deck surface, allowing a metal gasket. Even if it means the deck will need a skim.

If the piston breaches, there's a compound gasket for the 76.5mm bore. If it breaches even that, then you can lower the pistons with 1.6 16v rods and skim the deck to meet the piston then, and use the metal gasket.

The only question then is getting the con rod to clear the crankcase, which i can't see much of an issue with.

For the ABD internals route..

The ABD block is the same height as a 3F and has the same cambelt

..it looks like they share the same block then. An overbore to take the 16v pistons seems quite simple, plus adapting the rods to take them, then the same issue with decking the block to match the crown height. The only problem with that route is it takes you over 1400cc..

Seriously though, what you really need is ABD internals in the 3F to get it to 1391cc numbers matching, skim the ABD piston crowns down to meet the deck and angle pocket them for the 16 valves, use a metal gasket, hide a turbo in the centre box/muffler and disguise the turbo boost input pipes by using two small ones, painting them in rubber paint, then routing them via the heater matrix and saying they're water pipes.

50cc too big with AFH pistons on ABD crank...it really is a big bastard!

...so maybe it's ABD block, AFH pistons, ABD rods and PY crank for 1324cc

or...ABD block, AFH pistons, ABD rods and AFH crank for 1390cc...if the rods fit the crank that is.

Would love to have the 3 engines sitting here in bits right now. I guess the pick of it getting custom pistons. Then all the guess work and a few £100 goes out the window. PY block, crank and rods...custom pistons done. Doesn't seem as fun just making it fit when there could be a golden set of parts that work.

Edited 30 July, 201313 yr by Tav

somebody must have a dead afh they can send you parts of...

I've got a wanted add up Gaz, fingers crossed. I hear there might be one in local scrap yard.

I have a afh short motor In the shed, what do you want measuring ?

Would in not be easier to fit Honda cbr head to the 3f 1272cc block ?

Minimal machining required. Just a little off setting for the head bolts and a idler wheel on the block iirc

I have a afh short motor In the shed, what do you want measuring ?

Would in not be easier to fit Honda cbr head to the 3f 1272cc block ?

Minimal machining required. Just a little off setting for the head bolts and a idler wheel on the block iirc

I believe for the Honda bike treatment there is A LOT of machining. The whole timing side of the engine I saw was billet aluminium, insane levels of skill there.

If I had an engine here I'd be interested in:

• The internal diameter of the big end bearings/ external diameter of crank where said bearings are attached. See how these compare to the older con rod/cranks.

• Height from centre of crank to deck of block.

• Height piston protrudes from block at TDC.

I think that'd be a place to start? Others might have some input on what to measure...?

The AFH piston comes completely level with top of the block at TDC mate

And the Honda CBR head is a lot of machining yeah and is converted to timing chain instead of running a timing belt

standard AFH TDC

Edited 30 July, 201313 yr by Mclovin

Could you use the internals from the mechanical head engine? They have flat top pistons! Obviously the oil pump from the mechy might be a bit weak but maybe it could be changed for another?

The pistons particularly, yeah you might be onto something. Not all, but some mech head engines had flat tops. Maybe then they will go straight on ABD rods and crank, that lot will go straight into an ABD block if not even a 1272 block. The only machining required would be piston pocketing (very little to do there, the pockets are tiny as you can see in Guy's pic).

Standard/ABD block

ABD crank

ABD rods

Flat top mechy 75mm pistons

AFH oil pump

That lot should all be plug'n'play to give 1391cc. Then the piston crown just needs to be matched to the deck for compression ratio and fit, if it's not already (using the various mediums of machining piston/deck and choosing gasket).

The only other engineering then being pocketing.

Sounds like Tav needs to get some parts and get measuring...

Overbored 3F with custom pistons is the way I'd be tempted to go, sure it's £600 on a set of pistons - but you can get what you want then. Just need to work out what the combustion chamber volume on an AFH is and away you go. Bore will be similar or slightly greater than stroke, so it should rev nicely.

Off to the scrap yard today to see if the AFH they said is there, really is.

Oh they never had if btw. My head guy for G40 flow tested an AFH and the improvement is massive over an 8v, he was really impressed with it for a standard head.

Going to put up another wanted thread soon.

Hello ,

For me i have a 1.3 Hk engine with the combustion chamber in the head like the afh , it's possible to swap the cylinder head from the afh on to my Hk engine ?

Thanks

Antoine

Hello ,

For me i have a 1.3 Hk engine with the combustion chamber in the head like the afh , it's possible to swap the cylinder head from the afh on to my Hk engine ?

Thanks

Antoine

Any figures for the AFH over an 8v on the flow testing Tav ?

I think my head was 50-something CFM stock. Just over 70CFM modified. AFH is 'more than 30CFM above your modified head.' Flows the same as an ABF head from a 2.0 Golf despite 3mm smaller valves. Jason reckons little room for improvement. So with right cams etc. it's big power.

That's a massive improvement sounds like great news to me.

Hopefully help me achieve my power goal then

Well JMR reckon 200bp N/A is do-able...160-180 not terribly difficult.

So my aim of 300+ boosted should be achievable then. Oh goody :)

I don't see why not when 8v's are tipping over into the 200's...

Any progress on this Tav?

Been looking for oversized pistons for an ABD and in my research I've found the ABD has 127mm rods, not 122.

based on data from a kolbenschmidt catalogue

Compression height of MH/2G pistons is 42.87

Compression height of ABD pistons is 34.52

block deck height is the same

difference in compression height; 8.35mm

difference in stroke height; 78.7-72= 6.7mm, 6.7mm / 2= 3.35mm

difference in rod length makes up the balance; 5mm

Not sure what to do about the pistons yet. Don't really want to go to the expense of custom. Biggest OE oversize is 75.75 =1419cc. Can't use 1.6 stuff as I want to keep the heron head I've got, and I don't think the pistons have enough material in them to pocket them sufficiently.

Compression height on the AFH for reference is 28.92

http://download.ms-motor-service.com/ximages/PDF_Kataloge/ko_50003945_web.pdf(page 1027-1028)

Gaz are you aware of any differences between early and late abd engines? With regards to internals?

I've sometimes seen the stroke quoted as 79.1, which is the stroke of the 1W engine, but that would mean two different piston sizes and I've never found any evidence to support that.

Some have a deep sump and oil pump pickup, which you can convert back to the early type.

Edited 18 June, 201511 yr by Gaz