Then again wiseco say:

Wiseco pistons have offset pins. Pins must be offset same as o.e. for quietest operation (pin offset will be opposite of direction of engine rotation).

 

Well the one rogue piston has gone back for exchange. There's not actually anything wrong with it as such, it would be fine for the side I've already done, just not the side I need it to be installed...

 

ummmm, turn it around?

 

I'd like all the FWD marks to be facing forward. It's the kind of thing that will really bug me otherwise.

 

Nick , I did email you but I see your here hope things went well today.


All the pistons I have here have the fwd marks in the same directions so I will have to wait for wiseco to get back and see what they say . I understand what you are saying but they will work fine the other way

 

That's OK Chris, I know you're onto them already. I guess we really just need to know from Wiseco whether the FWD marks are there for a reason or not...

EDIT: and the answer is 'not' - only the offset needs to be correct, so I can crack on - see below:

Piston #1 installed, pin offset downwards, positioned at top dead centre here. I used assembly lube for the pin but normal engine oil for the bores and piston rings.



Checking for piston deck height with a straight-edge and feeler gauge. Piston comes out very slightly above deck of block, as expected; +0.25mm. According to Wiseco the expected was around +0.30mm (0.012") which they recommend a 1.3mm/0.051" gasket with. Min piston to head clearance they aim for is around 0.7mm meaning I could get away with a 1.1mm Cosworth gasket instead of the 1.3mm Cometic?



Installing #3 piston. It's positioned at the bottom so I can get the pin through the access hole, through the piston skirt and into the other side to butt against the circlip already installed before dropping the piston in. Essential tools are: a spare old piston and rubber mallet to guide the new piston in nice and square, ring compressor, old piston pin to guide the new pin in undamaged, circlip pliers, or in my case needle nose pliers modified with a file to have a slight 'claw' on the end so the circlips don't ping away at the crucial moment of fitting them in. Crank pulley loosely fitted to crank so I can turn it this way and that to get everything lined up.



Close-up of the pin already in position and outer circlip in its groove. All that remains to be done here is to refit the access hole plug.

 

Update: I need to get the compression ratio up as close as I can to 8.5:1, but I have to also keep the required 1mm squish clearance between piston crown and combustion chamber perimeter, by using 1.3mm gaskets. Therefore, the heads - which needed the surface tidying up anyway - are going for a 10-12 thou skim to take some volume out of the chamber and increase the CR. My calculations show that they'll end up at almost 8.3:1 once it's done.

 

Top work nick

 

Can't believe you're up and running so quick Matt!

Slight change of plan - I'm going back to work on the heads while I wait for some replacement rings (I overgapped a couple!). This means the heads are off to have the valve seats returned to spec by recutting the seat angles and the backs of the valves if necessary. Once that's done, it's back to plan A again, getting the skim done to raise CR.

 

My girlfirend always says about me being quick, I find it convient :P

 

Well I've taken two steps forward and three back this week...I'm now having not only the heads skimmed 12 thou to raise CR, but also getting the block skimmed 2 thou to tidy up the face. It seems flat enough to me with a straightedge but is covered in gasket residue still and I'm sure once I attack it with a scraper I'll start ploughing into the aluminium. I'd only fitted two pistons to my assembled crankcase, so I can easily enough take it all apart again tonight, then tomorrow morning, take it down the bare halves for machining, then take home the whole lot - heads and block - with nice fresh metal showing ready for a monster power build!

 

Just spend last half hour reading this whole write-up...very impressive!! hope it all works out.!

 

Still a great thread, reading with interest

Have you picked up any manuals that are worthwhile, in your travels?

 

The only ones I use are a bunch of PDFs that I got a year or two ago. I've found the most useful one to be the 2002 Impreza manual, which has proper PFD indexing and links and good clear pictures, all the specs everything. THe only thing you have to be careful with is knowing where an earlier car or engine will have variations. This is where you have to check and double check, but apart from that I wouldn't have got far without that trusty newage manual!

OK without further ado, here are the results of the heads' and crankcase halves' machining at Scholar Race Engines in Suffolk, my local place. They also did the overbore for me a few weeks earlier. The two crankcase halves we both skimmed by 3 thou/0.075mm which is the least they could take off to flatten the decks. This will slightly close up my squish clearance to 0.91mm but it's still going to be OK, just. Once I have the block assembled and can measure the piston protrusion over the deck I will be sure, but that's what I'm expecting. Lesson for the day - a straightedge and 0.05mm feeler gauge is not enough to check for block flatness! I can't deny that they do look very tasty now. Compare them with the state the decks were in before a few posts earlier ^^^^^



One of the heads that has had the max of 12 thou/0.3mm taken off, bringing both heads down to their min. height of 105.2mm. This gives me the scope I need to raise the CR into the area I want, closer to 8.5:1 than 8.0:1 which it would have been if I'd left everything unskimmed. Valve seats and valves have been recut to spec and guide/stem clearance checked which was actually the main job that I took the heads for. They also indentified two slightly bent exhaust valves which I'd missed, luckily Paul at Zen had a couple of second hand ones in stock so this little problem only put Scholar back a day. New genuine stem seals on the way from Mark at Lateral - the £14 copy ones that I used in my first head build came to pieces as soon as I popped them off in preparation for the machining! Next job is to 'cc' (check the combustion chamber volumes) and then equalise these with my dremel-style rotary tool and a 320 grit mounted buffing sponge, which seems to have the best characteristics for this kind of job.

 

Stupid question time.

In skimming both heads and block, doesn't this bring the pistons and valves closer together? even if squish clearace is kept the same? So do you need to add the total skim to the squish clearance and then work out the appropriate gasket thickness?

 

Not that stupid, as I'd been thinking about this too. Yes, it does bring the valves and piston closer together, in this case by a further 0.015"/0.38mm over standard. However the closest that anything will get will be the perimeter of the piston crown (the piston is dished in the middle) just under a mm away from the squish area of the combustion chamber. The valves will never be open with the piston at the top of its travel, only half way down or at the bottom where they will be plenty of clearance.

If anyone knows different though, feel free to correct me! I've just finished (at last!) building up the crankcase after various piston ring problems and of course having to take it apart to get the block faces skimmed. TIP! Make sure your piston ring compressor is TOTALLY down flat to the face of the block before knocking the piston through, I wrecked an oil ring by letting it slightly ping out through a tiny gap I'd left at the bottom of the compressor! Anyway the block's now in one piece on my bench; crank, rods and pistons all in, pin plugs in and sealed. Pistons are all protruding 0.35mm overdeck at TDC. Once I have cc'd and equalised my combustion chambers I'll run the numbers and work out once and for all what the compression ratio will be.

 

Now making good progress. On the flywheel end of the engine the plugs for the piston pin access holes are covers that need to be sealed with Threebond 1215 and screwed down:



I wanted to now get this thing up on the stand as it was getting a bit awkward on the bench, so that meant flywheel had to be fitted. Threadlock was required for flywheel bolts:



Engine stand mount going on through the four gearbox bolt holes:



Now on stand, so the block was flipped over to fit the oil baffle plate and oil strainer. The strainer needed to be cleaned out again as there was still the remains of the big end bearings in there!



Sump in position and bolted down with fancy cap head stainless screws off ebay and a good coating of Threebond again:

 

looking good,any update on costs so far?

 

Well the nearest I can say is we're out of three figures and into four LOL. But then I have achieved my objective of not borrowing a penny to do it all. Everything has been paid for out of my pocket and not off a loan, credit card or overdraft.

At the end of it I reckon I'll have built a full-on forged monster engine for the cost of a standard rebuild at a reputable firm like API. Let's just say I definitely could have done a standard rebuild for under a grand, quite easily.

But the 'might as well' bug got me and I ended up souping up everything. I tell myself it's futureproofing. Although at the rate I'm going, the world's petrol will have run out before I get it on the road!

 

Looks lovely....interesting choice of colour, but matches the body I guess?

 

getting there now fella

 

Had a bit of a disaster yesterday, one of the head stud threads in the block was knackered and I've made it worse...looking like I'll have to at least do some drilling and chasing out of the thread with an old head bolt as it's an awkward size M11x1.25. At worst, I might end up needing to helicoil it which will cost me £60 for the kit!

The sump was going to be gloss black all over, then I realised that I wouldn't be able to spot any oil leaks, so I did it silver first, then masked off a band at the top and went over it in black. So it will eventually be silver block, black sump and heads.

 

Headbolt thread disaster is almost fixed. I've managed to drill out the first couple of wrecked threads in the block with a 12mm flat bit and corrected the threads on the actual stud by filing. Now just got to wait for the right M11x1.25 tap and a couple of spare head bolts to come through from Mick and I should be OK...in the meantime work will progress on ccing and equalising the combustion chamber volumes, then building up the heads and shimming.

 

At least its looking more promsing than the other day

 

Nick, ive had a disastar! My internet has gone down. Just thought i would let you know that i managed to get that package sent off today for you, it should be with you tomorrow before 12am

 

Cheers Matt! Can't wait to check out your package tomorrow morning. And I don't mean that how it sounds LOL. I will be posting up a photo of it asap!

Meanwhile, today's news: I've moved onto assembling the heads again. Before they were skimmed, they cc'd at 48.2/46.8/47.8/46.4 without plugs, meaning one head had chambers that were 1.5-2cc bigger each, roughly. I cc'd them myself using my own method tonight, which may be inaccurate, , and they came out at 47.7/46.2/47.6/46.1. This averages at 46.9cc with a range of 1.6cc which is too wide I reckon. So seeing as the aim of the game was to equalise them as best I can, I set to it with the Dremel needing to take around 1.5 cc out of each of the left hand head chambers #2 and 4. In the end I stopped at 47.7/46.9/47.6/46.8 whcih gives an average of 47.25 with a range of 0.9. That's close enough I reckon.

I then cc'd the piston dish using the same method (16.7cc) so that I'd at least be consistent with plugging the numbers into the CR calculator rather than using Wiseco's spec dish volume (17.8), and it works out at 8.146:1.

Good. Now I can give the heads one final rinse through and start assembling the valvetrain. Then I'll start the daunting process of shimming...

 

sick

 

Just been reading up on your progress Nick , what happened with the threads on the studs? did they go in pi$$ed or something

 

No, it was my block that was at fault. The thread in it was no good, all crudded up or something, maybe when the old head bolt came out it had corroded and tore a bit out, I don't know. But anyway, when the stud went in it seized and wouldn't come out again so once I finally extracted it, the bottom two threads were ploughed up as were the top two in the block. Drilled out the block and filed off the stud and all is well as long as I can run a tap through the block thread and clear it out.

 

A picture of the bit of acrylic I used to cc the heads:



Matt (who is running in his own build) kindly sent me four head bolts so I could have a crack at making up a tap / thread chaser for my block. No way these bad boys were going to come to any harm in transit - there were even blue 'cut here' marks so I'd know where to open it - cheers Matt!