Need Input - 2056 Build

[Clatter]

Looks like you're on the right track..
If the heads are nice as you say they are, and you can get your CR out of them,
I think you'll be in for a nice surprise even with stock heads.


One thing you'll have to wait a while to appreciate with the type 4,
Is that they can last literally a lifetime.

Built right, in a light car and treated right,
You'll only ever pull it out because you want to change something,
Not because something broke.

[Clatter]

Don't forget to read the bulletin.. --. https://ratwell.com/mirror/www.dolphins ... hbull.html

[Vee Dub Nut]

OK, for those following along, I got some parts in today. Did some quick and dirty measurements:

AA 96mm Biral Cylinder
--length: I got ~3.615" with my chinesium HF calipers (77westy posted 3.614")

AA 96mm Hypereutectic Piston
--pin height: (pin centerline to crown) 35.114mm (AA's website says 35.5mm)
--valve relief: ~2.5cc (AA's website says 7cc)

The piston info that AA shows on their website is WAY off from the actual part Not sure how they can mess that up that bad. Parts look pretty nice so far though. Obviously haven't put them across the scale yet, but they look pretty good.

So again waving the magic wand with these measurements, I should have around ~0.053" deck in the hole, and a SCR of ~8.6:1 with my current AMC 2.0 heads. Less than ideal. Need to mock things up to be sure, but its looking like fly cutting the step or decking the case will be needed to get CR up.

All for now.

edit: I updated the AA spec for pin height that I goofed on earlier

[wreck]

If you have a read through that link I put up , Len does state that he has fly cut up to 2mm deep . So if you half that at 1mm you still should be safe .The step was just cast in to replace the head gasket , so by my calculations you should be able to remove the step and then remove 1mm .
also get a second opinion from who ever you decide to do the valves/seats etc .

[Deefer66]

If you have a read through that link I put up , Len does state that he has fly cut up to 2mm deep . So if you half that at 1mm you still should be safe .The step was just cast in to replace the head gasket , so by my calculations you should be able to remove the step and then remove 1mm .
also get a second opinion from who ever you decide to do the valves/seats etc .

Just watch out for cylinder shoulder hitting head before base seats in the chamber.. I've just been 'adjusting' head and cylinders to avoid this after a 0.75mm cut out of my 1800 heads..


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[Piledriver]

The 30mm pin height is for strokers. stock 2L pin height is 36mm.

The other option is trim the jugs, but that still wont get you to 9:1.
Cases usually just needs a shave to be true, ~5 thou at most per side.
Cut the consumables first.

[Vee Dub Nut]

If you have a read through that link I put up , Len does state that he has fly cut up to 2mm deep . So if you half that at 1mm you still should be safe .The step was just cast in to replace the head gasket , so by my calculations you should be able to remove the step and then remove 1mm .
also get a second opinion from who ever you decide to do the valves/seats etc .

Yea, removing the step is nominally a 1mm cut, so half of Len's stated 2mm cut. By my estimations, removing the step would get the chambers down to ~48cc, which would yield a estimated SCR of 9.5:1. This would be much better considering dynamic compression ratio.

Just watch out for cylinder shoulder hitting head before base seats in the chamber.. I've just been 'adjusting' head and cylinders to avoid this after a 0.75mm cut out of my 1800 heads..

Good reminder. I haven't looked at fit-up of the barrel in the head yet.

The 30mm pin height is for strokers. stock 2L pin height is 36mm.

The other option is trim the jugs, but that still wont get you to 9:1.
Cases usually just needs a shave to be true, ~5 thou at most per side.
Cut the consumables first.

Whoops.. You're right. I was totally looking at the wrong page on AA's site last night. They stated 35.5mm compression height, which is MUCH closer to what I measured. I updated my earlier post. The valve relief spec is still blatantly incorrect however.

I need to look at my case closer, but at first glance, it looks pretty good as far as deck flatness. I don't know if the previous owner of the Bus/engine builder decked the case or not when the 2L was built. Doesn't obviously look like it had any work done, but it does look pretty flat/true (I admittedly need to get an improved straight edge and get the case cleaned up to know for sure, so TBD).

There are a few ways to skin the cat at this point. Since we are rapidly moving into the Christmas holidays, I'm likely going to just take my time and get everything cleaned up and check the case deck, mock up the bottom end with the new h-beams and AA P/C kit, and see where I really stand before making any final decisions in regards to head work and how to manipulate SCR.