Initial plan was 86mm stroke and 83mm bores but after having one of my A15 cranks butchered by a crank specialist that hired a moron to take over while he was on holidays and ending up with garbage. Ive decided to stay with the stock 82mm stroke and go for just bigger bores.

The plan now is
A15 block and winged gated sump
83mm or 83.5mm iron sleeves (see whats possible)
ca18de pistons (valve recesses to suit 8v)
ca18de rods (lightened & fully prepped)
Rods lengthened to 134mm (hopefully 135mm)
Oval port head stock cleaned up ports
(mazda Z twin cam is nice but not proven
or detailed enough for me to tackle it
would love to though would be crazy)
better valve springs for 7500rpm redline
GX style camshaft with more lift
Quad 48mm bike carbs custom mani or single 2.25 inch SU
http://users.tpg.com.au/ntome44/SG/CV-Carbs/Honda-VTR1000-001.JPG
Headers by Highpoint mufflersf or american imported ones in stainless

The issue is the offsetting of the bores away from the camshaft also 2 and 3 towards each other might cause grief to the combustion chamber position.

Will post photos as the work and details are sorted for everyone to see but PLEASE keep opinions and hijacking out of here and do a search to see that this is possible and Lemonhead has done this already to 82mm sleeves in the past but no longer posts on this site so no further info is available except for what he posted on past threads.

The ca18det rods have plenty of meat on the rod ends to be lengthened are heavier duty than the A series but fit with little work, so no questions here needed, however they need a little weight removed as they are heavy suckers.
Unfortunately H beams versions cant be lengthened the pin are is too thin.
http://www.mmr-direct.com/Pictures/IMGA0347.JPG

All and anything is possible. Think outside the norm.
Look forward to seeing progress.

I really want to use the mazda head as it will allow the 83.5mm sleeving to be evenly spaced to suit the Maz head better than the A series head.
However Im worried i wont have the know how to sort out the nitty gritty of such a conversion and it would be easier to just go the proven L series KA head instead.

Quote:

Why would you go to all the trouble to build a bigger A series than anyone before and use a stock head and puny little OEM duration cam?
And what's with the carb options??? Quad 48mm bike carbs or single 2.25 inch SU? Other ends of the spectrum much? I go with the single SU. Take the engine back to the halcyon days of the 1950s! Remember, it's all about area under the curve.

Yes definitiely use imported American mufflers - that's the cornerstone of any engine build.

May I suggest isotropic finishing and friction coatings?

Nothing off subject there, just adoration for the Marque and general interest, as I'm sure you understand.

Regarding the rods,
I'm pretty sure that CA16de rods are very like ca18det rods, (look the same) only they're a bit lighter. I don't remember how much lighter, but when I did a comparo weighing a ca18det rod (less cap) and a Ca16 de rod less cap there was a difference.

Its interesting if this is the case as they have the same part number on some catalogues from Nissan.

I got word this morning the head is going to have some issues around the chambers hence I thought it would be easier to overcome by chosing to use the stock H89 valve sizes but there seems to be more issues than I thought with the chamber position so will have to go in and have a look to see if the A series heads are possible with such a big bore. :(

I remember Gary also mentioning the 82mm engine also had some issues with the A head fitment but there was no more follow up info stated as he was going for the combustion chambers that are equally spaced when using the ga16de head.

There is no plan B as Im too chicken to attempt the equally spaced Z or B maz head

That's odd?
If I ever get five mins to myself in the shed, I'll reweigh them, and compare the numbers off the beams.

If you can't get it to suit the chambers (or think you can't) swing past my place on the weekend, and we'll see what is what (I've got enough a15s and various heads here to work out spacing).

It should be doable. Initially I thought you would be worried about valve shrouding and did a diagram in ms paint showing that at that bore size (exaggerated diagram for clarity) increase, even a few mm shift of bore centreline should still hold up. I won't bother posting it here now, unless that _is_ the concern.

With regard to teh crank - who did it? (pm me if you don't wish to name and shame on a public forum, or call me - on the weekend if possible, and I won't reveal it here). REason I ask is I can put you in touch with the right people to do that sort of work, and I'll personally vouch for the work. In fact I'd be willing to send one of my a15 cranks to be done, so that you wouldn't be risking one of your own. Sometimes you get what you pay for (and i don't know who you paid, or how much) and the firm (actually I can think of another place that would do it just as well as them, so there's at least a choice of two I can vouch for. I haven't had datsun a15 cranks done by them specifically, but I've had some oddball cranks with fairly decent weldup/offset grind work done, so I can vouch for that). Done right it'll be cheaper and more reliable that a massive overbore (I'd also argue that the flow limitations will be with the head, so whether or not you go to a much larger capacity will only affect the powerband rpm range side of things, actual peak power won't be drastically different.

Let me know via pm if you can.

Any news on hunting down that s/charger part?

Boo!!

How bizarre... How bizarre... I haven't looked at this site for a long and the first time I do I see my name mentioned...

Yes it is possible to sleeve an A series motor, I have one sitting downstairs, 82mm pistons.
This block had my 88mm stroke crank in, 1860cc motor.
I have since taken the crank out and put it in another block with 79mm pistons, 1725cc motor, I've nearly finished screwing this motor together.
I'm just in the process of buying back my old rally car and will be putting the 1725cc motor in that, fed by some 50/48/45mm throttle bodies from Steve Newing.
I have imported a T50 gearbox from Canada which is a close ratio 1:1 fifth straight cut dog box.
The rear end is the one I bought of Feral years ago which is the Datsun Works 240rs triple tube diff housing and the 4.875 big pinion alloy centre with a brand new set of MK63's on it.
If you really want a BIG bottom end D I might consider selling the 82mm sleeve job, I have a few 88mm stroke cranks lying around somewhere and I could graft one into the block for you and you'll have an 1860cc motor.
Food for thought..... 1860cc with the Mazda twin cam head the gentleman has grafted onto an A series block.

Jmac just got back from Japan so just got my head together in the last few days.
I went today to look at the issue and it seems its not but could it cause pulse/vibration at certain rpm as the flow/combustion is slightly different on the off centred 2 and 3 pistons??. Ive got a simple stock head so only looking at more under the curve due to capacity increase and later if and when my special high port head with biggest valves possible using welded up guides to remachine new guides for bigger valves for both sides. Studying the head atm we think we can fit 42mm inlets like Bart has done in NZ and 35mm exhausts. The chamber will look like this one hopefully photo below at end of text, welded up and good enough for big hp as done in Japan for the supposedly 400hp L28 beasts that are all the rage in the Z circles.
This is where the money is been spent and its a long project as the welder takes his time weld by weld for now etc.

Gary, welcome back good to hear you havent left the Big block idea aside. Bit surprised you are downsizing the big block down to 1725cc any reason for this? We were really looking forward to the world record holding title as the largest A series every made. I know things always change without our control but youve left so many of us salivating at those pics of the 82mm big bore.
The Maz heads would be awesome but too far away at the moment.

Im looking at more something like this atm for the head as explained above 42mm inlets and 35mm exhaust.

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