I do believe you are right about a clearance issue. What is a little unusual is that it's on the side of the piston skirt Vs the thrust area of the piston. It would be a little hard to between that one piston would be cam ground different then the others. But it does look like you pick up on the problem early enough that you can save the cylinder with a light hone job. Davew7
Without a moments hesitation my machinist says "cold pickup" it didn't get warm enough before going for it on the track. Probably a hangover from Leyburn sprints that showed itself at lakeside on lap 3
Hoping he can save the block, I'll know more tomorrow. Random thought... Should I make a video about this rebuild?
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Could be, F1 engines need to be warm to certain temperature before start( tight tolerances), not even think about loading the engine.
Sorry what ignition system are you using?
Hopefully you can save the block.
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1st. The block is salvageable, thank goodness. Crank is good but doing a new set of bearings and pistions. The balancing and match grinding should be done in the next few days.
2nd. The ignition system at this point is a bigport dizzy with a MSD A6L. Set at 27° and a pair of 45mm webbers dribblimg in fuel. I plan to change over to an injection system later in the year. MoTeC and jenvy components.
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Great news on the block
Well precision ignition is needed for a high power high compression engine.
Either 36-1 or 60-2 crank trigger would provide a very stable platform, either if you use fuel injection or Ignition only as Nodiz , electromotive etc.
Motec it is the top in aftermarket ECUs.
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Yes. That would be nice if it fit in the rules for historic Group A but... the MoTeC will get a referbished small port dizzy.
I will have all the bits ready for an engine building day on sunday.
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Track\Daily challenge
Hi mate. Been following your thread for a while and love the build. Just curious why you want to preserve the 3rib block? Is it the matching number engine?
Cheers
Couple of reasons bazz.
Primarily there is a bit of nostalgia I guess. It is still pretty much as I bought it out of Japan where it raced all its life. TRD cup, N1, entry level N2 and club racing. Hence hanging on to the Webbers for so long. They will be replaced in the near future with a std RWD TVIS plenum and a MoTeC, even a stock exhaust manifold! WTF I hear you say. There is method here though.
On the other hand... I somehow have 2 AE86's, both dedicated race cars. This white one which you all know and, a nother which was built as a NZ Group A rally car. Mostly rallied but also did a hand full as a touring car. Slowly I have been collecting parts that fulfill the certificate of description needed for this one. Diff and gearing, gearbox (dogleg TRD straight cut dog) most of the suspension and so on. I am trying some 3 rib stuff in this old block which is too far bored out for grp a spec but, toying with plenum, cam, exhaust, ecu, bearing arrangements with rod/pistion/comperssion along with reliability for the grp a car is what I'm looking for. It would pain me to experiment with a fresh block and crank.
The current block and crank are on their last competitive build... so I am happy to give it 1 more go. But lets face it, 83.5 in the bore is just bonkers! Nobody make a 4A piston that size that I know of. 1.8l Mazda MX5 pistions are almost perfect though.and the crank is 0.5 under, that's the limit for competition bearings.
So, why keep playing with a bigport and a 3 rib and a distributor?... preparing for Group A racing is the big answer. It's the underlying guidelines/rules.
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Yeah I appreciated group a needs standard intake and exhaust. But were they allowed to use the 7rib block for the 42mm crank? I know Atlantic cars used the bigport with the 42mm crank?
For the certificate of description (COD) you have to nominate an event your car ran at and build it to that spec. In the later years ITB"s were allowed too. I have spoken to the guy who built my car in 1983 originly (1 of 4 in a special shipment of promotional cars) at length. He also helped the guy who bought it off him. This is when it did a combination of touring car races and rally.
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