The '2 ton bugswatter' - back for a gentle stroke

[biggerbigben]

Hey, thank you very much long time no speak. karls went back together last night, just waiting on the waterpumps to arrive so I can go and dial the cams in tonight. Then it's a waiting game for the new clutch plates and she'll be ready to rock n roll and get mapped with the new 1600cc injectors

Good stuff JP. Hopefully it will stay in one piece and he can see some track time this year. Once full power can be transmitted to the tarmac I'm sure we'll see some seriously good times! I still haven't seen it complete, I must make the effort to go to Santa Pod at some point!

Yeah its been a long time! The estate is just quality.. love it! Its a real sleeper in many respects! It must shift as well? Had a couple of years out of the scene myself but now its time to start the next project so hunting for a suitable donor car as we speak!

[JP]

Aaaaaargh

Yes that's the waterway. Was trying to slow the speed down a tad more on the exhausts to stop sonic choke and was doing the final polish on the last 2 ports before retest and broke through

Hopefully my mate has his new mini tig torch as the ports are so big now he should be able to get at it. If not back to square one and won't be done for dyno day

[diesel des]

Oh crap.

[Acidburn]

jp - was this after what you showed me on friday

[andy10v]

Thats one way of doing water injection!

Hope you get it sorted asap, awesome build and very educational.

[JP]

jp - was this after what you showed me on friday

Yes I decided to spend the weekend finishing my own head of so the engine can be finished in the next fortnight ready for the swap and an engine bay spray.

Anyway send some picies to my mate going to fly round to his tonight to weld it up. He reckons there is no problem getting into there

Also had a long chat with regards to cylinderhead coatings and have decided against them. It's not a lot of money but I think for the application and possibly any FI one it is the wrong route to take.

In very oversimplified terms the coatings are paint applied and heat cured so not a permanent bond by any means. And although it aids against pre ignition it potentially makes detonation more likely especially on a FI application. Which in my books is a no no.

[prj]

Ouch...
Oh well, it's just a bump on the road in the grand scheme of things
Good luck getting it fixed.

[JP]

Well it was a bit touch and go with the head this week we got it welded up on Monday night. Then on Tue evening I went to grind it all back to match the original port job to only break through again but worse. As the welding process had drawn all the impurities to the surface creating a very porous dirty weld. So back on Wed night to weld it up once again. This time round I've ground it back leaving a slight flat spot in the port. Not an ideal situation and not 100% happy with it but short of binning all the work over a neglible 2-3% percent on 1 valve out of 10 I'd figured finish the engine. Run it and if the head fails make another one, although I'll opt for a later AAN casting as the 7A has been of no amount of grief quality wise in comparison.

Anyway here's the dodgy repair job




This is the way the exhaust should look




And the finished intakes




Head being my original ported head just opened up for oversized valves still has the original deck cooling and now opened up H.bolt holes for the 12mm studs for the diesel block.




Crank assembly all balanced, real chuffed with the knife edging as the crank was out on the pulley end by 32gramms and on the flywheel end only by 37gramms. Normally when I change from an externally balanced configuration to an internal one on an I5 they can be out of balance as much as 100-110gramms on both ends, resulting in a swiss cheese effect like my original crank earlier in this build thread. I've lightened it by 2kg to bring it in line with the weight of a petrol crank, so coupled with the 4.5kg flywheel from Repo it should be a nice revy little motor.

(note our favourite special order diamond coated washer bottom left ) Saying that it is worth changing as there is just so much more surface friction than a used one and makes all the difference in keeping that pulley from spinning.




All the journals have been polished and clearanced




The block came back from Line Honing today, however a small oversight on my behalf means I still have to machine the mounting faces and threads for the knock sensors before commencing with the dry build.

Hopefully there is locations the same as the original AAN block as otherwise the old Motronic ECU may have to be superseded with an aftermarket unit sooner than anticipated. But this is a story for next week

[Rocco]

your work is crazy friend

[terrybullwon]

Looks Sweet Jp very good work!

[Acidburn]

Are you still planning on using the cambelt pulley shown in the bottom left or changing that for something else after what you mentioned?

[AndyP]

Nice work

Are you going to have to notch the bottom of the bores to clear the rods or do the Pauters not need this?

[JP]

@ Acidburn, I'll be using the stock pulley shown in the pic.

@ AndyP, not sure yet will find out tomorrow when I do a dry build. From experience though yes.

[Error404]

Excellent work as usual JP, glad you managed to rescue the head given the work thats gone into it

So in your experience are the 7A heads a poorer quality alloy / cast than the later ABY / AAN heads?

[JP]

^^^^ the actual alloy is pretty much the same across the board they all machine equally nice. The problem lies with casting moulds on earlier heads where they are just not consistent enough to push boundaries with. I've got several heads cut up and there is blatantly enough meat to machine out. Especially on normal port work ups, just when you go oversized valves it just seams to be unpredictable where the limit is going to be on the exhaust.

It might just be this head real difficult to tell until I try and push another 7A just when I've used later ones never had an issue.