EA81 heads ful of ... gunge

[cubastreet]

Hi guys,

 

I'm kinda new around here, but I've been lurking for a while ever since buying an 81 brat at Christmas time. I know that the 81 brat goes in the historic forum but I'm here to talk about the EA81 so thought it would be better off here.

 

I recently purchased a spare engine as a winter project to rebuild and do a little head work on. The guy told me it was low mileage and was running well. Anyway, when I got it home it woul turn, but not through a a full revolution. Don't panic I thought, perhaps it's a hydro lifter one and something's blocked after sitting for seven years in this guy's shed. His story was that he'd bought it to stick in a jetboat but opted for a ford 4 litre instead.

 

Anyway, it's sat in my shed for a couple of weeks but yesterday the curiosity got the better of me so I threw it on the bench (damn I love alloy blocks) and pulled the heads.

 

When they came off, there was a huge amount of carbon in the chambers, enough to stop the engine from turning over. After pulling off both the heads it turns fine. What amazed me the most though is that the engine looks to have been rebuilt but not yet run in. The bores still have a fresh set of cross-hatch honing marks. One of the pistons isn't black, and looks like it's brand new. The valves and seats all look brand new too, except for the carbon.

 

It's obviously a jap engine as the writing on the oil filter's all in kana. It looks as though the engine's been rebuilt (or possibly even new) and someone's filled the petrol tank with sugar. The oil in the sump looks new.

 

I just can't understand how this engine got to be in this state. Anyway, it's good for me, as it means I don't have to pay for a rebore, new pistons etc. What do you guys suggest I do with this engine. Part of me is saying I should just decoke it and throw the heads back on, but a bigger part of me says that's just way too risky for such a good condition engine.

 

I'm still planning to strip it down, check the bearings and the oil galleries and make sure everything is hunky dory, gring the ports a little and maybe shave the heads a little as well. I payed NZ$50 for this engine, and another $5 for a spare seized block, alternator and starter motor. It's looking like the bargain of the year.

 

Can anyone suggest anything in particular that I should look out for when I do the strip down?

 

Jeremy

[CHIM]

it,s acculy pretty comon to see hone marks in the bore, i have pulled several heads off of 100+ thousand mile motors and seen that, the bore's on these motors just don't wear very much.

As for the clean cylinder i would say either a leaking head gasket or it wassn't firing at all.

 

~CHIM~

[cubastreet]

Just to clarify - There are NO signs of wear on the walls of the bores. The crosshatch looks brand new. Also, the clean piston had a chamber full of carbon also, it just wasn't stuck to the piston. A little mild scraping reveals clean, unburnt alloy under the carbon on the other pistons also. These babies have not seen much action at all.

[GeneralDisorder]

Agreed - the cross-hatch usually still looks new even after 100k miles. Don't judge anything till you have looked upon the main bearings tho.... they get pretty sloppy usually.

 

GD

[cubastreet]

OK so after a stripdown, everything looks .... new. one of the pistons has some dents in it where something small and solid had been bounced around the combustion chamber, but other than that the whole thing is barely worn in. I was prepared to have to buy new pistons, bearings, rebore etc but now looks like I can spend that money on a rollbar or something instead. Or perhaps a supercharger

[Ross]

Get new bearings anyway, i got mine for like, NZ$130 ( mains and big ends) and then you know its all good.

When i had my ea81t apart (bearings all slogged out, no oil pressure, black gunky crap all through the engine) the hone still looked almost new after 150,000kms, so dont judge too much on that.... But if the carbon came off pistons easily, then it probably is pretty newish.

 

One of my pistons had small dents in it (looks like maybe the tip of a spark plug got loose) and i was told not to worry about it.

[cubastreet]

Do you know any good NZ suppliers of parts? apart from rebuild kit, new bearings, probably new valve springs I might like to try a different cam profile as I'm throwing on a 34/34 Weber from a fiat twincam and I'll do a bit of minor headwork at the same time.

 

The only other engine I've rebuilt was a ford crossflow. I'm not sure why these things are still so popular in England - heavy iron block (1600 can be bored out to 1900 tho), the pushrods weighed about 4x the EA81 ones, deep ridges in bores after 70,00 miles (although the guy at the machine shop said the wear wasn't bad), the list could go on a while. It's just a pity these old sube engines don't have the same supply of performance parts. I doubt the cams designed for aero use will leave me with much torque low-down.

[Ross]

Sorry about the delay, i have to use dial up at my new flat so i don't get on often....

 

I got most of my parts from Repco - if you go in there enough they'll give you a good discount, and they can get most parts. I wasn't able to get new valve springs, you may have to go custom for them....or go to subaru - their prices are good for some things, eg gaskets. Lifters were another thing i wasn't able to get anywhere other than subaru, and at nz$470 a set plus a three month wait it just wasn't worth it.

I got my cam reground to factory specs for nz$70ish, kelford cams, plenty of places that do them around. Shouldn't cost any more for a different profile grind as long as you know what you want..

 

Crank journal grinding is tricky, because they are so narrow very few places can do them - only place i know of is Chrischurch Engine Specialists, they were very good to deal with.