Rebuild Time

[Futal]

Hey guys.
This thread may seem a little bit similar to Maxhags, I was reading through his which was full of some really helpful info for the most part, up until it simply ended and no conclusion was given. it can be found here.


My situation is a little different.

Car - 1983 AE86

motor / part in question - 4age bigport 3 rib bottom end, bone stock from what I can tell

ECU - Motec M4 Clubman

Drivetrain - JDM t50 and t series LSD

personal situation (if applicable)- I've owned this car for a few years and have been restoring it slowly as time/money and how often I need it on the road for a daily vs have a company car.
Currently the little hachi is my daily so I can't take it off the road, which isn't a big problem in this case.

I'm trying to decide what direction to head in as far as what engine to rebuild.
the engine that's in her at the moment won't be rebuilt
however I have a fresh bigport 16v head, Decked, ported and looks to have std valves.
and as of today I have a 20v silvertop long motor, haven't stripped it down yet but this block will be rebuilt and one of the heads will be going onto it.

So the first question will be which direction to go as for as heads go.
20v or 16v?

I know people will ask, "what are your goals for the car?"

Use - daily/weekender (once I have a company car again) and a weekend warrior
Hardware - ITB's are a given (love that sound, so adapter +quads if bigport or bolt right onto 20v)
I already have a very nice management system so I'm lucky in that respect 16v or 20v doesn't matter
if I was to go a 20v I would like to ditch the dizzy so no firewall bashing is needed, but I don't understand the benifits of a cas system vs a dizzy relocation.

I guess thats a good start.... so please guys I'm open to advice and discussion, I've never built a motor before but I like to think I know at least a little bit about the process so not a total noob but certainly need advice.
16v or 20v head?
we'll get onto the rest later first things first

[dove grey 64]

20v is an improvement over a 16v so I'd go for that if funds permit for the rest of the stuff needed for setting the 20v in rwd format.
If your strapped chuck the 16v head on the 7rib block. Quickest and cheaper

[ae86 slide]

Yep, above post just knocked the nail on the head.
All about money and ease of installation. You will get a better performance result with a 20v though.

[Matt]

Do you own the adapter already for the quads? If not personally I'd go with the 20v head. Having said that the 20v head condition may not be in good condition. Youll also have to change the water routing too with the 20v head. You can also sell the 16v inlet / water bits to offset your costs.

as for the dizzy stuff , just get a blank off plate and run the 20v cas plus 1zzfe coils or even look into a crank trigger wheel setup.

Rebuilding an engine is a tricky one in that you think whilst I'm at it ill just do this too, which can make the rebuild cost up to 3x what the minimum is.

20v vs bigport is a big difference, pretty much same as going from 4ac to bigport again. Make sure you bump the compression a bit with thinner head gaskets etc.

[Futal]

No, the long motor didn't come with any manifolds, or accessories so no alt or ps pump.

This will be the defining factor, your not wrong there, my original post was assuming everything I have is in good nick.

Cool this is the sorta stuff I'm chasing.
But just a bit of clarification, what is it about the 20v that's such a quantum lead away from the 16? ie "4ac to bigport, bigport to 20v"
I understand the extra valve = greater intake volume.
I'm going to start posting some photo's maybe tonight, once I have the motor on the stand and start to strip it down.
To start with though, I've pulled the plugs out and they seem pretty shagged, just carbon build up nothing major, looks to be a nice amount of freshish grease on the back of the main crank bearing and the motor seems to turn over nice and smoothly by hand.

Is it worth trying to do a compression test while the head is still on?
Anything I should check while its still all together?

[Matt]

To be honest it is a combination of things. Increased compression, greater air intake and the vvt. In my experience a mildly built 16v is comparable to a 20v and the $$$ and effort to get there just isn't worth it.

At a minimum change the valve stem seals on your head. If you can be bothered doing the shims would also be worth while, but very time consuming.

a leak down test is easier to do out of the car and will tell you more info.

Your 16v stuff , alternator / power steer setup will bolt to the 20v block. I'm not sure if the lines that run across the top of the head will sit nicely though on the 20v head

[Futal]

no power steering, don't believe in the shit lol so no problem.

ok thanks matt and other lads. let ya know how I get on

[Futal]

ok, had a good think about it guys.

16v head it is. after looking into how much it would cost just for all the rwd conversion I'd rather just put half that kind of money into extra fruit for a the 16v and spend the rest on suspension.

Has any one got recommendations for pistons? I'll be taking the block down to a machinist for some work like acid dipping and boring/honing so once I've found out if std or .25 os pistons are best I'll order them.
after stripping the motor down quite a bit, discovered oil squiters in the piston bores. so this means I'll need to be getting pistons with the cut outs for the outlets.

[blair]

If std, just re-use the 20v pistons if in good nick? I did, and got a healthy 80rwkw (stock cams no headwork)

[Futal]

Pistons are shagged