4age cylinder head rebuild

[smithy4564]

Hi,

I've joined up to get some advice. I've got hold of gas-flowed cylinder head for the 4age in my kit car (16v bigport). I'm gonna rebuild the new head with all the parts from the old head. Any tips on what to upgrade while I'm at it?

My list so far is to add a new water pump, head gasket and all the other gaskets. I'm not gonna skimp on the head gasket, but can I get away with ebay jobbies for the rest? The BGB gives details of Special Service Tools (SSTs) are they worth it? Are they even still available?!

Oh and this is just phase 1. I've got some 272 duration Newman Cams ready to go in once I've got the new head up and running.

Many thanks,

Dan

[tottacrolla]

[smithy4564]

Cheers tottacrolla, already checked and they're OK That said there's so much conflicting advice on different forums about what lift/duration requires upgrading. I'm sure Newman know what they're talking about so I'll take their advice!

I'm interested to see what difference the gas-flowed head makes before I fit the cams. That and I want to make sure I put the head back together properly before I potentially ruin a new set of cams!

[smithy4564]

Right I've seen Payen recommended on the other thread for head gaskets. Rather than clutter that thread with my questions, where is the best place to get them? There are 2 different part numbers for the full gasket set, DN390 and DN392, is this for the small port and big port heads? Any one have any experience of aftermarket, thinner head gaskets? At the moment I'm looking at a 0.8mm TRD gasket, any one care to comment?

From what I've read the higher compression helps with uprated cams?

Help much appreciated.

[SuperRedMR2]

Are you running a standard ECU or aftermarket? The duration may be too much for the standard as i've read 264s are the longest without destroying your idle.

I'm running a 1.0mm Cometic HG to up my compression as i've got low comp pistons. You need to make sure your head and block are dead flat if you are using a metal HG.

I was advised that a dynamic compression ratio of about 8.5-9.0 for my cams along with the HG thickness to avoid DET, but that's because I've got 9.4 pistons opposed to 10.21 pistons usually found in the MR2 4AGE lump.

If you up the compression on yours you may suffer with ignition issues.

[smithy4564]

Ah, forgot to mention running carbs not stadard ecu.

Cheers for the response SuperRedMR2. I've got an Omex ecu to sort the ignition but good to know it might need adjusting. I was contemplating driving up to the dyno, but with that knowledge I might change my mind.

I bought the head off a guy on ebay with no specs and I've been umming and ahhing about getting it checked. Again I think that feedback has swayed my decision.

Thank you.

[tottacrolla]

[smithy4564]

Tottacrolla, are you talking about the capacity of the recess in the head or measuring the actual capacity of the engine? If I take too much off the head what problems could that cause? All I can think of is taking too much off so it's no longer an non-interference engine?

Given the points both of you have raised, is it worth trying to figure out the compression ratio and being a bit more scientific than I am at the moment?

[elbon50]

If I take too much off the head what problems could that cause?

Uncontrollable detonation is a possibility

[tottacrolla]

[SuperRedMR2]

I saw that for sale a few times, was it about £250 or something like that?

I considered it, but then thought i'd better off rebuilding my head myself and/or getting the work done, so I'd know everything that had been done to it.

Go to AE86.org - those boys have a lot of info on modding the 4AGE as that's where I got my advice from.

[smithy4564]

Ahh, uncontrollable detonation does not sound good! Is that because you increase the compression to the point where the fuel self-ignites?

I'll keep researching, after all I haven't even taken the old head off yet. I have had a quick look at some ae86 forums, but I was under the impression the serious guys all use 20v or swap out for other engines? The problem with a lot of forums like club 4AG is they're all US/Aus based, which is OK for general info but not great for specifics like parts etc.

SuperRedMR2 that's the one! Got it for £200 in the end, and he was just up the road. Really nice guy incidentally, building some crazy n/a mk1. I know it's got no history but thought it was worth a punt. We shall see!

The other thing I can't decide is whether to build up the new head with the old cams for now, or throw the new cams in and do it all at the same time. This is my first head rebuild, so I'm not sure about the added pressure of braking in cams at the same time. Especially all the stuff about starting up pretty much first time or your doing damage to the new cams. The carbs are twin 45s with no choke so cold starting is an absolute nightmare. On the other hand it's gonna be a ball ache stripping everything back down again and rechecking clearances etc.

I've even thought about taking it to a garage for the first start! But then which garage will want to accept any potential liability from some nutter who's stripped and rebuild the cylinder head on his own!? I've stripped and rebuilt engines at college but this will be the first time I do it myself on my pride and joy.

[SuperRedMR2]

The AE86 boys helped me decide what cams to get.

On here they are all for HKS cams, but not everyone can afford that, so they came up with 3 or 4 different manufacturers which are just as good and offer different affordable durations.

I'm running cat cams 252/260 duration, 8.5mm/9.00 lift. I haven't changed my valve springs as the cams specify that std springs will not have any issues.

Unfortunately i've been suffering with suspension issues since the car has been finished and i've only covered 400 running in miles so I haven't given it the beans because of the rear end.

I need to disconnect my stat pipes as they are leaking, need to do cambelt again, cam timing, replace a really awkward engine bay fuse and have a realignment (after all suspension is back together), before I can give it a proper run out.

[smithy4564]

Ha can't blame you, I've got some old Yokohamas on the back and that's skittish enough! Part of the growing to do list is replacing them with some Toyo T1Rs, along with a million other jobs while she's off the road.

Let me know how it goes, especially if you ever get it on a rolling road. Be interesting to see how less duration/higher lift compares. I did look at those cams on the Fensport site, can't really remember why I chose something different TBH! They seem pretty highly regarded.

The new head has gone to the machinist so I'll have a look on the AE86 forum while I wait.

Cheers,

[SuperRedMR2]

If you sign up, message a chap called Bean Bandit as he knows his stuff.

I've got worn bushes/seized ball joints/worn tie rods - i wish tyres were the issue.

[smithy4564]

Quick update.

Gaskets and head studs have arrived and the head is back from the machinist. Taken the intake and exhaust manifolds off, so I'm finally at the point where I can take off the head, strip it down and build up the new head. Decided to get it all done at the same time and put the 272 cams in while I'm at it.

Been reading up on the 4AG and AE86 forums as well as some good threads on here. I think, time permitting, I'm good to go!

Oh and one for the purists. I had a good conversation with a college tutor yesterday who once lapped a set of valves in with an impact gun! Apparently the electric drill wasn't fast enough!

Pictures will be back-dated in 5 posts time!

[stenky]

hey smithy. i am curious what results you will see after you head job. my spare head is being worked on as well. i don't know many details about it just that my valve seats are custom made from wolfram to suit oversized 7MGTE valves, valve guides replaced, custom springs installed, Yaris shimless buckets, head casting imperfections ground plus inlet and exhaust ports slightly enlarged. i intend to run some mild duration 264* cams with some mild 8-8.5mm lift and later a lysholm supercharger. compression lowered to 9.0:1 however so NA performance will ba a bit lower than one could expect

[smithy4564]

Stenky that does sound like a pretty awesome setup. I've been looking on the AE86 and 4AG forums which have some pretty good tech articles.

Interesting to see how it runs N/A with a setup optimised for a supercharger? I'll be honest after reading some of tech articles I did start looking at the US/Aus/NZ tuning companies.The amount of work (and money!) you can do N/A is crazy, or save yourself a load of hassle and go forced induction.

Your head specification sounds pretty impressive. What kind of rpm limit are you looking at? From what I understand from the articles I've read, for forced induction setups you want to go for as much flow as possible, so cams with high lift and plenty of head work? Are you using a bigport head?

I'll have to get the carbs, ecu and cams setup on a rolling road so will update with figures as soon as it's done! No idea what power it'll make. It made 134 BHP in it's current state i.e. completely stock with carbs and a 4-1 manifold.

[stenky]

Yes, its a bigport head. It will see no more than 8500RPM, because the supercharger cant spin forever
The flow has been increased by fitting oversize valves + higher lift. If you combine valve size and lift correctly, you don't have to fo for excessive lift, that needs stiffer spring and therefore timing drivetrain increases its resistance rapidly.
As of now, the head flow figures are 195CFM (140CFM stock) and intake charge speed is nearing 200m/s (100m/s stock). I wouldn't bet my neck for that as I am not doing the head myself and the guy who does that tends to exaggerate a liiittle bit but it still makes NA volumetric efficiency over 100% now. I expect NA performance somewhere in 150-160HP figures and SC double that

[aw11rally]

http://www.pistonheads.com/classifieds/ ... ne/1989670

If only money grew on trees!