Bigport Head Work

[charlie835egg]

Hi all,

 

Haven't been in the scene for a while but with the degree finished after a couple of exams it is time to blow a bit of money on my beloved KE55 corolla and get it on the road in good shape.

 

First off I HAVE a bigport head (bought from Brad Mav a while ago) and I'm going to use this on my 4K. (so no discussion about waste of money on bigports Jamie)

I've come to he realisation that I'm going to have to get a head shop to port and work the head. No home porting like Stew does, I'll try it some other day.

 

The valve seat don't look crash hot so I'm thinking a bit bigger valves with a double angle job will be in hand and valve stems. So the purpose of the topic is to ask firstly what bigger valves people have used in their 3K/4K heads in particular kangaroosa, Xany, and especially RedDwarf. I don't want shrouding, and I read that there is a nice guide in one a book by David Vizard (i've never seen one of these books yet). Anyone got one for sale??

 

Of course I'm going to be ask what cam I'm going to use, and I'm not 100% yet but I'm just going to get a Tighe regrind. So lets say the Tighe cam profile 104: (25-65 270 degrees adv dur, 0.398" lift) on Jamie's FAQ advice.

 

Now comes springs, I don't need doubles for under 0.4" lift, but would doubles not detension and valve bounce would be a non-event with much higher resonance?? This will probably come down to a $ thing, so I might be sticking with a single spring.

 

And anohter "What exhaust?" I'm thinking 2", but I don't want a blap blap so maybe a 1 3/4" for better flow and bit more ground clearance. Just be a pipe kink system with a straight through I think. Already got a set of cheap hurricance extractors running at the moment.

 

And maybe asked "What carby?" Weber 32/26 which I got in a box.

 

And of course the question of "What do you want to build the car for?" will arise.

 

So in list of priority;

-Amatuer Rally, hill climb and motorkana. Mind not overly competative, jsut wanta have fun and live.

-daily drivable, so that's why no SILLY ARSE cams and blap blap exhaust systems.

-good handling, that's why I'm sticking with a 4K.

 

Thanks in advance to the community

 

Later

 

Charlie835egg

 

PS

pity to see the death of the Yahoo Oldcorollas. Its easier to search.

But its move with the times I guess.

[Xany]

Gday mate,

 

You know us too well already....good intro there, you should be proud. :D

 

on the topic of bigport heads, blah overrated blah......i have one on my car that cost at least $700 to setup.....not cheap for an old corolla. However, it has been properly flowbenched and ported to suit...AFAIK the specs are:

 

Ported and polished inlet and exhaust ports

Mitsubishi Galant Exhaust Valves

Standard Inlet valves

Holden six valve springs

proper sealing valve stem seals (not sure what they are off)

Professionally Flowbenched and ported to suit.

 

so, theres about $700 worth of work just there.....is it worth it?....i'm not sure cause i can't really compare it to a fully done up 4K head. But i'd say if i was running a higher compression (currently about 8.5:1) i'd be pushing out a bit more than 70hp atw.

 

btw, if you get the head done up at a head shop, they should be able to setup a cam to suit the head....which is what you really want.

 

Also, with the holden six springs...you have to have the spring seat widened to fit them.....but i've never had mine valve bounce yet......and thats gone past 8500rpm.

[Super Jamie]

vizard books on ebay

 

i run hd single springs, no problems. i think the bottom end would break or it would run out of air before i hit valve bounce, i've found 8500rpm and haven't had the balls to go further. i don't think dual springs are required at all

 

i have had similar thoughts about exhaust, but i'm using the 2" on my pano because i have it and it was cheap to get setup. an exhaust is only as good as its first few feet

 

my only suggestion would be to get a real fuel supply. using a downdraft on a 700-900 dollar head is like buying a mansion and locking all the rooms except one, such wasted potential. get sidedrafts, or SUs if you can't afford a thousand plus dollars of carb and tuning

[Xany]

my only suggestion would be to get a real fuel supply. using a downdraft on a 700-900 dollar head is like buying a mansion and locking all the rooms except one, such wasted potential. get sidedrafts, or SUs if you can't afford a thousand plus dollars of carb and tuning

 

 

Which is why i bought your SU's off ya.... :D no more wasted potential...its only the compression letting it down then.

[Super Jamie]

and we all know how to fix that :(

 

hurry up with em too, i had the damn things on the head within 24 hours of buying them! pfft, never mind the fact my car then sat for 2 weeks while i sorted out throttle cable and fuel pump :D

[Felix]

i would keep the standard valves. big valves are more suited to top end cams. get a 3 angle valve job, and get the valves backcut, they will probably then flow just as well as oversized items for less cost. shim the standard valve springs to have 10 thou clearance between coils at full lift (will go over 8 grand). clean up the casting marks in the head with a dremel type tool. use the 25/65 cam you mentioned, but stay at 400 thou lift max. set it up to have a compression ratio around 10:1. make sure it has a double row timing set. shim the oil pump spring 2mm.

 

if you do the above to a healthy running engine it will cost bugger all, yet go WAY harder than a stock engine. if you start with a healthy bottom end it will cost under $400 for what i have outlined above, including valve/seat machining, a head skim, a reground cam and all gaskets, seals etc. the trick is with the headwork, supply the head dissassembled and cleaned to the machine shop. only pay for what you can't do.

 

i'd run a 1 7/8" exhaust, with a resonator and a straight through muffler, or a single reverse flow muffler and no resonator. press bends are ok, if you get someone decent doing them. find a workshop who doesn't mind you watching them hang your exhaust. get a 3 bolt flange put in behind your extractors.

 

for induction, your DGV is a little large for a 4k but will work OK if you drop the idle jet size. you will probably find a stock carb is quicker up to 3000-3500, but then the DGV is superior from then on. a DGV works better on a 5k as they suck harder on the carb at low revs. unfortunately they have cast in venturis. a DCD weber is a sweet carb, they have replacable venturis making them the most tunable of the weber downdrafts for varying engine combos.

 

better induction setups would include SU's and webers/dells etc. the SU's are better on a streetable engine as they have constantly variable venturis, and deliver better economy and flexibility. the DCOE's etc. are more suited to a particular narrower powerband depending on how they are setup due to having fixed venturis. the webers will more than likely make a few extra HP at the top end at the cost of flexibility and economy down low. the webers are more suited to a top end cam, and more a race engine.

 

to get the most out of your engine/induction/exhaust combo, fit a numerically lower diff ratio. say it had a 4.1:1, drop it to a 4.3:1. this will help keep the engine in its powerband and on cam, not to mention increasing acceleration. what a lot of people don't seem to think about is that if you fit a big cam, you should also fit a closer ratio gearset in your gearbox, to stop the engine falling off its narrower powerband between gears.

 

hmm, well things got a bit out of hand. my guide to going alot quicker on a budget, with a well balanced package.

 

welcome.

 

 

Doug

 

(was ke1x and previously procat_98 on oldcorollas)

[Redwarf]

Behold the K engine Guru. ^^^^^^

 

All very good words.

 

FWIW, I run later valves in my head, with later valve stem seals. Early O-ring type suck the big one.

 

If you're in Brissie, I can put you on to an excellent machine shop.....

[Xany]

FWIW, I run later valves in my head, with later valve stem seals. Early O-ring type suck the big one.

 

I learnt the hard way and had oil smoke pissing out the back from the valve seals.....i also run the later type valves.

[Super Jamie]

shim the standard valve springs to have 10 thou clearance between coils at full lift (will go over 8 grand)

that is cool, i've always wondered what that measurement should be, just been too lazy to look it up :( thanks :lolcry:

[charlie835egg]

Thanks for the rundown Doug.

Edit for my first message; the Weber is actually a 28/36 DCD. I was wondering why you were refering to a DGV for a while. So my wrong!

I'm goign to take you up on your advice for all the headwork.

Thanks for the advice for the 3bolt flange on extractors, but one question on the exhaust size. Why so 1 7/8". Sounds to be splitting hairs, so I'm guessing there is some calc behind this maybe, or just bit of gut feeling from experience between 1 3/4" and 2" setups you've come across? Any insight on this please.

 

For the diff ratio drop, I've got the 4.11 ratio, which I thought was standard for a KE3X/K35X. so where do 4.33 for Borg Warner's hide. behind autos/stationwagons?

 

Thanks again for you valuable advice Doug.

I'm in Townsville Redwarf, so the Brisbane shop is not of so much use to me unfortunately. I think I have a good shop lined up in townsville here. touchwood!

Don't suppose anyone knows of someone in Townsville who makes a Cams spec 6 point cage?? How's peoples contact's? That'll be next after I get the engine running well and front end suspension grounded.

 

Later

 

charlie835egg

[Felix]

the exhaust sizing is based on recommendations in one of Graham Bells books, "Performance and Tuning of New Generation Engines" (very good read). it was sized for a healthy 1300cc street engine. David Vizard in his writings, recommends the same size for similar performance/capacity minis.

 

all i can say is it works well. it suited my last 4k perfectly. if anything it is probably getting a touch to small for my current 5k.

 

i ran 25/25 chokes in my DCD on the 4k. think i had 50/70 idle jets, 130/135 mains, and 180/180 airs. i lost my little book i had after moving 3 times in the last 12 months. :lolcry: i can scan Vizards DCD tuning guide for you if you like.

 

i have no idea on the BW diff centers. all my experience is with the Jap diffs. i would definately have a look at a wagon though. somebody else may know.

[Super Jamie]

For the diff ratio drop, I've got the 4.11 ratio, which I thought was standard for a KE3X/K35X. so where do 4.33 for Borg Warner's hide. behind autos/stationwagons?

i don't believe 4.33 BW centers actually exist. change to a jap diff, they're easier to find good centers for, to swap when you break centers and/or want your locker in for weekend antics anyway :lolcry: 4.2 and 4.3 are pretty common jap diff ratios, 4.5s are in ke3x wagons and panos, 4.4 in ke2x wagons and panos, you can even get 4.1 and 3.9 (rare) if you want fuel economy

[kangaroosa]

i don't believe 4.33 BW centers actually exist.

 

 

Yep, they do. I am currently running one. I believe they were found behind the Automatic Corolla's.