12R Performance

[dsh04]

Just wondering if anyone has played around with the 12R engine? Looking for any performance mods, thinking exhaust and carby to start?
cheers

[thdevilshands]

Ah the ol 12R

A starting carb would be any down draft weber, go smallest you can find (28/32 or 32/36 on old 2l fords and some euro cars like alfas, fiats etc) it can be a DGV DGAV DCD doesn't matter, I have a 36/36 DCD on my stock internal 1400cc Datsun 120Y with 4-1 headers and a 2inch straight through and it is all sorts of fun.

Now the Datsun A series engiene dont need much back pressure but I have NFI how the 12R would go with such an open set of lungs, maybe go the 4-2-1 extractors and the 32/36 dgv/dgav jetted to suit.

Basically all webers can be choked down to your engines specs, get what ever is cheapest

As far as exhaust, I have never seen aftermarket gear for the 12r but it must be around

Cheers, Jon

[crowncustom]

Good motor in there time but waste of money to what is available nowdays.
There are no aftermarket performance parts for these engines and never was.
I played with these engines almost 20 years ago and even back then things weren't easy.
If you could find a 1600S 4R engine then you would have a start on performance.
These engines ran Twin Asian SU Carbs with cast iron split headers,very large ported head,high lift cam and 9.2 compression ratio.
I also used a 12R bottom end which was fully balanced lightened flywheel and flat top 040"O/S pistons and a 26 - 66 grind cam with the 4R head and this engine was a very slick engine in its time.
Cheers Brett.

[sbfoot]

Who made the cam and are they still around?
I know its a long shot.

[thdevilshands]

That sounds fun Brett
I really like the idea of getting a 4R head, was that 9.2 on the original block or once you'd put it on the the 12R?

I've got an rn20 short wheel base hilux ute... at the moment its languishing while I work on my other cars but I washed it today and just fell in love again, "jdm" fender mirrors bench seat colum shift 4 speed mmmm with decent carbs and zorst, it already spins the rears more easily than my 200B SSS, so the diff is must be pretty tall, yeah twin carbs would be ideal!

What is a realistic price for a 4R head and twin su manifold? I think I'm gonna have to have to do this.
Cheers, Jon

[thdevilshands]

Just found this:

"Hi Bob.
I ran an RT40 with 2R then a 12R and used lots of parts from the 4R 1600S engine.
I used the 12R as it had full flow oil flitering whereas the early 4R's had partial metered oil filtering.
Wade, or Crowe 24/80 cams worked fine most heads had dual valve srpings, but the best thing you could do is find a 9R head Yamaha from the 1600GT and fit it. QED using blank dummy oil shaft and front timing cover. I ran a 48mm weber on a 12r with high dome 4R pistons and it won rallies."

http://au.toyotaownersclub.com/forum...showtopic=3204

[dsh04]

sounds pretty sweet, keep the info coming guys.
I also have a 12r powered RN25 hilux, dont spose you have any spare parts?

[thdevilshands]

Sorry man
I only got random RN41 Hilux and RT104 Corona gear lying around.

Saw two sets of the 4R twin SU setups sold on Ebay in June or July ($112 for both sets) 1 complete and a semi complete set. So they dont look too expensive, just hard to find.

Haven't seen any prices on 4R or 9R heads yet, but I like frankenstein motors so I'll keep looking.

[old_school_jap1]

gonna be hard to come across a 4r head that someone will be willing to let go off, they're bloody rare these days. i reckon you'd be 2 billion times better off getting a 18r. i have an rn25 for parts, what you looking for?

[dsh04]

PM sent

[thdevilshands]

Heh heh when I saw those 2 manifolds go for like 100 bucks I was thinkin sweet, cheap as

I guess there's always that problem with old cars, people love to hoard, myself included


Couple of questions then about 12R to 18R convo...
Will the 12R box will bolt up to the 18R?
And what about engine mounts?

Hmmmm this is actually turning into something off topic

Time to do some searchin.

Never wanting to throw stuff away, I think I will keep a look out for a 4R engine,
Now that I think about it, i'm pretty sure I saw one at ezy scrap a week ago

Anyway, any other info about workin the 12R would be greatly appreciated

Cheers, Jon

[o_man_ra23]

I'm with oldschooljap1 - mostly because I have played with 18R's for some time now (got my first 18R nearly 10 year ago!!) Hardest part of the 18R swap is getting the 16R stamped block to make the engineering easy. Then again, I don't think it really matters in QLD, so the whole 18R-G would be the go. Then it is a matter of making sure everything fits in the engine bay. EFI is plenty available, and with that you can go turbo nice and easily. Being a full chassis ute with a G series diff, there won't be any issue for engineering there, just maybe some better front brakes. I wouldn't bother using the stock box either, a W5x from either an RT142 Corona or RA60/65 Celica would be the go.

[sbfoot]

Was interested in a more aggressive cam for my 12r.
Wade cams have a grind no. 104CB which is near enough to the 26-66.
"The cost to grind a cam that you supply to our 104CB profile is $92.00. Freight charges, if applicable, are extra. We can also re-radius grind your cam followers for $36.00"
as of 10/08/09.cam specs below


W A D E C A M S H A F T S P T Y L T D
A.B.N 62 004 544 996
27 Wells Road, Oakleigh, Vic, 3166
Phone (03)9568 0333 Fax (03) 9568 2633 Email info@wadecams.com

Profile Actuation Make/Model R/Ratio
104CB Flat Tappet Toyota 4cyl Push Rod In1.5 Ex 1.5
--------------------------------------------------------------------------
Cam Lift Duration Duration Valve Valve Lift Phase
Adv @050 Clr Lift tdc <)
--------------------------------------------------------------------------
Intake 282 274 212 0.013 0.4092 044 110
Exhaust 281 271 212 0.013 0.4077 038
--------------------------------------------------------------------------

Timing Timing
Adv @ 0.05
Open Close Open Close
Exhaust 66.5 Bbdc 24.5 Atdc 37 Bbdc -5.5 Atdc

Intake 28 Btdc 66.5 Abdc -2.5 Btdc 35 Abdc

52 -8
Deg Over-lap Deg Over-lap

Intake Centreline 108.75 Exhaust Centreline 111.25


LIFT AT TDC IS MEASURED AT THE LOBE

WARNING: Cam followers must have good surface finish and correct radius.
Lubricate well, avoid high RPM for the first 2 hours.
To avoid coil-binding, after the tappets are set, check that the valve-
spring can be compressed at least an extra .050" after full lift has
been achieved. This will stop the valve springs from binding

Hope this helps
Scott

[crowncustom]

Well I used to have a couple of sets carbs and head and other bits but like it was at the time no one wanted so they went to scrap.
No point just buying the twin carbs cause you need the head to go with them as they wont bolt to a standard 2R or 12R head.And trying to find a 4R or even the 9R head is like trying to find a cheap Toyota 2000GT sitting in a paddock.
I did own 2 1600S Coronas and spares and wish now I never got rid of anything.
As to the 9.2 pistons that is what the 4R had standard.Using the 12R pistons just lowers the compression.
The cam I said I had was a reground cam done by Crow Cams.
Converting the Hilux to 18R is a very easy job.If the bellhousing on your gearbox is unboltable then all that is needed is one to suit an 18R.A mid bath sump the same as a Hiace or Celica and a couple of plates to move the engine mounts back to suit the 18R then your away.
I did a 18RG conversion in my 1600S Corona nearly 20 years ago.Went extremely well.
Anymore info you need I hope I can help.
Cheers Brett.

[o_man_ra23]

Post up a photo of the block of the 12R side on where the engine mount is and I will tell you if you need to move the mounts or not. Or better yet, check out the tractor engine thread, plenty of 18R-G photos and info in there.

[old_school_jap1]

12r's have a ghey setup in that part of the bellhousing is actually a cast part of the block, so if you're looking at going to an 18r you'll have to change the gearbox. there is a problem with mounts, but i have solved it. there are about 6 different types of engine brackets for 18r's because they were in so many different cars. the engine brackets (that being the part between the engine rubber mounts and the block) you need to put the 18r on a 12r crossmember can be found in a rt72 corona mark II, good luck finding one though

[thdevilshands]

Thanks for the info guys

What has to be done to keep the colum shift when converting to a W5# box?

I really like the old school style of this thing so if I have to change the gear shift to floor mount then I'll just keep the 12R and go a mild cam, 36/36 DCD weber and good extractors, as I said the diff is so tall it gets sideways real easy, power to weight won't be a problem ; ) Just parts. Might have to make a custom twin weber manifold up and play around with the head a bit to see where we can get.

As an A series Datsun fan I know all about the rarity of certain heads and engine bits, try finding a genuine 1200GX head that someone is willing to part with, not a snowballs chance really.

Brett, I was sort of assuming that using the 12R bottom end and 4R head would increase compression? or is the bottom the same bore w diff crank, rods etc?

SBFoot - Those cam specs look good, I'm gonna have a chat with my head porting guru and see what he thinks can be done with the 12R head and how crazy you could go ; )

Does anyone have a pic of a 12R head, or, even better a cross section pic showing port sizes and wall thicknesses?

Thanks for all the advice, an 18R/RG swap would be great, just as long as I can keep the cars current flavour,

Keep it all coming

Cheers, Jon

[thdevilshands]

Maybe given enough info these guys could make a new 4R or 9R head, given they can do new cylinder heads for 12R (or at least claim they can),

http://www.made-in-china.com/china-p...d-SN4108-.html

anyone able to provide specs / pics of 4R and 9R heads?

[crowncustom]

12R and 4R bottom ends are identical except the high comp pistons.
12R and 18R block mounts are totally different.The 12R runs cast steel mounts right at the front of the block where 18Rs are almost centre to the block.But going from 12R to 18R is easy as.
I will have a talk to a mate of mine who still has his old race 12R in a RT 80 Rona which runs twin 2T downdraught carbs with home made mani,cam,extractors,modified 18R oil pump and a few more mods I cant think of off the top of my head.
Cheers Brett.

[o_man_ra23]

Have a look in the RN4x and later 2WD Hilux range (must be RNxx) for something with column shift. The gearbox from that will be what you want (if there is such an animal) to change to 18R.