4ac, Doing A Build

[tas_ae71]

hey,

 

I'm building a 4ac, i have got most of it covered exept for a few things

 

- where to get ARP rod bolts

- what i can do to the head apart from porting i.e. dobble valve springs..?

- what rings to use, have bigport pistons not sure if the rings are the same as 4ac or not ( ACL maybe?)

 

the build is on a low budget so not uber expensive parts for me.

 

regards

aaron

 

please people i do not want to hear how stupid this is and why don't i just buy a 4age. i have my resons

Edited April 29, 2007 by tas_ae71

[anastasios]

you going to turbo it?

[tas_ae71]

no, no turbo. this is an n/a build. turbo was going to be too expensive and i much rather revs over spool..

 

hoping themotor will be able to rev to 7-7.5 reliably, the bottem end should be ok with this just need to do more to the head.

 

the cam i have is rated to make power from 3500-7500

 

i figured with the combination i have i sould ge able to get simerla power to the setup that i was going to get with turbo exept more reliable and better power delivery, much less attention, than wwsssssss ptch

[Trev]

I took my stock 4AC past redline regularly even up to 7200rpm and never had a problem with it, I only took it off the road because the oil got a bit low 1 day and the cam semi seized so it spun the timing belt, I can't wait for the outcome of this build, It should be fun.

[flat out]

plane the head? higher comp? polished ports?

[oh what a nissan feeling!]

Get the arp bolts off american ebay, works out real cheap compared to here.

 

i figured with the combination i have i sould ge able to get simerla power to the setup that i was going to get with turbo exept more reliable and better power delivery, much less attention, than wwsssssss ptch

 

Ever heard of a plumbback bov, and the power you will have will be approx half what a turbo would give, but good luck all the same.

[tas_ae71]

I took my stock 4AC past redline regularly even up to 7200rpm and never had a problem with it, I only took it off the road because the oil got a bit low 1 day and the cam semi seized so it spun the timing belt, I can't wait for the outcome of this build, It should be fun.

 

yes while a dead stock motor will far exede the redline (i had my old motor to 7500 or a bit more once) they don't last too long at these revs as joash (<<r2blinky>>) will agree with me. i want it to do it all day long as they say. a strong motor that isnt going to brake as quick. yes I'm very keen to get it built, should be quick for a old banger 4ac, probaly the most redical N/A tuned 4ac on the planet :y: I'm so sad

 

plane the head? higher comp? polished ports?

 

yes indeed

 

Get the arp bolts off american ebay, works out real cheap compared to here.

Ever heard of a plumbback bov, and the power you will have will be approx half what a turbo would give, but good luck all the same.

 

yeah i have heard of those. by your forum name i asume you would rather spool over revs, correct? i don't belive that with the setup i was looking at, the power figures would not be much more than i will get n/a tuned. this is going to be much cheaper than turbo too. the turbo option would make it a pig to drive, attract more attention run like a 3 legged dog choking on fuel until it came on boost and took off like something gone silly.

 

 

 

this is getting away from my original questions, as i said I'm don't need peoples opioions I'm more after answers.

 

i did see those rod bolts on ebay america, would rather buy in australia much less stuffing around and i don't have a credit card. its too much hassel buying from other counties. i have got parts from japan, was a nightmare trying to deal with the banks. on the plus side i now have a contact who i can deal direct with, who can sorce any parts i want.

Edited April 17, 2007 by tas_ae71

[Retrospekt]

Its the best when people do something different and can't be swayed otherwise. I can't think of much else other than porting and enlarging valves, double valve springs should help you reach the revs you want.

Good luck with it, 'agricultural' engines like this sound awesome when worked radically.

[Felix]

Just a thought, maybe you could use the crank and rods from an earlier bigport 4age? They have the 18mm gudgeon pins like your 4ac. Should give you extra bottom end reliability. You might need to change the flywheel though, I'm not sure but the 4age crank may need an 8 bolt flywheel... Somebody else here who is into 4ages should know.

[Trev]

Just a thought, maybe you could use the crank and rods from an earlier bigport 4age? They have the 18mm gudgeon pins like your 4ac. Should give you extra bottom end reliability. You might need to change the flywheel though, I'm not sure but the 4age crank may need an 8 bolt flywheel... Somebody else here who is into 4ages should know.

 

That is correct, 4AGE's have an 8 bolt crank, some of the really early JDM AE86's had a 6 bolt and appararently so did the AW11, I was led to believe that all the GEN 1 bigports were 6 bolt but i was wrong.

 

A pic of 1 of my GEN 1 bigports:

Edited April 17, 2007 by Trev

[tas_ae71]

Retrospekt Posted Yesterday, 08:49 PM

Its the best when people do something different and can't be swayed otherwise. I can't think of much else other than porting and enlarging valves, double valve springs should help you reach the revs you want.

Good luck with it, 'agricultural' engines like this sound awesome when worked radically.

yeah it is rather agricultural, thanks :y:

 

but thats me, from the getto

 

 

Just a thought, maybe you could use the crank and rods from an earlier bigport 4age? They have the 18mm gudgeon pins like your 4ac. Should give you extra bottom end reliability. You might need to change the flywheel though, I'm not sure but the 4age crank may need an 8 bolt flywheel... Somebody else here who is into 4ages should know.

 

i am indeed using bigport rods. 4ac crank is heaps lighter so keeping that. less rotating mass=better

 

 

That is correct, 4AGE's have an 8 bolt crank, some of the really early JDM AE86's had a 6 bolt and appararently so did the AW11, I was led to believe that all the GEN 1 bigports were 6 bolt but i was wrong.

 

A pic of 1 of my GEN 1 bigports:

 

another thing is valve clearence from the piston? the cam is claimed to have a extra .8mm of lift, with a shaved head and (most probaly a thin head gasket .8mm- .5mm) is there going to enough room there? don't want the valves to smash on the pistons and don't want to get them cut out or shit..

 

how do you do dobble valve springs? do you just put 2 standard springs on the one valve?

 

 

thanks

aaron

[Nat-ae71]

Try Paradise Racign in the US, they do a kit for the 4ac of a cam, carb and valve springs, I'm pretty sure you can still buy it all seperate, so they maybe the ones to ask about the valve springs?

[Mosus]

I just spoke to my engine builder, he said he has had a bit to do with alot of the rolla engines building them for rallies et.c, and mine, i asked him about getting springs, rods and work on the head, he said he's got plenty of suppliers in queensland he can easily get his hands on the gear for you. If you want to know more give me a PM or you can call him yourself

 

Mick

Free Flow Cylinder Heads & Engines

(07) 3245 5044

 

I find if you want to know about building a engine talk to the guys who do all day everyday

Edited April 18, 2007 by Mosus

[tas_ae71]

PM'd mosus

 

can anyone shead more light on using dobble valve springs?

[oh what a nissan feeling!]

double valve springs consist of a smaller in diameter spring that sits inside one of the original size. YOU have the choice of upgrading the outer spring and adding an inner, or you can just add an inner and keep your old outer spring. I have used PERFORMANCE SPRINGS in the past, and they are very well priced. Being ohc the spring upgrade needed should be alot less compared to a pushrod motor, this does depend on the lift of your cam though. The danger with getting too heavy is you can wear your cam prematurely, i have seen one cam last 5,000 ks .