4ac, Doing A Build

[tas_ae71]

i wouldnt need them heaps stiffer, a standard head will rev to about 7500 but i though stiffer or dobble springs would make it more reliable, as in last longer before braking? maybe?

 

what rings would people surgets?

 

edit: got a price from vpw website, $75 for a set of aps rod bolts.. but revving to 7500 I'm not 100% that they are nessesary. but then again it isnt much money to make the bottem end unbrakeable..

Edited April 22, 2007 by tas_ae71

[Felix]

i wouldnt need them heaps stiffer, a standard head will rev to about 7500 but i though stiffer or dobble springs would make it more reliable, as in last longer before braking? maybe?

 

Also you have to remember that with a reground cam, you will have more lift and faster valve acceleration. Both of which make life a lot harder on the valve springs.

 

If you are going to run 4age rods, would you really need to worry to much about aftermarket rod bolts? Isn't a bigport 4age bottom end normally good for 8 grand?

[KE30_KE35_KE55]

I rebuilt my AE82 4AC using biger exhaust valves porting ect spent hours and $$$$$.

I eventually built a a stock 4AF (16 valve) head ported And polished, fitted it to my STD 4A bottom end in the car, same twin exhaust ect, that made a huge diffrence, had to do a drive shaft upgrade after that. lot better swept volume with 4 valves per cylinder.

 

good luck

 

Darren

[tas_ae71]

felix, i was thinking the same thing as you mate. but at a lowly $75 (buying from aus, us cheaper) it is very tempting to make the bottom end very strong in relating to a 4ac, but it will have a bit more compression than a bigport and it will be regularly taken to the nominated redline of 7500 (probaly more :)) just i think i would rather spend that little extra and have peice of mind that its only my head that can brake.

 

yes i see what you mean, and being a few thousand revs over standard with the cam it will wear the springs quickly and 7500 is probaly ok with a stock motor for short periods of time but sustained hi rpms...

 

darren, does the 4af head bolt straight on? or what is required to fit one? did you keep the carb or go efi? did you rebuild the bottom end with standard internals?

 

 

 

so it looks like i will have to spend a few bucks on the head, not too much hopefully. what about valves? will the brake because of the faster and harder movements of the stiffer springs?

[KE30_KE35_KE55]

I bought a whole pallet of 4a, s from rising sun engine reconditioners for $40, I dismanteled a low KM 4AFE with a spun rod bearing,I dismantled and ported, polished and faced the head.

 

then one saturday I droped the sump, pulled the head off, changed the pistons to 4af pistons (they have machining to allow valve clearance), honed and reasembled using my original rods.

fitted 4af head, re fitted cam belt reasembled. had to use denso electronic dizzy.

lengthen temp sender wire and coil power to new distributer.

 

I bought a carby manifold. used my tricked up carby i had on my 4 AC

[*]4ac has inlet exhaust same side (at firewall) 4AF is cross flow exhaust at front.

I am a qualified mechanic, my brother also did his apprentiship at a Toyota Dealership when the AE82 was new, so i borrowed his toyota school manuals.

 

new top radiator hose is required on a AE82.

 

I sold this car about 5 years ago.

 

 

Darren.

[tas_ae71]

fair enough, but wouldnt you of been better off just using the 4af bottem end..?

 

I'm happy to use the 4ac head, i have a cam for it and getting a 4af head will kind blow out the budget of the build..

 

what rings would people recomend?

[Emerson]

hey I don't have anything mechanical to add but its great to see someone else doing a build on a 4A-C it makes a nice change. Just wonderin what your motives were as it seems us to are the only ones interested in 4A-C tuning.

[chrisandliz[RL]]

Are you asking if you could buy new ones or use the old ones?

 

or are you asking if you should use chrome moly or cast?

 

I did a ring around and the price difference was only $20 or so.

 

Chrome moly are apparently better, hold up to more punishment. Never used them myself.

 

How long did you want this motor to last?

 

What is the grind on your cam?

 

The old saying that I was told was "Three C's of old school, Cams Compression and carbys"

[tas_ae71]

yeah all c's are big.. twin 40mm side drafts, 10:1 comp (aiming for)

 

want the motor to last as long as possible, is still going to be the daily. i figure the bottem end is going to be fairly bullet proof..

 

cam is a 290 degrees, rated from 3500/7500rpm extra .8mm of lift. I'm not sure about single cam profiles, is this big? want some bump in that idle

 

i was more meaning what brand, acl etc..? but yeah i recon i will be going for chrome molly, they seem the go. i don't know you couldget cast rings. someone said that they are all about the same because they are all made on basicly the smae machines, made by diffrent companies but the same machines...

 

hey I don't have anything mechanical to add but its great to see someone else doing a build on a 4A-C it makes a nice change. Just wonderin what your motives were as it seems us to are the only ones interested in 4A-C tuning.

 

so I'm not the only one :jamie:

 

PM me with what you have done with yours.. intresting to hear your results

Edited May 2, 2007 by tas_ae71