4ac Crankshaft Diameters

[Beams]

Hi,

 

Does anyone have the crank pin diameters (conrod) and main journal diameters of a 4AC crank? Ive tried searching with no luck.

 

Reason being I have a 4AG prepared block and crank, intending on a 4AG build, but might be cheaper to rebuild the stock 4AC at the moment and have something running, rather than something fast and expensive.

 

So really, can I bolt up the 4AC conrods to the 4AG crank? (47.982mm-48.000 Main and 41.989mm-42.000 crank)

 

Cheers,

Mark

[TRD ke70]

depends on what 4AGE crank you have, i think the 86kw crank has 40mm rods and the 100kw has 42mm, there is a difference but the mains are the same size.

[Des]

4ac is 18mm gudgeon pin and 40mm big ends. 99% sure.

Edited November 4, 2007 by AE70

[Beams]

Ive got the smaller crank (40mm rods).

 

Anyhow, 18mm pin would mean 4AC pistons could be placed on 4AGE rods? Does anyone have the 4AC Engine Repair Manual they can get the actual numbers off?

[Des]

I was going to use 4ac bearings in my 18/40 4age bottom end. Same bearings between 18/40 4age and 4ac.

[TRD ke70]

18mm pin will fit on the 86kw 4AGE, as the 100kw engine has 20mm pins.

[towe001]

You wouldn't be able to use the 4age flywheel. 4age's use 8 bolts to hold the flywheel to the crank where as the 4a-c (and f and fe) use only 6 bolts. Thats not counting the mystical 4ag "black top" that has a 6 bolt flywheel.

 

But all-in-all from memory there's a thread somewhere (here or toymods) about the 4a-c rods.

 

 

As a note - i've used my 4age head on a 4a-f block once. I was told that the combo would have "super" low compression and no power.

But i could still spin the wheels etc

[tas_ae71]

i have been told that 4ac and bigport rods are the same..?

 

i know that are the same dimensions.

 

if you need a running motor, buy a used 4ac for a 100 or so just to keep you going until you get the motor built..?

 

btw, 4ac crank isnt fully balanced and yes takes a 6 bolt fly as mentioned above.

Edited November 4, 2007 by tas_ae71

[Beams]

Arent ALL 4AGE Flywheels 8 bolts? Whats this illusive "blacktop"?

 

http://forums.toymods.org.au/index.php?t=m...art=0#msg_42656

 

"1. ditch the 4AC crank and use GE one from a 3 rib block, the rods will bolt on to this crank no worries. "

 

I hate heresay. Someone must have the 4AC/4AGE Engine Manual? Just need the measurements to confirm.

 

Still don't know if I want a 4AGE or something else. Toymods dyno records has the 4AGE producing something between 50 and 70kw stock. My stock Celica does 86kw now, so anything will be a downgrade maybe. RWD 4AGE motors are like 1K (Theres on on eBay for around that price). Ill need someone to install it, cos I suck at wiring. And then I wont be doing the work myself. At least with this slow 4AC build, I can do everything myself.

[towe001]

The skanky arsed "blacktop" was pretty well much the first of the 4age's. Nothing more then a twin cammed 16v version of a 4a-c motor.

 

2. I wouldn't even bother swapping the crank over.

 

The blue book that i've got on the 4a-c/4a-ge states that the crank is the same. Same mains and same crank pins.

[Beams]

Thanks for that.

 

Yeah not going for a 4AC power build. I have a 4AG crank, and a block, 4AC pistons will be cheap from wreckers. Give me something to pay with until I set aside the serious cash for the proper 4AG build.