What's Involved In Putting A Bigport Head Onto A Smallport Block?

[Jmuzz]

Hey guys,

 

I have a 4age smallport AE92R with a blown head. I'd love to put a new smallport head on it, however my funds don't stretch far enough to fork out $400 for a new one, and all the U-Pull-it wreckers around here only seem to have bigport TVIS motors available.

 

If I just get a bigport head/intake manifold do I also have to replace the ECU, Wiring loom, etc???

 

Or does anyone have any smallport heads they'd like to be rid of?

 

Any help would be appreciated.

 

Cheers,

Josh

[ke70dave]

what do you mean blown head?

[Jmuzz]

The head is stuffed...

It's been cooked a few times and now has a big gaping hole between the water jacket and cylinder 1. Also apparently the alloy's gone soft so welding and machining it is out of the question...

Edited October 9, 2012 by Jmuzz

[fumeck]

>.>

[Jmuzz]

From what I can find on google, the main differences between bigport and smallport top end are the compression ratio, the distributor, cams and the inlet port size...

 

I haven't been able to find much about it though.

 

If I get an adapter plate (smallport manifold to bigport head) and just run my smallport dizzy, manifold, injectors, and cams would this work?

 

Losing the extra compression is a bit of a bummer but I'm willing to deal with that to get the car back on the road for now (or maybe get the head shaved to bring it back up)...

 

Does anyone here know if this will work though?

[ke70dave]

smallport head also has an oil drain in the head which the bigport doesn't have.

[Hiro Protagonist]

Look around, you should be able to get a smallport head for cheaper than $400 (hell, you could probably get a full working smallport for that kind of price from someone wrecking a whole car). You're just making more work and life more difficult for yourself by trying to adapt the bigport head.

[Jmuzz]

I've looked into every wrecker in SA, Smashed Gumtree and Ebay, and gone through as many forums as I can find. There are no smallport heads to be found (well I have found one, but have to buy the complete engine for $850, which I don't have).

 

If I were to just put a bigport head and manifold, minus the TVIS plate, with my smallport cams/dizzy would it work? and would the lack of that oil drain cause me a massive headache? I'm grasping at straws here trying to get an air-conditioned car going before summer really kicks in, so I can avoid the pain of a cranky, nagging missus.