Xu10J4R Head Onto Xu10J4 Block Feasibility

[JeffR 51]

I hope I've put this in the right section. If not please feel free to move it.

 

I was asked today if the later J4R head I have for sale would fit onto a J4 block (S2 Mi16) & thought this the best place to ask. I've never seen this combination mentioned here before.

 

Apart from the inlet manifold locating dowel difference & the single exhaust stud repositioning, is it doable & if so what else would need to be taken into account?

 

Things like head chamber volume differences, oil & water hoses, cambelt cover compatability, engine management, head gasket standard or MLS, etc.

 

The J4R cams are pretty mild, but that's fairly easily overcome with J4RS ones or regrinds. No spray bars either AFAIK, but have read that plenty of engines run without them anyway.

 

So they're just a few questions off the top of my head which would need clearing up about the possible swap.

 

Thanks

[Vili 18]

I believe the exhaust ports are totally different between J4 and J4R. J4 has eight ports vs. J4R has four. This is quite important when choosing an exhaust manifold. You would need J4R cambelt covers for the engine which by the way essentially is XU10J4R engine with J4 conrods and pistons.

[welshpug 1,657]

As well as the timing covers, use all the J4R/RS timing bits, belt tensioners belt, sprocket on the crank is positioned 8.5 degrees differently (half a tooth) , make sure you also use the appropriate camshaft sprocket hubs as they vary from J4R to RS.

 

compression ratio will be slightly higher, standard gaskets are the same thickness iirc, you can use the standard J4RS which is MLS.

 

exhaust - bolt on the J4RS item.

[JeffR 51]

Thanks guys-that's good info. Wasn't aware that the crank sprocket was different with the timing pin hole.

 

I've passed this link onto him so he can evaluate the issues.

[welshpug 1,657]

timing pin hole is in the same place, but due to the different orientation and design of the sprocket you do need to use the later crank pulley, grab an alloy one if funds allow.

 

 

I'm not sure if the valve centreline is the same, but you will have decent valve clearance height wise, though I have not checked the radius of the cutouts