ogasman

Looking at building a forged short block for my car. Have a lead on a 94 block for a decent price. With all the covid delays in parts and machine work, I am thinking about building a block so I can just swap out the top end. Can I use a 94 block with the 2003 top end and externals?

Thanks
Paul

irollgen4s

I have a 94 block w/ a VVT head. Hardest solution is trying to plumb the oil lines for the VVT actuator. Factory is a hardline and banjo bolts, but 94 block doesnt have this drilled unless you have the machine shop do it. My buddy and I made a 4an line that is adapted through fittings into the block that then runs up to the vvt actuator. no clue whether its enough supply/pressure to run the vvt as i'm still on an MS2.

Ted75zcar

iTrader: (2)

2003 block has better thrust washers and the mbsp
1994 block has an oil feed on the exhaust side that can be used for the turbo.

I think emillio said someplace that the average cylinder wall thickness was better on NB2 blocks.

Mazda installed a higher flow oil pump in the NB2 for VVT.

The VVT hardline connects to the oil pressure sensor/switch port, which to my knowledge is present on all BP blocks, no drilling required.

irollgen4s

Sorry I must be mistaken, it's been a while since we built this setup. Couldnt remember why we couldn't use the factory hard line but i knew there was some sort of reason.

shuiend

iTrader: (24)

I replace my factory hard lines with -4an lines on all my cars. Mostly because I find it less cumbersome. If you are using FM LS coil brackets you also have to move to a AN line.

The hard line should work on the lower year blocks. I know I have done it before in the past.

deezums

iTrader: (3)

I think the pressure port is tapped 1/8 BSPT on a non VVT block, and 1/8" BSPP otherwise. The first one is tapered, the second one is not. You should be able to tap out a tapered thread to a straight thread and then use sealing washers like the factory did.

https://www.mcmaster.com/bspp-taps/p...type~straight/

The second port in the VVT feed line is 1/8 BSPT and would take the oil pressure switch or the 1.6 pressure sensor.

The pump, thrust washers, and MBSP would be reason to wait for a VVT bottom end, IMO.

irollgen4s

Ah that is why we didn't run it, it hits the fab9 LS coil pack.

I take it no issues with the 4an line feeding VVT then? We did it on a whim but neither of us have tried turning the VVT on yet due to a myriad of reasons.

shuiend

iTrader: (24)

FM directions call for the change. I assumed they made sure it was fine. Overall as far as I know though I have not had any issues in the last 8 or 9 years.