Tag Archives: valves

A12GX Head – A14 Sub – Dual SU's – Lightened Flywheel

What a busy few weeks getting the Bakkie in order.

Just want to give all that provided me with tips and tricks some feedback.
Got the Datsun

Comps spec on the flywheel, took the flywheel and a new pressure plate to the dude that does my machining, he got it down to 5.78kg, he also balanced the flywheel and new pressure plate for me.
Installed the A12GX head with worked ports and valves.
Fitted a 4-1 branch manifold, already had a 50mm Stainless Free flow System
HS4 Dual SU Carburetors, intake manifold ports matched to head intake ports
Fitted a electric fan, switch comes on at 85degrees, removed mechanical fan on water pump
Had to purchase a new Temp Sensor, could not get the old one out of the A14 head.

Here comes the interesting bit, somewhere down the line, they changed the resistance on these sensors, from about 560ohm to about 360ohm at 16degrees.
This caused more than enough problems. All of a sudden the temp gauge needle climbed way more that it should.

We started it up, all was fine, no bolts, pistons or valves flew around, tuned the su’s. The electronic fan came on, everything working as it should.

Once on the road it was a different story, torque there is a lot of, it is clean, revs up nicely, pulls excellent from 2k rpm right thru to the limiter (currently at 7k rpm), there is not even signs that you are about to hit the limiter, this means all is working together, producing nice bottom down torque and decent top end power.

Then, all of a sudden the motor gets hot. After a day or two and enough swear words to make a sailor look like a beginner. We figured it out. Once on the road there is enough air travelling over the switch to cool it down and not switch the fan on. This caused me more time under the bonnet than needed.

Obviously if the water gets way to hot, pressure builds

and want to escape somewhere, the place it picked was between cylinder 3 and 4 at the water ports on the intake manifold gasket. After taking it apart, I also noticed that the one exhaust manifold washer was pressing against a piece of welding on the branch. Smoothed it down, reassembled the lot. Also re-fitted the old mechanical fan on the water pump to be on the safe side.

Took it for a drive, no issues what so ever anymore, the fan doesn’t even switch on after some heavy spinning and gymkhana practice.

Saturday we have our next race meeting and look forward to the added power and overall better A14-A12 inbreed.
Just hope I will be able to keep the wheel spin to a minimum, we are expecting rain also, and that sure as hell wil not help.

Thanks a lot to all that helped and gave advice. Special thanks to Einstein(My Brother), My Father and Ruan.

Dual SU Carbs

Just a quick heads up on the Head and Carbs for the Datsun.

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The A12GX head is all cleaned up. After a 2 day long cleanup session, everything is ready for

fitment.
Ports is as clean as I can get them, gasket areas are shinning and ready for some new ones. The valves Seats are grind.
Yesterday, me and my brother prepped all the clean parts and reassembled the head. It is know wrapped and waiting for an installation date after the 2nd May 2009. We have a month gab between gymkhanas after the 2nd, so this will be the ideal time to install all these parts and eliminate all problems.

The HS4 SU Carburetors have been stripped and checked; so far I can so no damage to the parts. No cracks, holes or excessive wear. The next steps will be to get this all cleaned up for further inspection and reassemble them. Then they can also move next to the head on the shelf for installation.

This is killing me, knowing I sit with all these parts and have to wait to get them installed, o well; at least it gives me time to get everything ready.

Electric fan must be installed and wired up, the

brackets for the helper leaves on the back suspension need to be made and tested. Hope this stiffens it up nicely, could be a cheap mod for starters to the back suspension. The branch must be sources and wrapped with Heat Wrap, and let no one tell you different, this exhaust wrap is expensive, R450 for a 15m roll, just enough for a 4 cylinder branch.

I’ll be off to go pull some more hair, this waiting is killing me.