The Random Technical Question Thread

[Westfield 129]

I dry fit the engine back plate with the standard paper gasket (there is no oil back there). This includes the Rivergate 5 speed thick alloy adapter plate as well (the standard engine back plate is not used with the Datsun 5 speed conversion)

It's important that the plates are perfectly flat so that the paper gaskets can work. I have never had a problem with the fit of the front or rear covers using just the paper gaskets.

In the front, you can use some Hylomar, Hondabond or Yamabond around the oily bits if you are worried about the flatness of the plate and the engine block. A thin film of Hylomar or Hondabond will squish out a little, indicating a nice, tight fit. So far, I have not had a problem at all with the several engines I have assembled using just the paper gaskets. However, if you like to smear a little sealer around, it won't hurt.

The place to pay special attention to are the corners of the oil pan at the front and rear main bearings. Some of the kits have cork seals, while the best Payen kits have rubber seals that are much better. However, it is important to use a sealant on the pan seals around the bearings and at the edge of the seal and the pan where they come together. Often, a leak at the back of the engine is mistaken for a scroll leak, when it is actually just a pan leak that needs a little RTV when the pan is re assembled to the engine.

[jonclancy]

Detailed as ever - many thanks, Jan.

[jonclancy]

Chicken? Egg?

I've been wondering about this when I start my new engine for the first time.

Cam needs to be run in.

and

Don't run steady speed to avoid glazing the bores (like a motorway run).

Am I missing something, or are these two procedures at odds. The cam I guess will take about 20 mins at 2000rpm. This'll be the priority. Then off for the usual, mixed-revs and loading running in.

Any thoughts?

[Westfield 129]

The problems with the bores are a bit overstated.

The problems are related to heat build up. One of the reasons that you lift off occasionally with a new engine is to allow cool air to enter the cylinders, and to suck up some nice cool oil to wash down the cylinder walls. Revs are not the problem, its the heat that causes the glazed bores.

You can do the cam run in, and so long as you don't over heat the engine, you wont damage the bores. Just watch the heat. Sometimes, you need to run the two or thee times to do the cam break in. In any case, if you have a good quality cam, you wont have any problems at all.

Hopefully, you used plenty of moly grease on the cam and lifters. The break in should be uneventful.

[jonclancy]

Thanks Jan. That makes everything crystal clear.

Yes, we used loads of moly on the cam and lifter - should be fine.

Cheers

Jon

[erictharg]

I can recommend Graphogen for any rubbing surfaces. Better than the red jelly stuff IMO. Once you have done enough running to bed in the cam get out on the road for a few miles at varying speeds / loads. 30 mins driving should do it, but try to keep at a reasonable load on the engine (as little light throttle cruising / idle as possible), and max of maybe 4000 rpm. Spirited running around back roads is about what you want - accelerate, brake, accelerate again. That will help to bed the rings in nicely.

Then you're ready for the rolling road! Of course you can do that bedding in on the rolling road but at £75 an hour...

[jonclancy]

Thanks Charles. Spirited driving round the Cotswolds? Definitely!

Hoping to get some oil and water into the engine this weekend. Then set up the dizzy and clearances.

Soooo cold in the garage, though!

[jonclancy]

Quick one for the SU carb experts:

WHne rebuilding with the SU kit, do you use a non-setting gasket compound - or just the paper gaskets? The rebuild instructions in the manual don't seem to say either way. I guess it's only the float bowl cover anyway.

Secondly, the spindle seals. Turbo cars have the seals fitted reversed, for obvious reasons. But it's not clear which side of the seal is the gas-tight direction. Any hints, please? I'll try to see if I can find the mini thread which mentioned it!

Edit: Seal flat face goes into the carb body if using JZX-1994 parts.

Cheer

Jon

[Westfield 129]

No sealer on the paper gaskets.

Doesn't really matter which way the seals go for atmospheric induction.

[jonclancy]

Fab - thanks! I'll get on with that next week. I've made some good progress today. Just the "hot" side of the engine bay to do! Probably!