YES...Gasket time

[woops]

Hey all....new here!

Its time to rebuild the L28. I drove the car from Bend Oregon 5 years ago and it has been in storage since. My brothers bought me gaskets for christmas. I have a full set of engine gaskets plus a custom copper head gasket from a vendor out in cali.

We are planning to pull the engine in two weeks and begin the brake down and inspection. I have low compression on #5-6...so expect the the h/g is blown....but I am also running very low oil pressure at idle. The car is a 77 280, is 10-15 psi normal for idle on that engine? Sounds really low to me.

One final question. The copper head gasket is .031 in width. Does anyone think that I will create valve clearance probs by installing it. Will I have to step up the cam for higher cylinder compression (this is a plan that I have for the future anyway).

Thanks all

Dev

[Phred]

What kind of rebuild are you doing? The whole engine or just the head. As far as the oil press. goes, its not uncommon to see 15 lbs. at idle on an older eng. The things that affect the ability to produce oil pressure are the oil pump gear clearance, which increases with age and wear. This keeps it from pumping as hard as it did when it was new. The next thing that limits oil press. is the bearing clearance, which also increases with age. An increase in bearing clr. as small as .001/.002 can cause the oil to flow past the bearings more than desired, causing lower oil press. So if its an engine out rebuild, replace bearings, and oil pump. If this is a quicky rebuild, at least replace the oil pump with a turbo oil pump. There reasonably priced, and have slightly taller gears, for more volume. The pressure is controlled by the relief valve (springs) in the oil pump.

The solid copper .031 ( stock .047 compressed) head gasket has nothing to do with the valve clearance. It will move the valves a little closer to the piston, but stock cams have a lot of valve to piston clearance. The increase in compresson from a .016 thinner hd. gasket will only be about .3 or .4 of a point. What will have to be considered is the cam timimg. An old timimg chain tends to stretch, Which will slightly retard the timimg. A thinner head gasket will have the same affect. So if you don't replace the chain, Reassemble it using the #2 hole on the cam gear. This will advance the cam timing by 4 degrees, making up the retarded condition caused by the thin gasket and old chain. One last caution. Many people have had problems making the solid copper gasket seal up. The stock composition gasket allows the slight movement between the head and block which occures because of the different expansion rates of aluminum and cast iron. So the surfaces of the head and block must be perfect (freshly surfaced) because the solid gasket will not mold itself to an irregular surface. Beware.

Phred

PS Oregon's so nice why'd you leave?

[woops]

Phred,

Good stuff.......I am planning on a total rebuild. I think that it woud be a waste to replace gaskets and not rebuild at the same time. I am giving the block and head to my neighbor to magna-flux and measure (make sure Im solid and plumb) I will have him surface the head and block at the same time (good idea)

I would like a some vendor suggestions for pistons and rods. Also someone who does a good crank (Ive heard that the L28 crank it pretty damn good to begin with.

As far as the oil pressure is concerned, you are the second person I have heard say go with the turbo pump...I will most likely .

Phred: The solid copper .031 ( stock .047 compressed) head gasket has nothing to do with the valve clearance. It will move the valves a little closer to the piston, but stock cams have a lot of valve to piston clearance.

Yes thats what I was asking...valve to piston clearance...thanks.

I was planning on replacing the chain...thats a definate. I haven't looked at the cam gears yet...are you saying that they are adjustable straight from the factory. What do you mean by #2 hole???

Yes...Oregon is beautiful. My aunt and uncle owned a horse ranch right outside of downtown bend. I was out there for a few months five years ago...thats when I picked up the Z. Poor thing made it back from Bend Or to Westford MA in 22hrs 35 minutes. Its in suprisingly good shape. :classic:

[Phred]

Dev,

Since your in for a complete rebuild, buy a workshop manual. Haynes has good pictures and procedures, and is priced right. I have the factory manual too, which is all inclusive but expensive. The Chilton has its good points, But the Haynes has better pictures, and like they say, worth a thousand words. These will explain all the stuff you'll need to know about replacing the chain and cam gear, which has three holes for timing.

The Datsun crank is a real good piece right from the factory. Its forged, hard, and most are balanced very close. I have balanced many Z cranks, and they require very little work to get them spot on. There's no need to replace the rods. If you have the money, replace the rod bolts and nuts, and have the rods resized to

.0018 min. to .0022 max clr. for the street. Again, if you have the budget, bal the rods. If you replace the pistons, go with .5mm (.020) overbore. Go with flat top stock pistons. All this applies to a street Z, and should be considered my (experienced) opinion.

Phred