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Discussion Starter · #1 ·
I just spent the last 3 hours pulling a nasty black greasy diesel motor and I'd like to see if we can get some facts straight on what is interchangable and what isn't.

Let's see if we can get some true answers to some of these questions.

1: Main cap bolts (marked with a 12 on top).
Are they stronger and what is the proper torque?

2: Rod bolts (look the same as a L-28).
Are they usable and are they stronger?

3: Valve springs (green band painted at the top and only single outer spring).
Are they stronger, can you use these with the normal Z inner spring and at what
lift will you get coil bind?

4: Head bolts and washers (Major thick).
Are they usable, what modifications would be needed and what torque?

5: Crank shaft (Marked VO7 and VO740)
What modifications are need to it (drilling?, knief edging?, what else?)?

6: What other parts may be used to build on kick butt L28?

I'm compiling a list of Z-car modifications and I'll add these answeres to my list.

Let's get some good discussion,

JT240Z
 

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1: Main cap bolts (marked with a 12 on top).
Are they stronger and what is the proper torque?

Don't be cheap and re-use ANY bolts when building a hi-performance motor.

2: Rod bolts (look the same as a L-28).
Are they usable and are they stronger?

See answer to No. 1. Go with new rod bolts.

3: Valve springs (green band painted at the top and only single outer spring).
Are they stronger, can you use these with the normal Z inner spring and at what
lift will you get coil bind?

Again, don't take a chance on using used valve springs, especially from an odd-ball engine like the LD28. Make sure you order springs from a trusted source recommended by an expert on L6 valve trains. I would call Geralomy or Rebello and ask them what part they recommend. Dave Rebello has been helpful to me and has answered several e-mails I sent him.

4: Head bolts and washers (Major thick).
Are they usable, what modifications would be needed and what torque?

Use new Nissan "turbo" head bolts available from NISMO. Or, better still go with head studs. I am not sure what the best source for studs is. I would call Dave Rebello or Sunbelt Performance engines and see what they say.

5: Crank shaft (Marked VO7 and VO740)
What modifications are need to it (drilling?, knief edging?, what else?)?

For street, just balancing and polishing the journals. See Frank Honsewetz's (sp?) book for details on racing mods.

6: What other parts may be used to build on kick butt L28?

I have not heard that any other parts from an LD28 motor can be used. Stick with the crank.
 

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Discussion Starter · #3 ·
OK! LET'S GET THIS RIGHT FROM THE BEGINING!

This is purely a discussion on interchangeability. I don't want this to turn into a "do you reuse or not" topic. All these part can be purchased new or scavenged from an old wreck. You make the dissuasion on how you get these parts. The point is that Nissan made some parts that were specific to the LD28 that do fit other production engines. Some parts are inherently stronger because of the stresses induced by a diesel. Come on folks, this kind of discussion is how new ideas begin.

What parts can be used that are high quality (Nissan) parts to strengthen an L-series engine.

I would like to add one more item to the list:

7: Are the rods usable and are there any advantages/disadvantages?
 

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There was a long disscussion on HybridZ.org about using the whole bottom end and just putting a normal L head on it. turning it into a Gas motor instead of diesel. pretty interesting ideas. you might check it out . Later
~Kenny
 

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I would skip reuse of the rod bolts. No Nissan Rod Bolt is intened for re-use, period. It is false economy to "save" money on THAT part when you risk the entire engine by it's installation. ARP makes rod bolts that ARE reusable, and that's all I use in my motors.
The head and main cap bolts ARE useable, and are torqued to the spec of the LD28. The headbolts actually have a higher clamping value than the turbo bolts,and those thick washers help with the load distribution.
The Flywheel is a drag-race only item, weighing in substantially heavier than a stock unit, allowing speed shifting and no-bog launches. Note it is pinned to the crankshaft due to diesel torque.
Trouble withthe flywheel is you have to use the early 240 Pressure Plate and throwout bearing collar, due to it's increased thickness (5mm closer to the tranny, so you neeed the shorter 240 collar)
I would skip the springs, and go with the units recommended or included with the cam you buy. That's a mix-match, and they MAY work, but unless you test each spring to insure copatibility, you end up spending more time than it's worth IMHO.
Rods? Hey, it's an "L" block. You can make anything fit, but you're looking at custom pistons. If you retain the LD 28 Block, the rods are useable, but it's up to you to use/find the pistons to work with them.
The alternator is useable, and has a vacuum pump on the back of it, handy for keeping your brakes working in stop-n-go withthat big-overlap cam you willl be installing.
The intake and exhaust manifolds bolt up to the stock gasoline head, no problem. The exhaust is the only one worth utilizing, however, since it works regardless of what's passing through it. The intake would require major fabrication like installation of t/b mounting pad and injector hold down, fuel rail hold down points.
Long and short of it: I am sorry I didn't take the head bolts and main cap bolts when I harvested my crank. I am sorry I left the exhaust manifold behind, and was curious about the flywheel for a project I'm embarking upon. Anything else, I have no regrets or reservations about leaving in the junkyard.
 

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Discussion Starter · #6 ·
What are the torque specs for the main cap bolts? I heard 60 ft/lbs.

I looked at the head bolts and I believe that the holes in the head would have to be enlarged and the block tapped for a larger threads also. Is this true? Those were some truly thick head bolts.

Does anyone know what the spring force is at installed height?
 
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