Building A L24 Engine. Ideas Welcome

[caltanian]

So I have set about the process of building the engine in my 1970 240z. This is my project car, no intention to ever sell the car, and want to have a fun, reliable build for weekend mountain road runs, as well as docile enough to be driven around town.

 The local engine builder and I have talked, and I will be getting the block work and head work done there. I so far have been building up a parts list, and so far have a new high volume oil pump, Cometic MLS headgasket, full gasket kit for the engine, timing kit, and arp head studs. 

Im bounding around the stage stage two cam from MSA, or isky (or are they the same anyway?), using the stock springs if they are still any good, as I have heard the ones in the MSA kit will give you a flat cam fast, as they are built for the real race cams. 

I also have been looking for pistions, as while i'm at it, I might as well gain a little displacement. There appears to be a piston kit from Keith Black for .030 over,  but little else out there for the engine. I know that probe will custom make a set for me, but but its usually easier to just find what's available. Forged seems to only be available custom. 

What else am I missing, or what else would you recommend? I plan to also get ARP main studs and rod bolts. The exhaust is a 3-2-1 3" with magnaflow resonator and muffler, and ZTherapy carbs, so breathing and exhaust are fairly well handled. 

[240260280z]

Make sure no parts are made in China or India.  Made in Japan is usually the best.

 

Use aviation gasket maker on all gaskets except head gasket manifold gasket and oil pan.

 

coat manifold gasket with antiseize.

 

Do not use rtv,

 

Seal where the timing cover, block and head unite.

 

Read the two books on rebuild and hotrodding your datsun engine several times.

 

Port the head.

 

go for internally oiled can and use an oil bar.

 

use zinc oil additive

 

use anti seize on all bolts except head bolts

 

research upsizing some of the manifold studs and timing chain guide bolts.

 

replace oil galley plugs with threaded plugs.

 

pay extra attention to side seals on last crank bearing

 

balance pistons and rods to 0.5g if you can

 

use good brand and type of rings

 

use thread lock on oil pick up pcv strainer, crank cam bolts/screws

 

use some sort of pcv closed system or route to a draft pipe to flow oily air to asphalt

 

read about water pump impeller and timing cover erosion the look out for it.

 

get triple carbs for torque

 

check rocker wipe patterns

 

don't use fram filter

 

read about recent mech fuel pump sources

 

chase all threads

 

use ngk plugs

[caltanian]

All solid stuff. The aviation sealant is a good call. 

Its a nervous but exciting process to undertake. 

[Chickenman]

ARP Rod bolts are a good idea, especially if you have 8mm rods.

 

ARP head studs are a bit of over kill and make removal of head a PITA if you ever need to pull it. New factory Nissan head bolts are excellent quality and all you will ever require, unless you plan on Turbo charging over 15 lbs. The Later Turbo bolts are even stronger.

 

ARP main studs. Won't hurt, but not really necessary. New factory Nissan main bolts are fine to 7,500 rpm.

 

Have the Rod big ends checked for roundness. Usually good ( Z Rods are forged as is crank ), but check them and resize if necessary. 

 

Balance the COMPLETE rotating assembly. Including Crank, Rods, Pistons, Flywheel and front damper. Straight 6 engines can produce nasty secondary harmonics. Factory balance is usually pretty good, but can be made even better. And if you change pistons, or do any Rod work, you should re-balance a straight 6.

 

Have the clutch Pressure Plate zero balanced separately from the flywheel.

[siteunseen]

Oiler cam and spray bar = high flow oil pump too

[madkaw]

Check with who's making what as far as piston kits. Sealed power has limited sizes now, so stick with a popular oversize like 1mm-not .030 

Engines are pretty well balanced, but make sure the flywheel is balanced, might consider lightening it, and get damper rebuilt or get a new one.  

I have good luck with my Schneider cam, but Isky has history with racing Datsuns. Just have your original cam reground for 125$ by Isky or Sunbelt and save some $$ and have the proper metallurgy to match your stock rockers. The more money you put in the head will outweigh  anything else you do to the motor. Consider using an engine builder familiar with these engines. Check your rockers, since finding good ones or reputable rebuilt ones are hard to find.

Consider newer, better ignition system.   

[Diseazd]

ARP bolts are a PITA IMO. Rod ARP bolts must be hard pressed in by a machine shop, and if not installed all the way in, they will separate over time and you could put a rod through the block. For street use, use new Nissan bolts for rods and mains.....MSA sells turbo head bolts....worth the money. Same thing with Pistons......ITM makes a nice cast piston.....plenty adequate for the street. If it's your first engine, go back with the stock cam, if you don't want to have to use non stock valve springs, seals etc. .....not to mention new rockers and geometrying the cam. (Not for novices). When you remove the rockers, keep em in order if you're going back with the stock cam. Get the best rings.....Nissan, Total Seal, Perfect Circle etc. Early Z heads (E31) require hardened valve seats (a must) and a multi angle valve job. Use Nissan stuff when available all IMO.

Edited January 16, 2015 by Diseazd

[caltanian]

Much more likely to end up just going .020 over, as i have found a source for pistons matching same. 

Why the thoughts to stay with a stock cam? I have no issue spending the money for the full kit, but have read stories of many a flat cam, and that the stock springs are adequate for a stage two cam. Valid or not? 

I will be getting the best rings and bearings I can. As I said, this engine is hopefully going to be running for many many years to come. 

The builder here in town has been building engines for decades, and comes highly recommended by numerous people who have had engines built by them. 

[Diseazd]

Isky Stage II cam is .480 lift which requires aftermarket springs and a shorter seal for the E31 head. Stock springs are OK up to .460 lift supposedly. If you're having someone else build the engine that knows Datsun engines, by all means go with a bigger cam. Just understand that you'll need new rockers (IMO), springs, short seals and all new lash pads to make everything work. Cast pistons (ITM) and standard rod and main bolts will be adequate for the street. Nissan bearings are available.

[bartsscooterservice]

If you wanna make around 175/200 hp on the L24. I would use stock internal parts on the engine and nothing else, maybe a stage 1 cam and head ( flow ) work would be recommended. Also triple carbs would increase hp output.

[240260280z]

Maxima N47 is a nice upgrade head that has enjoyed the nismo racing advances from1970 to 1980 racing years where as the E31 was the seed head that started this period.

 

You will have to eyebrow/notch the cylinders if you use a maxima N47.