Project Crush

[HuD 91gt]

I thought I'd make my own thread as I seem to make a new one every week or so for this weeks issues.

Long story short if you haven't been following, or can't keep up. I purchased a 240z south of the border (yup I'm in Canada), last spring. Over the last year and a half I've managed to bring it back to life (stored for 10 years), get it passed inspection here in BC, and have finally started to have some fun with it.

The first day I insured "Crush"
Having done little to vehicles in the past, minus some lowering springs on my first vehicle, some minor wiring and a bunch of oil changes I'm new.

So far on the Z, I've replace all front end bushings, new tie rods, adjusted and refreshed the steering. Formed new brake lines, rebuilt the SU's and lastly swapped from an automatic transmission to a 260z 4 speed. A lot of headaches, but in the end success.

Last weekend I attempted my first engine swap. A generally unknown condition F54 flattop/N47 combo engine. With help and research she went in quite smooth. Minus a faulty electric fuel pump (see other thread). With the stock cam, I was quite impressed with the increase in torque. Unfortunately the engine is tired, and burns more oil then I can afford (jokingly of course, but I've got clouds of blue behind me).


The motor - At least it looked nice

Loaded up for the trip to Vancouver Island where I did the swap at a friends

before swap (sorry iPhone can't figure out which way is up)

Empty bay

Dropping her in

The new engine

I am going to put in the old L24 for the time being to get the most out of summer. My current plan is to certainly rebuild the bottom end. I'd like some suggestions on what to do with it. I have the "how to modify" book, and will order the rebuild book in short order. After going over a few threads, I see there are many options on rebuilding/refreshing a motor.

The engine needs to be re-ringed. I believe at this time id like to use my current head. I will be picking up a rebello cam kit. An aggressive street cam will be part of the order. One for the power, 2 to help with detonation on the high compression combination. To get the most out of this cam being able to rev the engine freely is the plan of action. (Were not talking 9,000 rpm, but safely to 7,000 would be great, a little higher if possible).

With budget in mind, how do I go about doing this? Balance individual pieces at home as per the how to modify book. Use the old pistons and re-ring (can you hone the block and use the old pistons).

I see some rebuild kits online. Some include everything, some are a refresh kit. Which do you guys suggest? What do I really need? I know the original datsun parts are better then most of the aftermarket pieces, so is a refresh all I really need to do?

 

I'll finish off with my favourite photo of the car.

Edited July 16, 2015 by HuD 91gt

[rossiz]

looks like you're prepped for a nice re-build process, as the starting point is clean and tidy. 

based on the general sturdiness of these blocks, i'd bet you just need a hone & surface to clean things up. i just finished up my rebuild, - see the thread "a project is brewing" -  there are lots of build threads on the forum which have far more technical detail than mine, but in short it's a pretty fun and simple process. if you don't have one, pick up an engine stand - makes life soooo much nicer.

 

some must-have tools/supplies include:

• torque wrench (get a good one - not harbor freight)
• taps to chase  threads (get good quality spiral taps for the few sizes you'll need vs. a cheap set - machine shop supply house vs. hardware store, definitely NOT harbor freight)
• ring spreader ($2 harbor freight works fine)
• ring compressor ($3 harbor freight works fine)
• gasket scraper
• valve spring compressor (to strip/rebuild the head and for swapping the cam)
• feeler gauges
• plastic weighted mallet (for tapping in bearing caps & setting front cover)
• good assembly lube (i used brad penn and liked it)
• good break-in oil (i used brad penn and like it)

when you take the block in to the machine shop for hone/surface, they can also lighten your flywheel down to ~10lbs (revs really nicely, very streetable)  and have them balance the whole rotating assembly (crank, pistons, rods, flywheel, clutch pressure plate) down to less than 1/2 gram. i was very pleased with the smoothness it brings up in the high revs - night and day from stock. none of this is particularly expensive either, especially if you have it all pulled apart for them. have them tank clean the pistons with the rods still attached unless you need to replace parts. then snap a ring in half and use the factory end (not the jagged broken end) to clean the carbon out of your ring grooves. lots will come out - it's a slow process that is very satisfying to complete. i also used small drill bits to clean carbon out of the little holes/passages in the piston behind the rings and feeding the bearings.

 

i looked at full re-build kits, but wound up buying a lot of things separately to get the quality i wanted - clevite bearings (ebay), nissan rings (msa has 'em) and nissan turbo head bolts (courtesy nissan) then i got a master gasket kit (msa) and sprung for the upgraded oil pan gasket.

 

here's a list that Blue published somewhere on his site with a lot of great tips: 

 

Re-Build Notes From Blue:

 

• 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 cam 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 pickup, 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 and 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

[siteunseen]

If your going to a higher lift cam you'll need different valve seals, here's where I found out; http://forums.hybridz.org/topic/25807-improved-l6-valve-stem-seals/

 

here's the part number, Fel-Pro # SS72686.

 

​See the difference in height,

[Martzedcars]

In your list: go for internally oiled cam and use an oil bar.

 

 

 

You mean :  Go for an externally oiled cam?  or??

 

An oil bar is never used on a internally oiled cam.. or do you want to do both?

 

Grts,

Mart

[rossiz]

i pulled this list directly from Blue's site - opinions vary on the dual-cam oiling strategy. i've read that many use both the spray bar and the internally oiled cam to double up on lubrication. proponents say that for track and heavy use it provides a belt & suspenders approach. others feel that this may reduce overall oil flow unless a high-pressure (turbo) oil pump is used - as with many of the finer points, this is pretty widely debated with lots of good info on both sides...

 

i personally went w/just an internally oiled cam because my p79 cam towers aren't drilled for the spray bar. the spray bar alone, if working correctly has kept many thousands of z cars running just fine for all these years, but the design is prone to failure and the small orifices are more easily clogged than the larger holes in the cam lobes on the internally oiled cams. 

 

i'm no expert, but i believe that if the system is clean and maintained and the proper oil is used either should work fine for the street - it just gets dicey when things are old, dirty, damaged, etc. and cam damage is no fun at all...

[HuD 91gt]

Thanks for the replies.

 

Looks like I have a majority of the tools required already.  With the purchase of a 240z, my tool collections has grown tremendously.  A few of the engine specific tools will have to be purchased.  I just purchased the how to rebuild book, so i'm sure i'll have some more questions after going through that one.   Your replies will certainly get me started.

 

Siteunseen, good to know about the valve seals.  I don't think the cam will be that aggressive, but it certainly will be something to keep an eye out for.  Not only that, those ford seals seem extremely cheap!

[Patcon]

Boring versus honing will ultimately be determined at the machine shop with dial bore indicators. If the bores are round and true, honing should be fine. The Japanese steel in these engines is very good and normally doesn't wear dramatically. The other info provided is all good stuff.

The new engines is using oil and blowing smoke? Are you gonna switch back or run the F54 you swapped in? The motor that has been sitting may take some time to quit smoking and seal up. How many miles have you put on it so far?

[HuD 91gt]

It was smoking a huge amount. I burned halfway down between the full and minimum mark on the dipstick in about 40-50 miles. The plan was to swap in the old L24, and then work on the F54. The valve seals were brand new. They should not need a break in, should they? The smoke was during deceleration and during hard throttle after decel. It smoked throughout the rpm range but a ton during decel. Compression check showed 150-158psi across the board which was consistent but I think low for the head/block combo.

 

Edit:  A friend just reminded me this also which may have affected it, I honestly forgot about it.  When I put in the oil pump, I never primed it.  When we started the engine, the gauge did move, but very little.  I've had sticky needle issues with the gauge before so I assumed I had some oil pressure.  Well, the car idled for 5 minutes without oil pressure.  Could this tear brand new valve seals?  We poured oil onto the cam prior to, thank god.  

Edited July 18, 2015 by HuD 91gt

[HuD 91gt]

I don't know how long the motor was sitting, but if say at least a year. I ran it hard for the small amount I drove it.

[Patcon]

No oil flow on valve seals for 5 minutes could damage them. Blue smoke on Acceleration and Deceleration is normally rings not valves. I would suspect they are damaged, stuck or haven't seated in yet.

[HuD 91gt]

Well, before I pull the engine out, I will put a table spoon or two of sea foam in each cylinder and let it sit for the evening.   The next morning I will crank it over a few times with the spark plugs removed.  Then give her a few good rips up the road.  If it isn't any better i'll start pulling the engine.  I can't really think of anything else to do.  Unfortunately the car is a 1.5 hour ferry ride away now, and a 1.5hr drive ontop of that, so it's a bit of an inconvienece to do troubleshooting.  If something doesn't correct it self quickly, i'd rather put the old engine in and get the car home.

[EuroDat]

Im wondering what the compression is. A F54 flat top with a N47 head will be running high compression somewhere around 10.5:1.

Valve seals typically smoke when you coast down a hill then use the throttle. The high vacuum when coasting sucks in a lot of oil and the engine burns it all when it back under load.

If he did this N47 mod on an old tired bottom end it could be ready to give up. Thats often the trouble with unknown history. Its generally not very good otherwise he would tell you all about it.......