L24 9MM Rods

[vintageracer]

Looking for a rebuildable set of L24 9MM rods. Building a Vintage race motor.

[panchovisa]

Vintageracer,

Did Datsun make such a rod? I didn't think yhere were Datsun 9mm rod bolts until the 280 or turbo.

You could always drill out 8mm rads to accept 9mm bolts. Otherwise an aftermarket rod could be used. High dollar teams in the '70's did use Carillo and others.

Pancho (vintage race Z owner)

[Bambikiller240]

I've always heard that the 73 L24 motors came with the 9mm rods. Ealier L24's did not.

Here's a copy of a previous post I found on the subject.

HTH,

Carl

Carl Stahlnecker

IZCC #8648 & CZC#791

72 240Z "Bambikiller"

Pleasanton, CA USA

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Posted by tanny on 11-15-2002 03:57 PM:

Question" Rod bolts

I have a 1973 240 and am rebuilding the engine. When I measured the rod bolt threads to determine whether I have 8 or 9 mm bolts, I came up with 8mm. From what I read the 1973 is supposed to have the 9mm bolts(I think). Any ideas as to what happened and should I torque these to the lower value as specified for the 8mm bolts. Are the threads where I am supposed to measure? Thanks, Vic.

Posted by Phred on 11-15-2002 06:26 PM:

Rod Bolts

Tanny,

I have built several L-24's and have seen both 8mm & 9mm bolts in that year. It seems they just used up their bolt stock, and then switched over to 9mm at some unknown (to me) eng. #. The bolt is measured at the thread. If you have 8mm bolts and are rebuilding, replace the bolts with ARP #202-6002 8mm bolts. They are actually stronger ( in tensile strength) than a stock 9mm bolt. The torque for the ARP bolts is 30 lbs. with Moly lube. When replacing rod bolts, The big ends should be checked for cap shift, (ID roundness and taper) and proper brg. clr. with the caps torqued to spec. About 90% of the time they require resizing. Wherein a few thousanths are ground off the mating surfaces of the rod and cap, the caps are then torqued to spec, and then honed back out to the proper size, which makes them perfectly round, with the correct brg. clr. All this can only be done by a quality eng. rebuilding shop. Prefeably a race eng. shop. This can be done with the pistons attached. If you are also replacing pistons, you could also balance rods and pistons at this time if your budget allows. Hope this helps.

Phred

www.arp-bolts.com

[vintageracer]

Being I'm just learning about this motor I have read that the 9mm stuff is the way to go. I have used Carrillos and Pauter in my Spitfire but was reading that the Z motor rods are pretty good to use for Race motors under 8,000 RPM. I was already going to use ARP but would like to start out with the 9MM stuff. Seems like Rebello is buying all they can find. I also heard some models were actually already shottpeend? If the 9's can't be found then 8MM would be good to with ARP's. Just figuring out a budget at this time. thanks for the input

[Bambikiller240]

Originally posted by vintageracer

I was already going to use ARP but would like to start out with the 9MM stuff. Seems like Rebello is buying all they can find. I also heard some models were actually already shottpeend? If the 9's can't be found then 8MM would be good to with ARP's. Just figuring out a budget at this time. thanks for the input

If memory serves me, I seem to remember a thread on the IZCC mail list a couple years ago indicating that the difference between the 8mm v.s 9 mm rods is only the diameter of the holes for the bolts. Don't remmber anything about certain rods being shot-peened and other not.

Check w/ Phred, bet he knows. (I'm sure he knows more than I about this.)

[Phred]

Hey Carl, thanks for the pat on the back. But don't over do it or I'll have to buy a bigger helmet.

I have never seen a stock Datsun rod that was shot peened from the factory. Mainly because its so labor intensive. For more info, stay tuned and I'll post a new thread, a short article I wrote that explaines what shot peening is, how its done, etc. But right now, its time for dinner. Stay tuned.

Phred

[rightwayismyway]

Hey if 73 L24's do have 9mm rods, hit me up. I have a decent set of rods. rightwayismyway@hotmail.com

Nathan

[gundee]

From the reading I did, Datsun switched to the 9mm rod and rod bolt in April of 1972.

In 1990 I purchased a set of 9mm bolts through a dealership for my engine. The part number for the bolt was 12109-N0110 and the nut was 12112-N0101.

My engine builder had them fit to my 8mm rods.

The bolts were $2.00 ea. and the nuts were .42 ea.

I wonder what they go for now. Maybe the ARP is cheaper.

[spudz]

I have a set of Late L24 rods with the 9mm bolts I will sell as well....

roadsterx@hotmail.com

[Ben]

Another question that was posted on the IZCC was; How many people have seen an 8mm-equipped rod fail?

No replies....

Fresh bolts, a balanced assembly and a sensible rev limit will see a fresh (new bolts) setup last.

Plenty of people (myself included) have pushed the L24 to over 250HP with 25-year old components. I replace fasteners during a rebuild now cause I can afford to. But years ago, unless they were markedly stretched or damaged, they got reused.

(Flawed logic I know, but that's what was done....)

If you really want 9mm assemblies & cant find any Z engines locally, broaden your search to ANY L24 post 1972.