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rod cap bolts


David K

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Guest Anonymous

I'd get the ARP's from somewhere like Summit, think they're around 60/set but free shipping and probably the lowest price around with Summit vs a marked up price and shipping charge from MSA.

 

As far as I know the ARP's are the only better than stock direct replacement available. The How to mod your L series book talks about using Chevy ones that have been ground and knurled but I think that's probably alot more trouble and machine work than you're looking for and probably not any better than the ARP's anyway.

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Guest Anonymous

Straight from www.arp-fasteners.com:

 

The 202-6003 is the 9mm rod bolts for any L24/L26/L28 engine except the really early 240's which used the 8mm bolts.

 

202-4206 is for the Head stud kit, (118 bucks ouch) and the 202-5406 (88 bucks) is the stud kit for the main bearing caps.

 

Honestly for the hardiness they put into the bottom end assembly vs the hassle and expense of replacing parts resulting in a failure of the Mains and the Rod bearings. I'd consider the main kit as well as the rod bolt kit as relatively inexpensive insurance.

 

Having acquired a Geo Tracker from my wife's uncle for free as a result of a rod bolt failure a few years back, I still find pieces of the old engine block in the engine compartment when I work on it at times. The oilpan was full of shattered pieces of connecting rod cap that I found when I took it apart to satisfy my curiosity after replacing the engine. This is on top of the huge hole in the side of the block and the main intact piece of the con-rod being bent beyond belief. The rod bolt(s) on that thing were just sheared right off though as a result of oil starvation.

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Guest Anonymous

I'm planning on just doing the whole ARP Z catalog of studs next build up because I think studs are a better way to go especially for stuff like the head where it's sometimes a pain in the butt to line it all up during assemply with the bolts.

 

The fact that they're alot stronger than the turbo head bolts is a big plus too. I think it comes from when I was an aircraft mechanic in the military, I'm pretty anal about fasteners now in general but it's not a bad thing as alot of the automotive fasteners really are crappy and especially 20-30 year old ones that have undergone who knows how much abuse already.

 

Admittedly the head studs are probably less crucial than the bottom end ones in terms of being easy to replace and a head bolt letting go won't break a ton of stuff like a main or especially a rod will, but I've snapped a regular head bolt before just torquing it to specs (not happy about it either at the time lemme tell ya and it probably served me right for reusing a 23 year old at the time fastener.)

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In my book its RPM that kills rod bolts - not boost. The additional stress to the rod is in compression - not tension - when you have more cylinder pressure from boost. Therefore - the rod bolts are not under additional stress if the redline remains the same. If the redline goes up - the rod bolt comes under increased tensile stress trying to slow down the rod/piston from higher speed at the top of the stroke. That's what kills the rod bolts. Just my .02 but why spend money where you don't need to. BTW - Corky Bell says the same thing in MAX BOOST. ;)

 

I run a 240z/l28et/p90a. Stock rod bolts, stock main cap bolts, ARP head studs. No problems and I'm now in the high 12's with a stock turbo. Car is not really set up for drag racing.

 

 

cheers - Doug

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Doug is spot on about the rod bolts. Pressure isn't the killer but tension at high rpm. When my L28 was built, there were no aftermarket bolts for Nissans. It has the turned down big block chevy ARP bolts, but that wasn't cheap! Contemplating all of the ARP fasteners? FWIW, I just put an ARP 8mm stud setup on the intake/exhasut. It had to be added to the system at Summit with a part# I got straight from ARP. SO I didn't know the cost until it showed up at the door. $114 for 16 studs (the biggest package they sell.) Ouch. And the stupid motor needs 17! (I used an original one under the water neck since you can't see it.) They are slightly shorter than stock so I bought arp 13/16 hardened washers .125 thick, but not available in stainless so I had to go black oxide. Looks pretty, though... I would like to replace all of the Nissan hardware as it seems really soft, but at those prices I'll deal with it!

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Guest Anonymous

Yeah using the ARP stuff is probably overkill and not absolutely necessary. But take the case of the rod bolts you're going to pay about 20 bucks more for ARP vs the stock ones. Not enough price difference to not go with the ARP's to me.

 

The main and head studs, on the other hand I can see the price difference justifying going with the Nissan stuff. There are some benefits to studs over bolts of course but I guess it just comes down to how you want to spend your money.

 

In any case, replacing the old ones with something new be it Nissan or ARP is always a good idea.

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Well I have never heard of someone pitching the crank out of a datsun, although I am sure there is some knucklehead out there who has.

 

The main reason to go to the ARP rod bolt is becuase in the hotrodding Nissans book, they say it is the weak link in the bottom end. I figure if you are going to build an engine and you know you are going to flog it, fix an acknowledged weakness.

 

As for the head studs, I think they would not be a bad idea, but if your block is true, and head true, a stock nissan gasket should work fine. I have a stock nissan one on my turbo car and it has been thoroughly tested.

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Guest Anonymous

The way i look at it ARP rod bolts are cheap in surance, i ran about 80 bottles of nitrous through a stock parts 3.0 bottom end and had no reliabitiy problems.As for the main cap bolts diesel main cap bolts were used on that motor which is still running in my friends 240z.The current motor I have in my car has ARP head studs /rod bolts/main studs.It`s cheap insurance compaired to a broken motor.I would also look into an HKS head gasket ,for the hassle of tearing a motor down ( which i had to do due to a stock head gasket, and the machine depth being wrong for the 0 ring wire). cheap insurance.

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