Are ARP head bolts really needed for a mild build?

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oliver

oliver

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I'm building a pretty mild .060 over 340, kb243's, h beams, ported j's w/ stainless valves, chambers at 66cc, .550 lift solid roller, around 10.5:1 comp 4 speed, 3.9 gears. Planning to spin it to about 7k at the most. I'm not one to cheap out on things like fasteners, but after looking at the stock bolts and realizing they are pretty beefy, im not too sure if they really need to be replaced. They are not stretch bolts, and im thinking some arp moly lube on the threads and let it rip. Anyone have any problems with stockers?
 
oliver said:
I'm building a pretty mild .060 over 340, kb243's, h beams, ported j's w/ stainless valves, chambers at 66cc, .550 lift solid roller, around 10.5:1 comp 4 speed, 3.9 gears. Planning to spin it to about 7k at the most. I'm not one to cheap out on things like fasteners, but after looking at the stock bolts and realizing they are pretty beefy, im not too sure if they really need to be replaced. They are not stretch bolts, and im thinking some arp moly lube on the threads and let it rip. Anyone have any problems with stockers?
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Personally I wouldn't call your 340 a mild build, either way the ARP's are cheap insurance considering you don't know how old the existing bolts are or whether they've been stretched one to many times. Nothing lasts forever IMO. For 7K I'd be replacing the main bearing and con rod bolting also, same reason.
 
demon seed said:
Personally I wouldn't call your 340 a mild build, either way the ARP's are cheap insurance considering you don't know how old the existing bolts are or whether they've been stretched one to many times. Nothing lasts forever IMO. For 7K I'd be replacing the main bearing and con rod bolting also, same reason.
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That's true, but they are non stretch bolts, heck they are not even brought close to the yield with factory torque specs. I'm running h beams with ARP hardware, but i'm going to use the factory main bearing caps bolts.
 
I've been to the drag strip and every once in awhile racers give me parts that broke from whatever, i got pistons, spark plugs, fan belts, heads. I don't think I EVER seen a sheared ARP bolt, EVER...
 
I guess it depends on what you pay for head gaskets and how much you enjoy turning wrenches. Those original head bolts have seen a countless number of heat cycles while under a stres load. A new and different load could begin stretch. Once a bolt begins to stretch it gets weaker and continues to stretch until its pulled in two.
A Fist Full Of Dollars was followed by A Few Dollars More. LOL
 
For what you're builing you should replace the bolts regardless. IMO, I would have studded the main caps too. You have more of a risk of cap walk than heads moving around. If you chose not to, do not use anything but straight 30wt oil, and make sure the holes are tapped and the threads on the bolts chased so the torque can be set properly. By using moly paste you run the risk of way overtorquing/stretching the bolts or distorting the hell out of the tops of the bores.
 
I have reused the factory 340 main bolts 3 times now.

I buzz the motor up 7 grand.

The bolts are not going to break with the build you have.
the only bolts I ever up grade in 'stock stroke' street/strip motors are the rod bolts.

I only use main studs in stroked or above 7500 rpm motors.

I run the same kb243 pistons , use ported heads, solid cam, and have a 4 spd behind it.
 
demon seed said:
Personally I wouldn't call your 340 a mild build, either way the ARP's are cheap insurance considering you don't know how old the existing bolts are or whether they've been stretched one to many times. Nothing lasts forever IMO. For 7K I'd be replacing the main bearing and con rod bolting also, same reason.
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x2!! Why would you risk it when arp bolts are so cheap?

At the very least,buy thier rod bolts. Those take mega punishment.
 
Well, it seems the consensus is to run the arp head bolts. I'm sticking to my original plans of using the stock main bolts, and im running h beam rods with screws. Has anyone ever had any experience with a failed stock head bolt? I personally own a shop and been professionally wrenching for many years and i have never seen a failure of a bolt itself except for torque to yield bolts and bolts that pull the threads out of an aluminum block.
 
I believe the problem is getting even torque on each bolt--and it holding that spec longterm. Your taking a chance of having a blown head gasket with the 40 year old bolts.

I did re-use the main bolts on my 340 since the bearings were still 1972's. Rods got new bolts and head bolts were changed back when APR price was only $50 a set and were used once.

Your pushing the compression for pump fuel, any pinging isn't going to help. Only time I blew a head gasket was on the freeway going all out--then you see lots of white smoke and the car slows down. I still was able to get the car back home, smoke and all

Edit..oh you could damage the block threads, least take a good look at all the threads on each head bolt, if all good-no nicks, then you MIGHT get away with it but for how many months or years ?
 
oh head bolts too?
Those are the last bolts i would replace, the water pump/intake bolts would get more attention before the head bolts.

look at what chevy uses for head/main bolts sometime..
 
if you are running a real 10.1 plus ratio....you need to use the right head gasket 1008 has the wire around the flame ring to help keep from pushing out.

Im finishing a 10.1comp solid roller 410 using stock head bolts and 8553 perma torques, Ill let you guys know if push any head gaskets out.
 
1wild&crazyguy said:
if you are running a real 10.1 plus ratio....you need to use the right head gasket 1008 has the wire around the flame ring to help keep from pushing out.

Im finishing a 10.1comp solid roller 410 using stock head bolts and 8553 perma torques, Ill let you guys know if push any head gaskets out.
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well hell, i'll save the 75 bucks and try it myself also.
 
1wild&crazyguy said:
I have reused the factory 340 main bolts 3 times now.

I buzz the motor up 7 grand.

The bolts are not going to break with the build you have.
the only bolts I ever up grade in 'stock stroke' street/strip motors are the rod bolts.

I only use main studs in stroked or above 7500 rpm motors.

I run the same kb243 pistons , use ported heads, solid cam, and have a 4 spd behind it.
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Yeah I agree, I used the nice factory main bolts, I don't want to compromise the original line bore, I've noticed that different bolts can cause things to shift from the original placement. I even us the nice factory head bolts. I just inspect them and if they don't look good and most importantly if they don't thread by hand with ease to the dead end (usually the shoulder of the bolt) I discard them. But yes for sure better rod bolts, for that matter better rods if racing is going to take place but that isn't the case here.:-&
 
That was another reason i went with stock main bolts, it was not getting line hone

I did have 2nd thoughts a few times, timing keeps going, those bolts are 40 years old now, that is 2X 20 years, lol

Those bolts are in better shape at 40 than I was, ha ha.
 
oliver said:
I'm building a pretty mild .060 over 340, kb243's, h beams, ported j's w/ stainless valves, chambers at 66cc, .550 lift solid roller, around 10.5:1 comp 4 speed, 3.9 gears. Planning to spin it to about 7k at the most. I'm not one to cheap out on things like fasteners, but after looking at the stock bolts and realizing they are pretty beefy, im not too sure if they really need to be replaced. They are not stretch bolts, and im thinking some arp moly lube on the threads and let it rip. Anyone have any problems with stockers?
Click to expand...

I've reused the stock head bolts on many occassions and the only problem I experienced was during the torquing sequence. I did have some bolts that...yielded, and you could feel the torque wrench get real easy to turn just as you were pulling the last value.

I removed the defective bolt and replaced it with one from my 'bolt stash' and never looked backed. Never had any issues. But I don't recommend the "black grease" from ARP. Motor oil is what's recommended by the factory. The ARP grease could pull your bolt beyond yield values...

Also, the engines I rebuilt saw regular 7000 rpm blasts and I never showed them any mercy. They never broke, but the rings did finally give up after many years of beating them as I TRIED to blow them up. Damn them Chrysler engines ! If it had been a Shivvie, I could have done it - with ease. ~{:>)

Southernman
 
oliver said:
They are not stretch bolts, and im thinking some arp moly lube on the threads and let it rip. Anyone have any problems with stockers?
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I would reconsider using the moly lube on the threads before torquing. The torque specs are developed on the nuts and bolts as delivered from the manufacturer. Approximately 75 - 80 % of the torque for the bolts is affected by the friction of the threads. Adding moly lube to the threads will reduce that friction therefore increasing the clamp load or stretch of the bolt. Your bolt will be much tighter when you use the lube than when you don't. This could cause an overtorque condition with your bolts beyond what the spec was developed for. The torque specs are developed to put the bolt at the maximum allowed clamp for that bolt and nut combination to be slightly into the yeild point.

I woud recommend chasing the threads with a tap and die and then torquing them dry.

Let's just say that I used to be involved in developing torque specs and setting up the machines that tightened them. If anybody would put any other oil or lube on the nuts or bolts different than what was originally supplied on them, it would create many torque rejects.

fyi: The fastener group that developed the torque specs only recommended torquing them 5 times. The factory was allowed to torque them three times and leave two times for service/rebuild. Beyond that the connecting rod bolts could become overstretched and compromise clamp ability (break).

Also keep in mind that the factory has clamped the nuts and bolts on the connecting rods at least twice on a "first time through" engine where everything went well building. The first clamp cycle is made on the connecting rod machining line before they machine the crank journal bore. Then they get unclamped and assembled on the engine assembly line to be installed in the engine. So every engine that comes out of the factory has at least two clamp cycles on the nuts and bolts for the rods.
 
Excellent post KrazyKuda, which leads back to my original comments. These engines, especially the 340's are 40 years old, or more, and you have know way of knowing (unless you've owned it since day 1) how many times it's been rebuilt and more to the point the heads have been removed. I stand by my original statement to replace the head and crank bolting and I use engine oil (couple drops) on my threads definitely not moly or any paste for that matter. :glasses7:
 
demon seed said:
Excellent post KrazyKuda, which leads back to my original comments. These engines, especially the 340's are 40 years old, or more, and you have know way of knowing (unless you've owned it since day 1) how many times it's been rebuilt and more to the point the heads have been removed. I stand by my original statement to replace the head and crank bolting and I use engine oil (couple drops) on my threads definitely not moly or any paste for that matter. :glasses7:
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New bolts are sooooo cheap! It's really silly to not replace at least the rod bolts.

Stock main bolts and caps tend to walk about when your looking for all the h.p you can get,especially when using a stock crank. Im planning an upgrade with arp studs and program caps. But Im in for an alignment bore and hone anyways as a 440 crank is going in a 400 block.
 
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