ARP Connecting Rod Main Bolts (1 Viewer)

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I just got off the phone with ARP's custom manufacturing department and the guy was a bit shocked that they didn't make any bolts for the 2f engine. I told him that I found it odd too and that I know of a lot of folks that would love to buy ARP bolts for their engine rebuild.

I am specifically looking for the connecting rod main bolts from ARP as the stock Toyota ones are known to be a bit on the weak side. It looks like I am going to have to have them specially made. The ARP guy said that if I can get a bunch of folks to order them it would significantly reduce the cost.

That being said, if you want ARP connecting rod main bolts, please contact ARP at 805-525-1497 and ask for them. I already gave them the specs and they are doing a quote for me now.

Perhaps we can get them to put together a whole engine kit if they get enough requests. :)
 
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Post here if you are going to call or you have called to request them. I just want to keep track of the number of requests just in case ARP balks.
 
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So I got this email back from ARP.

Hi Joe,



I came across a bolt from our inventory that is very similar to your request. The length is approx .035” too short and the “knurl” is .0015” too small, both too close to rule out with test fitting.

The PN is 203-6004, set of 12 pieces.



Basically this means that given the specs I got from Matt.Mcinnes

The Knurl 10.25mm
Thread 10.00mm
Length from under the head of the bolt 56.00mm


The ARP bolt is for a 3.0L (7MGTE) inline 6 (1986-92) Supra:

The knurl is 10.2119mm
The length is 55.111mm

Does anybody see any reason why I would have an issue with this? Seems WAY to close to have an issue with it but I need the advice of the forum... or Matt. :)
 
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It would be great to hear from Mark W or some of the other engine guru's on the board. I bet they would have some sense of where to get high-strength connecting rod-end bolts.
 
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Stand by for ARP's low quantity run pricing. Ouch. I priced out and had quoted prices for lug studs for an 80 series(longer and stronger than stock) and they were nearly $27/bolt. that's for a fastener that is simpler to make and looser tolerances...

did matt measure a used bolt for the knurle diameter? its going to have shrunk some in the installation process so that might make it even more out of spec. I would send a con rod to them(with bolts) and let them decide.

-brett
 
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Stand by for ARP's low quantity run pricing. Ouch. I priced out and had quoted prices for lug studs for an 80 series(longer and stronger than stock) and they were nearly $27/bolt. that's for a fastener that is simpler to make and looser tolerances...

did matt measure a used bolt for the knurle diameter? its going to have shrunk some in the installation process so that might make it even more out of spec. I would send a con rod to them(with bolts) and let them decide.

-brett

Yep bolt was used.
 
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The continuing conversation with ARP goes as follows:

I sent:
Hi Jay,

So the wisdom the the Ih8mud.com forum seems to think that the knurl on this is going to be too far off. The bolt that was measured was used and had probably shrunk some in the installation process.

The thread for this is here.

I did find some info from another thread that says there is a big block rod bolt that is only .001 or .002 over the knurl and has enough length. With some heat and a press these should work just fine, but I don't know what BB they are for. Perhaps you can look for these? The rod bolts now with lock washer and nut on them have about 5 MM of extra thread if I recall correctly. It gives us some room to experiment with the length.

Joe

He replied with:

Joe,

Our bolt (kit 203-6004) does not actually have a knurl. I still think it should be tried even though the locating diameter is .0015” too small. Differences in locating diameters are often “made-up” in the concentricity.

The only BB rod bolt I can see is for a Ford 428. This does have a locating knurl and it is .003” larger than yours, the press knurl is .4095”. The kit number is 155-6001, 16 pieces. Kit 155-6021 contains 2 pieces.

Regards,

Jay
I really don't know what he mean when he is saying in the first paragrapgh about "Differences in locating diameters are often “made-up” in the concentricity." So an explanation would be nice.

The second conversation has me completely baffled so an explanation of that would help as well. What the heck is the difference between a locating knurl and a press knurl?

TIA (Matt) :)

Joe
 
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2F ROD BOLT
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Well I sent Jay at ARP the picture that Matt posted up here and he offered to send me a pair of the Supra bolts for free to test fit. He really thinks that they should work just fine and well, they are company that specializes in engine bolts. He is really going out of his way to prevent me from having to have custom bolts made. If these work I will let you all know.
 
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I got the sample Supra bolts from ARP. My machine shop said that they fit good with one exception. They want to mill the head on the ARP bolt to match the chamfer on the stock one. You can see what I mean from the pictures. They believe that the chamfer is there to prevent the bolt head from hitting something. I can't test fit this right now to see if it will interfere or not so I was wondering if I could get the opinion of those who know more than me. Thoughts?

I asked the same question of Jay Coombes from ARP and this is the response I got from him.

Hi Joe,

Thanks for the update. Glad the bolts fit well except for the head style.

Your machine shop is most likely right. The angle is probably to clear something as the assembly rotates. Without a test fit I can not definitely say. Modifying the head of our bolt will not weaken its strength or performance so if necessary it can be done. I’m not sure how you will modify the head but make sure the material temperature does not get too high, keep it as low as possible.

Ok so it looks like for the cost of the Supra ARP bolts part #203-6004 and the price to get the head milled right, for me it is going to be about $100 ( :eek: everything is freaking crazy expensive in NJ) you too can have ARP bolts!
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Have a search of pictures of 2F cranks to see if you can see any interferance issues.
I can't see what they would catch on, more likely the way the bolt head was struck but could be wrong.

Matt
 
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So a final report on the ARP bolts. The heads of the bolts from the Supra definately needed to be machined down to clear. Otherwise things will be uncomfortable close if not hitting the cam shaft. Also, the bolts need to be put into the connecting rod with green thread lock otherwise they will spin when you go to tighten them down because they are litterally a half a hair smaller. That's all you need to do!

Joe
 
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How hard to machine the top to fit? Bench grinder?

I would not do it with a bench grinder considering where they are going. You don't want to heat up the bolt at all. I just had my machine shop do it. Since I am moving into my new house soon, I would just use my vertical mill to get the angle of the dangle right. If you put to much heat into the bolt using a bench grinder you will weaken the overall metal structure of the bolt and defeat the purpose of using ARP bolts. For 100 dollars or less any machine shop should be able to do that and it is worth the peace of mind.

Joe
 

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