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| ARP rod bolts - interference issue https://slantsix.org/forum/viewtopic.php?f=19&t=63301 |
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| Author: | jcc [ Thu Feb 14, 2019 2:48 pm ] |
| Post subject: | Re: ARP rod bolts - interference issue |
I would be beside myself if I had to grind an ARP rod bolt ( one of the highest cyclic stressed non redundant catastrophic preventing fasteners in a car) as the OP pictured. Guess I don't know too much. |
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| Author: | GregCon [ Thu Feb 14, 2019 3:48 pm ] |
| Post subject: | Re: ARP rod bolts - interference issue |
I agree. Fancy words aside, you don't seem to know too much. If you looked in just about any professionally built engine you'd find pretty much every part has been modified, massaged, and otherwise made to fit as necessary. The ARP rod bolt needed that little tiny extra bit of metal not in the least. What it DID need was a good surface to support its head and that's what it got. |
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| Author: | coconuteater64 [ Fri Feb 15, 2019 5:32 am ] |
| Post subject: | Re: ARP rod bolts - interference issue |
and739 wrote: coconuteater64 wrote: Now I'm worried because my ARP rod bolts fit perfectly.  In that case, I recommend the break-in procedure described here: http://slantsix.org/forum/viewtopic.php ... 75#p475522   That'll let me know real quick if there's a problem! |
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| Author: | CNC-Dude [ Fri Feb 15, 2019 5:46 am ] |
| Post subject: | Re: ARP rod bolts - interference issue |
You could try comparing the old rod bolts you took out of the rods in that area where you are having the problem to the ARP bolts. Also if I remember correctly, these AR P rod bolts are not made specifically for the slant 6, but they were borrowed from the Pontiac V8. So in all actuality, there are going to be some instances due to production variances in the connecting rods through the decade, there are going to be fitment issues from time to time. I have experienced similar issues with some Ford production rods before and had to spotface the rods to allow the bolts to seat fully into the pocket where the head of the bolt rests. |
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| Author: | GregCon [ Fri Feb 15, 2019 5:57 am ] |
| Post subject: | Re: ARP rod bolts - interference issue |
That's correct - the other post said the bolts were originally a Pontiac-designated item. The stock bolts have no inner-side shoulder and fit (as expected) perfectly. The ARP's - at least the set I received - have a shoulder that needs to go. Alternately, you could relieve the rod but that is far tougher to do and not a good idea IMO. |
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| Author: | CNC-Dude [ Fri Feb 15, 2019 6:53 am ] |
| Post subject: | Re: ARP rod bolts - interference issue |
Its also a common practice to clip the front edge of the connecting rods and some portion of the rod bolts on a grinder when you swap 350 Chevy connecting rods into a 400 Chevy engine because the 350 rods are longer than the 400 rods, and also use a longer rod bolt, and will hit the camshaft. So, tweaks and grinds are often a common practice when dealing with performance oriented applications that some may not be aware of, but are perfectly acceptable to perform. |
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| Author: | jcc [ Fri Feb 15, 2019 5:39 pm ] |
| Post subject: | Re: ARP rod bolts - interference issue |
GregCon wrote: I agree. Fancy words aside, you don't seem to know too much. If you looked in just about any professionally built engine you'd find pretty much every part has been modified, massaged, and otherwise made to fit as necessary. The ARP rod bolt needed that little tiny extra bit of metal not in the least. What it DID need was a good surface to support its head and that's what it got. “Appear weak when you are strong, and strong when you are weak.” ― Sun Tzu, The Art of War I'd also guess you can't see the concern beyond the fancy words. I won't bother challenging your use of "any professionally built", "made to fit as necessary", "needed that tiny extra bit of metal not in the least", etc I'd also guess you are pretty confident in your knowledge on the subject. |
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| Author: | GregCon [ Fri Feb 15, 2019 6:07 pm ] |
| Post subject: | Re: ARP rod bolts - interference issue |
There's plenty I don't know. But when it comes to taking a little metal off a rod bolt to ensure proper fit, I am supremely confident. |
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| Author: | Doctor Dodge [ Fri Feb 15, 2019 6:16 pm ] |
| Post subject: | Re: ARP rod bolts - interference issue |
There are 2 different listings for ARP Con Rod Bolts: 142 - 6001 (full head coverage, more work to install) 142 - 6002 (less head coverage, less work to install ) Use the 142-6002 for most applications because they press-in and re-size with-out much "fuss". I use the 6001 for high HP engines because the larger head has more contact area but... you have spend time making "room" for the bolt head to fully seat, as seen in this post. You can spot-face the con rod's bolt hole entry surface and / or grind the bolt head, as shown earlier. DD |
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| Author: | Dart270 [ Sat Feb 16, 2019 5:35 am ] |
| Post subject: | Re: ARP rod bolts - interference issue |
Thanks, Doug. That is a helpful and concise reminder. I just put a set of the 6002s into a set of stock cast crank rods and had them resized and balanced. They appear to fit perfectly. I have not tried either one in forged crank rods yet. Lou |
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| Author: | DadTruck [ Sat Feb 16, 2019 11:48 am ] |
| Post subject: | Re: ARP rod bolts - interference issue |
Quote: helpful and concise really at the ARP web site the 142-6001 says it is for slant six rods 76 and earlier 142-6002 adds that it is for 77 and later slant six motors. no more , no less. Both have the same torque spec, if one is for performance applications, why have to grind it to fit,, bolts when they fail need to fail in the shank, not under head so additional under head area for a performance application is an opinion, but not a fact. it is great that time and energy was spent to find an existing bolt that fits a slant six requirement, but if one has to grind on it, and that added operation is not called out, in the part instructions, is that great work? |
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| Author: | Rick Covalt [ Sat Feb 16, 2019 2:36 pm ] |
| Post subject: | Re: ARP rod bolts - interference issue |
It would be nice if they could add that little bit of info to the ARP packaging. Then everyone would know. However I have complained on here about other things that come from the factory (at a high price no less) and have to be modified right out of the box to work. Valve notches in new Wiesco pistons for one! Others have reminded me that this is the nature of our little hobby. And we need to be happy that someone is still making something for our 50 year old "racers"! And I would guess they are probably right. 
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| Author: | slantzilla [ Sat Feb 16, 2019 3:57 pm ] |
| Post subject: | Re: ARP rod bolts - interference issue |
I had at least 5 sets of rods done by Mike and/or Blaine, and none of them had grinding on the bolt heads. They used ARP bolts for a 340 IIRC. Has ARP changed the bolts for some strange reason? When I worked at High Speed we did a 632 Donovan with Big Chief heads. That motor got the best of the best parts and very little of it went together without at least a little massaging. You pissed off about you're $75 bolts being sketchy? How about tossing $3200 for a Hogan sheet metal intake that leaks water into your $65K race motor the first time it ran? If it was mine I would have killed somebody. |
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| Author: | GregCon [ Sat Feb 16, 2019 4:14 pm ] |
| Post subject: | Re: ARP rod bolts - interference issue |
Yeah, I will reiterate that I'm glad they sell bolts for the Slant Six at all. It's not a big deal grinding them. But I also am sure a lot guys (and machine shops) don't catch this and assemble the rods without properly seated bolts. As for making parts fit...I've done a number of 392 and 426 Hemis and that's a whole other world of making things fit. The fun of the Slant Six lies in the simplicity and ease (and low cost) of working on one. It's a breath of fresh air.... |
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| Author: | Exner Geek [ Sat Feb 16, 2019 4:28 pm ] |
| Post subject: | Re: ARP rod bolts - interference issue |
I always used the ARP bolts for a 340, I don't recall any interference issues. I am sure I also put them in sometimes without resizing the big ends, just lucky I guess. |
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