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Small Block Duster

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Hi guys. I started a thread pertaining to this issue and got no answers on the last question in the thread. I appreciate your help and I wonder if any of you have experience with this?

I was trying to find some main cap bolts that would torque to stock Mopar specs to mount my kevko oil pan pickup. I settled on the Mancini racing windage tray attaching bolts. Listed as a Mopar performance part. Part number MOPP3690939.

When I received them I found that the washers that go between the main cap bolts and the main caps are not flat. They're convex. Obviously the other side is concave. I'm used to flat washers. For that matter there are no washers between the rest of the bolts and main caps. I have only used washers in this scenario when I switched to aftermarket bolts or studs and those were always flat washers.

It seems logical that I place the washers in such a way that the convex side goes against the bolt head. As the bolt torques down and the washer flattens it would seem to change loading on the bolts and therefore the main caps and block.

No information found anywhere from Mancini or my machine shop or any written source I can find about what the torque should be but the whole reason I bought them was to maintain stock torque because the block line bore came up straight and I want to keep it that way.

The answer to my original question was to torque the bolts to the stock 85 foot pound spec. Does this still hold true with the strange curved washers?

The advice I was given originally was to weld a smaller stud to the bolt head of the main cap bolt. I didn't do that because it seemed to me like the heat of welding would compromise the bolt.
 
I would use the recommended torque. The washers won't make a difference in clamping force .
 
I would call the place where you got the bolts and ask them about it. They made them and sold them to you...
 
Use the washers and torque the bolts to the recommended torque. The washers spread the clamp load of the bolt over a larger surface area. 65'
 
The wavy or curved washers are not typically grade 8 because they have to flex. Grade 8 flat washers Were used for hardness so they would not allow the bolt to sink in and loose any clamping force.

If you use these bolts- do you have a picture of them and the markings? Factory studs or bolts were Grade 8. Use nothing less.
Wavy or curved washers in my own opinion would be affected by heat. Weakening and giving way over time allowing the bolts to loosen up. Something sound wrong for her for main bolts.
 
When you complete the installation, would you please post fotos and part numbers? I have a Kevko oil pan and need to brace the oil pickup on a main cap bolt also.
 
I sorta get the feeling that the convex washers are going under the small tray screws. If that's right then the washers go on like upside down saucers; the smaller contact side against the screw-heads. They always go on that way no matter the application.
Washers for main bolts or headbolts should be flat and hardened. The factory main bolts AFAIK, do not have washers, at least I have never seen washers on any engines I have torn down, including 340s.
If you flip the stockers over and look under the heads, you will find a raised circular area there, that prevents the hex-corners from digging in.
If you have received new mainbolts with washers, they will need to be correspondingly longer to maintain the thread-engagement in the block, like of the stockers.

Hardened washers are usually bluish in color, and will resist being scratched by a small file. I install them, smooth side under the head, except on aluminum; then smooth next to the aluminum, unless the bolts have the raised circular areas, then smooth under the heads .
Washers are usually stamped, so the side the punch comes down on will have downward curved edges; this is the smooth side. The underside will have a sharp perimeter that digs into aluminum. I usually rub it off on Emery paper; then it's smooth side under the head again, filed side against the aluminum.
 
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I was disappointed to find my aftermarket head bolts (with washers) were not longer than factory bolts to compensate for the washer thickness.
 
AJ/FormS said:
I sorta get the feeling that the convex washers are going under the small tray screws. If that's right then the washers go on like upside down saucers; the smaller contact side against the screw-heads. They always go on that way no matter the application.
Washers for main bolts or headbolts should be flat and hardened. The factory main bolts AFAIK, do not have washers, at least I have never seen washers on any engines I have torn down, including 340s.
If you flip the stockers over and look under the heads, you will find a raised circular area there, that prevents the hex-corners from digging in.
If you have received new mainbolts with washers, they will need to be correspondingly longer to maintain the thread-engagement in the block, like of the stockers.

Hardened washers are usually bluish in color, and will resist being scratched by a small file. I install them, smooth side under the head, except on aluminum; then smooth next to the aluminum, unless the bolts have the raised circular areas, then smooth under the heads .
Washers are usually stamped, so the side the punch comes down on will have downward curved edges; this is the smooth side. The underside will have a sharp perimeter that digs into aluminum. I usually rub it off on Emery paper; then it's smooth side under the head again, filed side against the aluminum.
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I've never seen washers used with the stock main cap bolts either. They are listed as Mopar performance bolts. I don't know who makes bolts for Mopar or if these are even the real deal. They are sold as such and they come in a Chrysler plastic bag. The washers are large-diameter, they fit loosely under the bolts. They're too large to set under the small bolt head at the top, the small bolt up top falls right through the center of the washer. Later today I will be able to put them side-by-side the bolts that came in the motor originally. They don't look anything like ARP bolts and they don't look like factory bolts either. I was wondering if anybody had used this package before and seen this. They seem to be sold as replacement high performance 340 windage tray attachment bolts. Mancini racing has zero knowledge of them even though they sell them. I'll take pictures of them later today an attempt to post them. Hopefully somebody has seen this before. Maybe someone has a line on actual 340 bolts?
 
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Trying to upload photos. Sorry about the duplicates. I'll upload a couple more. I apologize for not getting this posted correctly. More pictures coming.
 
I wouldn’t use washers. You want the entire boss on the grip of each bolt to make contact with as much of the cap as possible. And like you said, they didn’t make the bolt longer for the washers.
 
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You see those raised areas I spoke of under the heads? That is your pressure distributor.If your washer does not fit tight to the shank under the head next to that pressure pad, Do Not use them in any case no matter their shape.
Clean out the threads in the block and screw down the bolts by hand, every one of them, and make sure the exposed length of the bolts is less than the height of your maincaps. If they are not, then the bolts are too long. If they are more than, (I'm guessing) ~1/4 shorter , then they may be too short.
The top expanded portion of the bolt, under the head, is to align the caps to the block, therefore the fit should be fairly close; snug but not tight.
I'm kindof leaning on; for peace of mind, I would order up a set of ARPs. I got too much invested in my engine to gamble it all on unknown mainbolts
 
Yes it is a big investment. I have no peace of mind with these main cap bolts. For some reason I keep thinking they're imposters, they're not Mopar. If I did run them I would run them without the washers. The length is approximately the same.

The problem I ran into when this first became an issue is that I can find no other bolts that have the extended area on the end of the head to mount a windage tray or a oil pump pickup with the exception of a Ford bolt that torques to a different spec.

There is a ARP bolt for a 351 Cleveland that seems to be exactly the same size. But it torques to 100 foot pounds with ARP grease on the threads. That's a long way from 85 foot pounds with oil on the threads. ARP said to torque it to to the same spec as the stock bolts...

The only other thing I can find are studs. I can almost guarantee that pull my block out of alignment and then I'll have to line bore it. That's not possible at this point. So I'm still looking for factory bolts such as a original 340 main cap bolt or the high performance 360s from the 70s that had the windage tray. I've been looking for months now no luck so far. Not that I would trust it, but does anybody out there think that from the pictures those are actually Mopar performance bolts?
 
I would call Maurer Performance in Tempe Az. He is an expert on small blocks and May even have some stock bolts. Dennis Maurer. Been workin on em for 40 years. He has a 72 Duster, and I saw him run 10.74 in Denver, with a 408. We were racing at Bandimere.
 
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Garys72Duster said:
I would call Maurer Performance in Tempe Az. He is an expert on small blocks and May even have some stock bolts. Dennis Maurer. Been workin on em for 40 years. He has a 72 Duster, and I saw him run 10.74 in Denver, with a 408. We were racing at Bandimere.
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I`d install them and torque them to what is directed and not look back-------
no washers.
 
Overthinking this.
New bolts with/without washers.
That washer thickness doesent change the length of thread grip so its irrelevant. Mopar bolts in a mopar package, i dont see an issue.
 
famous bob said:
I`d install them and torque them to what is directed and not look back-------
no washers.
Click to expand...
This is what I would prob do, too. Use the stock factory torque specs. Those factory bolts are extra large, and we'll suited for the job. Have you ever compared them to a small block Chevy cap bolt? They are HUGE! Plenty strong. If you're still worried about it, call Dennis.
 
Don't see anything wrong with the bolts in the pictures, they appear to be the right ones. Torque em to 85 and go ahead with the build. You'll be OK.
 
Those are definitely the replacement main cap bolts for use with a windage tray. I used a set in a 330-horse 360 which I put 25k miles on over 6 years and plenty of passes down the drag strip. Recently swapped them over to a Magnum block. I purchased them from Mancini back in 2010 IIRC.

Don't use the washers just put them in and torque to spec. You notice how much bigger these bolts are than a Chevy or Ford? That's the reason you don't see 4-bolt main conversions or block girdles on all the hot SBMs like you do the other stuff.
 
I thank everyone that has helped me here. The people on this forum have an incredible amount of knowledge. After reading all of your replies I feel much more confident in this engine build. I know I'll have more questions on the build but I'm starting to gain some confidence with all of the help. You guys are correct in telling me not to overthink this. I have learned in the past that that can create new sets of problems and I'm glad you have reminded me of that. You're right, the Mopar bolts are a lot bigger than small-block chevy bolts. I have to get out of my thinking about this as if it was a small block chevy. Thank you for the information on who to call. I'm gaining confidence.
 
Do not use the washers for 340 and 360. They are for use on 273's and 318's to get the right thread engagement and windage tray position since the main caps are "shorter". The washers are hardened and the concave side goes toward the cap for the 273 and 318 only. 2 washers per bolt as I remember.
 
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