dhughens

Looking for used 230 rods with the oil hole on top rather than slots cut into top. Need one odd and one even but would consider any amount. Thanks for taking the time to read this, dan...

I speculate that pre ww2 bolts were more likely to be cut but with the advancements in the military equipment, i.e. planes, etc, stronger threaded fasteners were needed. Just a thought. dan...

When I take the rods in for resizing with "rolled thread" bolts, I am going to ask if the reaming can have an outward bias. Don't know if this is possible. MATT, I hope you saw that you nailed the problem. Isn't it odd that no one has ever mentioned this situation? dan...

That is a very reasonable answer. I have some smallblock dodge ARP rod bolts and just like the pontiac bolts, they also will not go into the 218 holes. I would appreciate your efforts in measuring your flathead rod bolts to compare numbers when you get the time. Thank you and anyone else who has early flathead dodge rods available to measure the rod bolts. This seems like a plausible answer. WELL AS A MATTER OF FACT: You are the man of the hour. I just went out to the garage with my nut/bolt gauge and also a 3/8-24 standard bolt with nut and amazingly so, they fit the Dodge rod hole, rod bolt, and nut exactly. Additionally, the pontiac and ARP bolt will not thread onto the nut/bolt gauge or the 3/8-24 bolt and nut. We have a winner!! Sorry, no chicken dinner. But many thanks for the solution. I never would have thought in that direction. Now it's a matter of if the rod and cap will take a reaming without interfering with the bearing. Thanks again for all the responses and especially the solution. It does seem odd that in all the builds online, no one mentions this. Thanks again all. dan...

That's a reasonable thought except the existing 218 bolts are snug in the rod and cap holes. I absolutely cannot put a standard 3/8-24 rod bolt into the 218 rod or cap. ( I could problably smash them in and destroy the threads in the process. ) The 218 hole diameter is too small for a 3/8-24 bolt. Attached is a pic of the two bolts. Best harbor freight caliper dimension of hole in Pontiac rod cap with 3/8 bolt is .384. Best harbor freight caliper dimension of hole in Dodge 218 rod cap is .370. Doesn't make any sense.

Thank you both for responding and your suggestions. I spoke with vintagepowerwagons earlier and they referred me to Tony Smith at moparmontana.com. I've sent moparmontana this same question and am waiting for a response if possible. I could put stock rod bolts back in but as was said, it doesn't explain what it going on. It's almost as if the bolt thread is between 11/32 and 3/8 which is not possible. We certainly wouldn't have used Whitworth thread and there was no such thing as metric here at that time. I've spent a lot of time online searching this issue and see absolutely no other mention of an odd rod bolt fit. I've downloaded Chrysler and Plymouth service manuals of the 40's and 50's and nothing there. I've downloaded Dodge flathead builds and nothing is mentioned, although I've seen torque specs which refer to the rod bolts as 3/8-24. If the rod bolt holes were larger diameter or the rods came from a single source, something could be inferred but neither is the case. Somewhere in all the performance flathead builds, someone must have installed ARP, Pioneer, or other aftermarket rod bolts and encountered this. I mean, Spitfire flatheads ran hard in the past circle track days. I simply cannot find a single mention of my rod bolt diameter issue. It is not possible that I am the only guy in the entire Mopar world in some 75+ years of flathead sixes who has encountered this situation. Anybody else curious or have some input? dan

I am doing a project with a Pontiac 268 straight8 using Dodge 218 rods for the extra length. The rods allow me to use a slant six piston which has the appropriate compression height. I acquired the rods which were all supposed to be resized, however the rod bolt threads were awful. No big deal, I want better rod bolts in them anyway. so just match up a set of 3/8-24 rod bolts with the right length and there we are. Well, here comes the issue: the 218 rod bolts seem to be @.015" smaller diameter than they should be. I have 3/8-24 rod bolts from the pontiac and the nut will go on the 218 rod bolt, although it is really, really, sloppy. However, the 218 rod nut will not go on the 3/8-24 rod bolt from the pontiac. If I measure the thread outside diameter on the pontiac rod bolt it is @.380. When I measure the 218 bolt outside thread diameter, it is @.363 (this is in a good thread area). The pontiac rod bolt shank is @.382 and the dodge rod bolt shank is @.368. I have 9 Dodge rods and they all measure the same. The rod part number is 617925. The pontiac 3/8-24 rod bolts will not go into the dodge rods. If it matters, these rods are the lock washer type rod bolts if it matters. Does any of this make sense? Is there something odd about the rod bolts used in the Dodge 218? I would typically have the rod bolt holes reamed for a 3/8 rod bolt but the holes are so close to the bearing, I think it could put pressure on the side of the bearing. dan...