Matt Wilson

I'm afraid I'd crater my engine if I ran at those speeds and power levels.

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FYI - I added a little more info to my original post for clarification.

Good Sunday to all of you. I've seen several mentions of a 50-hour test that Chrysler used to conduct on its engines. It's been said that such testing is mentioned in a particular book written a couple decades ago (I think?). To those who have read that book, does it say in what era this testing took place? By that, I mean, do we know that flathead sixes of the design used in our vehicles underwent such testing? I see discussions that make me think so (certainly the people posting the info think so), but I'm wondering if the book was that specific as to state the era when such testing was done. Has anyone ever run across any examples of this data, or a source that provides any kind of detailed description of the test and its outcomes? Maybe that book provides some detail. I'm sort of a junkie for this kind of information and would find it interesting if anyone can offer up anything. I found info online from a Chrysler engineer who said that the next generation (overhead valve) engines in the 60s were being tested under a graduated schedule consisting of 10 hours at 800 rpm, followed by 10 hours at 1600 rpm, then 10 hours at 2400 rpm, 10 hours at 3200, 10 hours at 3600, then 9 hours at 4000, and finally 1 hour at 4400 rpm, all at wide open throttle, which adds up to 60 hours. I'm wondering if the 50-hour test was similarly conducted on an rpm schedule, or at 3600 rpm continuously, as is often mentioned here. EDIT: After a little more reading, it turns out the article discussing this test schedule was related to the development of the hemi-six engines, and testing took place circa 1966. Not sure if they tested all development engines in that manner during that era, or if this was something specific to the hemi-six. Thanks for any insight into this that you guys can provide.

Wow, that looks fabulous! Right at home in the bay!

Ok, I have an update. This past Wednesday evening, I decided to give it a little go, by just trying the worst-looking stud. It was the rear-most stud. I turned the engine on its side (on the engine stand), took a pair of nuts, tightened them against each other and began applying some force with an open-end wrench on the bottom nut, in the loosening direction. At first, the nuts just turned on the stud, so I tightened up the nuts about as hard as I felt comfortable without stripping them. Then it was back at it with the wrench on the lower nut. To my surprise, the stud started to turn. I kept at it until I thought I could grip it with my vice-grips (not clamped down, but just using them like an ordinary pair of pliers) and I did this until the stud was out. Ok, I said, that went well....let's try another one. So I moved on to the next one and did the same thing. After the third or fourth one, I stopped using the two nuts and just used the vice-grips to get a very firm grip on the studs and removed them that way. Unbelievably, they all came out that way in less than an hour, except for the final one, which was the front-most one. I worked on that one for a little while, spraying penetrating oil and tapping with a brass mallet, grabbing with vice-grips, double-nutting it, etc., and it didn't budge. So....I let it sit with penetrating oil for a couple of days, till just a few minutes ago, when I went out there and tapped on it some more (actually several fairly sharp raps in all directions), then did the double-nut thing with the open-end wrench AND the vice-grips clamped down really tightly, placed 180 degrees opposite the wrench. I grabbed the wrench with one hand and vice-grips with the other and applied quite a bit of force to each. I was a little afraid I was getting close to the point where the stud could twist off, so was about to give up and try some heat, when.....voila!....the stud started to turn. So I kept at this until it was removed, though it fought me most of the way. But in the end, I prevailed. Now I have a nice, stud-free manifold mating surface. I'm glad I went ahead and did this. It was really a pretty small effort. I think I will now try to clean up the surface with a few light file strokes, or maybe a very brief/light sanding with my Black and Decker Mouse (which is a small orbital type of sander, I guess you'd say), as the manifold surface looks somewhat pitted. I suppose I could even take it back to my machinist and have him surface that region to get it really good, but not sure if need to do that and I'd prefer to avoid it if possible. Following that, I will clean out the threaded holes with a thread chaser, and spray the holes nice and clean with brake parts cleaner and install new studs with sealant or maybe anti-seize as suggested by MB Fowler in his post above. Thanks to everyone for the tips and more importantly for giving me the nudge to proceed with this. I was afraid it would going to turn into a nightmare, but it worked out amazingly well. I know it doesn't work out this way a lot of times, but I suppose I got lucky. I guess I was due, considering the trouble I've had with other areas of the project, LOL.

Not sure where you sourced your head gasket. Maybe you mentioned on a prior page. The gasket manufacturer should tell you whether or not you should apply a sealant/spray or not, and if so, what kind. My gasket set came from Best Gaskets, and their website recommends use of copper spray, at least for the gaskets that have a copper sheet on both sides, like mine. In general, though, I tend to think that a little copper spray is good for most head gaskets.

The new machinist said he uses a ball-type burnisher. The saw blade marks are at the bottom of the bore, where the force is large, but they are so narrow that I'm not concerned. Also, they don't go the whole length of the bore. Rather, they are restricted to the ends of the bores. At least half of the bore length (probably more) does not have any saw markings. I purposely avoided making cuts along the sides of the bores because this is where the metal sees the highest tensile stress when the piston reaches TDC on the exhaust stroke, and I see saw cuts as the perfect way to introduce stress risers that can produce fatigue cracks. My previous machinist had also made his cut on the bottom of the bore, although he is a bit more skilled than I, so his cuts are a bit shallower. The bushings I can purchase from Sealed Power are all solid bronze with no steel backing. This is the case whether I purchase standard sized bushings or oversize ones (despite advertisements that say they are steel-backed). I'm not set on steel-backed bushings at all. In fact, I like the idea of using the bronze ones because my new machinist says he'll burnish them, which he won't do if they are steel-backed. I'll just have to consult with him about options for getting a bushing that will fit that one rod, or even making one.

Sure, here you go! www.hudsonjet.hetclub.org/hudsonjetengine.html It's interesting to note that this page says the bushings should be pressed out, but my previous machinist said this can often lead to problems because the thin-walled bushings most engines use can easily become cocked in their bores and cause damage on the way out. He thinks that's what happened to the one rod of mine. He prefers to use a hacksaw blade and carefully slice through the bushing and then it is easy to remove. I did that with the remaining bushings after I picked up the rods from him. It was a little work, but not bad. I did leave small hacksaw marks in the the bores of the rods, but they are small enough that I'm not worried. In the one rod bore that was damaged, I took measurements using a telescoping gage and an outside mic, and the damaged area appears to be about 0.010" oversize or more (0.9326" in the damaged area vs about 0.9314" in the undamaged regions). The damage covers about half the length of the bore and about half of the circumference of that portion of the bore. It looks like even the oversize bushings won't be large enough to make up for that much damage, as they are only intended for a 0.0055" oversize. I'm guessing my new machinist will have to try to find a bushing from a different application to adapt to that rod. I hope he's able to find such a thing. If not, then I'll have to go hunting for a replacement 265 rod, and they are not easy to find.

Aah, yes, I've seen that video. Didn't make the connection that this was the same car I was talking about in my post above.

I agree, he is fortunate to be able to do what he does. I wasn't entirely sure how much he was doing these days. I only know that one time when I spoke to him a year or two ago, he was still doing some of that. He mentioned having just completed a race engine for a younger guy in his seventies - a 230 for a vintage race car. When I spoke to him last Friday, I didn't ask him how much engine building he was doing. Apparently he's still doing carbs, manifolds and cams, as he asked me if I needed any.

I think George Asche still build engines for guys who race them. Tim Kingsbury may actually be racing sometimes.

Ok, I think I'm starting to get convinced to at least try replacing those couple of corroded studs. Depending on how those go, I my tey my hand at the others. Good idea on the welding. I have a welder. I've also heard of a technique whereby you heat up the area around the stud and hold a candle or other wax item up to the base of the stud and if you have heated the area enough, but not too much, the wax will wick into the microscopic gaps between the stud and the parent part (in this case the block). The wax provides lubrication to allow the stud to come out when no other technique will work. Some guys swear by this technique. It's also reported to work for removing other types of corroded threaded fasteners.

Sometimes people true up the surfaces on the intake and exhaust manifolds themselves. Not sure about the surfaces on the block where the manifolds mount. If you did that, it would of course require removal of the studs. The crankshaft main bearing bores/saddles occasionally require line boring to get them all to line up with each other, but that's not a must on every engine. It just depends on the condition of those bores. I don't know of any other surfaces on the block that are routinely machined (aside from things you probably already know about, such as cylinders, valve seats, etc.). If a gasket surface, such as the ones you mentioned, is damaged, of course the shop can machine it to correct the issue, assuming it's not too badly damaged. There is another thread on this site (can't recall which thread), where the gentleman describes having to braze some damage (maybe a crack?) to the thermostat housing mating surface on the top of the head, and his shop machined it nice and flat again.

Compression ratio varied for all engines over the years, but if we take a smaller engine and a larger engine having the same compression ratio as each other, then the larger engine will see a bump in compression when the smaller engine's head is installed onto the larger engine. For example, if we take a 7:1 218 head (25" engine) and put it on a larger 25" engine that also had a 7:1 ratio with its own head, the result will be a higher compression ratio. Of course, you also have to take into account any milling of the head that may have been done over the years. I'm using the head off a 251 that came out of an early 60s Power Wagon and putting it on my 265. The manuals say the stock compression ratio for that 251 in the Power Wagon was 7.2:1. When I cc'd the combustion chambers and ran the calculations, I came up with 7.2:1 for that 251, so that all made sense (for this reason and others, I believe that engine had never been rebuilt, by the way.) I then ran the numbers for that head on a 265 and got about 7.75:1. I don't recall if that included boring the block oversize or not, which would have the effect of raising the compression a bit more. Of course, now I've since had the head milled just enough to make the gasket surface flat again, which was about 0.015", and I cc'd the chambers again, but have not run the numbers on compression ratio yet. However, the cc numbers didnt change much (I think they went from around 98cc each before milling to about 94 or 96cc after milling - going by memory), so I expect the increase in compression to be mild, which is what I wanted. I suspect it'll be about 8:1 now, and I don't want it to be up much higher than that. I also had the block decked, but I haven't taken the effect of that into account yet. I doubt it'll be much .

I'm not particularly worried about new ones leaking. I'm more concerned about old ones leaking if I don't replace them. As for snapping off later, most of them look almost new, so I doubt that's an issue on those, but a couple look a little worse, so could be an issue for those. I just don't want to break any off while I'm replacing them when it might not even be necessary to replace them. That would make a bunch of work for sure. I appreciate all the replies. Still pondering.... Maybe I'll have time to look at it this weekend.

I spoke to George Asche last Friday and he told me about someone he knew many years ago who got a 265 up to 7200 rpm during turns in races. Stock crank, rods, rod bolts, etc, except the guy had to modify the bearing oiling configuration by cutting grooves in the rod bearing halves and cutting grooves in the main bearing journals (not the main bearings themselves, as they already have grooves, but the main journals). It had some power boosting mods or else the engine wouldn't rev that high, but the engine was capable of taking those revs repeatedly. George also tells a story about cruising from Salt Lake City to Los Angeles in 1953, averaging between 4000 and 4500 rpm for 9 hours straight. Again, there may have been some intake and exhaust mods, but he says it was otherwise stock, and was either a 251 or a 265. He also had a 265 that he routinely took up to 6000 rpm during races, again with power mods, but stock crank, rods, pistons, etc. Maybe not proof, as we're not there to see it ourselves, but I tend to believe George. I've also read about tractor pull competitors using 265s and other Chrysler flatheads and taking them up to 6000 rpm and beyond, with mods of course.

Thanks, guys. Hmmmm.....more food for thought. Most of the studs are in really good visual condition, with very little rust. It's only a couple that have significant rust, but even those don't look terrible. Anyway, I'll be thinking about what you guys said. Much appreciated.

Yes, I pulled the bushings out of a couple of 251 rods that I believe have never been reworked and they were steel-backed. They even had the DPCD logo on the back. Interestingly, I found a Hudson flathead six rebuild page online, and it talks about using steel-backed bushings, but then goes on to say they should be burnished in place using a particular burnishing machine. It looks like it's an original factory set of instructions. This seems to contradict what my new machinist told me the other morning. Oh well, in any case, my bronze bushings will be getting burnished, and that's what matters to me.

I was about to bring up the same point. If dual carbs and dual exhaust didn't make any difference for low and mid-range rpms, Dodge would not have equipped the flatheads in multi-ton trucks with these features.

I'm doing such a conversion right now. The 265 crank and rods will fit into the 251 block. Earlier 251 blocks need to have clearances ground into the very bottom of the block, adjacent to where the oil pan attaches. Later blocks already had these clearances cast into them. I'm not sure what year separates an "early" block from a "later" block. My block is a "later" 251 block from a 1963 Dodge Power Wagon. I don't know what the crank and rods came out of. I managed to buy them from a salvage yard out of state, and they shipped them to me. All other parts are interchangeable. Be aware that things like timing chains and gears, and pistons (number of rings) and valves (sodium-cooled vs. ordinary), and thermostat housings, can vary across year models or when crossing over from commercial to industrial engines, but not because of any difference between 251 and 265 engines. Some or all of these differences can be seen between two 251s. Using the 251 head on a 265 setup will give a decent bump in compression ratio. On my setup, the crankshaft rear flange bolts right up to the flywheel from my 230, but I'm not sure if they are all interchangeable like this. The rear engine bolt pattern is the same across all flathead sixes. The same water pump will fit, too. Be aware that some blocks have the fuel pump opening near the front and others have it near the rear. Others may be able to add more about this. Good luck!

Thanks, Jan. Believe me, I know about doing things twice, and I hate it. When you mentioned not having problems with leaking studs, are you talking about studs you've installed? I'm talking about having leaks with studs that I haven't replaced. Not sure if leaving the original studs is a known problem area for these engines, in terms of leakage.

Got an update. I called a couple of other machinists and they couldn't tell me how much interference there should be. I even found a copy of a 2006 edition of the AERA connecting rod manual, and while it provides this kind of info for some engines, it doesn't for our flatheads. I then called Sealed Power yesterday and they told me the bushings need to be installed with about 0.004 - 0.0045" of press fit. I thought the rep didn't know what he was talking about and so did my machinist. That sounds like a ludicrous amount of interference. So I dropped into another machine shop - a big outfit - and talked to their head machinist, who has been doing engine machine work for 40 years, and he said that was about right for bronze bushings, which is what these are. I thought they were going to be steel-backed bronze, based on the description on NAPA's website, but they are bronze all the way through. I know this because I got a hold of three different parts (three different part numbers - one standard outside diameter and two different oversizes) and looked at the parts myself, and they are bronze. Anyway, the machinist said if the interference is only 0.0015" or so, which is what I was thinking, then the bushings will "fall" out. He also said burnishing them to expand them out against the rod bore is the best way to do it, but not many shops have the setup to do this, but he does. He also said such a large press fit is not needed for steel bushings, nor is burnishing. I got the impression from him that steel bushings only need about 0.002" interference, bit I'm not sure how accurate that is.Further confirmation of the tight press fit for bronze bushings is the fact that when I measured the three different bushings I got a hold of, the ODs were all 0.004 - 0.005" larger than advertised online (again by NAPA as well as other sources). I guess when the OD is stated, they mean the final installed OD, which is essentially the size of the rod ID, but that was not clear from the specs they provided. I think I'm starting to understand how this works, though.Since the machinist I spoke to this morning really seemed to know what he was talking about, I went and picked up my rods from my previous machinist and am planning to take them to this new guy.I'm posting this in hopes it will help someone else at some point, maybe even me

Yeah, I have a thread chaser I can use on them and maybe I'll leave them. I guess I was mainly trying to get a feel for people's experiences with leaving the existing studs and then having them leak later on. I figured now would be the time to replace them if leaving them would pose a significant risk of leakage. But I also don't want to have issues with studs breaking, etc.

Thanks, I will certainly do that.