I'm rebuilding a 1927 Chevy engine, the first early Chevy I've worked on. I've had the cam re-reground through the filling station, who apparently sent it to Oregon Camshaft. But I'm still not sure what to do about the lifters. I've machined a test lifter and have experimented with different grinds to "radius" the end of the lifter. In reality I'm actually grinding the lifter to a very shallow point (using a lathe with a grinding attachment) pretty similar to how a purpose built tappet grinding machine usually works. The small diameter of the lifter is causing great difficulty in this. If I grind the lifter with a shallow angle that would facilitate rotation it digs into the camshaft on the ramp up and ramp down. If the grind it with a greater angle then it does't dig into the cam but only touches along a line in the center of the lifter perpendicular to the camshaft. It looks like the lifters were originally ground with a fairly small radius, giving an effect similar to my more aggressive angle. It this original setup it looks like the lifters didn't rotate well and wore the came out very quickly. I don't like the way the lifters are "smaller" than the cam; the OD of the lifter is smaller than the width of the cam. A larger diameter lifter would seemingly solve all my issues. So.... There's enough room between the camshaft and the block for me to fit lifters of the style found in Model Ts and old Briggs, among other engines; lifters shaped something like an intake/exhaust valve. This would let me have a lifter face large enough to eliminate the issues I'm encountering. I see that M2 tool steel is used for some lifters today. I have no experience with M2 but have machined W1. Does anyone know if W1 would be suitable for this after its been hardened? Other material Ideas? Or maybe I should research re-grinding the original lifters some more? Perhaps flat in the middle, shallow angle halfway out, and then a steeper angle closer to the edge? I'm open to all ideas. This is a low speed engine with low spring pressures and it won't be driven hard. I'm not worried about the rest of the engine lasting 10K miles or more, but the cam/lifter setup looks like trouble. Thanks in advance for all input.
There's some discussion of 'roll-your-own' lifters in www.jalopyjournal.com/forum/threads/1928-chevy-4cyl-motor.463465/.
SR100, you beat me to it Paul, you might try contacting Herb Kephart (ebtm3)- he has probably done the most successful machining for early C4 engine!
Are your '27 Chevy lifters the same as the '28 ones on a motor I'm rebuilding? -the lifter at the top is the factory item. The one underneath is from any British BMC "A" series motor (Bugeye Sprite, Morris Minor, Classic Mini etc.) it's .020" larger on diameter than the Chevy item. I've reamed the lifter bores to take these lifters and am getting a friend to profile the cam for me. The lifters are available new at a reasonable price (equivalent of $18 for a set of 8 here)
If you have never worked with M2 you won't like it, it sucks. It is very hard and abrasive before it's heat treated, almost impossible to grind after.
Thanks all. SR100/ Mac The Yankee: I've read a good portion of the tread you steered me to, although I've not finished all 70 pages. There seem to be some roller lifter ideas, but I think they only work in the 28 block which is different. But more to to read still!! Stueee: Unfortunately the 27 lifters are much different. Only about 0.608" in diameter. In the picture below the one on the left is a 27 chevy, middle 28 chevy, and right 25 model T, the design I want to copy. NoboD: I was worried M2 might be a challange to machine, its also got a pretty big price tag. I've done some more research into W1 and it doesn't look to good for the lifter use. Although A2 looks somewhat promising and D2 looks even better, I don't know if they will help with the machinability. I still need to do some more research. Right now material/heat treating is my biggest concern with this idea. I'm no metallurgist. Also, just for curiosity's sake. I've always heard that the 28 engines had more valve lift than the earlier engines due to the 1.5 to 1 rockers. The engine I'm working on is a late 27 with the larger 28 size valves but still the 3 port head and 1 to 1 rockers. I also have a 28 engine. Compared to the 28 the 27 cam has higher lift(even before it was ground), but without the 1.5 to 1 rockers it ends up with the same amount of travel at the valves. Did Chevy increase the cam lift in late 27 when the valves changed ? Maybe the issue I have is only unique to a few months worth of "transition" (for lack of a better word) engines?
D2 is not much better to machine then M2, lots of chrome in both. A2 would be my choice as far as machining goes. Look into S7, it's a mold steel, very strong and stable , easy to machine and grind. Does not swell or warp much when heat treated
Hi Paul, Interesting that Chevrolet made so many changes for the final year of production, I've only had '28 engines in bits, so was only aware of the external differences (fully enclosed valve gear dual port head etc.) Are the model "T" lifters you pictured available new? it would surely be worth buying a set and putting some bronze bushes in the '27 lifter bores to make them fit if so. If the "T" lifters aren't available. The British Ford "Kent" engine lifters look very similar to the "T" ones. https://www.burtonpower.com/camshaft-follower-each-711m-type-ford-x-flow-ohv-kent-fp211.html Not so cheap as the BMC ones that I posted earlier, but at least you could be confident of these lifters having the correct heat treatment etc. for the job they need to do.
I think '27/28 must have been an inserting year in the automotive world . Ford dropped the "T" for the "A". It looks like this forced Chevy/Dodge/etc to all spiff up their cars in order to compete. That's my guess as to why the '28 motors are different. Then I'm guessing the '28 motors didn't hold up to the "A" or Chevy wanted to take the initiative and one-up Ford; so they dropped them after just 1 year. Anyway, for maybe someone's benefit, the other internal difference I've noticed are: # 1 main is about 1/8" longer on the '28 over the '27. the crankshaft is the same, the '28 just uses what was a space between the front of the main and the cam gear as more bearing surface. The 28 has a thinner steel plate behind the timing gear, forced this way because the block is a bit longer to make room for the longer #1 main bearing Camshafts are the same length but the '28 has a bigger diameter front journal, maybe middle and rear also, I didn't check. The '27 has a fiber crank timing gear and metal cam gear, the '28 has the reverse of this. (I'm not going to use a fiber gear on either one on re-assembly) I think oil pumps might have been different also, but I'm fairly sure neither of my engines has the original pump. Okay, back to Tappets. New "T" parts are everywhere (and fairly cheap) in the USA. I think if you have a bare block, frame, and rear axle housings, it's possible to buy re-production parts to build the entire rest of the car. The only small issue I see with doing as Stueee said is that that "Ts" are side valve engines and the lifters don't have the cup for the push rod to set in. The lifters come hardened so adding it in would be a challenge. But wait! There were so many overhead valve conversions sold for "Ts" that one can buy new adjustable lifters and new "little things" that replace the adjustable part of the lifter with a cup to accept the push rod. One would have to shorten the push rod slightly. Model T tappets (at least the original ones) are perfectly flat where they meet the cam. I talked with the company that ground my Chevy cam and also measured it myself. the lobes aren't tapered and (from what I'm told) were not tapered when the cam was new either. So it should be okay to use the flat "T"lifters on the flat chevy cam. I personally don't like to do press fits into into cast iron. I'm always afraid I'll be off by .0005 and crack the block. Otherwise I would probably go for Stueee's idea. I've done a fair bit of research into making my own lifters and have decide to roll the dice. I'm going with A2 tool steel for several reasons. D2 or M2 would be better options but have more completed heat treatment processes that I don't have the equipment to do properly. Also there could be machining issues, but if it wasn't for the heat treating I would at least buy a small piece to test machine. For property comparisons I'm using M2 (Since it appears to be the gold standard) and chilled iron(it looks like this was what was used originally) as benchmarks. For chilled iron I've only been able to find hardness data. It looks like for lifter use its usually around 55-62 on the Rockwell C hardness scale. A2 can reach 65. I plan to shoot for 60, as there is a trade off between hardness and brittleness. Using M2 as a standard A2 is actually tougher and is more stable during heat treatment. A2 has about two thirds the wear resistance of M2. I looked into S7 also but decided against it since it only wears about half as good as A2 and is not supposed to be quite as stable during heat treatment. I've also found that some of my original concerns aren't as big of a deal as I thought. The model "T"and many other cars into the '40s (I'm assuming early Chevys) didn't have tapered cam lobes and and domed lifters to create lifter spin. This worked fine for the lower spring pressures and engine speeds. But would be a disaster in a short amount of time in a modern car engines. Using A2 tool steel even though its not as good as M2 should still be overkill for my old chevy.... but time will tell. I've not been able to find anything indicating that A2 won't play nice with my cam material or vise-versa. But I haven't found anything saying it will be good either, so I'm still rolling the dice on this part a bit. I've ordered some A2 steel and plan to make a set of lifters. I'll post back with my results/design/heat tretment/etc.
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