Great find on the Chicago, Bill. You're one lucky guy! If you are going to keep the cast iron pistons and if the grooves are wider than 1/8, I would suggest at least putting two modern rings in the top and bottom grooves --2 3/32'' in 3/16''groove (or 2 1/8'' if quarter inch grooves) do this on the top groove, and also two oil rings in bottom. Leave any other grooves empty. In any event, spring for a set of new rings. Are the CI pistons the ''skeleton'' type? They are lighter than the full skirt type, used earlier Herb.
Herb, No, they are the early full skirt... I do have some later skeleton type spares though... may have to do some diggin' in the parts boxes to see if I have a matching set! If I do add a disc to the top of the pistons, how tall and wide would you recommend? I'm really excited about the Chicago- it really sets the build off nicely! Hoping to get together with Stevie G and get his students working on the spacer and sleeve, as well as some other class projects
Bill Had this all typed out, then lost it. Damn this system! There were cast iron truck pistons that were cataloged as ''low compression-truck'' Don't know how to tell them from std. car pistons, without having one of each, side by side. Anything that you add to the piston is going to increase the already heavy weight. so I wouldn't go over a 3/8'' disk, about a sixteenth less than the piston head diameter. Keep the revs down--the Chicago will help with this IF you have the low rpm HP to pull the car at speed. If you can tell me how far the top of your pistons are when they stop at top dead center, I can tell you more. Herb, who hates computer programs
Oh, That Herb. This discussion is interesting. This is how our forerodders did it back when low rpms could be a good thing.
Okay, just popped back in from the oven, errr... I mean the garage (it's 10pm and the garage is 90+ degrees). Anyway, the pistons are: 3 11/16" wide 3 5/8" tall the wrist pin center line is 1 7/8" from the top rings are 3/16" the top ring groove is 1/8" from the top looks like I have 1" of space at TDC Doug, I was wondering about aluminum as well- if I allowed for the increased expansion. Trying to remember if I have any stock aluminum pistons, then it wouldn't be an issue And the Victory is still in focus- picked up a pair of Carter BB1's at Brad's last swap for $25. One was filled with water/rust and is pretty much junk, but the other is pretty darn clean AND found a Stromberg UX2 with a cast iron top for parts, so if I can find a good U2 base, I might be able to come up with a legit stock carb!
Bill why dont you throw Ford Model A pistons in the block - or if your worried out boring it too much chevrolet 261 pistons are an easy fit and gives higher compression. I picked up a set of nos standard 261 pistons that i intend using. Herb as mentioned this before. The Model A pistons are much lighter and readily available. Kume
Thought about A pistons or 261's, but for time's sake (and cash is getting tight), I didn't want to bore out the block. This thing is supposed to be back together and running/rolling by Sept 1, and with marching band season starting back up (first game is tomorrow night), time is fleeting.
Bill, Doug, and others. I put aluminum disks on top of the cast iron pistons in the infamous John Deere tractor that is still running (for some reason)--sorry if I inferred cast iron disks. Doug--While 7075 is the strongest of the non aero-space aluminums, were you aware that above somewhere around 500*f (not sure about the exact temperature) 2024 is stronger? Strength of 7075 falls off dramatically at elevated temperatures, but below 200*f or so it is great for structural parts. Like 2024, it should not be welded. While they can be stuck together with weld, what you are doing is two things--first, the welding wire is changing the composition of the joint, so the basic metal in that area isn't as strong, and second, you are destroying the heat treating, where some of the strength comes from--and you can't re-heat treat as the joint isn't 2024 (or 7075) anymore (reason number one again) In any event, what I used was probably good old versatile 6061. Always have some of that around, and would be easier for Bill to source, I have thought at times in the past about making steel pistons -- Ford put them for a year or so in the pre 49 flathead V/8, when he was having a pissing match with the aluminum manufactures. A .090'' steel sheet top, pressed into a dome, for strength, welded to a minimal steel machined ring belt, with a couple supports for thin bronze wrist pin bushings, then a .063 steel skirt. Never did the numbers, but I suspect that a steel one could actually made lighter than a stock aluminum one, with a little playing around. The compressive force of combustion is in the head, and transfered to the wrist pin. In comparison, the skirt is just along for the ride---especially with the long rods that the C4 has. I think that Ford returned to aluminum, because he forced the Alum people to accept his price. Cost of fabrication (never saw a drawing) and heat transfer were against the steel, but obviously it worked My clock is running down, so this is one more idea that I will never get around to. Herb
If there is any man who I have ever met with more kick, spunk, and grit in him, it's you Herb! So 6061 it is, 1/16" less than the top diameter, and 3/8" thick. Now as far as how to attach them, I'm guessing a pair of countersunk bolts with lock washers, nuts (all spaced and measured/weighed for balance), and heavy-duty loctite?
Herb, I did NOT know 2024 is stronger around heat. I did know about welding both flavors though. McMaster Carr would have plenty of 6061 by the foot, look in the index under compression enhancers. Another question, would steel fasteners cause hot spots?
Herb, Thanks for sharing this stuff with us. Bill thanks for trying it. And thanks to the rest of you for keeping this going. This is a really informative thread. Is what Herb said true for all aluminum welding? Not that I can weld aluminum.
I think with a light top end ( you are running aluminum pistons correct? I didn't see it mentioned), a heavy flywheel (add some weight?) and some decent induction....it will pull the Chicago. The Mark-E Chicago is an Under, Direct and Over box....so by the time you run it up through the gears high enough to get into overdrive....it'll be movin'. You could probably split your shifts too Mac: Chevy 1st, Chicago low (1st) Chevy 2nd, Chicago Low (2nd) Chevy 1st, Chicago Direct (3rd) Chevy 2nd, Chicago Direct (4th) Chevy 2nd, Chicago Over (5th) Chevy 3rd, Chicago Over (6th) Now.....if you put a Ruckstell in it......you'd have 12 Speeds...
Clayton, Too many choices for me!! I'm a coffee (instead of chocolate) and vanilla kind of guy, and probably would coast to a stop at the side of the road wondering what sticks to move what way next ;>) Bill, thanks for the kind words--I owe you a milkshake at JJ's next time you are up North. Don't use hardware store store bolts. Get some flat head ''Allen'' (with holes for a hexagon key in the head --for those not familiar with the name Allen), and all metal locking nuts. Loctite looses it's strength at high temperatures. I would use four 1/4'' per piston, and be sure to space them so that you can get a socket on the nuts around the wrist (gudgeon) pin. Allen screws equal, or exceed ''grade 8'' rating--as long as not Chinese. Get from McMaster. Doug. Using flat head bolts cuts down on the chance of hot spots--although as with all of this wacko stuff I come up with it's a possibility. All I can say is that it worked for me, albeit with a tractor engine that I ran for years at full load. When will you guys come visit again? Six Ball All of the other aluminum that you find in bar stock can be welded, as is the case with most cast aluminum. The exception is an alloy that has magnesium in it--air cooled VW and Porsche crancases, and some lawnmower decks-- and they can with a special filler rod. Herb[/QUOTE]
Herb, I was thinking today, dangerous I know. I found heat treated aluminum flathead rivets in McMaster catalog. I wonder if they would work? And I'm a Ready Freddie to come visit, just need an open weekend. Clayton, that sounds like a Mack!!
That's how my T is too now, with the Ruckstell. T low, Chicago low (1st) T low, Chicago Direct (2nd) T high, Chicago Low (3rd) T high, Chicago Direct (4th) T high, Chicago Overdrive (5th) Then, you have Ruckstell Low (4.60:1) and High (3:1)...and you can use that to split your shifts again... In between each.
Doug To Properly use heat treated aluminum rivets, they must be annealed (heated) and then used promptly --within hours. The alloys then ''age harden'', If driven in the hard condition, they tend to crack, and not ''head over'' correctly. I think that you would have to use a whole bunch because they would soften to some degree when the engine was running hard. Since I brought up the steel piston idea--by coincidence this is a portion of a post by Jonto, in the ''Auto Racing -1894--1944'' Forum, today. ''Steel pistons machined from the solid billet, as was the usual Sunbeam practice, were fitted". (A S Heal).'' Talking about a 1913 Sunbeam, built to race at Indy Love to see a drawing, or even a photo of those suckers. I'm ready ---let me know Herb
Hey, Herb; Been following this thread, (& thanks for your input/info) on bangers, & while I don't have one (may soon end up w/a couple of ~'17 Stude 6 flatties - but those have the heads cast w/the block/cyl package), I'm curious about a few things/ideas. Since it seems that almost all of the chambers ( I'm talking about the OHV-type heads here, although it partially applies to flatties too) back in the teens->30s were open chamber-style, & that there is such a large piston-to-head distance, & you can bolt a spacer disc to the piston top for more compression, - which I'm guessing is limited by the engines' bearings & crank strength, is there any reason that you couldn't use a different shape than a flat disc for the now-new-piston-combustion-surface? Say, like a 'U' , or an 'L' (looking at it from the side). I'm guessing it'd best be cast/machined or fully machined for accuracy, but doable as a hobby project, even as hand-made. What I'd be looking to accomplish: would be to create 'squish' more than just addition to compression. Of course it'd have to be orientated & clearanced for the valves, etc. I realize that the 'L' top may very well introduce uneven piston-weight distribution, as would the 'U' if both sides were not even, but I suppose an additional bolt or two could be used to offset that. Which might make the piston kinda heavy, but I don't suppose that these things will be hitting 8k rpm any time soon. The other goal w/the squish/turbulence, is that the increased compression will (should) run on less octane, as proper squish = artificial octane (& I realize that this only works so far... ), which should help the spindly cranks live through less detonation issues. I have to assume that this has been done multiple time already, just haven't found any examples of it, pro or con. [& of course, there's always the Singh Grooves concept if the squish clearances are kept ~ .100", but that might be harder to implement - although they should work on the piston-top as well as in the head. If they don't work in this application, at least in the piston-top, those could be replaced easily]. Something to think about, although not traditional - but speed 'tricks' are... . Thoughts? Marcus...
Of course high compression pistons come with big bumps located in the chamber area. So the piston-weight distribution wouldn't seem to be a problem. I can not see why you couldn't bolt on a shaped filler as well as a round one.
Hmmm- No theoretical reason I can think of, except that the hump would have to be a lot higher than we are used to seeing. The last set of pistons in my avatar car were extensively modified GMC 270's, but as I recall they stopped 3/16'' or so below the head, so provided no squish. Had to do some gnawing away at the domes with the mill to insure that the valve heads would clear if they floated Sold the car shortly after this improvement (?) (needed $) was made, so can't really comment on performance. Some caclkalatin could be done to come up with a disk height/hump height, to possibly come up with a means to get some squish, but two things should be kept in mind. One, the hump wants to be opposite the spark plug (Gee really?) and, Two, the hump is going to end up pretty narrow--more so in my case, as my head had the maximum valve size that I could squeeze in, to miss the valves --the valve heads protrude from the C4 head by the valve head thickness--so how much mixture is going to get squished out is limited. Any would be better than none however. Tried the Singh grooves in an expendable, but rebuilt flathead---didn't make a damn bit of difference that I could tell. Thanks for your interest, Marcus. Herb
Below is a pic of one of Chris Egsgaard's T hill climb engines- so the high sides are a possibility and have been proven to work The engine is at a local shop getting hot-tanked, a quick honing, and one broken water pump bolt removed. Herb, I'm trying to remember what valves to get- were they Ford 223?
Bill- Took me a while to dig out my notebook on the C4 build Here is what I used- Intake- Sealed Power V1932 69-78 Ford 302, 351 Windsor Exhaust- SP 1823 '68 350 Pontiac with 4 bbl carb '70 400 '' with 4 bbl carb ''69 428 '' Largest that will practically fit, with 3 3/4' bore, both require machine work on stem. Herb
A nice 490 speedster down in God's own. The long bonnet gives it a great side profile and improved leg room.
Another NZ 490. I think this is the Dennis Belch speedster now residing in the US. The last time I spoke to Dennis he was designing another Chev 4 speedster with billet crank in a 25 block. Hope he is still out there.
Kume, those pics are fantastic!!! Looks like the spring pockets are flipped on the last pic- what I'd really like to do Herb, thanks again for the info!
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