I have read about cars with 292 cubic inch engines using 261 block, but no details on how it was done. I am assuming (we all know what happens when you do that) an off set ground crank to make it a stroker. Special rods, pistons with different pin height? Any insight is appreciated, Thank-You Robert J. Palmer
I believe there was an article on that in an older Inliners Mag. no clue when. check inliners website.
I think the formula includes Cadillac 368 pistons and Chevy 292 rods, and offset grinding the crank. A friend did it yeas ago, so I forget he details...oh, here they are in TRJ 65. Yup, that's right. I'm not sure of the final displacement though
Steve Centracchio's coupe is the one I was thinking of, issue 65 is sold out. I think he is @gear jammer here
How far can you bore a 261 with a offset grind to a 2" rod 4.2 stroke is about it and that would take a .080 over bore to get in the 290 range
Yeah that cadillac/Chevy isnt such a viable combo anymore. Pistons are a bitch to get. Do a search for Tom Langdon Cadillac-Chevy engine. It was in Inliners several years ago.
I was planning on doing mine with Buick V6 pistons and GMC rods. It leaves the pistons down the bore a bit, but I have a set of "unfinished" GMC rod bearings that will allow a tiny increase in stroke. Ends up about 270 cu. in. and 10:1 compression. The limiting thing will always be the head. Easier to go with custom pistons and not worry too much about displacement, IMHO.
I ran that "Cadillac" six in my street pickup for many years and it was a great engine. I picked up a couple 1/0's of a second in the 1/8 mile from the 261 version. (It's a street truck, but that doesn't mean you can't make a few passes at the strip - right I am helping a friend here in town build that same combination.
The Cadillac 261 by Tom Langdon At the Charlotte, North Carolina swap meet (April 2002) last spring, I talked with Inliner Troy Robertson about the 261 "stroker" motor in his '55 Chevy pickup. After many trials and tribulations, Troy has his 292 cu.in. 261 installed, running and quite impressive. Like most first attempts, Troy experienced some difficulties but his perseverance paid off with a very impressive combination. Learning from Troy's experience, I went back to my books to try to come up with another combination, which would be simpler than Troy's combination. Several Chevy 261 truck engines have been built up with custom pistons and Chevy 292 rods to displacements of 300 cu.in., but these require custom racing pistons (expensive), require sonic bore thickness checking, and cannot use conventional head gaskets. To avoid these difficulties and achieve most of the benefit for street applications, here is pre-sented a combination that achieves the following: * 281 to 290 cu. in. * Over the counter pistons currently available at reasonable price * 5 piston sizes available all within the safe and usable 261 size capability * Moly rings available * Lighter pins & rods * Adequate rod clearance to camshaft without grinding * Uses regular 261 head gasket * Uses quality forged production rod * Compression ratio 8.58:1 nominal with 261 head * No welding for stroker crank * No need to find "848" head (which requires steam hole drilling) The engine uses 1980-1984 Cadillac V-8 pistons, Chevy 292 six cylinder rods and an offset ground 4.125" stroke crank-shaft. All parts are easily available at reasonable prices. Most good crank grinders can offset grind your 261 crank if the journals are in good condition. Piston: Use 368 cu.in. Cadillac V-8 pistons (1980-1984) which are 3.80" standard bore size. Oversizes are +.020", +.030", +.040", +.060". Moly rings are available. This is a cast flat top piston with no valve notches. Rod: Use Chevy 292 six cylinder truck rod which is 6.760" long. The pin end must be enlarged to accept the press fit Cadillac piston pin. Crank: Offset grind the stroke from 3 15/16" to 4.125" by reducing the pin size from 2 5/16" to 2. 100" diam-eter to fit the 292 rod. This size reduction is sufficient to create a "collar" to limit side clearance to normal specifica-tions. No rebalance is required. Tapping the front of the crank for a 1/2" fine bolt is always good insurance to keep the balancer from shaking loose. Without decking the block, the piston should be.046" below the gasket surface. This is fine, or you could machine the surface to get more compression ratio. With these cubic inches to feed, larger inlet valves and definitely improve induction/exhaust is a must to achieve expected performance. This size engine will also handle more camshaft while retaining good idle quality The chart below shows possible bore sizes and resulting cubic inches: The chart below shows how the components "stack-up" in the 261 block to put the "Cadillac 261" piston at .046" below deck. Dimensions are shown are nominal Based on the original nominal 261cu.in. compression ratio of 7.80:1, the new compression ratio of a 285 cu. in. version would be 8.58. This is due to two effects: 1. Larger displacement and 2. Piston slightly higher in bore.
Ross or Arias can make up a set of forged pistons... about 700 bucks..piston down .036 in the the cylinder greatly reduces the squish effect.The 235 head has an odd combustion chamber but does respond nicely to .035 squish..I had a .080 overbore 261 with a stock crank running Ross flattops at near zero deck with tight squish.. Had a two barrel, mild cam, headers and the throttle response was exceptional for a lump..
I want to post it mainly because I have found things like that on the old interweb and then lost it. If it's on the good old H.A.M.B. I can't lose it
We need to find new combinations that work. I'm also wondering if de-stroking is an option, to reduce crank harmonics and spin it a little tighter. Drop in a drilled 216 crank. The head is the limiting factor for power.
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