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Mexican Camshaft Specifications (266º and 302º) |
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Rambler Mexicano
AMC Addicted Joined: Mar/05/2011 Location: Guadalajara Status: Offline Points: 970 |
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Posted: Feb/10/2019 at 2:15pm |
I was able to obtain the specifications of two out of three of VAM's most well known and used camshafts, the inhouse 266º unit for standard production vehicles and the also inhouse high performance 302º degree unit. The third most common unit used by VAM being the 244º unit originally designed in the United States by AMC and used in the VAM 232s and 199s. These specs come from the 1981 VAM Factory/Dealership Tech Manual. The manual was obviously in Spanish, I did my best to translate the engineering jargon to its correct English terms. If anyone notices any mistake in this department please let me know. Stock 266º camshaft Introduced in 1969 in the also new VAM 252 six cylinder (1969-1972) based on the AMC 232. Used in all VAM 258 sixes (1973-1986) and all VAM regular production 282 sixes (1971-1986). Compression ratio used wth this camshaft ranged from 7.6:1 through 9.8:1. High Performance 302º camshaft Introduced in 1967 as part of VAM's own six cylinder Go Pack designed by VAM's engineers and pilots. It was available as a dealership option for virtually ANY VAM engine ranging from the 199 all the way to the 282. Compression ratio used with this camshaft ranged from 8.5:1 through 9.8:1. It would become factory equipment in two models, the 1979 American 06/S (Concord two-door sedan with a Hornet SC/360-like focus) plus the 1980-1981 Rally GT (Spirit GT coupe, high performance version). STANDARD UNIT Length Slack: Zero (0) with the engine in operation. Bearing tolerance: 0.025 to 0.076 mm 0.001 to 0.003 inches Standard Pivot Diameter: Number 1 - 51.537 to 51.562 mm2.029 to 2.030 inches Number 2 - 51.283 to 51.308 mm 2.019 to 2.020 inches Number 3 - 51.029 to 51.054 mm 2.009 to 2.010 inches Number 4 - 50.775 to 50.800 mm 1.999 to 2.000 inches Gas Pump Eccentric Cam Diameter 41.021 to 41.275 mm 1.615 to 1.625 inches Maximum Lobe/Cam Lift 6.756 mm 0.266 inches Valve Adjustment Intake Opens - 16º30' Before Top Dead Center Closes - 69º30' After Bottom Dead Center Exhaust Opens - 62º30' Before Bottom Dead Center Closes - 23º30' After Top Dead Center Valve Overlap 40º Duration of the Intake and Exhaust Event 266º HIGH PERFORMANCE UNIT Length Slack: Zero (0) with the engine in operation. Bearing tolerance: 0.025 to 0.076 mm 0.001 to 0.003 inches Standard Pivot Diameter: Number 1 - 51.537 to 51.562 mm2.029 to 2.030 inches Number 2 - 51.283 to 51.308 mm 2.019 to 2.020 inches Number 3 - 51.029 to 51.054 mm 2.009 to 2.010 inches Number 4 - 50.775 to 50.800 mm 1.999 to 2.000 inches Gas Pump Eccentric Cam Diameter 41.021 to 41.275 mm 1.615 to 1.625 inches Maximum Lobe/Cam Lift
7.679 mm 0.298 inches Valve Adjustment Intake Opens - 36º Before Top Dead Center Closes - 86º After Bottom Dead Center Exhaust Opens - 86º Before Bottom Dead Center Closes - 36º After Top Dead Center Valve Overlap 72º Duration of the Intake and Exhaust Event 302º |
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Mauricio Jordán
Cuando no se es una empresa famosa se deben hacer mejores automóviles. - VehÃculos Automotores Mexicanos S. A. de C. V. |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19611 |
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The 266 duration cam is about what most aftermarket companies sell as an upgrade from the stock AMC cam. They range from 256-266 degrees duration, like the Isky 256 (0.450 lift) and 262 Supercams (0.445 lift), and Comp 260H (0.447 lift -- 0.280 lobe lift). Just a little less duration and lift than the Mexican 266 performance cam. Isky makes a 270 duration/0.475 lift cam, but it's listed as needing higher compression and rear axle ratios than stock (9.5:1 w/3.70-4.11 gears and stock converter... could get by with less gear with a higher stall converter). If that Mexican performance cam is readily availble it might be a good choice. It was made with the thinner air around Mexico City in mind though, so it might be a bit much for lower altitudes and probably requires a higher grade fuel (than 87 regular), at least at lower altitudes.
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Frank Swygert
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