I am in the process of putting the Jones & Benisek 1970 GS back to its original Stage 2 trim using the original Buick parts. My intention was to duplicate the original specs as closely as possible to see what power that combination made back in the 70's. A special thanks to the boys at AMP (Mike, Wink, Bobby, Billy and the late Fred Wilkerson) for the expert work and patience during this process. Also a big thanks to Mike and Sherri at TA Performance not only for quality parts for our Buicks but for the continued R&D they do in developing new parts. Without them I'm not sure how many of us would still be able to race Buicks. Here's the build. 1975 Block .038 over, hardblocked 1/2 way up. Lifter galley filled for reliability. Stock Buick crank. Carrillo stock size Buick rods (came in car when I bought) about 780 grams Replacement J&E pistons to specs of Jahn's Stage 2 pistons, 12-1 version Factory unmolested (no porting, blending etc!) Stage 2 iron heads, 3/8 Stage 1 TA valves. TA 1.385" springs, retainers and locks. Original Stage 2 Holley mount only B4B, unmolested except center divider cut down about 1/2 inch the full length to match the notch in the back in the facory casting. (It was cut out for optional 950 Holley 3 barrell carb). Stock 850 DP Holley carb #4781, choke plate still installed and no porting or grinding ,air bleeds and jets changed. NO carb spacer! Custom 107 "window rattler" cam trying to match factory duration with about .530 net lift (this is cam approved by IHRA for the factory Stage 2 engine combo). TA solid lifters. With current technology this cam is an improvement over cams that would have been available in the 1970's even though the overall specs would be close. TA 1.60 roller rockers (for reliability over the 1.59 ratio factory rockers) and 5/16 pushrods. Kustom 2399 Factory Stage 2 headers (on dyno we used TA Stage 2 headers that were fitted with EGT's but the overall design matches the Kustom's almost perfectly). Stock collectors. TA custom 7 quart steel oil pan, timing chain and hardware used throughout the engine. ATI external balancer and flexplate. Except for a few changes for reliability, the B4B divider being cut down the1/2 " and the replacement cam I believe it shows what this combo was capable of thanks to Dennis Manner and the Buick engineers. Dyno pulls were only made to 6000 (last pull to 6300 rpm) and it was not "flogged" for every last HP. Only a jet and spark plug change. Timing at 34 degrees. Factory estimates were 50-75 HP over the Stage 1 engine. Any guess on HP and torque? Tom
Tom, Thanks for going through all this trouble and expense. I'm sure there are many who want to know how much power the the original Stage 2 equipment would have made. I find it interesting that you made no mention of any port matching as this would probably make a huge difference in performance. That being said I'll guess the combo made 490 HP and 525 TQ. Steve
Tom, I'm going to guess 488 hp and 525 lbs torque. I'm looking forward to hearing what the actual numbers really are. I am trying to find a set of Stage 2 unmollested heads for a project I'm want to complete. If you know of anyone-anywhere that I can work with to buy a good set of heads I'd be forever greatful! Sounds like a great project and I'll keep an eye on this thread to learn more about your interesting project! THanks, Rob
It is a weeeee bit more I will post the dyno sheet in a few days on my website when I get the page done on Tom's car Mike
Tom, are you going to change it back to a 4 speed? When was it converted to an automatic? What else are you doing to it as far as interior/ dash? When were the mini tubs installed? Any old pics of the car that we havent seen? This has got to be one of my favorite cars!
520 hp @ 5800 rpm & 555 tq @ 4100 rpm Tom and or Guy. About 20 years ago I read a re-print of an article that was a first person description of a journalist that was at the Stage 2 car flogging, the journalist in line before him is the one that blew the engine. Have you seen this article?
Not I...but sure would like to. Must have been about car 4085 ***edit*** I remember hearing that story from Dave Johnson
Talked to Doug Jones and he said they figured about 550 HP back in the day with calculations done by Jim Bell. I believe Jim's numbers had to be pretty close. Mike at AMP will post the build and dyno sheet on his website soon. In the meantime the HP number at 6100 rpm (peak power) was an astounding 597.7! Torque was about 540. If you take into account the improved cam and carb technology, the cut down B4B center divider and quality machine work witch would add about 35 HP it is correct. Again this engine has absolutely no port matching, trick ring package, carb spacer or trick exhaust collectors. It was not flogged on for every last HP or I feel confident it would have hit 600. The stock heads flow about 270 on the intake (yes the runner design is different than the Stage 1 although the port is in the same place). So if you take 270 flow x 2.2 hp per cfm that is 594 HP. Mike will probably post the flow numbers also. The Buick engineers were definitely "on their game". As a side note I personally contacted Hemi Dave Dudek and offered this car in the Hemi shootout last year but he didn't think a "stocker" could my run with him! Tom
WOW! Great numbers, and great info. Can you post some pics of the car and motor when you get the chance? Will you be able to take the car to any of the national Buick events? THANKS!
