PhatNBad Posted January 2 Share Posted January 2 Happy New Year everyone! Debating doing some performance upgrades to my 402 or going 454. I just wondering what y’all have done to upgrade your 402’s to get a little me more HP. I’m not trying to get 500hp. I’m totally ok with 400-ish. Thanks for the advice! 2 Quote Link to comment Share on other sites More sharing options...
jft69z Posted January 2 Share Posted January 2 My 72 came with a 402. The upgrades i did to it was replace it with a 454 LS6 😁. 4 Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted January 2 Share Posted January 2 Obviously 50+more cubic inches automatically means more torque and HP right off the bat. If the 402 is numbers matching, making 400 HP is not hard. But also like Joe, you could put the 402 on the side if eventually you want to go back to numbers matching or if you sell the car, you could give the next owner that option and possibly get more money for it with the original engine. 4 Quote Link to comment Share on other sites More sharing options...
jft69z Posted January 2 Share Posted January 2 21 minutes ago, MC1of80 said: But also like Joe, you could put the 402 on the side ... Here's my 402. Makes a nice table. 7 Quote Link to comment Share on other sites More sharing options...
502ci Posted January 2 Share Posted January 2 My original 402 had some simple mods that woke it up which included a 750 Holley, dual plane aluminum intake, headers, electronic ignition, hotter cam (I do not remember the specs), and the heads milled for a bit more compression. It ran pretty good, went from a stock high 15 second quarter mile to high 13 second quarter mile times. Eventually I put a 502 in it and cut off another 2 seconds in the quarter. 5 Quote Link to comment Share on other sites More sharing options...
MCfan Posted January 3 Share Posted January 3 Juan, the 402 in my numbers matching '70 was highly modified before I bought it in 2010 and I have added some refining touches. It was bored .030'" over to 408 CI, decked .010", larger valves in '74 heads, Sig Erson 396 Hi Flow hydraulic cam and lifters, 11.9:1 TRW pistons, Torker II single plane intake, 750 cfm AED carb, Patriot 1 7/8" headers, 2 1/2" exhaust with turbo mufflers, Cloyes gear drive timimg, HEI distributor, Hayes clutch and pressure plate, Lakewood bell housing. The rest of the drivetrain is stock M20 4-speeed with Hurst Competition Plus shifter and a 3.31 posi. I've never raced it or had it on a dyno but I'm certain it's power potential is somewhat north of 400 hp which is more than I need for use as a daily driver. Due to its high compression, It requires the highest 93 octane gas generally available plus 108 octane booster and lead substitute. For 8 years, I simultaneously owned and drove a stock '70 SS454 which was a great cruiser with a 2.56:1 rear gear but my modified 402 would easily run circles around it. Your 402 is just an air pump. A balanced set of components to increase the air flow and deliver adequate fuel is all you need. I suggest you look for a 750 carb on a dual plane after market manifold, a mild performance hydraulic cam (roller or tappet) and a set of tube headers mated with a free flowing exhaust system. If you are going to completely rebuild, over-boring and higher compression pistons would be next but I do NOT recommend a compression ratio greater than the 10.25:1 the factory used in '70! JMO Good luck! 2 Quote Link to comment Share on other sites More sharing options...
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