Difference between Dart 347 and stock block 408
Dad's Maverick....(not mine)
Been running a Dart block 347 (4.030 bore and 3.400" stroke) for a couple years and it's been doing good. Methanol injected, 13:1, solid roller (268-274 @ .050", .688 lift on both), out of the box victor Jr heads, victor JR 302 intake, Powerglide w/5500 converter, 5.13 rear gear, backhalf ladder bar car 32x14 slicks, weighs 2703 with my brother in it-he is around 310 lbs. Always dialed in the 6.35-6.40 range depending on weather.
Last weekend they went to the track, car ran a few 6.36's in a row. Next pass, it died and would not restart. Broke cam dowel and bent some valves. I had a 408 built at home but no camshaft. Same exact out-of-the box victor Jr heads on it. The 408 is also 13:1 (actual 12.93), victor jr 351w intake. We pull the cam from the 347 and put it into the 408, with a new dowel pin and a new bolt just to get the car back to the track. No major changes to the trans or anything else for that matter, just the engine. Even the little 1 5/8" Ford VAN headers got re-used. They were on a 302 that was in a junkyard van; got them for $5 when I was helping the original car owner build the car (before my dad bought it).
It went 2 6.01's in a row yesterday, with too much timing. I had him pull it back to 32° from 36, which should pick it up a few hundredths and probably 2 or 3 mph. So what's that? Nearly 4 tenths improvement? Oh, did notice that the stall speed is up to around 5800 based on the LM-1's log, from 5600-ish with the 347. Torque will do that. Don't have any timeslip because the printers were screwed up; and I didn't think to get any pics of the nice wheels-up launches.
Just thought you guys might be interested in the real-world difference.
I wonder how much ET gain there is with some decent headers, if any.