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500Hp ,401,J10 update, test drives, tuning begins! |
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amc401t10
AMC Addicted Joined: Mar/09/2009 Location: east tn Status: Offline Points: 903 |
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Posted: Sep/20/2020 at 2:56pm |
had my share of problems. Oil line Fire, the worsr(all burnt wiring repaired except fuel gauge wires),727, pan leaks,(mopar gasket fixed),belt alignment(pressed WP threaded flange fix),stock air cleaner to Holley DP HO 750 carb(1/2in adpt fix), dialing in the big cam and carb to work with the mild(1800 stall, 2100rpm flash converter), carb benn off 20 times for changes, it finally got time for some short test rides!
Drove several 4-5 mile slow(3500rpm max) test, returned for adjustments. My 10 year old son(I'm 62), loves off road, was with me yesterday, and on several other test. Almost home he said, it just don't run like it did when it was in the car dad. Now it's still choked down with only 2in cherry bomb style pipes, and the single valve springs still on(I have triples to install,4500 max untill), we left the last stop sign turning right,1/4 mile from home, I laid into it hard, Lit the rear tires up for just couple seconds, tact hit 5k before I could get out of it, he grinned ear to ear,said now that's what I benn missing. Springs going in soon, then going to muffler shop to uncork, I think I'll be happy. |
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1-owner 74 gremlin x 401, t10,3.73 12 bolt,750carb,reed 250@50 cam, roller rockers,msd,offy int.
72 amc matador 401 727 84 j10 ,360, 727 1970 4-door rebel sleeper(455 pontiac,turbo 400) 79 spirit,4.2 |
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amc401t10
AMC Addicted Joined: Mar/09/2009 Location: east tn Status: Offline Points: 903 |
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Ok, I'm getting excited now. Got springs in this week, finished last night bout 2am!
I set the the Rhoads V-max lifters @ .044 (.030-.060) when used on solid lift cams. The more the lash, the more it tames(reduces lift and duration), o f the cam. My cam( 250@.050,.590 lift), needed taming for power brakes ,and 1800 converter. It now has a deeper tone, really thumps @ idle(1000rpm,750,in gear). I put a 5400rpm pill in the shift light for now(Will go to 6500 later). Its still choked down with 2in cherry bomb exhaust! Still got. Some ATF and oil seepage (drip) going on to Chase down? I've drained my break in oil,it was kinda black(supprized). I've added 1gallon rotella 15-40,1qt,Lucas 20-50,half bottle STP,half bottle,cam lube(with Solid cam and 300lbs of spring pressure, I add this every oil change(bout once a year). Test drive soon! My son,s going to help post a utube video of the 401 soon!
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1-owner 74 gremlin x 401, t10,3.73 12 bolt,750carb,reed 250@50 cam, roller rockers,msd,offy int.
72 amc matador 401 727 84 j10 ,360, 727 1970 4-door rebel sleeper(455 pontiac,turbo 400) 79 spirit,4.2 |
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232jav3sp
AMC Addicted Joined: Jan/09/2013 Location: Texas Status: Offline Points: 2451 |
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That is awesome that you're ten year old is head over heals for this!
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amc401t10
AMC Addicted Joined: Mar/09/2009 Location: east tn Status: Offline Points: 903 |
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He's had a yard tractor at 4years old,then first bike since 5, now rides. 125 he can't reach ground on.
He got my DNA for sure, my 30 year old son has more ATVs than me! Now back to 401! Test after spring install! I put a 5400 pill in the shift light, son and I headed to county line and back(1/2mile straight). Turned around at crossroads, an hammered it, away we go, starts pulling HARD bout 2500, Took it to 5000, shifted to 2nd, nice little chirp of tires,took it to 90mph, hit 3rd and let out. Slowed to 60mph,hammered it again, snap, lost throttle, coasted to nearest pull off. Cable poped off ball stud on Holley, replaced and drove home. More fine tuning to carb, small hesitation when accelerating from cruise to speed up. Pulls better off idle than I expected, but it don't explode @3000rpm like it used too. Think the puny 2in exhaust is the problem !
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1-owner 74 gremlin x 401, t10,3.73 12 bolt,750carb,reed 250@50 cam, roller rockers,msd,offy int.
72 amc matador 401 727 84 j10 ,360, 727 1970 4-door rebel sleeper(455 pontiac,turbo 400) 79 spirit,4.2 |
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BassBoat
AMC Addicted Joined: Aug/29/2008 Status: Offline Points: 1714 |
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That hesitation with just the slightest pedal pressure is what I interpret as a lean primary jet. As a diagnostic you could raise the front float level and see if that enrichment solves the problem, then increase primary jet a size or two. If you are going to take the exhaust restriction out, the lean problem will get worse. Another thing that you can try is simply open the idle mixture screws a quarter turn or so out. Again, a change that is easy to try and easy to put back where it was if it doesn't help. I enjoy your stories about your 10 year old. My oldest grandson is 10 and is enthusiastic about all things cars.
Good luck, BB
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amc401t10
AMC Addicted Joined: Mar/09/2009 Location: east tn Status: Offline Points: 903 |
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I went from 71s to 72s. And increased front squirt from 31 to 35.
No more hesitation when accelerating. And yes may have to retune after exhaust mods. I had leaned it some because of the heaver truck, it's now back to Same setup as in car, except for a 3.5 PV due to the low vac in gear.(6-8hg) |
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1-owner 74 gremlin x 401, t10,3.73 12 bolt,750carb,reed 250@50 cam, roller rockers,msd,offy int.
72 amc matador 401 727 84 j10 ,360, 727 1970 4-door rebel sleeper(455 pontiac,turbo 400) 79 spirit,4.2 |
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RandyB
AMC Nut Joined: Aug/04/2020 Location: Florida Status: Offline Points: 458 |
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I was thinking lean primaries or the secondaries are opening early. Also, OP what gears are you running, the reason I ask is you said big cam and 1800 stall converter, that usually does not work with some gears.
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Randy B
68 Javelin SST 343 73 Charger Rallye 340 triple Blk |
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amc401t10
AMC Addicted Joined: Mar/09/2009 Location: east tn Status: Offline Points: 903 |
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3.55s
Only got 235/70/15, stock size, street tires. Launch from stop,idle, hardley spins, starts pulling g hard@2500rpm. Power brake from stop,1800rpm, frys them till u let out. Haven't tried a 4wd power brake yet? Any idea what this thing weighs ? I'm guessing around 5K ?
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1-owner 74 gremlin x 401, t10,3.73 12 bolt,750carb,reed 250@50 cam, roller rockers,msd,offy int.
72 amc matador 401 727 84 j10 ,360, 727 1970 4-door rebel sleeper(455 pontiac,turbo 400) 79 spirit,4.2 |
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