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Mild 401,2.73 gear, looking for a cam,+ car pics |
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FSJunkie 
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Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742 |
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 Posted: May/11/2015 at 2:09pm |
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The bigger your engine the lower you can gear it and still have enough torque off the line.
2.73 works well withy my little 232 so I have no doubt a 401 will have plenty of torque off the line with it. 2.87 would be nice as well. I would definitely not go any higher than 3.15. Muscle car guys like 3.15 and up gearing for acceleration, burnouts, etc. but I like cruising modern interstate speeds in quiet comfort without an engine screaming away at high RPM. Sustained high RPM is hard on an engine and hard on you. Wears things out faster, uses more fuel, creates more heat, etc. Everything wears out faster, even accessories like alternators. 3.54 with an automatic is a massive no. I've had manual trans cars with that and I don't like running 70 on the highway at 3600 RPM as the temperature gauge slowly climbs. |
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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amc401t10
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Joined: Mar/09/2009 Location: east tn Status: Offline Points: 903 |
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Posted: May/11/2015 at 4:43pm |
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Ant changing the gear , this was which cam should I use not ,how to make my car quicker. Thanks for all the input.
My pick so far is the lunati 10100702lk kit, maby advance it a couple degrees to bring it down a little more. But I still haven't decided, I also post on a jeep forum and they are recommending cams also. Ps how much difference in a performer (not rpm) intake and a offy 360 ? I think I had the performer on 15 years ago and now I have a offy 360. Thanks for any advice. |
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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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Boris Badanov
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Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4209 |
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Posted: May/11/2015 at 5:35pm |
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Dang it I should have this on my desktop so I can copy and paste it everytime someone wants to run an Offy.....
First, I have used the single and dual four barrel Offy 360. IMO they are best suited for a stick shift car as they do not make a lot of low end torque. On a stock converter you may be making for a sluggish start off the line. For a stock automatic rig I would select a dual plane manifold like the "Performer" or the air gap. Even a stock 4bbl manifold is good, but very heavy. I always block the heat riser if the car is driven only in warm weather. |
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Gremlin Dreams
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Sonic Silver
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Joined: Nov/23/2011 Location: East Tennessee Status: Offline Points: 7966 |
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Posted: May/11/2015 at 5:44pm |
Edit: After reading Boris' post, my Offy is on a 70 AMX with a 4 speed and 3.54, so your mileage may vary with a heavier car, auto, and rear gears. Edited by Sonic Silver - May/11/2015 at 5:47pm |
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Boris Badanov
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Posted: May/11/2015 at 5:57pm |
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By the way, I am NOT dissing Offys, I love em!
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Gremlin Dreams
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amc401t10
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Joined: Mar/09/2009 Location: east tn Status: Offline Points: 903 |
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Posted: May/12/2015 at 8:32am |
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Ok, benn driving the car some after sitting two years in basement.
It seems really weak. Benn scratching my head trying to remember What was in the engine from 15 year ago build. I think I have a bunch of mismatched parts! I found the box my cam came in, it was a crower 45243. This cam is listed as being for upper bottom to top. Also says need gears, 9.5 and up comp. 1800 - 5000 rpm range. These specs aren't 2.73 gear friendly! I used this cam because it was leftover from another job(bad mistake). I researched the offy intake, and it's power started at 1800 rpm,not low enough for 2.73s. I used this intake because it was leftover from another job,mistake. I have a performer here off a customers repair job years ago. My plan is to use it and whatever cam I decide on. I also have a 600 Holley to try if the 750 is too sluggish . I have a b-m converter that power breaks to around 1900 rpm. I think my comp is 8.5-9 to 1. Here the specs on the cam I am fond of. Lunati 10100702 Int. Ex 262. 268. Adv dur 220. 226. @.50 507. 527. Lift 112/108. Lsa 1600-5800 power range If I advance the cam about 2 deg then power should be close to 1400-5600? Should this work with the performer and 2.73s? Ps which carb would u start with? Thanks Ps this engine has never launched as hard as the mild 360 that it replaced,on mid and top The 401 feels just slightly stronger. Gotta get some torque back, |
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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
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Posted: May/12/2015 at 8:39am |
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Ps- I love my offy 360 on my 401 in my gremlin, it pulls hard from around
2000-6800 rpm with a aed 750 double pumper. It will break the tires loose (295/50/15) at 30 mph if u nail the gas at two grand in first. But since it is a stick I am never below 2000 rpm. |
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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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amxdreamer
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Joined: Jul/30/2008 Location: Vancouver, BC Status: Offline Points: 8511 |
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Posted: May/12/2015 at 8:53am |
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When I built my car (360 amx) I had the 2.87 rear and built the engine around that as wanted the car to stay original. Performer intake and a comp 268H cam. Was pretty happy with the results but did end up swapping the 2.87's for a set of 3.31's. I would look at the next cam up the list 270H if you want off idle for the 401. The 280H works well in the 401 but will be higher up the RPMs
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Tony
Vancouver, BC 1970 AMX 1972 Badassador AMO#10333 |
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RamblinMan
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Posted: May/12/2015 at 9:36am |
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A lot of street cams have 4 degrees of advance built in. Your 112/108 lsa spec says that it DOES already have 4 degrees. An extra 2 degrees *might* help. That cam is not terribly radical for a 401 but your compression is pretty puny. The RPM range given on the spec sheet for that cam is likely for a 360. When I built SBC engines, the cam RPM range was almost always for a 350 and I always built 400+ CID engines.
The Holley carbs - if the 750 is a vacuum secondary carb, I see no benefit in changing to a 600. IMHO the 3310 or 40508 Holley 750 vacuum secondary carbs are good for pretty much anything 350+ CID. If the Offy intake is the 360 degree single plane you will gain a little bottom end by changing to the performer, but the change won't be huge. A 400+ CID engine can usually handle a single plane intake for most applications short of rock crawling. Overall, it doesn't look like a terrible combo. The compression is very low and with modern head gaskets of .040"+ thickness, it may be even less. If it were me: stab in a smaller cam, slap the performer on it, check your timing curve (I am suspicious of it based upon your symptoms) and I think you'll have a nice, albeit very mild, combo. I still say switching to gears would be an absolute given if it were me (probably 3.15 gears). ;-)
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The Right Reverend of Blessed Acceleration
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Red Devil
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Posted: May/12/2015 at 9:39am |
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Crower: 45243(284HDP) 112° 284° 290° 228° 234° .512" .525"
Lunati: 10100702 112° 262° 268° 220° 226° .507" .527" Neither is particularly "big" ... but the Lunati will be slightly better at lower rpm ... but still too "big" to get off the line with authority with a low-stall, 2.73 gears and a 3700lb car. If you like Lunati and want to keep the 2.73 gears, the 10100700 or 10100701 is a better choice ... and drop on the Performer ... but it won't pull much over 5000 rpm. 10100700: •Duration @ .050 (Int/Exh): 208/213 •Gross Valve Lift (Int/Exh): .484/.484 10100701 •Duration @ .050 (Int/Exh): 213/220 •Gross Valve Lift (Int/Exh): .484/.507 Also, what are you running for exhaust? Could gain torque with a nice (not too big) dual exhaust. Hope this helps,RD. |
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amc401t10 wrote: