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4 barrel intake |
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DaemonForce
AMC Addicted Joined: Jul/05/2012 Location: Olympia, WA Status: Offline Points: 1070 |
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This is the kind of question I had long ago that would keep me up every night considering upgrade options for the 258 and what all could go wrong. The answer is don't think about it. You'll ask yourself weird questions like why did they do X with the L6 but Y with the V8 and which cylinders are firing more lean than the others and why is there this massive concentrated hotspot at the middle of the head...Bottom line is carburetors take up weird space while injectors only take up necessary space. I eventually went MPFI out of longevity concerns and to circumvent future issues I foresaw with the Clifford conversion.
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1971 Javelin SST
American 304 2v | FMX | AM20-3.31 1983 American Limited Jeep 4(.7)L S-MPFI | 1982 NWC T-5M (4.03/.76) | Dana30IFS/35-2.72 |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19679 |
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I had twin carbs (1V) on a six once, and a jet got trash in the rear most carb. These were close together near the center of the intake, one carb was about the #3 cylinder position, the other #4. Rear cylinder (#6) ran lean enough that it eventually burned a hole in the piston -- that's when I found out there was a problem, as it ran fine up until it got that hole!
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Frank Swygert
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Lyle
AMC Addicted Joined: Jul/17/2014 Location: None Status: Offline Points: 772 |
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Injectors really were the answer the the Jeep hill climbers. That Offy I mentioned was purportedly developed for them as the carburetor floats mounted sideways were very problematic on steep inclines. I have no idea how it would run for a street application.
Hill climbers had a multitude of custom intakes, many home made.
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1982AMCConcord
AMC Addicted Joined: Jul/13/2012 Location: Kenosha, WI Status: Offline Points: 1287 |
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Scroll right through the pictures on this web page...
http://www.performancempg.com/projects/amc_gremlin/clifford_intake_holley_600_001.htm It's surprising how many guys get this totally wrong.. Like the AMC Hornet with the I-6 that Mike Finnegan and his friend built... its got the carb on wrong. I even emailed them about it.. they of course are so smart.. they NEVER fixed it! SIGH! Several videos they mention it runs bad... https://www.youtube.com/watch?v=SuMHZ5omheI
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matty 401
AMC Addicted Joined: Jul/06/2007 Location: Iowa Status: Offline Points: 1727 |
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so going with a 350 or 500 holley on a stock aluminum intake is easier lol
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72 matador 401 the beast
79 concord 2 door 72 matador 304 grasshopper 68 Rogue 406 93 Cherokee 4.0 5 speed |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19679 |
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500 Holley 2V is too big unless you're building a full race engine that will run high rpm a lot... too big for a street car. The 350 is a good size. The stock 2V is only ~200 cfm, maybe a little more (or less), so the 350 gives you a good bit extra. A lot of Jeep guys like the Weber 32/36 or 38/38. The 32/36 is ~270 cfm and is a manual progressive carb -- runs on 32 until throttle is opened a certain amount to start opening the 36. 38/38 is a standard 2V carb -- both open at the same time. It's ~325 cfm. For a street vehicle I think I'd use the 32/36 for a bit more power and still good economy. The Weber takes a bit of effort to get tunes right, but once it is you can forget about it. TomJ has some experience there, runs a Weber (I forget which!) on his 195.6 roadster/rally car.
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Frank Swygert
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tomj
AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7544 |
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i ran the 32/36 DGEV on a 195.6 OHV in stock form for years, and it ran great, better than the NOS Carter WCD. with the new engine, which has had fairly substantial head and porting work, a 38/38 was an immediately noticable improvement.
but everything in an engine involving state-of-tune is interconnected -- with the new engine and especially transmission, i realized that i had been in the habit of lugging, a lot. i've been keepign the revs up -- by that i mean 1800 - 3500 -- because i now have a usable transmission and a willing engine -- tuning the carb required re-mapping spark, to get rid of almost all of a low-speed bog/flatspot i've had for a year. the driving changes, and now proper jetting, allowed far more (proper) spark advance. at mid loads i'm running 34 to 38 degrees of advance, high loads (5 InHg) 30 to 34, and light load/highway cruise, 45 degrees. no pinging unless i lug it, eg. 1200, 1400 in 3rd at too-low speeds, when i should have and now do downshift. compression is about 9:1, and i run the cheapest pump gas i can buy. often 87 octane on road trips. i'm gonna push spark advance for another week, then back the whole map -2 degrees in all slots and drive it on a long trip. none of this is even remotely possible with a distributor. even modified i couldn't get more than 22 degrees mechanical advance. |
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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