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| Author: | 74SCAMP [ Tue May 03, 2005 12:49 pm ] |
| Post subject: | new to forum |
Hey guys, i'm new here and i have been reading this forum for a couple of months. first of all i want to thank you for all the help you have given me. i recently bought a 1974 Scamp with automatic transmission and "225" engine and 55,000 miles. the car was all stock except for the radio. i have a problem... i have to set the idle at about 1400 rpm so when i put it in drive it drops about 400 rpm and if i turn on the a/c, it drops another 100 rpm. i read here that it is usually because of a vacuum leak. so, i have done the following, changed oil & filter, changed belts, new coil (someone filled top with oil ), put "985" plugs and tuned to "tdc",put a new distributor (vac. adv. diaphram dead), new carb., wires, new air filter, new vacuum lines, and i took manifolds off and put new gasket which i torqued to 10 lbs.. i drove the car this weekend 130 miles to my sisters house and back and got 19 mpg. going and 21 mpg. at about 85 mph.. i still can't figure out why it drops so low in "drive". any suggestions will be appreciated. sorry, if this is too long, and thanks again for your help. [/b] |
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| Author: | Slant6Ram [ Tue May 03, 2005 3:00 pm ] |
| Post subject: | Welcome |
Good to see that there are new people learning and working on these cars. It looks like you've got a good start on your tune up. You've left out a couple of things that might be important: A proper valve adjustment, making extra sure to check for clearances which are too tight. Leave them a little loose your first try is the safe way to go. PCV valve, it's the little elbow that connects a vacuum line into your valve cover. A stuck pcv can cause too much air to flow into the carb at idle. A new one is only a few bucks, so it hardly hurts to replace a 20 year old item. EGR valve. This could be stuck in the open position, which will cause problems. I'm not saying to remove it, but perhaps take it off and see if it looks clogged. Keep searching for vacuum leaks by spraying carb cleaner on different parts of the intake/carb system (with the engine running) if the engine speeds up, you've found a leak. After checking out those cheap fixes, I would take a look at your carb. It sounds like it could be adjusted very lean at idle. It's also possible that the idle jet is gummed up. You'll want to identify the carb, either a holley 1920 or a holley 1945 usually (if it's all stock) , and then do a search for more info about how to clean or adjust it. Hope the gets you on track, I'm sure many others will have suggestions if that doesn't help locate the problem. |
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| Author: | 74SCAMP [ Wed May 04, 2005 1:40 am ] |
| Post subject: | reply to Slant6ram |
thanks for replying to my question. i would have gotten back sooner but i had to go to work (gotta eat). anyway, the Scamp has a rebuilt 1245 carb., and i did adjust the valves at .010 and .020 after i did a compression test. a couple cylinders were at about 112-115 all the rest were at 120. i readjusted the two cylinders to .012 &.022 because the plugs looked a little lean compared to the others. as i said i went out of town and on the way i got 19 mpg. on the way back i noticed the car had more power and i got 21 mpg. so i am guessing that at 85 mph i knocked off some carbon= compression went up a little. so i figure i better do another compression test and see where i'm at. and maybe set them all at .012 & .022 to be safe. if i'm guessing right the egr is the valve that is on the exhaust manifold that rotates open when revved up?? if so it seems to move just fine, but i'm not sure how to test it for a vacuum leak. what i did do was put the car in reverse (w/brake on) and started pulling vacuum lines one at a time to see if i could hear any difference in rpm., i didn't find anything. i did notice when i first got the car that the "choke control switch" has what looks like a small resister (block) that connects to the "choke heating element" and it was smoking so i unpluged it. the first carb i had (#1245), would run rough at idle and wouldn't let me turn the idle screw more than 4 1/2 turns in, so i rebuilt it and it smoothed out but still would not let me past 3 1/2 turns in. i don't think the problem is with the carb. because the new one is the same way. i had a slight missing at idle until i went back and reset the valves to .012 & .022. i went to checkers and bought a new pvc filter. i have the original shop manual from Chrysler, i just saw the egr valve. i will get a new one. again, thanks for your help. i will get back wih you on the results. |
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| Author: | Jeb [ Wed May 04, 2005 2:12 pm ] |
| Post subject: | |
Don't you mean 1945 instead of 1245? |
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| Author: | 74SCAMP [ Wed May 04, 2005 2:22 pm ] |
| Post subject: | your right |
i did mean "1945". |
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| Author: | Slant6Ram [ Wed May 04, 2005 4:01 pm ] |
| Post subject: | Right |
Sounds like you're doing pretty well for a new guy. Let us know if you get stuck or have questions or post back when you get the problems resolved. |
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| Author: | 74SCAMP [ Fri May 06, 2005 1:09 am ] |
| Post subject: | more questions |
well, i got ahold of a local dealer to get a price for the egr and they couldn't tell me if they had one because their book doesn't go back far enough. so i called "checkers" and it's about $30.00. is their anyway to check it to make sure it's bad? also, i noticed that my car has had a new power brake booster put on. could it be the cause of the drop in rpms.? also, how can i tell if the pcv is stuck? is it a one way valve? as you can probably tell, i know nothing about emissions. thanks! |
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| Author: | Slant6Ram [ Fri May 06, 2005 7:35 am ] |
| Post subject: | More advice |
Quote: how can i tell if the pcv is stuck?
Buy a new one, they are cheap, under $5.Quote: it's about $30.00.
I agree that this is expensive enough to be off the random replacement list. You can remove it (2 bolts, but a replacement gasket may be needed) and take a look to make sure it isn't clogged open with carbon deposits. A vacuum pump/gauge is the only way i can think to test it for 'leaks'. 'checkers' might have a pump/gauge that you can use to test it. (does checkers do lend-a-tool?)Quote: a new power brake booster put on. could it be the cause of the drop in rpms.?
It would have to be defective. A faulty power brake booster can be a giant vacuum leak. It's simple enough to test, by disconnecting the booster and temporarily plugging the vacuum line that leads to the carb. If the engine runs noticably different, then you've found your problem. I don't suggest you do any driving without the booster connected.Plugging off vacuum lines is a good way to test for vacuum problems. I have found several bad 'choke pull off diaphrams' that way. Quote: 55,000 miles.
If this is actually 255,000 miles (like my aspen's motor), you may be experiencing very weak compression problems.
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| Author: | 74SCAMP [ Fri May 06, 2005 2:09 pm ] |
| Post subject: | update: |
well, i took the egr valve off and it as well as the manifold was totally clogged up with carbon. so i cleaned the valve and checked it for leaks and it seemed to function ok. after i put it back on i drove the car around the block. i then put it in "park" and it was at 1400 rpms., than i put it in "drive and it dropped to 800 rpms.. so now i will go buy a new pcv valve. but i'm having a problem believing that this will fix my problem. something is definitely going on. thanks. |
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| Author: | 74SCAMP [ Fri May 06, 2005 11:16 pm ] |
| Post subject: | i think i know this one... |
all right guys, it bothered me all day and i kept telling myself "i know this one". rpm drop from the time i bought the car 2 months ago, history of work done(??), i tuned up car, adjusted valves (all very loose), could not find vacuum leak, rebuilt carb., bought new carb., still rpm drop. carbs act the same (identical) can't be carb.... hmm. when i bought the car, it had new plugs (nothing to read). tuned it up i put new 985's (nothing to read). went to see sister 130 miles each way. plugs look lean...idles lean... on my way home from my sisters i hit an incline that lasted about 5 miles. started at 85 mph. slowed down to 70 mph. (pretty weak)....lean? car has a flat spot just off idle that will do ok if accelerated slowly. lean, lean, lean! needs to be rejeted! all i kept telling myself was emmisions...hmm, i know nothing about emissions. if i were a gambler, i'd be willing to bet it's lean. tell me your thought's guy's, you think if it were a train would i have been hit? so now my next effort is i'm reaming the "main jet" a little and see what it get's me. do you think the idle jet is ok? thanks. |
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| Author: | argentina-slantsixer [ Sat May 07, 2005 6:02 am ] |
| Post subject: | |
maybe (just maybe) your timing is too advanced. Lean condition can be "simulated" by initial timings from 12 BTDC on. You're getting nice mileage, so that's my point for this figuration. The flat sport off idle (wich also can mean very retarded timing, you know....) can be due to "lean" condition caused by your carb ain't following up your initial timing. Did you ever get pinging? like up that incline or a hill? do you get pinging at certain RPM's? About the carb, I have to say (and give that I love some holleys) that 1945 is a worthless piece of crap. You'll do better with a 1920 wich by the way can be turned in quite a performer by reaming out 3 jets. You ain't gonna feel eddy 500 cfm but it's gonna be more close to a supersix. You have to ream the main air jet (located on the bowl's side near the venturi, you have 2 holes: large: idle air jet, small one main air jet. Don't ream the idle air jet or your car won't idle anymore) to about .8 mm, the accel pump jet to .6mm (you are to remove one lead pig and then install it again) and your main fuel jet 1.36mm (screwed on your metering block) and then you tell me.... wish you good luck on this. |
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| Author: | 74SCAMP [ Sat May 07, 2005 8:45 am ] |
| Post subject: | carbs... |
Argentina: thanks for the help! the manual calls for 0* (tdc). most i tried was 5* and she didn't seem to like it much. i have her at about 2-2 1/2* right now. no i didn't hear any ping, it was just gutless. actually, if i'm gonna invest in another carb., i want to move up to a 2 bbl.. but, being it's my daily driver mileage is a concern for me. just tuning this carb. may cost me a couple mpg. which is fine. i'd rather have a well tuned car any day. after the carb. is set right, then i can try to find a sweet spot with the timing. does that sound right? to be honest, all the work and money i've put in so far has made a big difference in a good way. all except the fact that now i own 2ea 1bbl. carbs. yesterday i could hardly tell she was still running at a stop light, before i used to sit there worrying if she was going to stall. performance just keeps getting better, but then i really don't know what to expect. so far i'm impressed. for a 6 cylinder rated @105 hp. she keep right up with traffic just fine in the city and the freeway. thanks! |
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| Author: | 74SCAMP [ Sat May 07, 2005 3:17 pm ] |
| Post subject: | is there hope?? |
i'm beginning to wonder... the NEW carb i bought just about got me killed. the step up fell off on my way home from work and jammed my throttle. i also noticed that it's leaking at about every gasket and when i went to tighten them down i noticed that about half the screws were striped. so now i have the old one back on (it worked ok anyway). i also noticed that the old carb. had a #612 main jet and on the NEW carb. it was a 603. i have read about your carbs. and all i ever see is #58,#64, ect. so anyway, i drove the car and the high drop in rpm is still there, but the flat spot seems to be almost gone (the old carb. always worked better than the NEW one). so, all i can hope is that the jets are too close together in size to make much difference, but i'm going the right way. any help will be appreciated. |
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| Author: | SlantSixDan [ Sat May 07, 2005 3:32 pm ] |
| Post subject: | Re: is there hope?? |
Quote: i'm beginning to wonder... the NEW carb i bought just about got me killed. the step up fell off on my way home from work and jammed my throttle.
Fun and excitement on the way home from work! Yikes. Go through the carb and tighten up all the screws and fasteners that are meant to be tight. Was this a new new carb, or a "reman" unit?Quote: noticed that about half the screws were striped.
Sounds like probably a "reman".Quote: old carb. had a #612 main jet and on the NEW carb. it was a 603. i have read about your carbs. and all i ever see is #58,#64, ect.
3-digit Holley jets are the high-precision original-fitment types. The first two digits are the jet number (in your case a 60 vs. a 61) and the third digit indicates whether that particular jet is on the small end (1), big end (3) or right in the middle (2) of the size spec for that particular jet number. So a 603 is a large 60, while a 612 is a "dead nuts on" 61.I'm curious about something: With the engine at idle speed, do you have any vacuum advance pulling? Use your timing light. With the engine idling, watch what happens to the timing mark when you alternately disconnect and reconnect the vacuum advance hose. |
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| Author: | 74SCAMP [ Sat May 07, 2005 4:21 pm ] |
| Post subject: | reply: SlantSixDan |
thanks for answering my questions. yes, it is a reman., actually, i'm glad the jets are so close, and no, there is no vacuum at 0* (tdc),but thats what i read some say is correct. i went as far as to test the vac/adv. and it was totally stuck. the dealer said it was discontinued but that he found one for $38.00. i bought a aftermarket distributor w/pot for $58.00. but even though i tested it out and it does pull, it has no effect if i plug the hose at idle. i've replaced about everything but the engine, also replaced the int/exh manifold gasket, adjusted valves tried 5*, 2.5*, and 0*. now i'm going to try reaming the "main jet" and see if it helps. thanks, again. |
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