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Can't get 340 to idle down #1161524 01/20/12 06:29 PM 01/20/12 06:29 PM
Joined: Jan 2012 Posts: 12 Forth Worth, TX L Limabean70 OP member
Limabean70 OP member L Joined: Jan 2012 Posts: 12 Forth Worth, TX	so I bought a 340 longblock from a guy off craigslist who said it was a runner. he kept the intake, carb, and distributor for himself and I still have mine that I took off my 318 about a month ago so I know they are fine. now when I put the motor in i cant get it to idle under 1500 rpm no matter what i do. ive changed the timing a bunch and no change. i know everything is good as i had it running on my 318 so it has to be something in the longblock. i also tried a diff carb and no change. so what in the longblock will make it so i cant get it to idle down? just wondering how far im going to have to tear into this motor and how much this is going to cost me. thanks and love the site!

Re: Can't get 340 to idle down [Re: Limabean70] #1161525 01/20/12 06:37 PM 01/20/12 06:37 PM
Joined: Oct 2003 Posts: 21,345 Marysville, O-H-I-O 70Cuda383 Too Many Posts
70Cuda383 Too Many Posts Joined: Oct 2003 Posts: 21,345 Marysville, O-H-I-O	what do you mean by "won't idle" what cam is in it? can you physically not get the RPM down, even if you turn the idle speed screw all the way in? is there a vacuum leak somewhere? I don't know of anything in the long block that will make RPM stay up. it's got to be in the cam timing, spark timing, or carb setting I would think. Photobucket sucks

Re: Can't get 340 to idle down [Re: Limabean70] #1161526 01/20/12 06:37 PM 01/20/12 06:37 PM
Joined: Feb 2005 Posts: 4,310 Prospect, PA BSB67 master
BSB67 master Joined: Feb 2005 Posts: 4,310 Prospect, PA	Is it possible that the intake is not sealing against the head? End rail pins or too thick end rail gasket could keep it from sealing

Re: Can't get 340 to idle down [Re: Limabean70] #1161527 01/20/12 06:39 PM 01/20/12 06:39 PM
Joined: Jul 2008 Posts: 72 Home of the Dart C cudarroger member
cudarroger member C Joined: Jul 2008 Posts: 72 Home of the Dart	Sounds like it could be intake gasket leak. You said everything else has been run before but now you have your intake on different heads. Could be mating surface.Are you sure the heads were not resurfaced?

Re: Can't get 340 to idle down [Re: cudarroger] #1161528 01/20/12 06:46 PM 01/20/12 06:46 PM
Joined: Jan 2012 Posts: 12 Forth Worth, TX L Limabean70 OP member
Limabean70 OP member L Joined: Jan 2012 Posts: 12 Forth Worth, TX	i dont know if the heads were resurfaced. the seller said he degreed the cam in at 106. i checked the cylinder pressure numbers and they were all right around 160 psi on my gage. i just know the intake, carb, and distr were all running fine on my motor before and theyre not working on this motor so it has to be the longblock. im just looking for ideas before i take it out of the car cuz my place sux to work on cars so i need to know what im dealing with before i get started. plus with school I dont have unlimited time.

Re: Can't get 340 to idle down [Re: Limabean70] #1161529 01/20/12 06:47 PM 01/20/12 06:47 PM
Joined: Jan 2012 Posts: 12 Forth Worth, TX L Limabean70 OP member
Limabean70 OP member L Joined: Jan 2012 Posts: 12 Forth Worth, TX	70Cuda, to answer your question i tried playing with the carb as much as possible with all the adjustments and it still wont idle below 1500 rpm. all the ports on the carb are plugged up with little rubber nipples.

Re: Can't get 340 to idle down [Re: Limabean70] #1161530 01/20/12 06:51 PM 01/20/12 06:51 PM
Joined: Apr 2005 Posts: 12,271 Overpriced Housing Central RobX4406 I Live Here
RobX4406 I Live Here Joined: Apr 2005 Posts: 12,271 Overpriced Housing Central	Carb/intake combo? Some carbs have linkage interference issues on certain intake manifold creating a vacuum leak.

Re: Can't get 340 to idle down [Re: Limabean70] #1161531 01/20/12 06:55 PM 01/20/12 06:55 PM
Joined: Jan 2004 Posts: 27,347 Today? Who Knows? 1_WILD_RT Management Trainee
1_WILD_RT Management Trainee Joined: Jan 2004 Posts: 27,347 Today? Who Knows?	At 1500 rpm is the idle still choppy? Cause if not the problem is elsewhere.. If the cam timing where wrong but the cam still mild it would idle down to some extent.. What your describing sounds like it's carb/ignition/vacuum leak related... Something happened between removal & reinstallation... "The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."

Re: Can't get 340 to idle down [Re: RobX4406] #1161532 01/20/12 06:55 PM 01/20/12 06:55 PM
Joined: Jan 2012 Posts: 12 Forth Worth, TX L Limabean70 OP member
Limabean70 OP member L Joined: Jan 2012 Posts: 12 Forth Worth, TX	Quote: Carb/intake combo? Some carbs have linkage interference issues on certain intake manifold creating a vacuum leak. its an edlbrock torker and edlbrock carb. like i said this combo worked before so it has to be the longblock. i know you guys know more than me so if I have to take it back to the guy or try to get him to pay for some fixes i need to know what to say to him.

Re: Can't get 340 to idle down [Re: Limabean70] #1161533 01/20/12 07:00 PM 01/20/12 07:00 PM
Joined: Dec 2007 Posts: 18,157 Mass DAYCLONA I Live Here
DAYCLONA I Live Here Joined: Dec 2007 Posts: 18,157 Mass	I had this problem one time before,...turned out to be a piece of gasket mat'l from the carb baseplate that got stuck on the SECONDARY throttle blade holding it open ever so slightly, just a tinny, tiny, winnie little bit! that the idle would never go down no matter how far you backed the idle screw off or OUT!...take the carb off and check to make sure the shaft blades are sealing front and rear completely.....

Re: Can't get 340 to idle down [Re: DAYCLONA] #1161534 01/20/12 07:03 PM 01/20/12 07:03 PM
Joined: Jan 2012 Posts: 12 Forth Worth, TX L Limabean70 OP member
Limabean70 OP member L Joined: Jan 2012 Posts: 12 Forth Worth, TX	Quote: I had this problem one time before,...turned out to be a piece of gasket mat'l from the carb baseplate that got stuck on the SECONDARY throttle blade holding it open ever so slightly, just a tinny, tiny, winnie little bit! that the idle would never go down no matter how far you backed the idle screw off or OUT!...take the carb off and check to make sure the shaft blades are sealing front and rear completely..... thanx, i cant right now cuz im on vacation in portland, or (rain sux) but I did have a friend helping me tune it who's a lot more experienced than I am and he said the carb was closing all the way. hes also the one that said it has to be the longblock cuz the intake and carb were working fine on my other motor.

Re: Can't get 340 to idle down [Re: Limabean70] #1161535 01/20/12 07:09 PM 01/20/12 07:09 PM
Joined: Jan 2004 Posts: 27,347 Today? Who Knows? 1_WILD_RT Management Trainee
1_WILD_RT Management Trainee Joined: Jan 2004 Posts: 27,347 Today? Who Knows?	Quote: Quote: Carb/intake combo? Some carbs have linkage interference issues on certain intake manifold creating a vacuum leak. its an edlbrock torker and edlbrock carb. like i said this combo worked before so it has to be the longblock. i know you guys know more than me so if I have to take it back to the guy or try to get him to pay for some fixes i need to know what to say to him. You bought a motor on C/L & you think your gonna get the seller to pay to fix it.. Never mind that it's not gonna be a problem with the long block.... Find someone with more experience than your friend... "The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."

Re: Can't get 340 to idle down [Re: 1_WILD_RT] #1161536 01/20/12 07:13 PM 01/20/12 07:13 PM
Joined: Jan 2012 Posts: 12 Forth Worth, TX L Limabean70 OP member
Limabean70 OP member L Joined: Jan 2012 Posts: 12 Forth Worth, TX	Quote: Quote: Quote: Carb/intake combo? Some carbs have linkage interference issues on certain intake manifold creating a vacuum leak. its an edlbrock torker and edlbrock carb. like i said this combo worked before so it has to be the longblock. i know you guys know more than me so if I have to take it back to the guy or try to get him to pay for some fixes i need to know what to say to him. You bought a motor on C/L & you think your gonna get the seller to pay to fix it.. Never mind that it's not gonna be a problem with the long block.... Find someone with more experience than your friend... why cant it be the longblock? my intake and carb were working fine before so it has to be the longblock right?

Re: Can't get 340 to idle down [Re: Limabean70] #1161537 01/20/12 07:14 PM 01/20/12 07:14 PM
Joined: Jan 2012 Posts: 12 Forth Worth, TX L Limabean70 OP member
Limabean70 OP member L Joined: Jan 2012 Posts: 12 Forth Worth, TX	oh, and the cam is a comp cams xe274h, he said it should idle at about 950 to 1000

Re: Can't get 340 to idle down [Re: Limabean70] #1161538 01/20/12 07:15 PM 01/20/12 07:15 PM
Joined: Apr 2005 Posts: 12,271 Overpriced Housing Central RobX4406 I Live Here
RobX4406 I Live Here Joined: Apr 2005 Posts: 12,271 Overpriced Housing Central	How long has the carb been stagnant. If it was sitting, was it completely drained and blown out of ALL fuel... Sure can be the carb in that case.

Re: Can't get 340 to idle down [Re: Limabean70] #1161539 01/20/12 07:17 PM 01/20/12 07:17 PM
Joined: Jan 2003 Posts: 32,910 Grand Prairie,Texas stumpy I Win
stumpy I Win Joined: Jan 2003 Posts: 32,910 Grand Prairie,Texas	Because there is nothing in the long block assembly that can cause that problem. If it won't idle down it's a carb intake or linkage problem.

Re: Can't get 340 to idle down [Re: stumpy] #1161540 01/20/12 07:19 PM 01/20/12 07:19 PM
Joined: Jan 2012 Posts: 12 Forth Worth, TX L Limabean70 OP member
Limabean70 OP member L Joined: Jan 2012 Posts: 12 Forth Worth, TX	Quote: Because there is nothing in the long block assembly that can cause that problem. If it won't idle down it's a carb intake or linkage problem. are you sure? im not disputing you but the score is tied right now 1 to 1 lol my buddy says it is the longblock and you say it isnt

Re: Can't get 340 to idle down [Re: Limabean70] #1161541 01/20/12 07:21 PM 01/20/12 07:21 PM
Joined: Jan 2004 Posts: 27,347 Today? Who Knows? 1_WILD_RT Management Trainee
1_WILD_RT Management Trainee Joined: Jan 2004 Posts: 27,347 Today? Who Knows?	Quote: Quote: Quote: Quote: Carb/intake combo? Some carbs have linkage interference issues on certain intake manifold creating a vacuum leak. its an edlbrock torker and edlbrock carb. like i said this combo worked before so it has to be the longblock. i know you guys know more than me so if I have to take it back to the guy or try to get him to pay for some fixes i need to know what to say to him. You bought a motor on C/L & you think your gonna get the seller to pay to fix it.. Never mind that it's not gonna be a problem with the long block.... Find someone with more experience than your friend... why cant it be the longblock? my intake and carb were working fine before so it has to be the longblock right? Because the long block is a mechanical device, if it has compression which you've verified it's gonna run, the cam timing could effect that but it would cause a choppy race car sort of idle... Thats not what your describing... You have a carb/ignition/vacuum leak issue... You might try talking to the guy that sold you the engine, he might have the tuning skills to help you if your cool about it.. You call him up & expect him to give you money back & he'll tell you where you can go.... "The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."

Re: Can't get 340 to idle down [Re: Limabean70] #1161542 01/20/12 07:23 PM 01/20/12 07:23 PM
Joined: Jan 2004 Posts: 27,347 Today? Who Knows? 1_WILD_RT Management Trainee
1_WILD_RT Management Trainee Joined: Jan 2004 Posts: 27,347 Today? Who Knows?	Quote: Quote: Because there is nothing in the long block assembly that can cause that problem. If it won't idle down it's a carb intake or linkage problem. are you sure? im not disputing you but the score is tied right now 1 to 1 lol my buddy says it is the longblock and you say it isnt You say 1 to 1 but we have allot more than one guy here saying look again... Your buddy is wrong... "The Armies of our ancestors were lucky, in that they were not trailed by a second army of pencil pushers."

Re: Can't get 340 to idle down [Re: Limabean70] #1161543 01/20/12 07:24 PM 01/20/12 07:24 PM
Joined: Jan 2003 Posts: 32,910 Grand Prairie,Texas stumpy I Win
stumpy I Win Joined: Jan 2003 Posts: 32,910 Grand Prairie,Texas	I've been a mechanic for 45 years and have built engines for that long.There is nothing in a long block that can cause a high idle problem. BTW it's more like 8 moparts guys aginst your buddy.

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