Need help with original 340 challenger!

[moparmade43]

Guys, I have an original 340 challenger r/t, 1971, with 32,000 original miles on it. Recently, there has been a ticking noise coming from under the hood, and I have finally pinpointed it I think, using a wooden dowel and lots of patience. The tick is loudest using the dowel on the timing mark directly beside/behind the balancer. The balancer and pulley are original. My question is, if a balancer is bad, would it cause the noise I am hearing? Any other ideas. It could be chain/sprocket, but with that low mileage I'm skeptical, especially as the rest of the timing chain cover does not produce the same amount of noise as right beside the balancer. By the way, this is not a knock, like a rod, but a very distinct tick, almost tinny sounding. At first I thought lifter, but the sound is very week at the intake and heads. Any help would be GREATLY appreciated, I am trying to get it fixed for a big show on sunday. My buddy has the new challenger and we were going to park them side by side. Thanks in adance.

Will

[wilks3]

Could it be the fuel pump or fuel pump rod?
Take the fuel pump off and start engine, it'll run long enough to see if noise goes away. My fuel pump rod was worn, didn't tick but caused fuel delievery problems.

[dodger1]

No fuel pump rod on smallblocks, but it could be the pump arm/ eccentric contact area is damaged. Although that's a stretch. I can't think of how a damaged balancer would make such a noise either, but others here certainly have more experience than I do.

[moparmade43]

yeah, the more I think about it, I think it must be the sprocket/chain or both. I just can't imagine with that low of mileage, but i've seen stranger things. Does anybody know if a 71 340 used a steel sprocket and chain, or if it was that nylon or whatever else they used?

[dodger1]

According to "How to rebuild your small-block Mopar", all 340s had a 2-row roller chain, steel crank/iron cam sprockets. The comment is "slightly noisier but much more durable---" I have a Cloyes roller chain set in my 360, but never noticed any noise increase. Something to do with the leaky headers and unsilenced air cleaner, I suspect. Given the age of your 340, the chain may be noisy anyway.

[DonCarr]

could the noise be a sticking vane in the power steering pump ?

Usually hydraulic lifters tick when gummed up or low oil pressure..

[moparmade43]

I think I'm just going to take the timing chain cover off and see what I can find. This noise just appeared, it never made it before. It had 14,000 miles when dad bought it in 1995, it now has 32,000, and this is a first. Good thought on the power steering pump, but it is a manual steering car. Also oil pressure looks good, so I guess I'll see what I find out tomorrow. I just dont see how a double roller chain with iron sprockets could go bad after 32,000 miles, regardless of age?

Thanks,

Will

[moparmade43]

Thanks for all your help, It was in fact the timing chain was shot. The chain was SCARY loose, and the cam actually jumped a tooth or two, but I got all that taken care of and fired up, and all is well. Thanks for your advice. Now on to the second part of the problem. The car surges at cruising speed and has a lack of power, and really falls on its face when you get on it, especially at high rpm. I think it is fuel pressure, as it doesn't do it nearly as bad if you rev it up to redline with the car parked. If it was timing or electrical, it would do it at all times I would think. Also, I have eliminated the carburetor as I have put a known good rebuilt thermoquad on it, and no change, although it starts much better now. I'm thinking the sending unit sock is shot, and is starving the engine. It is the factory pump, lines and tank, never been opened up. The lines are 5/16 also, which is probably not helping if the engine is starving already. I fabbed up a fuel pressure gauge into the cockpit, and after dinner. I plan on takin it down the road and seeing what it reads. I know you want fuel pressure around 7-7.5 psi, but my questions is should the pressure drop as rpm's increase, or should it be able to supply a steady 7 psi throughout the rpm band? Thanks for any help, this is the last thing to get this car road ready!

Will

[wilks3]

YIKES!!! Rev to redline in park? To me it would be time and money well spent to just change the fuel pump. How about just mounting fabbed up fuel pressure gauge to windshield wipers instead of inside by you?
If car still surges after pump change, change the sock out.
..........but what do I know, fuel pump rod on a small block.......sorry.

[aarracer]

Will

The thermoquad has an idiosyncrasy of having/mandatorily requiring a lower maximum fuel pressure.

There's some info/a thread here from Demon Sizzer under "Thermoquad's"that is the best!

[Dick]

Are you sure the chain jumped a tooth or two? If you replaced the chain and hopefully sprockets and put it all back together, correcting the "jumped tooth or two," and now it has no power under load, I would suspect the cam timing was off.....maybe a tooth or two. It may have been right before.

[Dart 65]

I thought R/Ts were only big blocks.

[moparmade43]

Dick, this problem has been happening for a while, before I changed the chain and sprockets. The car acts just like it did before, only starts much easier and the total timing is back down to where it should be, around 35-36*. The suspected fuel problem has been this way for a year or two. This is why the car sat while other projects were finished. Now I have the time to fix it.
I may be wrong, but I dont think the chain and sprockets are related, and I am suspecting fuel starvation, either from a pinched line, clogged sending unit sock, or both. The tank has never been dropped off this car, and the car did sit for many years. Dad bought it in 1995 with only 14,700 miles on it, and the last inspection sticker was in 1976, so it did a lot of sitting around. Any other suggestions?

Dart 65, I think that in 1970 you could only get a big block in a challenger r/t, but in 71 they added the 340.

[dwc43]

Originally Posted by moparmade43

Also, I have eliminated the carburetor as I have put a known good rebuilt thermoquad on it, and no change, although it starts much better now. I'm thinking the sending unit sock is shot, and is starving the engine. It is the factory pump, lines and tank, never been opened up. The lines are 5/16 also, which is probably not helping if the engine is starving already. I fabbed up a fuel pressure gauge into the cockpit, and after dinner. I plan on takin it down the road and seeing what it reads. I know you want fuel pressure around 7-7.5 psi, but my questions is should the pressure drop as rpm's increase, or should it be able to supply a steady 7 psi throughout the rpm band? Thanks for any help, this is the last thing to get this car road ready!

Will

5/16th line wont starve the car at all. That's all it needs. We run the same line on our race car at over 400 hp and there's no starving issues due to the line size. Most everyone likes to go too big on the lines. A 3/8 line 400 plus hp cars would be the max you should ever need on a street car. Only six pack cars and Hemis got the 3/8 line anyways.

7psi is the max pressure for any carb. Your stock car should be about 4.5 to 6 psi. and it should read pretty steady.

A clean sock would not hurt. They tend to break up due to the fuel over the years. And they usually get sucked closed when you stand on it, but work fine under idle or cruise.

[Dart 65]

Originally Posted by moparmade43

Dart 65, I think that in 1970 you could only get a big block in a challenger r/t, but in 71 they added the 340.

I'll see if I can find something in my library about this. Thanks.

[moparmade43]

ok guys, I have the sending unit out of the gas tank, and I believe the unit is good, I have around 11 ohms at full, and around 73-75 ohms at empty. Can anyone confirm this is correct or not, so I don't buy a sending unit I don't need. Also, the sock looks nasty, and is probably part of the reason the engine is starving for fuel, but unfortunately I cannot find a replacement one at any of my parts stores. Have any of you bought one from your local parts stores or dealers, or is this a "year one only" type part?

Thanks,

Will

[BigBlockDude]

I got a sock filter from the local dodge dealer before.

[JVMopar]

Float setting could also cause your problem. or how about restricted needle and seat. Change the sock and fuel filter and drive it again. If you still have problems I'd pull the carb apart and check the float setting, check the needle and seat, and clean it.

[ehostler]

Originally Posted by moparmade43

Dart 65, I think that in 1970 you could only get a big block in a challenger r/t, but in 71 they added the 340.

That is correct

[moparmade43]

Found the problem, several of the cam lobes are wiped, and others are on their way. Thanks new oil!!!

Appreciate all your help guys, now comes the fun.

Will

[cudabob496]

Over 7 fuel pressue seems too high. My dual feed 850 Holley does great on 6 psi. High fuel press can mess up a carbs performance.

[70Ted]

and hope the cam debrie didnt kill the bearings. what oil was used?