Where do I start?

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gtgto

gtgto

FABO Gold Member
FABO Gold Member
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After my cam, lifters and pushrods got replaced in my 340 I fired up the car and it seemed it was running good....Not great. Drove the car for a few miles without any issues. I have heard a lot about valve adjustment and preload being a 1/4 to 3/4 turn after 0 lash. I initially did 3/4 of a turn.I removed the valve covers and backed it off 1/4 turn to 1/2 turn from the initial 3/4. I'm using 273 adjustable rockers that were already in the car. Today I took the car out and when I started it up cold it sounded like a hot start with the timing advanced to much with starter kick back. It did start and the idle was low and the engine was bouncing all over. I bumped up the idle a bit and it eliminated some but not all of the bouncing. I went out for a ride and it was running ok. Then I got to a big hill my car has climbed before and it was way down on power and pinging. I nursed her home and now thats where she sits. On a side note when I try to time the car I cannot see the balancer line ever moving the timing advanced or retarded where it runs. Where would you start? Do any of the symptoms sound like maybe my chain is off a tooth? Did I fry my new cam? A little freaked out. Or should I put the preload back where it was? The timing line not being visible has been that way since I initially got the car running.
 
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Are you 100% sure you have the firing order correct?

gtgto said:
I initially did 3/4 of a turn.I removed the valve covers and backed it off half turn to 1/2 turn from 3/4
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Also you said you turned it 3/4 turn then backed off 1/2 turn that would put it at 1/4 turn.
Iirc the lash on a hydrolic lifter cam will change the valve timing a few degrees ( I may be remembering this wrong???)
 
There’s been a few threads about similar issues this week. Was the cam degrees in during the cam swap? Was the balancer check to TDC along with distributor gear dropped in to the correct tooth for timing? Plug wires correct? How old is the coil?
 
The car was running ok before I went and backed off the preload a 1/4 of a turn making it 1/2 turn total. I will check the plug wires again and the coil is fairly new. I broke in the cam by running the motor at 2200 for 20 minutes on initial start up. The cam was degreed and was put in straight up. As far as dropping in the distributor gear, I have no idea if its on the right tooth. I dropped it in while the motor was at TDC and when I put the distributor in where the rotor is #1. Since the car was running ok to start and things have now gone wrong pretty quickly things were right and now they are not. What would cause that? I am having bad feelings but I plan on first removing the valve covers and putting the additional1/4 turn back in on the preload. It would be great if thats the issue. Other than that I will most likely pull the distributor and the wires and re install them step by step and see where that takes me. Hopefully later today, if not today tomorrow since I am off.
 
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383Scampman said:
If you have adjustable rockers and hydraulic lifters you need different pushrods .
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I measured and ordered them from Smith Brothers. They are great to deal with. So far today I put the 1/4 turn back into the preload so I am at 3/4 turn now again. Checked where my rotor is when getting to TDC on compression stroke. Put the wires back in place and had to go. Will try to fire it up later hopefully.
 
Well I put the car back to TDC and turned my distributor gear to the point where the slot is pointing at number 1 cylinder on front drivers side. I moved it about 3 teeth I think. Reinstalled the distributor and checked and rechecked my firing order. All looked good so I turned the key and she fired right up. Set timing to about 10 deg BTDC and can now see the timing mark on the balancer. Sweating like a dog in my garage and its getting late so I should be able to wrap it up tomorrow and go for a ride.
 
Kinda weird, backing off on the preload could make it noisy and lose some duration and lift. Not tragic. Too much preload could hold the valve open. That you would notice! What cam and Ignition is in it?
 
furrystump said:
Kinda weird, backing off on the preload could make it noisy and lose some duration and lift. Not tragic. Too much preload could hold the valve open. That you would notice! What cam and Ignition is in it?
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I ordered a 68 340 4 speed cam that Oregon Cam Grinders made for me. Great guy named Ken took care of me. FABO member krazycuda recommended them and has helped them by sending them an original cam for the specs to use. They also supplied the hydraulic lifters. Took a couple weeks to get to me in the east coast but well worth the wait for sure. I'm not sure what has been done to the bottom end of my engine in the cars 50+ years of the existence and it had adjustable rockers with hyd lifters previously. I debated going back to original rockers but was swayed to keep them from another FABO member. Glad I did or I wouldn't have learned how to adjust them. The ignition in the car is Mopar electronic ignition with an orange box and an MSD Blaster 2 coil.
 
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My thought is...you don't go and fix what isn't broken.

If it were me...id now add more preload and see if it gives better performance. If not.. set it back to where to where it was n leave it alone.
 
Definitely keep the rockers. Funny, I have a new 68 340 hyd cam sitting in my original 340. Put it in the motor and then never finished putting it together. Installed another motor so I didn’t have to worry about the original block. Will never use it, not a “stock” specs guy. Plus not a fan of hyd cams. Bought it back when I was young and foolish, now that I’m old and foolish solid flat tappet guy or solid roller.
 
After going for a ride today I need to re phrase what I thought was running good is not even close to good compared to the ride I just went on. Other than the idle being a little to high after getting up to temperature the car ran great. I was going to try and add another 1/4 turn preload but I'm happy where I'm at now. Totally happy with the way it runs right now. Cam sounds great at idle and just choppy enough to know work has been done. Now I can't wait to put the factory 3.91 center section back in to really get in trouble although from a dead stop and pounding the pedal the tires broke loose. Can't remember the last time that happened in this car. Oh yeah , never.....Great day for me plus I didn't have to work today.
 
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