70 Challenger T/A - No Idle, runs poorly after lifter/pushrods replaced

[Russ Furchner]

Did you do a compression test after the installation of new pushrods

No, I did not. I'm going to get everything sealed properly and deal with center carb. If that does not resolve it, I may revisit this. I very comfortable I set up the valve train correctly, I've done that before on this engine with no issues. New parts should not change that, I was very careful on making sure this was all correct. There could be a bad component in there, but there is no lifter noise anymore, it's moving and oiling properly.

 

[budascuda]

I was wondering ..... a vacuum test is quick and establishes whether the seals are good. If that's the case, when you re do the
work, you would know off hand what the problem is and you won't go too deep into the engine.
jmho

 

[Old Mopar]

Good to hear this. I love the idea of the six pack, but keep 3 carbs in sync is not easy. I've rebuilt them as well, so the outboards seem to be working well and the are probably original, The center carb has been messed with for sure, so I have no idea of a baseline. This weekend, I'm using the old metering block, which lacked a vacuum advance, but worked. Replacing the .070 jets/power valve delete with .061 and a 7.5 power valve. I'm also suspicious that the block may have been decked given the tolerance between the block and intake manifold on the block ends, it's only about .070, so very tight for cork gaskets. Going with the black RTV instead, just to guarantee a seal. Because I'm OCD, I'll re-check everything along the way. 3rd time is the charm.

Please stop repeating wrong information about six paks. Why do you insist?
That is so untrue "but [to] keep 3 carbs in sync is not easy." BS BS BS BS
70 jets in the ctr carb and a power valve delete to 61 jets and a 7.5 pwr valve? What?

As for the op's problem you should have just replaced the lifters and pushrods and left the ctr carb alone. One crisis at a time
You set the preload to how many turns of the screw? one turn = 0.040 and you want .040-.060 preload.How many threads are showing below the rocker arm?
Does the intake fit the engine properly? Bolt holes should line up with the gasket installed, no compromises.
You should not use the cork end gaskets. The intake gaskets should be the type that block the cross over and you should have a 190 or 195 thermostat in the car

 

[fastmark]

I agree with old mopar. Six packs are just as easy as a four barrel if you know how to tune. First thing that pops in my mind is the fact that you changed more than one thing at a time. Old racers advice is change one thing at a time. Cams develop a wear pattern on lifters. Now that you have disturbed that wear pattern by changing all the lifters, get ready to flatten a lob on the cam. Maybe several. Been there, done that. But to the carb problem. What is the list number of the carb we are talking about? All oem 6 packs had a metering block with a vacuum port for the advance. If yours does not, someone replaced replaced it. There are many different metering blocks out there and all have different internal orifices. Stock on a 4792 or 4791 is 6610. Since Bill Overcash has passed, I’ve decided to start a six pack restoration service. It’s not quite up and running yet. I really want to build a test mule engine to at least set carbs up before I send them out. Now one option you need to try. Promax makes a metering block that is billet and he sets it up for a six pack. I just installed one one a customers car. It works perfect. I installed an wideband O2 sensor in the exhaust. It really helps tuning. My customer read an article on the internet about the absolute best way the tune a six pack. He had some good points but some were just acceptable. Well at his request, I tried it. It was so far off, it would not even idle. I went back to my setup and perfect AFR readings. With my tune, it will put a grin on your face. It idles perfect. The off idle is great and power is, well, let’s just say. If you were on a date in high school, you’d forget all about the girl in the seat next to you.

 

[Chryco Psycho]

If it helps I can call you & we can discuss the 6 pack tuning

 

[Chryco Psycho]

I also agree that 6 packs are not hard to work with & tune have set up numerous systems .
I agree with blocking the heat crossover this helps a lot .
changing 1 thing at a time is the best way so now you have to figure out which change hurt you .

 

[Russ Furchner]

Update: Installed the new intake gaskets, did not use the cork end pieces, just black silicone. Old metering block, new jets and restored the power valve. Runs great and no lifter noise. Job done.

 

[Russ Furchner]

I also agree that 6 packs are not hard to work with & tune have set up numerous systems .
I agree with blocking the heat crossover this helps a lot .
changing 1 thing at a time is the best way so now you have to figure out which change hurt you .

Thank you for the offer. I do want to restore the vacuum advance at some point. Why it was deleted in the first place is still a mystery.

 

[fasjac]

Interesting, I’ve just developed a leak at the accelerator pump diaphragm. Gonna go do em all as they’ve been there for 10-12 years. I’m running 64’s in the center. Runs great.

 

[71Cuda4fun]

Frustrating for sure. I would put the old metering block back on. I lean towards a manifold leak since you mentioned something about the block being decked. Run the car and spray carb cleaner around the carbs and manifold. Then spray each intake manifold runner to the head to see if you get a rise in rpm. I had to reseal my son’s 360 intake 3 times. Be sure to put silicone at the corners of the manifold to the block/ head locations. His had an issue between 3-5 intake runners.

 

[Russ Furchner]

Frustrating for sure. I would put the old metering block back on. I lean towards a manifold leak since you mentioned something about the block being decked. Run the car and spray carb cleaner around the carbs and manifold. Then spray each intake manifold runner to the head to see if you get a rise in rpm. I had to reseal my son’s 360 intake 3 times. Be sure to put silicone at the corners of the manifold to the block/ head locations. His had an issue between 3-5 intake runners.

It was frustrating, I believe the main issue was the metering block. I'll post a picture of it if I can get the right resolution, I think the person I worked with at Holley just sent me the wrong part. Too many things did not look right, it would be interesting to get other opinions on the possible application. I put in stock sized jets and a power valve in the old metering block and all is well. It's not the end-state because I want the vacuum advance back, but it runs better than it did before and the valvetrain is quiet.

 

[Phillip Reeves]

Hello I just wanted to ask what was your overall pushrod length the TA is 7.23 as seen on the Chrysler sheet shown if the pushrods it causes issues the only replacement manufacturer I have found was melling to have the correct length. I have had quite a few years with mopar six packs and they are something to drive when they are running correct .

 

[Phillip Reeves]

PS since pump gas is running Alcohol in the fuel year round should you be running on that use the Holley diaphrams with the green inner liner they are made for withstanding Alcohol regular ones can get eaten up along with regular fuel line with in months and the Alcohol eating at the rubber will put all that into the carb continuously until you either switch fuel or replace the damaged components with Alcohol resistant pieces.
just don't want to see anyone loose something nice to a disaster.

 

[Russ Furchner]

Hello I just wanted to ask what was your overall pushrod length the TA is 7.23 as seen on the Chrysler sheet shown if the pushrods it causes issues the only replacement manufacturer I have found was melling to have the correct length. I have had quite a few years with mopar six packs and they are something to drive when they are running correct .

It took quite a while on the phone with Comp Cams to get that right. Most people don't understand the T/A engines are different in some areas, they stop listening past 340.

 

[Russ Furchner]

PS since pump gas is running Alcohol in the fuel year round should you be running on that use the Holley diaphrams with the green inner liner they are made for withstanding Alcohol regular ones can get eaten up along with regular fuel line with in months and the Alcohol eating at the rubber will put all that into the carb continuously until you either switch fuel or replace the damaged components with Alcohol resistant pieces.
just don't want to see anyone loose something nice to a disaster.

I know the rebuild kits and the fuel valves were for modern fuels, but since I ordered them from the same guy that spec'd the metering block, I'm going to check again. You are not talking about the vacuum pods on the outboards are you?

 

[Phillip Reeves]

so are you any further on the problem or still with no idle?
just out of curiosity were the original pushrods bent or the tips worn significantly being a low mile motor they should have still been in decent condition unless something significant occured

 

[Phillip Reeves]

as far as the green liner no I was referring to the accelerator pump

 

[Russ Furchner]

so are you any further on the problem or still with no idle?
just out of curiosity were the original pushrods bent or the tips worn significantly being a low mile motor they should have still been in decent condition unless something significant occured

It runs better than before and no noise from the valvetrain. I'm pretty sure that while the intake did not seal perfectly, it was the metering block that was the problem all along. There was only one lifter making noise and only under certain conditions, I just did not want a failure where something major breaks and I wanted my eyes on as many things as possible so I knew the condition. There was almost no wear on anything, which is why I stopped at the lifters and pushrods. The car was supposed to be a "survivor" when I bought it, but it was clear when my brother and I inspected it, that was not the case. Body and Interior, yes, but not the engine. All the numbers match, build sheet and fender tag are correct, but it was fairly obvious that work had been done to at least the top end and carbs. I bought it accordingly expecting to spend money on the engine at some point. I was just hoping it had not been bored past usable. I don't plan on selling it anyway.

 

[Phillip Reeves]

Here's what the resistant pump look like the regular ones are black.
Glad you got it running The Holley 2 bbl carbs they used on these were fairly straight forward
usually the only things that got messed up were fuel bowls and base plates.
As far as gaskets for my setups over the years I used the plain aluminum manifold gasket from Edlebrock or MRG
now if I have trouble with something sealing I use the grey motoseal very resistant to anything gas synthetics etc.
and the old gasket comes away decently when servicing.
there is a service note on using standard silicones on surfaces that get in contact with synthetics
the synthetics in oil tend to attack the silicone and you end up with a leak.
Thats why theres a green silicone for gear oil applications that is synthetic resistant
High Tack , Motoseal and good ole #2 don't do that so one of those I use for gaskets sealing oil
I don't use silicone on gaskets unless sealing water
I will be doing a cam and lifter change on my TA to the restocam kit since the previous owner changed the cam.
3rd original TA for me but this one is only 68k miles so in very good shape.
Phil