360 wont crank

[Chryco Psycho]

Sure , Happy to !
There is a lot to this , Mopar uses a larger diameter lifter which is a big advantage IF you design the cam to take advantage of it so the cam can ramp open & closed much faster without getting to the edge of the lifter . Comp designs are mostly based on Chev lobes using a smaller diameter lifter so the advantage is lost . In fact i Have seen the exact same cam spec on chev & Dodge cam grinds . By using the Mopar specific lobes I have been able to run solid flat tappet cams that are similar to smaller solid rollers cams without the expense . Even when the cam specs are similar you are only looking at 1 point on the lobe not the whole curve up & down , for example 240* @.050 , ok so .050 from closed the duration is 240* but what happens between .050 lift & .340 lift , how fast is the valve opened or closed ? This makes a huge difference as the longer the valve is opened the more air flow in & out & the motor is Only an air pump so more air = more power !
Back in the 80s there was a cam company called Ultradyne , & a man named Harold who designed those cams using the advantage of the wider lifter , later when Ultradyne closed down Lunati hired Harold & redesigned all of there cams thus the Voodoo line of cams . For example I often used a TF57 lobe which was 252* @ .050 duration with .578 lift in street engines & it was awesome , for example I built a 440/512 using 2 lobes , the exhaust was using this lobe & I was able to get 660 Grosshp [1970 rating ] while getting 17.9 mpg at 75 mph
Other cam companies have also used this wide lifter advantage in their cam designs Engle & Hughes come to mind & truely max out the advantage .
I have dynoed a lot of engines & the cam is really the most critical part of any build & the Mopars running Comp cams tend to be generally down on power & often significantly as in sometimes 30% .
SO if you spend all of the $$ to build an engine why throw away power that really costs no more , it is not like Comp cams are 1/2 the price of a Lunati !
Questions Please ask .... I am happy to share & If you feel I have helped I also accept donations .
I am also happy to call you & discuss things if that helps .

 

[jdcarnathan]

Chryco that’s some good information. Too often we see, use Lunati or Hughes or insert brand because that’s what I use on everything. No technical basis.

You are a wealth of knowledge and willing to help, I am sure once I pick a direction to go on a motor I will be hollering at ya to get an idea of the cam suggestion so I dont leave unnecessary power on the table.

 

[CMC]

Good to know!! ))

So can we stir lose those 2.0+ stainless steel valves?

What lunati would be the best for my 340?

KB pistons.

Maybe J heads

Building a cruiser but want to be able to get out of the way.....

 

[Chryco Psycho]

Cam choice involves everything , Auto or manual trans , vacuum for power brakes , stall speed for the converter , intended use / range where you need power , rear end gearing , headers or manifolds , intake manifold , after market or ported or stock heads [ if the port stops flowing at .500 lift no point in have the valve open to .575 ]

I would serious skip the X or J heads CMC , if you can find them the 308 swirl castings from 87-92 will kick their ass ! Also skip the KB pistons , the Speed Pro forged don't cost much more but are a far better piston , I refuse to use Hyperutectic pistons in any build the price difference is less than the cost of a gasket set to rebuild it .!

OK story to back it up , I swapped ported X heads for Ported 308 castings , we dynoed the 340 on Thursday swapped the heads on the weekend , went back to the same dyno on Wed & made 41 RWHP more .

 

[jdcarnathan]

Ok. So I took my ignition box off. Made sure the box was grounded well. Checked all plug/wire connections. Checked cap was connected in the right order 18436572.

Took the eddy 1806 off. And bought a brand new eddy 1906 650cfm carb. Set the idle mixture screws to 1 1/2 turns out. Didn’t touch idle speed or choke. Cranked it up. Fired off and ran high idle with the choke. Let it run prolly 20-30 seconds. Blipped the throttle a few times to see how it did through the range. Did great. Go back to idle and died and would t restart. I admit I’m not a great carb guy. Only messed with efi or diesels. Plenty of time with small race quad carbs. Just not sure.

 

[Chryco Psycho]

Ok well start with the basics the floats are never set properly after shipping so check that first

 

[jdcarnathan]

I’ll make sure a 7/16 bit goes under while touching it but not causing deflection. Once I get off work.

 

[CMC]

Good Stuff!!! Chryco....good stuff

So I checked into the 308s; sounds good. and i like sealed power too.
But where does one get lifters to go with that set up?
springs, and the right rods??

I plan to run 3:55's in the back, A/T 727, TTI headers,,,AAR side exhaust; PWR Brakes, and not sure what im going to do with the Torque Converter at this point.....just tryin to plan a buil dof a kick ass motor

HP does matter----Std manifold - maybe Holly 4 banger

....CMC

 

[jdcarnathan]

We got a split thread here. I got the eddy adjusted today. She is still a bit fat but she is running and idling. Took her down the road. She loads up a bit, need a bit more adjustment. Time to get a calibration kit. The idle isn’t affect by the idle mixture screws either, I think that’s because she is fat. Thoughts?

CMC sounds like you got a good plan going, I have some worked j heads that I’m rethinking now for some 308s or aluminum heads for the next motor.
Thanks for helping me spend money

 

[Chryco Psycho]

we should really split this thread out .
CMC
I am not helping either of spend you money , I am just helping you spend it wisely as you would spend it anyway !
Roseville has the Mopar lifters , Lunati sells kits with lifters & springs . You will need 10* locks & retainers .
the stock intake is remarkably good on the 340 , The LD 340 is a great intake if you can find one & the RPM air gap is good too but tall .
You can probably be looking at the Lunati 703 or possibly the 704 cam

JD
Often if the mixture screws have no effect the throttle plates are open too far & the idle slots are uncovered so opening the rear throttle plaes is a good solution but you cannot do that with the Eddy Carb also going to a smaller air blled is a good move but you cannot do that with an eddy carb .... so maybe you need to drill a small hole in the throttle plate so more air gets in while the throttle plaes can be closed down to make the mixture screws effective .

 

[jdcarnathan]

I’ll give that a shot potentially CP. I tried to crank it this morning and drive it. Did great. A couple hours later same. A few hours later while on uneven ground no luck. I think I still have a float issue potentially, right at 7/16 like the manual says but I will check my fuel pressure. If it’s high I am thinking of squeezing the floats another 1/16 closed and see if it helps. Correct me if I’m wrong (prolly am) if I swap to a leaner main jet. That’s still part of the idle circuit no? Would that not help a bit?

Other thought is I have some worked J Heads and an air gap Intake on the shelf and that crappy comp cam. (Just buy another most likely) but thinking may just do a new top end on it and that should help the richness albeit in a crazy round about more labor involved way.

 

[Chryco Psycho]

if the fuel pressure is high add another 1/16 so the float sits lower .
Main jets have nothing to do with Idle

Your call if you want to redo the top end

 

[jdcarnathan]

Losing my mind I think. New mechanical pump dead. Old pump installed and now dead. I’m keeping the arm beneath the eccentric. And they pump well for a bit then quick. Could the eccentric have any issue or thoughts? Half tempted to put an electric pump and regulator on it and be done with it.