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Old 02-24-2012, 07:07 PM
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392 trouble

Hello, I am new to the forum. I like alot what i have read so far, so maybe someone could help.
Ive posted this elsewhere but have no success.
Chrysler 1958 392, fresh rebuild, with now 1500 miles on it.
10 to 1, msd electronic dist., mild cam, balanced /blueprinted, running a 750 edelbrock, with headers.Motor really purrs.
This is the problem: car starts, runs and idles well, but when i step into it, and rpm rises to about 3200rpm, i get "pinging", or the motor runs rough. Wont pull any more beyond this. If i accelerate slowly, the car will drive 75 , 85 mph.etc.
I believe i have the timing set to 12 degrees initial, 30 degrees total, all in by 2500rpm. I have switched the advance springs in the dist, run without vacuum advance, to no avail.
I am getting adequate fuel, and switched carbs from holley 750 to the edelbrock thinking the trouble was fuel related, but i am pretty certain it is ignition now. btw, matching msd coil, 8.8 mm wires (msd also )
something is amiss. Thinking of send dist. back to company for checkup.
Thanks for any thoughts.

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Old 02-24-2012, 08:07 PM
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I was going to say fuel but you already said its not ! another cause could be valve float, I don"t see it much any more but it can have the same symptoms! Loss of power at rpm, pinging & will pick up a little more speed after lifters settle down if throttle is applied lightly! 392 Hemis & other chryslers valve geometry is very easy to throw out of wack if you dont know Chrysler!! (Its not like a chevy, EASY!) LOL

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Old 02-24-2012, 09:52 PM
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Jester is correct that early hemis had fairly radical valve train geometry and they need to be set right or won't perform. Valve float could be a problem if your running a high lift cam and using stock springs, especially if they're original to the engine. However, if your running any cam that has a higher lift than stock you need to run adjustable pushrods, otherwise your valve lash will be WAY off. Another thing to think about, 10:1 compression is on the ragged edge when it comes to pump gas. Try a 104 octane booster and see if that helps the pinging.

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Old 02-25-2012, 08:43 AM
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Thanks for the rapid replies.
I am using adjustable pushrods, with hydraulic lifters. Using new Chrysler 300 (1958) valve springs.The shop that did the assembly installed them. I have not checked clearances.
If you would please indulge me, what would i set them to?
I believe i could handle the task having owned slant sixes, and early mopar flatheads, just not sure what they should be.
I picked up a copy of The early hemi handbook, but i dont believe there is any reference to adjustment.thanks, Russ
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Old 02-25-2012, 10:38 AM
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When it comes to adjusting valves on an early hemi using hydraulic lifters, it's the same procedure used on any small block Chevy. Once you have the cam lobe bottomed out for a particular cylinder, simply adjust the pushrod to take the "play" out of it and then continue one full turn on the adjustment and lock it down. This gives the lifter the proper preload. Since the firing order on an early hemi is the same as the small block Chevy the same valve adjusting sequence can be followed as well.

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Old 02-25-2012, 11:46 AM
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You need to know what lifters are installed Standard, anti pump ups, roads etc? some are adjusted with a preload some aren't. Chrysler used different length push rods and valve lash caps not adjustable push rods at the time. I only use adjustable push rods to check rod length I never run them on any engine I build! But thats my choice do what your comfortable with Also lifters on Chryslers were clearanced and measured at full collapse like a ford F.E. side oiler. I would have thought your engine builder would have used (or talked you into ) adjustable rockers and the right length custom push rods. I also use the valve lash caps with roller rockers or standard rockers on Chryslers especially with stainless valves ( because of the softer stainless compared to steel with hardened tiped valves) and it gives a little more surface area for your roller to ride on. Its just the way I do things

Adjustable push rods may add to your problem some of the cheep brands flex at high rpm and pressures! Try setting your rockers at .000 lash and see if the problem goes away or appears at a higher rpm if it does you need better lifters or redo your valve geometry (and I would suggest a builder with more experience with older Chrysler engines) If you cant adjust them you have to change your set up so you can!!!

These are just suggestions: Jester

Take some pics of your valve train from different angles so we can see the geometry and set up it would help

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Old 02-25-2012, 01:13 PM
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Jester's method is the "expensive" right way to do it. However, those parts are pricey. For street motors most now use adjustable pushrods, which are plenty strong enough for 99% of the street engines out there. And.... only cost around $150. A set of adjustable rocker shafts will cost you a minimum of $400 and they'll probably need to be rebuilt. Add custom length push rods and roller tipped rockers and you're going to be spending upwards of a grand. Money well spent if your going racing, but for a mild street engine it's probably a little overkill. Just my opinion.

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Old 02-25-2012, 03:10 PM
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Quote:
Originally Posted by Russchiappa
Thanks for the rapid replies.
I am using adjustable pushrods, with hydraulic lifters. Using new Chrysler 300 (1958) valve springs.The shop that did the assembly installed them. I have not checked clearances.
If you would please indulge me, what would i set them to?
I believe i could handle the task having owned slant sixes, and early mopar flatheads, just not sure what they should be.
I picked up a copy of The early hemi handbook, but i dont believe there is any reference to adjustment.thanks, Russ
Ok: first thing the solid lifter cams in the 300 in 1956,57,58 had spring pressures of 158# at 1&7/32" at an installed height of 1&21/32" and the hydraulic on others engines had 170# at 1&5/16" at an installed height of 1&11/16" in 1959 , 60 & 61 the 300s ran all hydraulics and spring pressures climbed to 195# at 1&15/32" at an installed height of 1&55/64"

What spring pressures and installed height did the cam co. recommend for the cam your running What are the cam card specs ?

In 1955 spring pressures were only 126# at 1&5/16" at an installed height of 1&11/16" You may have the wrong springs installed! Some auto parts stores will list one spring for all assembly's on the early Hemis and if you don't specify exactly what pressure & height you need your screwed especially if they are not checked by the builder before installing!!

The adjustment is the distance between the rocker arm and valve tip when the valve is fully closed and lifter is fully collapsed! Its very hard to explain that to people that weren't trained on the early Chryslers & Fords LOL There is a tool made that will help if you do this. At Chryslers and Fords when you cut valve seats and dressed valve tips or changed a lifter with the non adjustable rocker arm shaft for hydraulics you might have different length push rods or valve lash caps for different cylinders Thats where the saying came from " make sure the push rods go back on exactly in the spot you removed them from" Ford was the same way LOL!! Ford and Chrysler called the adjustment when the rockers and shaft was installed .000" or Zero lash because the lash was already set when the shaft and rockers are being installed. Guys that really know Chryslers & Fords Know this very well !!! I work on a lot of Chrysler engines and I have to do this quite a bit! thats why I said Chevys were easy

Most Chrysler hydraulic lifters collapsed to within the specified clearances so it wasn't very often you had to do any changes on stock builds but once you change to high performance lifters, rocker arms, cams etc, etc, you are changing the entire valve train geometry and opening a can of worms if you don't know what your doing!

Im sure Im going to get a lot of disagreements on what I wrote you LOL so take it as a grain of salt!

Jester
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Old 02-25-2012, 03:13 PM
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[QUOTE=Centerline]Jester's method is the "expensive"

Centerline is 100% right its very expensive

Jester
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Old 02-25-2012, 03:22 PM
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Valve timing could be off. Double check the timing chain.

vicrod
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Old 02-26-2012, 02:25 PM
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valve adjustment is not going to cause detonation. You most likely need to back the timing down or increase the octane of the fuel. Either will have the same overall effect. 10:1 is pushing the limit but the limit also depends on other variables. Something as simple as spark plug reach can make a difference.
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Old 02-26-2012, 07:12 PM
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I don't think it is detonation! Because even if it is detonation when he showers down on the throttle! He should easily pick up speed beyond that rpm range when the throttle is applied slowly. But floating valves can cause a pinging or clicking noise, caused by the lifters lofting off the the cam lobes and when the cam lobes comes around again the lifter hits it and lofts again ( its called float)! the valves are open for the entire revolution of the cam causing no vacuum and no compression (loss of speed, and the engine wont accelerate beyond or near the same rpm each time) until the valve train slows and settles down again and then you might pick up speed to about that rpm again maybe a little more till it starts to floats again! The way Russ explained his problem and just having the engine done with the early 300 valve springs and a different cam then the springs were designed for and probably other then stock lifters and adjustable push rods which could be heavier!! valve loft is a very reasonable assumption especially an an early Chrysler Hemi with a very critical valve geometry!!!

He also said it was built in a shop and blue printed at 10to1 comp so he already knows the octane needed ! And like I said (octane) I don't think is his problem! He already backed off timing, he said it started good,, that must mean hot or cold and he didn't mention any other problems that would point to low octane! But then I could be totally wrong it may be something else

Jester
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Old 02-27-2012, 06:40 AM
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Quote:
Originally Posted by painted jester
I don't think it is detonation! Because even if it is detonation when he showers down on the throttle! He should easily pick up speed beyond that rpm range when the throttle is applied slowly. But floating valves can cause a pinging or clicking noise, caused by the lifters lofting off the the cam lobes and when the cam lobes comes around again the lifter hits it and lofts again ( its called float)! the valves are open for the entire revolution of the cam causing no vacuum and no compression (loss of speed, and the engine wont accelerate beyond or near the same rpm each time) until the valve train slows and settles down again and then you might pick up speed to about that rpm again maybe a little more till it starts to floats again! The way Russ explained his problem and just having the engine done with the early 300 valve springs and a different cam then the springs were designed for and probably other then stock lifters and adjustable push rods which could be heavier!! valve loft is a very reasonable assumption especially an an early Chrysler Hemi with a very critical valve geometry!!!

He also said it was built in a shop and blue printed at 10to1 comp so he already knows the octane needed ! And like I said (octane) I don't think is his problem! He already backed off timing, he said it started good,, that must mean hot or cold and he didn't mention any other problems that would point to low octane! But then I could be totally wrong it may be something else

Jester
Detonation, if bad enough will cause a lack of power and acceleration. He said pinging so I assumed he knows what pinging is. I could be wrong
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Old 02-27-2012, 08:26 AM
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Quote:
Originally Posted by Russchiappa
Hello, I am new to the forum. I like alot what i have read so far, so maybe someone could help.
Ive posted this elsewhere but have no success.
Chrysler 1958 392, fresh rebuild, with now 1500 miles on it.
10 to 1, msd electronic dist., mild cam, balanced /blueprinted, running a 750 edelbrock, with headers.Motor really purrs.
This is the problem: car starts, runs and idles well, but when i step into it, and rpm rises to about 3200rpm, i get "pinging", or the motor runs rough. Wont pull any more beyond this. If i accelerate slowly, the car will drive 75 , 85 mph.etc.
I believe i have the timing set to 12 degrees initial, 30 degrees total, all in by 2500rpm. I have switched the advance springs in the dist, run without vacuum advance, to no avail.
I am getting adequate fuel, and switched carbs from holley 750 to the edelbrock thinking the trouble was fuel related, but i am pretty certain it is ignition now. btw, matching msd coil, 8.8 mm wires (msd also )
something is amiss. Thinking of send dist. back to company for checkup.
Thanks for any thoughts.
392 Hemi combustion chambers/pistons aren't known for their "quench", at least not in the same sense as a wedge chamber w/quench pad(s). The domes needed in most higher compression applications also don't do a lot for flame propagation unless some tricks are used, like Dick Landy did on the Hemi piston on the right (below):



Because of that- and just because that's a lot of CR for ANY engine w/iron heads and a mild cam- I would be looking at the dynamic compression ratio- using 10:1 on an iron head Hemi w/a "mild" cam and today's for-**** gasoline is an invitation to severe detonation.
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Old 03-05-2012, 07:11 PM
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I was able to find the original distributor in storage, so i am going to install that asap, to rule out the MSD that is currently firing the motor.
I purchased the MSD "ready to run" distributor through HotHeads, as well as all the other ingredients to put this motor together, then a very reputable shop did the assembly. Old school racers, who have done hemis.
I have heard much heresay that the msd s are often culprit, (find this hard to believe,) so just to rule it out, going to try the O.E. dist.
btw , this motor really runs pretty nice, but i know there is untapped power on hand once this trouble is sorted.
Thanks for the replies. I will do update asap. Russ
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