440 problems/quenching?/advice needed

-
dkbug

dkbug

Well-Known Member
Joined
May 11, 2011
Messages
413
Reaction score
11
Location
Norman, Oklahoma
Ok, I reached out to people on a facebook post and got blown away by the information. I a 24 with experience with mechanics and the assembly but not much on the technical side of compression/combustion facts. So I turn to you guys to school me up.

I am a mechanical engineering student in my senior year, so don't be afraid to throw some big words at me....

The motor runs and drives, but I had a go kart in middle school that I think was 5 hp that ran MUCH better than this... The 440 is detonating.

I did some reading on quenching and how it effects performance while avoiding detonation. From what I gathered, quenching is basically the excitement of the fuel in a specifically correct amount of space between the piston and the flat part of the chamber. Quenching from what I understand it to be, helps with fuel combustion and "atomization" of the fuel providing great longevity and effectiveness of the process. Phew, that is very hard to explain and it sure took me awhile to get into my head.

Here is my combo. I understand why I am having a problem, I am just here to learn how to fix it.

440 - 1978 block.

FROM WHAT I HAVE BEEN TOLD~~~

it is a stock stroke with a 20/20 crank
stock rods
aftermarket flat top pistons (.030) WITHOUT VALVE RELIEFS
ZERO DECKED....
I have 516 close chambered heads from a 1967 383
fresh valve job with very little porting done
springs to match the cam
STOCK VALVE ROCKER ASSEMBLY... I know..
Weiand dual plane intake
750 edle carb

Cam specs~~~
Mopar performance .528 purple mechanical camshaft/ I measured this lift to be correct.
Didn't calculate the duration..

Now when you guys stop laughing at obvious mistakes... feel free to chime in to what I can do to have a decent cruising street motor. I have no intention on going 11 in a quarter mile or blowing the doors off of someone. Just want to enjoy the car.

Now the obvious mistakes that I pointed out, is that the lift of the camshaft is WAY to big for non-adjustable rockers. I am sure the cam has already been smoked in the process of this motor running... Quenching is going to be absolute garbage since the motor is zero decked on stock stroke with a closed chambered head without valve reliefs.... I am sure my TDC piston to flat chamber height is less than the recommended .040". Not really sure what the compression ratio is, but with a stock style head gasket I am sure this thing is well over 11:1 compression and will not run on the fuel I have hear in my state..



Now with that all said and done.... I want to do this with a budget. Surely I can keep the crank and rods/piston combo that is already there.

From what I can think in my head and calculate, I plan on running a much smaller cam. Probably within the .484 range so that I can avoid spending the big bucks on adjustable rockers... Next is the heads, I am going to trash the close chambered heads and get an open chambered cast to help with the compression ratio, as well as a thicker head gasket or head shim.

Experts of FABO, you guys never let me down. I admit I am young and not as knowledgeable as some of our members, so I ask for the common courtesy and respect I give you guys.

Thanks a million.


Here is a video of how it runs. Since the video I have fixed the RPM drop between park and gear, with a stall converter. Sorry for the video quality. There is no knocking in the motor, but a little valve rocker clatter. Expected with a big solid cam and non-adjustable rockers...

[ame="https://www.youtube.com/watch?v=FwAXUiEZr0k"]70 dart swinger 440/727 first move in decades. - YouTube[/ame]
 
did u use shorter pushrods to get some valve lash?? solid lifters need like .015-.030" gap/lash!! how thick u think the head gaskets are? or what is the part number. u might be around 10.7:1 comp which with that size cam can run on 92 octane. did u check valve to piston clearance? zero deck(did u measure, cuz block would have been cut alot) and no valve reliefs it will be close
 
are you certain its a solid lifter cam? I doubt its zero decked with no reliefs and a .500 plus lift cam.
 
.104" clearance from the valve to the piston. Not sure on the timing. Haven't had time to get out there and check it. I know the timing is close to where it needs to be. It starts with a bump.
 
Lash and ignition timing will make more difference than the quench.
Don't get hung on the little things (quench, compression, etc) until you establish the big'uns (ignition timing, valve lash, cam advance).

Also do a compression test. Wet and dry. The cranking PSI will matter more than some 'ballpark' static compression ratio and also give you some insight into the condition of the engine.

Once those tasks are complete, and notes taken, THEN you can tune based on the little things.
 
To me listening to the video it sounds like the first place to start is valve train, if the cam is a solid with non adjustable rocker they are definitely tight. To me it sounds "lazy" and unresponsive when loaded. Timing isn't going to do a thing for an improper set up valve train. 516 heads factory had smaller 1.60 exhaust valves and could be choking the air flow. That cam and set up should eat a lot of airflow. To me it sounds like there are a lot of unknowns that need to be verified, and unfortunately that may require diving deeper into it to figure it out. To be zero decked they more than likely cut a lot of material off the decks, most flat top Pistons I've seen without valve reliefs are .080" plus in the hole. With that you get into either cutting the intake or intake side of the head to properly mate the intake. That being said there could be vacuum leaks in that area if it wasn't done properly. Quench in and of its self isn't a bad thing, but there were a boatload of engines that ran like a scalded dog without it being the primary focus. Also things to consider beyond the engine are converter and gears, but I say work the engine first. Just my thoughts.
 
open chamber or closed chamber does not affect valve to piston. my guess is wayne did not have 0 deck. do U have shorter than stock pushrods to get LASH with solid cam/lifters and stock rockers???
 
@dubob

I am going to change the cam to a mechanical type mopar cam. Probably going to go with the .488 MP purple shaft based on you guys' opinion.

When I got this motor, it had 906 heads on it with adjustable rockers, which are open chamber. It ran 11's in a pickup with that combo on pump gas. I think when I put the 516's on it, it completely jacked up the compression as well as stiffening up the valve train with factory style rockers. Thus the reason it runs like it does...

I think what I will do is change the cam to a smaller lift with open chamber heads to cut back the CR and allow me to run factory rockers.

What do you guys think? I just want a good running motor. No interest in taking it down the drag strip.
 
Marcohotrod said:
open chamber or closed chamber does not affect valve to piston. my guess is wayne did not have 0 deck. do U have shorter than stock pushrods to get LASH with solid cam/lifters and stock rockers???
Click to expand...

I would have to compare them. I ordered the pushrods at the exact length that it had previously. Does 8.9" sound right? Been too long. I will have to break open the motor again.

I am going to be changing all of this back to hydraulic with a smaller cam so that I can keep my factory rockers.
 
Marcohotrod said:
"U are running solid lifters with non adjustable rockers" said the plugs, and carb and cam etc. could be done with the exact length custom pushrods, I bet it was not done here:eek:ops:
Click to expand...

My plugs are telling me I am running a fat cam that is running rich. Like big cam motors do.
 
If you run any mechanical cam (solid lifter) personally I feel adjustable rockers are required. You could go thru and measure every push rod and have it be specific to where it needs to be, but there is absolutely no way to adjust lash to compensate for wear. What was the reasoning for putting the 516 heads on in place of the 906's? If it ran that well before hand or was there a thread somewhere else about it all? As far as The purple shafts, not saying they are bad, but unless I had one on hand I'd do something different but that's me. Sounds like you want a nice cruiser, which is cool, but gotta remember with solid lifter cams there is some routine up keep. A nice hydraulic will accomplish your stated goal and not require additional upkeep etc.
 
Dubob said:
If you run any mechanical cam (solid lifter) personally I feel adjustable rockers are required. You could go thru and measure every push rod and have it be specific to where it needs to be, but there is absolutely no way to adjust lash to compensate for wear. What was the reasoning for putting the 516 heads on in place of the 906's? If it ran that well before hand or was there a thread somewhere else about it all? As far as The purple shafts, not saying they are bad, but unless I had one on hand I'd do something different but that's me. Sounds like you want a nice cruiser, which is cool, but gotta remember with solid lifter cams there is some routine up keep. A nice hydraulic will accomplish your stated goal and not require additional upkeep etc.
Click to expand...

The reasoning behind the 906 to 516 swap was the trade I took in didnt include the heads. I got everything but the heads and valve train. Bummer I know.

Ill be in search for some heads to set up that already have valves. What castings are open Chamber?
 
dkbug said:
Open chamber heads?
Click to expand...

They wer e 516 close chambers milled .030 pistons were .020 below deck.... And yea the solid cam with factory rockers is no good, save up for a set of adjustables!

And just saying I've had no luck with an edelbrock carb, I know some guys do and have no problems with them but I had a warmed over 440 with edelbrock 750 and it was a roach untill I put the Holley on it.

But as everyone else has said get your timing set and get the cam/valvetrane issues fixed then go from there
 
minus the problems,your 70 440 dart sounds mean.i have a 71 440 dart i have been havin electrical problems with mine.516 closed chamber heads are good heads to use on a 78 440 since there a low compression engine.unless the 78 is rebuilt.
 
dkbug said:
My plugs are telling me I am running a fat cam that is running rich. Like big cam motors do.
Click to expand...

Your plugs may be sooted, but a big cam causing this is simply not true. You have a host of other problems.

I have a small block with .570" lift and a big block with .600" lift, both have beautiful light tan coloring on the plugs.
 
I'm sure you've noticed not one person is laughing or ridiculing you. If it were mine and I were trying to work on a tight budget I'd start by changing the cam. There are so many good hydraulic cams to choose from and most are reasonably priced. Some of the other guys have mentioned the intake fitment with milled heads and decked block. I agree, you may also have a mis-match between the intake and heads. Since you will need to remove the intake to swap the cam and lifters anyways it gives you a chance to check that out. When the heads sit lower because of milling them and decking the block it requires the intake to be more narrow to fit. One tell-tale sign the intake is too wide is trouble getting the intake bolts in. if you look into the intake bolt holes and they appear to be higher than the bolt holes in the heads than the intake is too wide. If so you either need to get the intake milled or the the intake mounting surface of the heads milled. The general rule is the intake gets milled 123% of what was milled off the heads on the combustion chamber side. I.E. if the heads were milled .050" you would mill .062" off the intake mounting surfaces. With all that said once you get the cam swapped do a cranking cylinder pressure test to see where you're at. With iron heads you should be OK for pump gas up to around 150-160 psi. Remember when doing this test you either do it with no carb on or have the throttle wide open when you're doing it. If the cranking pressure is too high then you will need to go to larger chamber heads. Once you get all that sorted out its a matter of tuning and a decent 440 will give you plenty of power for cruising and burning rubber, you're going to love it.
 
Well it is set in stone then. I will be investing in a set of open chambered heads. I am going to be putting a bit smaller cam in so that I can avoid getting rid of my rockers.

I am going to call Hughes engines to have them custom make me a cam as I have heard nothing but awesome things about them.

I am hoping that after all of this, I will have a good cruiser with plenty of power for the street.
 
Doosterfy said:
I'm sure you've noticed not one person is laughing or ridiculing you. If it were mine and I were trying to work on a tight budget I'd start by changing the cam. There are so many good hydraulic cams to choose from and most are reasonably priced. Some of the other guys have mentioned the intake fitment with milled heads and decked block. I agree, you may also have a mis-match between the intake and heads. Since you will need to remove the intake to swap the cam and lifters anyways it gives you a chance to check that out. When the heads sit lower because of milling them and decking the block it requires the intake to be more narrow to fit. One tell-tale sign the intake is too wide is trouble getting the intake bolts in. if you look into the intake bolt holes and they appear to be higher than the bolt holes in the heads than the intake is too wide. If so you either need to get the intake milled or the the intake mounting surface of the heads milled. The general rule is the intake gets milled 123% of what was milled off the heads on the combustion chamber side. I.E. if the heads were milled .050" you would mill .062" off the intake mounting surfaces. With all that said once you get the cam swapped do a cranking cylinder pressure test to see where you're at. With iron heads you should be OK for pump gas up to around 150-160 psi. Remember when doing this test you either do it with no carb on or have the throttle wide open when you're doing it. If the cranking pressure is too high then you will need to go to larger chamber heads. Once you get all that sorted out its a matter of tuning and a decent 440 will give you plenty of power for cruising and burning rubber, you're going to love it.
Click to expand...


This my friend, is why I only use this forum. I can't be asked to deal with children. I have plenty of that at work/home :D

Thanks for the info again. You guys are awesome.

The heads on the motor are un-milled. HOWEVER, I did have vacuum leak problems and had a good friend of mine mill the intake to fix the angle between the heads and the intake. No problems there :)
 
You must log in or register to reply here.
-

Back
Top