Author Topic: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas (Read 4260 times)

robenger440 · « **on:** October 11, 2011 - 06:00:27 AM »

Hello,
car is a Dodge JS23U0 4 speed, and the big issue is about the engine, a 1970 casting 440 block bored 0.60 with KB Hyper pistons installed, top sufaces are not milled.
heads are old iron stage IV open chambers 86cc that have been ported with MP templates, valvetrain is stock, dual springs, stamped rockers ecc..
exhaust manifolds are HP factory casting with correct exhaust tubes, mufflers and resonators.
Intake is on old 7500 Weiand aluminium dual plane and new carburator edelbrock avs thunder 800, dual snorkel factory correct air cleaner.
Ignition was upgraded from points to orange box, only change was the spring of mechanical advance installed a bit lighter.
Cam installed was (i said was because last sunday I took it out the motor) a Hughes HE2330BL (duration 223-230 at .50" lift INT.504 EX .515 and lobe sep.110�)
ok now the point is, after tried many settings of carb and ignition timing and some hundreds kilometers made with a sever smell of unburned gasoline inside & outside
and the frustration of have a car that dont want to rev over 4200-4500 rpm , I decided to take the time (to try ) to understand what it was so wrong and what to do..
To keep the pure stock looking (apart the carb) I prefer to keep a dual plane intake and stock exh manifolds, this is very important to say.
Any help from you Mopar guys with lots of experience and driving these muscles on its native Country will be appreciated very much!

Roberto

Cooter · « **Reply #1 on:** October 11, 2011 - 07:41:19 AM »

"valvetrain is stock, dual springs"

NEVER run the stock Valve springs on a new cam....There's most of your problem...Keeping it "Looking" stock is one thing, but actually using stock, 40 Y/O parts is another. The valve springs from the factory were good to around 4500 RPM when NEW...

Chryco Psycho · « **Reply #2 on:** October 11, 2011 - 09:47:01 AM »

I tend to agree that valve spring are the first place to look , ign second , are the springs dual springs or single with a damper , wer ethe spring replaced / matched to the cam ?
What does the engine do @ 4200 rpm when it quits revving ?

robenger440 · « **Reply #3 on:** October 11, 2011 - 11:49:12 AM »

yes, here we say that "le valvole sfarfallano" when valve springs are not able to handle their job at high revvings . At time i reckon we checked valve springs pressure and found them to be quite in the range, they are with damper spring inside. Now I recognize it was an error considering even the more lift of the new cam.
in 2nd gear hitting on the pedal it was very fast to reach 4000 rpm than the power collapse and there is something that hold the engine from revving more and if you dont release immediately the foot there is some bog with total lack of power. I tried some different settings on the Thunder's secondaries opening but the problem was still there.
Anyway the most annoying issue that made me dismantling again the engine was the terrible smell of unburned, at every speed, even granpa cruising.. I noticed a large amount of "raw" gasoline on the iheads intake ports as I pulled off the intake manifold, so the poor burning is a sure point.
I ask you some patience because of my narrow english vocabulary...thanks

Cooter · « **Reply #4 on:** October 11, 2011 - 12:20:03 PM »

WARNING:

IF you keep "Floating" the valves with those Stock springs, you will be dropping a valve and destroying your 440.....With that said, to understand WHY there's Unburned fuel in the intake, you need to understand what all is happening when the valves bounce off the seats and stay open at the wrong time. Cylinder pressure comes Backward into the intake and causes the fuel to puddle in the intake cause the carb is still dumping fuel in, it just can't burn it...

robenger440 · « **Reply #5 on:** October 11, 2011 - 12:57:04 PM »

Cooter,
this motor was a job made many years ago, than the car has been sitting for a while...anyway In the meantime I made a quick check at home and found that the old springs were retained on the previous 383..actually when i purchased the cam i also get new springs, pushrod,lifters,valve guides,(plus 3 angle job) head bolt kit etc...the only 40 yeras part were the rockers since i wanted to get the 1,6 ratio ones and the I remember I quit the idea..this is just to give more complete information.
I agree with you about what happens with "floating"..I do know how this situation can destroy an engine even strong like a RB Mopar.
It can be up with revving but I dont understand is at low speed what happens, because this way valves I dont believe start to bounce, but
I repeat I'm here to learn!

robenger440 · « **Reply #6 on:** October 11, 2011 - 02:31:02 PM »

Chryco Psycho, about ignition..i tried advancing and retarding, with and without vacuum advance , the best balance I got was with vacuum advance disconnected , though quality of spark was pretty good every time i pulled off the plugs they were too much dark.
All regulations were made "by ear" and this is everything but a safe method to do these things! but believe me , here mechanics see other kind of cars in their shop, and sometimes you end in the do-it-yourself because of poor answers from who is
supposed to be a pro.

Chryco Psycho · « **Reply #7 on:** October 11, 2011 - 03:22:52 PM »

if the valves float the pressure in the cylinder can close the valve faster then the spring wil return & the locks can drop out causing the valve to get pulled into the cylinder , the valve can then distroy the heads block & or piston so you take your intake manifold & start again with a new engine .
the carb could be the cause of the problems , I have seen more then a few Eddy carbs that did not work , this would limit rpm as well , if the air door flips open & then there is no fuel that will cause a bog , it works the other way to , if the air door will not open it will run out of air & bog down so it could be just the carb causing the problem . You may need to adjust the float level , they often get bent during shipping , if it is too hig hit will run rich & flood
I generally do not use the vacuum advance & time by ear at 3000 rpm , keep advancing until the rpm quits rising & just back it off until you hear the rpm drip slightly

robenger440 · « **Reply #8 on:** October 11, 2011 - 04:00:30 PM »

thanks for quick tips about ignition and carburator, the latter could be really co-responsible of the problems. I had their calibration kit and tried more combos changing jets-needles and springs, but honestly I havent ever paid attention to float lever, a critical issue.
Before putting the hands on the engine, I have to order missing parts from the States, apart gaskets, from your experience and known this engine main feautures,which parts did you suggest I should buy.. in particular what spring set and which cam considering it's a stick car and there are no torque converter's hassles, I was disappointed about my choice of the mentioned Hughes 2330BL.

Chryco Psycho · « **Reply #9 on:** October 11, 2011 - 05:20:48 PM »

assuming you want a drivable street / cruising car with a hyd cam a Lunati 60302 or 60303 with matching springs & a good quality double roller chain Felpro 1215 intake pan

robenger440 · « **Reply #10 on:** October 11, 2011 - 06:06:40 PM »

yes, this not the car to race..in tuscany streets with aged poliglass F60 and stock suspensions..but you know power is like health, thanks God we have some, but more is better.. i was comparing numbers among possible grindings from CompCams, Mopar Performance, Crower and still Hughes but I see now Lunati has a lot of interesting Mopar stuff, anyway from what I saw the 302 seems to be quite conservative , I think the 60303 fits better, also the have low prices...again thank you for your time!

Strawdawg · « **Reply #11 on:** October 11, 2011 - 07:09:32 PM »

Did you look into the carburetor when the engine was idling to see if there was gasoline dripping into the carb? Almost sounds like the needlevalve was sticking open and not allowing the float to shut off flow from the bowl into the carburetor.

robenger440 · « **Reply #12 on:** October 12, 2011 - 02:44:07 AM »

Strawdawg
nope, i have looked inside more times and i believe mixture was ok, more or less rich, but no fuel drops. i bought the carb new and i think there was no manufacturer's defects. thanks for hint

Strawdawg · « **Reply #13 on:** October 12, 2011 - 09:54:29 AM »

Well, I don't think you are going to find too many Mopars in Firenze, or in the area, but, your car should really stand out so I hope you get it running well.

Check the float and other things that Chryco suggested. He knows the problems well with these carbs

robenger440 · « **Reply #14 on:** October 12, 2011 - 10:57:28 AM »

He sure does! I read o lot of articles from Chryco and I found them very accurate and helpful..he does quite an excellent service to ebodies' people here!

Author Topic: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas (Read 4260 times)

robenger440

'70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas

Cooter

Re: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas

Chryco Psycho

Re: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas

robenger440

Re: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas

Cooter

Re: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas

robenger440

Re: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas

robenger440

Re: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas

Chryco Psycho

Re: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas

robenger440

Re: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas

Chryco Psycho

Re: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas

robenger440

Re: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas

Strawdawg

Re: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas

robenger440

Re: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas

Strawdawg

Re: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas

robenger440

Re: '70 440 engine rebuilt -some mods-doesnt rev high-lots unburned gas