New 383 wont fire

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What could be wrong............

cam could be installed wrong.

You may have the wrong lifter/ pushrod/ rocker combo, and or decked block and milled heads. This means the lifters may be holding the valves OPEN

or you may be misinterpreting the symptoms.

First step----------- is get a cam card for the cam, make some degree marks on the dampener, and determine if the camshaft is "reasonably" in time. Run a compression check with a good gauge---good ones are not all that expensive, and EVERY guy who fiddles with engines should have one. Buy one with a "quick disconnect" air fitting that you can hook to an air hose. There are several different connectors that are not compatible, so make sure you get one you can work with.

Second,-----------determine if the valves are ACTUALLY opening and properly closing, IE valves are not held open.

Third,--------- if the above is correct or repaired, make sure the dist is installed as described

And last, -------- make sure it actually has fresh gasoline and not diesel or something else, and that the plugs are not fuel fouled, and that you actually do have fuel and spark.
 
unfortunately i just checked the engine at TDC and the exhaust valve is pushed down....
makes sense why there would be no compression. wednesday i am off an pulling timing chain cover..what could have happened to the motor while trying to crank with cam in wrong?
if it is off by a small amount do i need to be concerned about pushrods?
thanks for the help and hopefully wednesday all will be well and it will fire.
 
tommy383 said:
unfortunately i just checked the engine at TDC and the exhaust valve is pushed down....
makes sense why there would be no compression. wednesday i am off an pulling timing chain cover..what could have happened to the motor while trying to crank with cam in wrong?
if it is off by a small amount do i need to be concerned about pushrods?
thanks for the help and hopefully wednesday all will be well and it will fire.
Click to expand...
just take the pushrods out and roll them on a flat surface. get the cam timing dead nuts and it should be fine
 
Exhaust valve open...remember there are 2 TDC's....so with ex valve open and TDC, couldnt that be "exhaust" stroke??
When you chk TDC, how are you checking?? By the piston at the uppermost travel, or by the marks on the balancer??
Another thing to chk make sure balancer reads correct or coincides with piston travel... dad n I had a ***** of a time as balancer didnt jive with #1 piston TDC.

Good luck and post what you find out!
 
would the piston at TDC have both valves closed regardless of the stroke?
 
tommy383 said:
would the piston at TDC have both valves closed regardless of the stroke?
Click to expand...

Im no expert, but I would say NO. Intake, compression, power, exhaust are your 4 strokes....if on TDC(or just before) of compression both valves closed....if on TDC of Exhaust I would think exh valve open and intake closed...
 
4spdragtop said:
Timing marks on cam gear should be 6 oclock and crank gear 12 oclock
Click to expand...

I agree with 4sp on this one but I do have a 64 383 that I rebuilt
And I found the timing marks on the cam and crank
Ended up being twelve o clock on both cam and crank gear
 
cudascott said:
I agree with 4sp on this one but I do have a 64 383 that I rebuilt
And I found the timing marks on the cam and crank
Ended up being twelve o clock on both cam and crank gear
Click to expand...

Not sure how it relates to the timing, but if you take my 12 oclock crank dot and 6 oclock cam dot, rotate the crank 360 degrees, the crank dot again is at 12, but now the cam dot is now at 12 as well....1 crank revolution equals 1/2 cam revolution
 
Well so did I but that is not the way my build ended up everything I read said
6 and 12 but while the intake is off it is very easy to put no 1 at tdc and look at the camshaft to verify your on the back side of the cam lobes this how my 383
Ended up timing 12 and 12
 
so when i pull the cover, i need to make sure they are 12 on crank and 6 on cam right?
 
Ok there is a clear pic for the SB(273/318/340) and cam dot is 6 oclock and crank dot is 12 oclock.
When I checked for BB the pic isnt as clear, but it sure looks to be the same as for SB
 
4spdragtop said:
Ok there is a clear pic for the SB(273/318/340) and cam dot is 6 oclock and crank dot is 12 oclock.
When I checked for BB the pic isnt as clear, but it sure looks to be the same as for SB
Click to expand...

That is what the book recommends BECAUSE it is easier to line up, BUT that is NOT no1 ready to fire but no6 ready to fire.

Rotate the crank 1T and both marks will be at 12 o'clock, no 1 ready to fire.

AND EXHAUST VALVE OPEN does not mean squat BECAUSE

Bring no1 up on TDC and you have a 50-50 chance---either both valves will be "about equally open" (used to be called "split overlap) or they will both be closed.

IF THIS DOES NOT HAPPEN, either the timing mark is wrong or the cam is installed wrong.
 
Damn yall make this confusing. Bring the piston to the top.If valves arent closed bring it around one more revolution. If valves arent closed this time cams installed wrong. You dont even need dots to figure this out.
 
I will throw up some pics of a 68 383 I have the short block together
And it timed 12 on the crank and 12 on the cam give me a sec to post them
 
67Dart273 said:
That is what the book recommends BECAUSE it is easier to line up, BUT that is NOT no1 ready to fire but no6 ready to fire.

Rotate the crank 1T and both marks will be at 12 o'clock, no 1 ready to fire.

AND EXHAUST VALVE OPEN does not mean squat BECAUSE

Bring no1 up on TDC and you have a 50-50 chance---either both valves will be "about equally open" (used to be called "split overlap) or they will both be closed.

IF THIS DOES NOT HAPPEN, either the timing mark is wrong or the cam is installed wrong.
Click to expand...

yessir , this is what i read before LOL thanks Del
 
first pic tdc #1 ,
 

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sec pic verifying backside of camshaft (both valves closed)
 

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and lastly the timing marks at 12 and 12
 

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sorry i had to do the pics one at a time as the file was too large
 
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