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Compression reading? Distrubutor timing?

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Morris

Morris

Yoda
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Does anyone know a good compression reading for a 9:1 1500 with a stock cam? I am getting 135psi.

I am trying to diagnos a no start condition after my engine rebuild. I am pretty sure it is a combination of my distributor being 180 out and a non-firing fuel injector. But I want to make sure all my other ducks are lined up. If I messed up the cam timing, I would not be able to get 135psi, right? I have only checked #4, so far. But it seems unlikely that I could have randomely misaligned the cam in such a way that only #4 is getting compression.
 
dizzy at 180 out ain't the end o' th' planet: just juggle the wires to be 180 out as well. It's a 'bodge' but a good 'un compared to having to pull it all down again /ubbthreads/images/graemlins/wink.gif
 
135 psi is fine for a 1500.

With the valve cover off, turn the engine so that the #1 cylinder is at top-dead-center *and* both valves are closed (so that the rocker arms are slightly loose).

Then check to see that the distibutor rotor is pointing to the #1 plug wire (or at least, pretty close).
If all this is OK, it should at least pop and snort a bit....then you can rotate the distributor a bit to get it firing.

If the #1 wire is off, I'd do as Doc suggests and move the wires around so that #1 wire lines up with the rotor.
Then put the rest of the wires on the cap using the firing order.
1-3-4-2

For the record, getting a 1500 cam lined up right can be a bit of a pain. I always use a degree wheel. Did you mark the sprockets before you took it apart? Many 1500 sprockets are not marked with "aligning marks" or they have crazy marks. Mine has marks that would put everything about 30 degreees off if I used them.
 
I did not mark the sprokets (DOH!). But, the marks for aligning the cam (on my car anyway) seemed very straight forward and easy to read.

Still, it seems unlikely I would get any compression at all, much less 135psi if my cam was off... Is it wrong to make that assumption?
 
Nahh... you're second guessing yourself. Stop it! /ubbthreads/images/graemlins/jester.gif

Do as Nial suggests: get it to #1 TDC on compression, (valves "rocking" --ie: intake just closed, exhaust "fixin' to" open) have a look at the rotor. Use that as your "starting point" for #1 and go to it. 1-3-4-2. Static time it and I'll bet it lights off.
 
The cam gear going on 4 different ways scares the heck out of me. I got so used to american cams and their alignment pin that I didn't even think to mark mine when I took it apart. <runs to garage to see what the heck he did>
JC
 
On mine, the "locating pin" was a hole on the gear and a dimple on the shaft. If you can see the dimple throught the hole, in theory you are golden. I will let you know how that theory tests out when I get mine running... if I get mine running.
 
Me an' Jeff are sittin' here waitin' fer th' "VROOMM!!!" POST!!! Whaddya waitin' for?
 
To get off work.

Vroom post may be a while yet, as something funky is going on with my funky fuel injection setup,too. Gott plug R2-D2 into the computer.
 
We're patient.
 
Vrooom! Sputter sputter sput. err-err-err-err-err-err-err-err-err-err-err-err-eh.

*sigh*
 
hmmm. THAT didn't sound right.

Fuel supply? You *did* remember to put gas in the tank, right? /ubbthreads/images/graemlins/devilgrin.gif
 
Hello Morris,

"Do as Nial suggests: get it to #1 TDC on compression, (valves rocking" --ie: intake just closed, exhaust "fixin' to" open) have a look at the rotor."

Sorry but the doctors advice is wrong, when number one is about to fire, number four valves will be rocking, the original advice would put the ignition 180 degrees out of phase.

Alec
 
Alec, you are correct, I'm a putz. DOH! "Rocking" puts it on the "suck" stroke.

Mia Culpa!
 
Hello Doctor,

thank you for the response, but we all make mistakes and usually learn more as someone corrects us.

By the way Morris, for most engines if the number four is rocking with number one at TDC your cam timing is about right. If your cam has a symmetrical timing (as most have), e.g. 70-30, 30-70, you can time the cam without any markings by setting one cylinder to TDC and the the opposite cylinder to equal lift on intake and exhaust.

Alec
 
/ubbthreads/images/graemlins/blush.gif I'm contrite. I've done literally hundreds of these engines in one form or another. Dunno what I was ingesting to get that sideways... I *think* I was junxtaposing the 180 out dizzy shaft to the cam position or somesuch. Good eye.

I'll be available for the beating after five PM EST on Monday. /ubbthreads/images/graemlins/wink.gif
 
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