454 engine don't start after camshaft change

[bolbic33]

hi all,

i just overhauled my OMC 454 engine, do valve job, and change the camshaft because of cracked surface on it.
i ordered a marine camshaft for 454 at summitracing.

Everything was ok when i reassembled, untill i put the camshaft in place.
I first put the camshaft with the dot on it to 6 o'clock, and the crankshaft at 12 o'clock.
( i do not changed the bearings that were OK )

After turn the engine by hand, i noticed that just after TDC, the N?1 intake valve opened ....
So i decided to make a complete revolution of the camshaft ( the dot on camshaft was at 12 o'clock after that ) and the result was : i saw just after TDC the N?1 piston go down and and the exhaust valve opening when the piston going up.

I thought it was right position for the camshaft.

I'm now trying to restart the engine, and after 2 days of cranking ( and 1 dead starter ) it still doesn't want to start, may be 1 'BANG' or 2 ...
So i presume i had put the camshaft upside down ? Do i have those symptoms ?
i even tried to start it with "Start Pilot gaz" , with no result ...

Do you think my engine doesn't want to start because of the camshaft put in the wrong position ?

Of course i had verify : i have sparks , and fuel comes to the carburetor ( coil and fuel pump are directly connected on the +pole of the battery )

Thanks for you help by advance,

Bolbic,
France

 

[Don S]

Re: 454 engine don't start after camshaft change

This is how the timing marks should line up when installing the timing chain.



That is only used for installing the chain properly, it is NOT #1 TDC on the compression stroke.
It's one revolution of the crankshaft off.

That get's people in trouble many times, for setting valves and and the distributor.

 

[bolbic33]

Re: 454 engine don't start after camshaft change

Thanks Don S,
I think the picture you show is identical to what i've done, here is a picture of my assembly , i put a white point on the camshaft dot.
The A and B points seems to be a the same place on my engine.
Does that mean my camshaft is correctly in place ?



If camshaft is OK, i still don't understand why this engine doesn't want to start...

 

[Don S]

Re: 454 engine don't start after camshaft change

When you have the marks lined up as shown in the drawing I posted, is that where they were when you installed the distributor?

What year is your engine? Are the valves adjustable, or just torqued?

 

[bolbic33]

Re: 454 engine don't start after camshaft change

my engine is a 1992 GEn V Big Block NOn roller
The picture i shown is the position is the final positioning i made, and after that i install my distributor , with rotor pointed on N?1 spark plug and cranck on the TDC.
i just torqued the rockers arms to the torque the manual specify.
The manual also specify that after torquing the rocker arms bolts, there is no need adjustment.
I have verify and re-verify by turning engine by hand if everything was ok, and for me, it was ok !

 

[Don S]

Re: 454 engine don't start after camshaft change

First thing you need to do, is remove the cam gear and timing chain. They are wrong in your picture.

Now turn the crankshaft so that #1 piston is at the top of it's stroke. Then look at the mark on your crankshaft gear and make sure it is pointing at the 12 o'clock position. You have two keyways in the gear, and you may be in the wrong one.

 

[bolbic33]

Re: 454 engine don't start after camshaft change

Don, it's a cloyes timing chain, there is 3 keyways on it, one is OEM specs , and naturaly, i install the crankshaft sprocket on OEM keyway.
When piston 1 is on TDC , the crankshaft sprocket is well at 12 o'clock, and the cam gear dot is at 6 o'clock.

During verify and turning by hand, when crankshaft sprocket was at 12 o'clock, i well saw the N?1 Exhaust AND Intake valves closed.
Then the piston comes down and when comes up , the exhaust valves was well opening.

At my sense, i had there all clues telling me timing was OK ...
The engine is totally reassembled now, do you know a faster way to check my timing without remove all front accessories ?
( mainly i also broke my damper install tool, and it takes 1 or 2 weeks to get from US :grumpy: )

Thanks for your devotion

 

[Don S]

Re: 454 engine don't start after camshaft change

Find #1 TDC on the compression stroke like this HOW TO: Find #1 TDC on the compression stroke.?/ 427081

Then look at where your rotor is pointing. That will be #1

 

[bolbic33]

Re: 454 engine don't start after camshaft change

Don , i've already do that, and when i'm in compression stroke on cylinder 1 , my rotor is pointing on the n?1 spark plug.

If my camshaft is upside down, the result of this test would be the same, right ?

I realy don't understand why this engine is not firing, he had sparks and fuel ...

 

[Bondo]

Re: 454 engine don't start after camshaft change

The engine is totally reassembled now, do you know a faster way to check my timing without remove all front accessories ?

Ayuh,.... Do a Compression test,... That'll tell ya if the cam is in right, 'n the valves adjusted right...

Cam installation timin', 'n Ignition timin' are 2 very different things, that Don't really relate to each other....

The cam is aligned with the crankshaft, 'n ignition timin' is done well after that....

 

[Don S]

Re: 454 engine don't start after camshaft change

I have no idea of your knowledge of these engines, so will just throw some items out for you to check.
Are you sure the plug wires are in the right order 1,8,4,3,6,5,7,2 and going the right direction. rotor turns clockwise.
Cylinder numbering is port from front to back, 1-3-5-7 stbd 2-4-6-8
Do a compression test and make sure it has compression on all cylinders.
Are you sure it's getting plenty of gas?

 

[bolbic33]

Re: 454 engine don't start after camshaft change

...You were right telling me to verify plug wires connexions ...
I have interchanged 5 and 7 wire plugs .... sorry
i cannot test if there that was the problem because my starter passed away after so many cranking during 3 days.

Do you think that N?5 and N?7 plug wires swap can cause the problem i encountered ? ( no firing , just some 'BOUM' and other 'PSHIII' )

 

[bolbic33]

Re: 454 engine don't start after camshaft change

.........

i check it out .... there was NO wire goin to the right plug ... Sorry !

 

[Don S]

Re: 454 engine don't start after camshaft change

Do you think that N?5 and N?7 plug wires swap can cause the problem i encountered ? ( no firing , just some 'BOUM' and other 'PSHIII' )

Sure it could.

 

[jeromeb]

Re: 454 engine don't start after camshaft change

Sure it could.

Crankshaft as 12 o clock and camshaft at 6 o clock doesn't equate to #1 being at TDC compression on all engines. Not sure about Chevy but #6 and #1 pistons move simultaneously. You might have the distributor rotor 180 off.

 

[Don S]

Re: 454 engine don't start after camshaft change

Crankshaft as 12 o clock and camshaft at 6 o clock doesn't equate to #1 being at TDC compression on all engines. Not sure about Chevy but #6 and #1 pistons move simultaneously. You might have the distributor rotor 180 off.

Read the thread, we already been there done that.

 

[chrisrooter]

Re: 454 engine don't start after camshaft change

3 days of cranking:facepalm: that would have been merit to take a closer look at firing order, distributor, etc... A 180 out distributor will not start your motor, especially with 2 plug wires crossed. You would not even be close to trying to start. I own a chevy motor in my classic car. If everything was in place and just 2 plug wires off you should start but it would have 2 dead cylinders and you will sure know it. So, I would think distributor 180 out. It looks like the timing marks are correct, crank 12 o'clock and cam 6. On compression stroke. also usually when pointing rotor to #1 it is set to fire just before top of compression stroke, so if you are just on or past it you could be set a tooth out, also not enough to keep it from starting just a lot of stumbling trying to start. Also a 180 out distributor will cough like hell through the carb. At least it did on my cam job (car) 180 out I was, we all been there like stated. Goodluck don't tear things down any further until you get a starter and reverify things.