Timing problem

[sgt1022]

Ok I had a previous thread for ignition problem got that sorted out. I cant seem to get the timing down right on my 454. This is my first big block chevy. I have done everything I know to do. I have #1 on TDC(compression stroke), Timing mark on cam is at 6 crank is at 12. Distributor is pointed toward #1. Installed wires in correct sequence it is backfiring through carb. So that tells me that an exhaust valve is open when firing. Camshaft is a Summit 1301, advertised lift is .502 on the intake and .501 on the exhaust. advertised duration 277 intake 287 exhaust.

[magicoolbus]

Hydraulic lifter or solid. Either way, if the timing chain in on correctly, the distributor is inserted correctly, the plug wires are not crossed and the timing is reasonably close, it should fire. Recheck the valve lash and ensure a valve isn't being held open. A simple compression check on each cylinder will help determine if one isn't closing.

[69chevytrucker]

Like he said sounds like lash

[sgt1022]

I went to Summit Racing tech support for answers. One of their answers was that some cam manufacturers switch the firing order. Instead of 1,8,4,3,6,5,7,2 it could be 1,8,7,3,6,5,4,2. they didn't specify that on my cam card that came with the camshaft. I'm waiting for confirmation from them.

[hugger6933]

It could only be a couple of things. Check to see if crosswired. sometimes we recite the 18436572 so fast that when we are looking at the dist we may miss a wire or the curve around back behind thew head throws us a curve and crosses one there. Next double check the static timing to make sure that when your up on the compression stroke that you are on the compression stroke. So while your checking that pop the V/C and if both #1 valves are at rest off the base circle of the cam as they should be. That would be when you check the rest of the valves to make sure one is not too tight and the take off the cap [if you haven't already] to see if your pointed towards the #1 cylinder. Once all of these things line up and are checked off the list, it ought to be might close the last step would be cranking on the dist to get enough advance in the dist to start that thing. I kmow the factory spec is WAY low on the bigs and they respond well to more timing than the factory recommends. Even the newer later injected ones that have their timing set at 0 unplug the timing adjust plug and crank in about 10 degrees and then plug up the timing plug and you have a whole nother truck. I know that has nothing to do with this just another little big block nugget I thought I throw out in case somebody had a later 454 truck and wanted extra power.It is amazing the difference it makes. Jim

[geezer#99]

When #1 is on tdc the cam gear is at 12 and the crank gear is at 12.

[sgt1022]

I went to Summit Racing tech support for answers. One of their answers was that some cam manufacturers switch the firing order. Instead of 1,8,4,3,6,5,7,2 it could be 1,8,7,3,6,5,4,2. they didn't specify that on my cam card that came with the camshaft. I'm waiting for confirmation from them.

[hugger6933]

You will be hard pressed to find a different firing order cam made just for the street. There just is not that much benefit down in the rpm range that the street cam needs. I don't ever recall seeing it on anything but a roller type cam either not to say their is not such a thing just I don't see the need/use for it on a regular street cam. Jim

[sgt1022]

Hugger, I had the crank/cam timing marks in the right position(cam at 6 crank at 12). I loosened the valve lash so I know they weren't to tight. When I wired the plugs I followed the wires to their repective sylinders so I knew the were installed correctly. I friend who is a retired GM mechanic told me the alternative firing order is most likely the problem. He worked on it to dial it in and couldn't get it either.

[geezer#99]

Originally Posted by geezer#99

When #1 is on tdc the cam gear is at 12 and the crank gear is at 12.

Dude!!
Did you read this!!
When you put the cam gear at 6 and the crank gear at 12 you're timed at #6 tdc. The chevy engineers designed it this way. To get to #1 tdc you rotate the crank once which puts the cam gear at 12 and the crank gear at 12.

[kwmech]

Originally Posted by geezer#99

Dude!!
Did you read this!!
When you put the cam gear at 6 and the crank gear at 12 you're timed at #6 tdc. The chevy engineers designed it this way. To get to #1 tdc you rotate the crank once which puts the cam gear at 12 and the crank gear at 12.

Bingo!!! I gave up years ago telling people this, small block is the same way

[sgt1022]

Ok if TDC for #1 is Cam at 12 and crank at 12 then why does all the timing info on the interweb have the cam at six and crank at 12? I'm confused

[geezer#99]

They say cam at 6 and crank at 12 because that's how you put your timing chain in.
Any who say that's #1 tdc are wrong.
Was designed that way 50 years ago. Easier for the assembly guy to get it spot on. Then you crank it around once for final assembly.
If you try at 12 and 12 when you install the chain there's a good chance you'll be off a tooth or two.

[jjzepplin]

Originally Posted by sgt1022

I went to Summit Racing tech support for answers. One of their answers was that some cam manufacturers switch the firing order. Instead of 1,8,4,3,6,5,7,2 it could be 1,8,7,3,6,5,4,2. they didn't specify that on my cam card that came with the camshaft. I'm waiting for confirmation from them.

I would think that this would be highlighted in huge print on the cam and tech should be able to tell you right away. Honestly- I've never heard of alternate firing orders but read up now and it is possible but highly unlikely. If you read the instructions (I know-we don't need them) on how to install the timing chain then there would only be one way to do it. Double check before installing timing cover by temporarily installing harmonic balancer and checking for valves being closed on #1 When timing marks are aligned and boom-button it up and start that mother.
Have never had an issue with this doing this way.
Don't be afraid to start over.
Be afraid to keep going cause if your wrong you get bent valves...

[sgt1022]

I made sure #1 was on compression stroke by keeping my finger over spark plug hole while rotating engine. That put crank gear at 12. I then set cam gear at 6. at this point is engine set to fire on #6 or #1. I would think #1 is set to fire.

[geezer#99]

If both are at 12 then that's #1 tdc.

[sgt1022]

Ok. thanks for all the advice. I have a gameplan and will implement tonight.

[geezer#99]

If you leave it as you have it set up with the rotor pointed at #1, just loosen the dizzy, lift it up and rotor the rotor so it points at #6. Button it all down and it should fire up.