I just upgraded my 75 Corvette 350 top end, the bottom has been recently done. I installed a new dist,air gap intake,Heads,Holley 650 DP,sidepipes. Now when I start it only the drivers side fires up

 

That's not possible. Some more details describing your issue may help us to help you.

 

Check the firing order.

 

I have checked the firing order many times, I even tried 180 off, just in case. I replaced the spark plug wires one at a time. the headers on the left (drivers) are hot, the pass. can be handled

 

I would be glad to provide any info needed

 

Check compression. Valves may be to tight on that side.

 

Check for spark and fuel (are the plugs wet with fuel) on the dead side. If that checks out pull the valve cover and see what's happening when you turn it over without starting it.
Check if valves are being opened and closed fully by movement of rockers and compression of the valve springs.

 

You've lost me. I would be surprised if the engine would run on only four cylinders.

 

Well I did once pull a valve cover on a engine (new big block) and accidentally left all the spark plug wires off on one side and the engine did run.... very slow and odd but it did run so this is completely possible.

You have put in several items all at once making it harder to determine. Seems very odd to be just one side but that should make it a little easier as its not on both sides. But we dont know what you put in so we are a little blind to your new parts.

Distributor
Now... before replacing anything do some tests. Get your timing light out and hook it up. Start the engine and use the timing light on each plug wire one at a time to see if you get a pulse from each wire. This will at least tell you if your getting pulses to each and every wire. They should be rythmic and not sporadic.

You dont have a funky cap on there that puts all the wires for each bank on the same side of the cap as that head do you (makes the wires look cleaner no overlapping side to side)?

OHM out the wires just to make sure they are all good. I cant see the distributor giving you issues for a side to side thing unless maybe you have a 6cyl trigger (dont remember what they call the inductor/reluctor that spins past the pickup but it should have 8 points not 6 or 4)) in an 8cyl distributor but funny things can happen. Again I have no idea what distributor / ignition module or cap you are using.

Heads and valves
Do a compression test on the "questionable side to see if you are getting compression. Could be an improperly assembled head or you tightened your valves too much.

I would expect backfiring if you had the valves on the intake side too tight leaving them open to let hot gases backup through the intake. But exhaust valves being open would lead to no compression and complete loss of power to those cylinders.

Did you replace the cam as well and rockers and push rods?

headers
If there was a blockage in the one header/side pipe baffle stopping exhaust flow you would wind up with a back firing type experience as the hot gases had no place to go and would come out the intake when the intake valves opened.

 

ok heres the update, I forgot I had ordered heavy springs and didnt change them out before installling them (I was going to wait till next year). I ordered the cam since I already installed the heads and I didnt want to go backwards. Now the cam button hits the stock valve cover, so I ordered one of those too. Thanks for the help guys!!

 

sorry stock timing chain cover