l82 to lg8 manifold swap (no start/Backfires)

[Spankdamonkey]

As the title says, I just finished putting LG8 manifolds on the l82 heads (spent 3 hours making sure they were properly clearanced for the stamped steel rockers) but now the damn car won't start up

Everything went relatively well, but now when I went to start it up, all it does is backfire (very powerfully I might add, enough to blow out the PCV valve bypass from the upper plenum with a 4 inch flame) So now I am at a loss to understand why it will not crank over......it has fuel, it has spark, and I know it is somewhat igniting because of the backfire.

Anybody have any ideas? Any help is highly appreciated!

(I'll see if I can get a vid up of the backfiring and cranking too)

[SappySE107]

Pushrods in the wrong spot?

[Spankdamonkey]

While I could have swore they were in the right spots, I'm going to take it apart again to double and triple check everything.

*UPDATE

I disconnected the fuel injector harness and went to crank it, sure enough it started up for about 2 seconds (and I didn't even remember that i had removed 4 rockers beforehand.......oops )

[IsaacHayes]

Did you put new o-rings on the injectors?

[Spankdamonkey]

Actually I didn't put new o-rings on the injectors (but I did hose 'em with wd-40 before I pulled them out and put them back in, so they look to be undamaged) Are you saying that it isn't sealing right?

After pulling it apart now, I found that the pushrods were all in the correct spots, so I am officially f*cked if it doesn't start up this time......

[bszopi]

When mine did that (after my 3400 top end swap), it was because I hadn't clearanced the LIM (because no one knew you had to back then), and the rockers were taking chunks out of the manifold. Best reason I can figure it was backfiring was because the rockers interfering with the manifold ended up failing at least half of the lifters and who knows what else. But if you've taken it apart and see no metal shavings (I had a ton), then that probably isn't it....

Sorry, long story, probably no help...

[Spankdamonkey]

Quite the contrary, I just got finished disassembling it now, and did see that it still rubbed the manifold (which is strange as I bolted down the manifold and rotated the crank by hand to make sure it wasn't rubbing....oh well) it didn't take 'chunks' outta it though, just a nice friction streak was visible...so there was a little bit a shavings. But it didn't punch through an intake runner though

However, I examined 2 of the 4 lifters that were paired with the ground-down rockers, and they appeared to be just fine.......if it doesn't fire up this time though I'm just going to replace all 4 of the lifters to make sure. I have until Friday at 4 pm to get it running

Got new spark wires too, maybe help it fire up better

[Spankdamonkey]

Today I tried cranking it again after re-assembling it for the THIRD time

Here's what I have: the car will start, but only momentarily. It will STAY running if I keep my foot on the gas.....but it sounds awful

Any ideas? I only have time to tear it down once more and change out the lifters, after that I'll have to bite the bullet and take it to a repair shop and pay $650 :'(