Working on a 08 5.3 LC9, does not have vvt only dod/afm. The dod had issues so decided to delete it. Installed 16 new lifters, new oil pump, ls3 valley cover. Disabled Dod in the tune and dtcs. The engine runs really bad at idle. Texas speed assures me every time I talk to them the stock camshaft will work. They do them all the time with the stock cam. Thunder Racing disagrees they say it will NOT work. The cylinders that had dod have 100psi compression and the ones that did not have 150 psi. In theory the factory cam should work, people delete it thru the tune and basically it should be the same as what we installed. I dont get stumped often but this has got me. I have spent hours searching forums and still have not come to a conclusion.

Anyone have any experience at this that can help me to figure out what is wrong? I no the cam has diffident lobes on the dod cylinders 1.3mm difference i believe.
Thanks,

 

Made sure the cam went back in straight up? Can you live scan and see if there's any misfires?

 

You arent preloading the lifters where the dod use to be. They are a smaller lobe which actually requires you to change cams.

 

We never pulled the timing chain so the cam is not off. Comparing the cylinders they seem to have the same preload non dod vs dod cylinders. With that said that is checking at top dead center, the height of the lobe is the only thing different isn't it?

 

I would have put a small aftermarket cam or something like a stock LS1 cam back in it.

 

He was not wanting performance, and I taked to three different people at Texas speed that said the stock cam will work. Have called them like 8 times every time they say it will work, even after telling them thunder racing said it wouldn't. Has anyone else tried this and it worked?

 

Do the new lifters and the DOD lifters measure to the same height using a caliper?

 

What size pushrods did you use? Ls7s require 7.425 typically

 

LS7 requires a 7.425 on a cam swap bc it is cut on a smaller base circle than a stock cam. The LS7 lifter is shorter than dod lifter yet they use the same length pushrods throughout

 

Using 7.421 they could use a longer but still have a half of round preload on both the dod and non dod cyl. I do not believ that is enought to make a difference at idle?