rebuilt a ls and now it wont start i first compression tested it and this is what i got 120 120 90 30 ... i know for sure the block was honed correctly and the rings were put on right. from there on im not sure what is wrong. when taking apart the motor cylinder 4 did have most carbon build up but nothing alarming. i used a new HG and arp head studs torqued to 30,55, then 80. all numbers sound low so i will check timing tomorrow but that still wouldnt explain the variance between cylinder compression. atleast i dont think. and also the car did start before rebuild but did not run well

 

No, timing won't cause a compression variance between cylinders, just low all the way across. Check your valves. You may have some bent, burnt, stuck, valves. Could have them adjusted too tight. Could have soft carbon built up on the valve seats. Before you tear it back down, do a wet compression test (add oil to each cylinder before you put the gauge in, several drops or a squirt from a oil can) and see if the readings change at all.

 

yea i will do a wet compression test for ***** and giggles but thats only gunna tell me its not the rings. but even if it was the valves in that cylinder i still must have an over all timing issue bc 120 in the first 2 cylinders is no good.