I just did a head gasket kit on my 88' and when i went to start it there was nothing it will crank for a sec then makes a thud sound and continues to crank. Ive done the rebiulds on four of my other XJs in the past and have never had this problem before any ideas on what it might be im at a loss after four hours of trouble shooting.

 

Check the pushrods and seated in the rockers and lifters.
Its very possible you got one off center on a lifter and its opening the valve to far and contacting a piston.
Hope you didn't bend a valve.

 

Will do that tomorrow and i hope it didnt bend a valve that would bite

 

is there any other suggestions

 

Did you check the valve train this morning?

 

Yep its all fine but still no start and the thud is not realy there any more just no start

 

does it have compression? Maybe cam sprocket is just spinning on cam? Just throwing out ideas.

 

Reseated the valve stems and retorqued all the head bolts and clean fuel injectors & spark plugs and it started up like a champ thanks for the advice and thoughts in the right direction