Welcome to Mustang Works
willboske.
In any case, I would replace the header bolts. U can easily find them at Pep Boys or any other parts place, or the Ford Dealership.
It could be coming from there, but it also could be coming from the flange where the header meets the h-pipe. If it's not seated correctly and tight enough, you will here it leaking there. Do you have an aftermarket h-pipe or the stock 4-catalytic converter h-pipe?
-------------------------------
'79 Mustang Coup
4" Cowl
Weld wheels (15x6;15x8)
Stock 5.8L
C4 w/ shift kit
1 5/8" MAC shorty headers
Holley 750 CFM
Edelbrock Performer RPM intake
2.5" Off road H-pipe, 2-chamber Flowmasters
8.8" Rear end w/ 3.55 gears (Now that's more like it!!)
Front: 225/60/15 Rear: 255/60/15 Eagle GT II
14 x 4” K&N air filter (getting the Xtreme setup soon)
"Red, thou art my companion. Hasten now your quickened metamorphosis to Green that I may conquer all who dare abide there beside me. May they be left thither behind burnt black." ---Fox Body