Join Date: Aug 2008
Location: Orange County CA
A possible fix fro broken LT1/LT4 exhaust bolts
Go to a muffler shop or friend with a good welding skill set, place a steel washer over the hole where the broken bolt is, weld the center/internal edge of the washer to the broken bolt end (just a small weld and avoid the manifold inner edges). Next weld an old/short bolt to the center/outer edges of the washer, no need to be perfect just a healthy weld. While still hot from the weld, place your socket on the temp bolt head & out is comes. Find some Flanged grade 8 replacement bolts and never have to do this again. If you are real concerned even after all of the above, or you are into overkill, get Stainless Steel Grade Nine Flanged bolts and this set up will outlast us all!! No need to get headers unless you are into those mods/have the extra money/need the added HP.
The reason for them braking: GM used Grade 5 bolts and with the normal "elongation" response of these bolts, the heat soaking cycles and time causes metal fatigue. Bolts will show more elongation characteristics than say screwed in studs. When we use studs, the torque & twist loads that are on the none threaded & outer threaded areas of the studs and are only seen when the assy is tightened with header/manifold in place. Therefore, the studs do not get subjected to being screwed into the head under loads. With regular bolts, the torque loads are seen as the bolt engages/rotates into the head material. Therefore, lower grade bolts tend to start out weaker by the nature of the threading-in/torque loading process & where the thread pitch diameter has changed/been altered at the thread ending (a natural weak point). Again, Flange Grade 8 bolts are strong enough to overcome this issue on 99% of our stock applications. Good Luck! :-)
Last edited by LT4_TA; 08-14-2008 at 04:52 AM.