Back story on this is that I purchased a set of Flowmaster headers for my Monte project a year or more ago and put them on the shelf until I was ready for them. Bought them through my local speed shop. Finally have reached the point where I can install them, started to do so, and found that the number one exhaust tube crashed heavily against the motor mount. By heavily I mean that to get clearance I would have to cut away, starting at the back face of the engine half of the mount, a wedge section that would include about half of the top face all the way out to the edge to get room for the pipe. Doable but not desirable, structural integrity of the remaining amount of the mount being a significant concern. There is room to do the cut away but migging in a brace or rib to add some strength would be problematic. And before anyone suggests pulling the mill to modify the mount, given the hassle with the mounts that I had just to do the drop, that option is not on the table.
Phoned my supplier. They phoned Flowmaster. Major Denial; website says that system will fit the 78-88 Monte's. Paperwork included for the install clearly says it does not. Rep won't concede there is a problem. Bottom line: the headers got put back in their bags and it all went back in the box. It goes back to the shop next week. Getting them returned to the distributor for credit, given the time lag between the initial buy and now, may offer a problem but not at my end. Spent a few hours this evening surfing various mfgrs, Patriot and Dougs among them, and they all seem to offer a design that, while it would fit the 1st gen 1970-77 Monte with the rubber engine mount and solid frame bracket, won't fit the 2nd generation that had that design reversed to eliminate torn and blown out mounts Same problem, tube hits the engine half of the mount; at least it appears to do so according to the pictures , most of which are taken from a poor angle. It all seems to devolve down to them building for what they term the 1st generation SBC engine, 58-86, in a CID ranging from 265 to 400, but not paying attention to the fact that the engine/frame mounts for that engine series came in two versions; 58-77, and 78-86 (88). They did not remain as originally designed and used until the mid 70's, but changed completely in design and installation in 78.
Finally found one builder that I have used in the past who still offers a version/design that I have used in the past that does clear. They have a ceramic coated variant that I think I want to use. The only difference is that the one model uses a 1/4" mounting flange thickness and the second one uses a heavier flange @ 3/8ths". Think most of the old ones I used in my 78 were the 1/4 version. Apart from thicker, the 3/8ths" would offer a stiffer flange that would provide a tighter seal against the gasket and not deform under bolt tension. My concern is, like always, clearance. The tube would clear but the thicker flange could push it far out towards the frame. May have to unpack those Flowmasters again and measure the flange on them just for a reference.
Opinions being solicited here, who here on the board prefers the thinner 1/4 flange or the thicker 38ths one?
Phoned my supplier. They phoned Flowmaster. Major Denial; website says that system will fit the 78-88 Monte's. Paperwork included for the install clearly says it does not. Rep won't concede there is a problem. Bottom line: the headers got put back in their bags and it all went back in the box. It goes back to the shop next week. Getting them returned to the distributor for credit, given the time lag between the initial buy and now, may offer a problem but not at my end. Spent a few hours this evening surfing various mfgrs, Patriot and Dougs among them, and they all seem to offer a design that, while it would fit the 1st gen 1970-77 Monte with the rubber engine mount and solid frame bracket, won't fit the 2nd generation that had that design reversed to eliminate torn and blown out mounts Same problem, tube hits the engine half of the mount; at least it appears to do so according to the pictures , most of which are taken from a poor angle. It all seems to devolve down to them building for what they term the 1st generation SBC engine, 58-86, in a CID ranging from 265 to 400, but not paying attention to the fact that the engine/frame mounts for that engine series came in two versions; 58-77, and 78-86 (88). They did not remain as originally designed and used until the mid 70's, but changed completely in design and installation in 78.
Finally found one builder that I have used in the past who still offers a version/design that I have used in the past that does clear. They have a ceramic coated variant that I think I want to use. The only difference is that the one model uses a 1/4" mounting flange thickness and the second one uses a heavier flange @ 3/8ths". Think most of the old ones I used in my 78 were the 1/4 version. Apart from thicker, the 3/8ths" would offer a stiffer flange that would provide a tighter seal against the gasket and not deform under bolt tension. My concern is, like always, clearance. The tube would clear but the thicker flange could push it far out towards the frame. May have to unpack those Flowmasters again and measure the flange on them just for a reference.
Opinions being solicited here, who here on the board prefers the thinner 1/4 flange or the thicker 38ths one?