Project regress

CopperNick

CopperNick

Master Mechanic
Feb 20, 2018
270
43
Canada
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?
 
GuysMonteSS

GuysMonteSS

Royal Smart Person
May 21, 2011
1,310
113
Kentville,Nova Scotia,Canada
DSC_0260 (2016_04_18 13_36_38 UTC).JPG


If you mean that you would have to trim the motor mount like this one on my 650 HP Big Block,I wouldn't worry about it.
Mine has been like this for years now and it hasn't fallen off yet.
Guy
 
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565bbchevy

565bbchevy

Geezer
Aug 8, 2011
7,519
113
Michigan
I also did a similar notch on my stock clamshell mounts when I installed my 496 BBC many years ago and it actually called for it in the Hooker super comp instructions and it was never an issue. I later installed aftermarket solid mounts to clear the Lemons Headers on my 565 BBC.
I also had to do that for my stainless Ebay headers I recently installed in my Regal with a 355 SBC pictured below
20190520_175234-1_resized.jpg
 
565bbchevy

565bbchevy

Geezer
Aug 8, 2011
7,519
113
Michigan
Opinions being solicited here, who here on the board prefers the thinner 1/4 flange or the thicker 38ths one?
The $180 Ebay headers I posted above have the thicker header flange and I used slightly longer bolts to mount them and had no other frame or body clearance issues other than the notch on the driver's mount which I cut with the engine installed.
I say cut the mount and move on with the install.
 
GuysMonteSS

GuysMonteSS

Royal Smart Person
May 21, 2011
1,310
113
Kentville,Nova Scotia,Canada
I say cut the mount and move on with the install.
X 2 !!!
I also had to trim the flange on my Hookers to clear some of the header bolts.
It's all part of Hotrodding..
Theres no such thing as "Bolt On",LOL
Guy
 
D

Doug Chahoy

Royal Smart Person
Nov 21, 2016
1,996
113
Flowmaster was the first header I bought for my Elco. I couldn’t even get the one side in. I ended up with Hooker SS that were a PROBLEM fit, but finally worked. I wouldn’t go with less than a 3/8s flange.
 
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CDUNIGAN1981

CDUNIGAN1981

Master Mechanic
Mar 15, 2015
284
63
Serious question...
Not trying to highjack your thread.

If you don't have an engine hoist, how do you go about jacking the motor up so you have extra space for things like header fitment?

After removing the motor mount bolts, do you just use a board under the oil pan and let the transmission keep the motor from falling forward or backward while you use a floor jack?
Is it safe to do without an actual hoist?

Thanks,
CD
 
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pagrunt

pagrunt

Geezer
Sep 14, 2014
5,711
113
Elderton, Pa
Another brand that others have went with is Hedman. In my opinion is they do have one of the better selection of headers for SBC powered 4th gen A/G's & the only ones that clear factory clutch linkage.
Here'd a link using a '81 MC with a 305: https://www.hedman.com/passenger-car-headers?cpable=1&&YearID=1981&MakeID=47&ModelID=470&CID=305
I had a set on when I first put the 305 in & sold the set of Elites I was going to use to another member just cause I don't feel like dealing with the typical headaches from headers you get down the road.
 
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Texas82GP

Texas82GP

Geezer
Supporting Member
Apr 3, 2015
5,731
113
Spring, Texas
Yeah, I bought those Flowmaster headers too. No way they fit. I had them for a long time before I tried to install them. Summit wouldn't take them back. I sold them on eBay but took a bath on them.
 
CopperNick

CopperNick

Master Mechanic
Feb 20, 2018
270
43
Canada
Thanks to all who responded. Good? to hear my problem wasn't me doing something stupid and failing to recognize the problem. My solution/decision was to rebox the Flowmasters. They are going back to the speed shop, hopefully for a credit on account. Did some serious digging and diving on the net and found that my old go to, Hedman Hedders, has the pipe design that I want and offers them specifically for my application, and they come in the HTC coating. The only differences between the two variants listed is that one is offered with a 1/4" flange and polished finish on the coating, the other comes in dull or matte finish but with a 3/8ths" flange thickness. The Flowmasters came with a 1/4" flange( actually had to go out and measure their flange to be sure of that) as have all my previous buys. Going to be discussing the Hedman's with the shop either on Tuesday or Wednesday and will ask them to discover whether or not the 3/8 flange version has an HTC coating like the 1/4's do. Polished or unpolished is irrelevant. I get that the thicker flange would offer more rigidity and less deflection meaning the seal at the exhaust port would stay tighter. That understood, I have run copper exhaust gaskets in the past with my old sets of 1/4 flange headers and plan on doing so again. I like them and they seem to seal better than the composite ones. Also using header bolts that I have cross-drilled so that they can be tightened up and then safety wired. The wire isn't pretty but it isn't supposed to be; it is meant to keep the bolts in place and, like doing it for two piece rotors, it works.

As for the pictures of the cutaway clams, All I can say is nice work. When I went to do the drop initially I found that it was the clams that wrecked against those metal tabs on the shell inserts. My solution at the time was to swap them out for a set that I had trimmed/modified going back to when I used my 400 block as a test dummy to set up the clutch linkage. The ones I pulled out are now sitting on the 400 and I have them marked so that I can give them a little 4 1/2" cut off love!!. Not too much, just a bit of relief around the tab that holds the hole for the bolt. If I score another set at some point I may cut the top face away by about 50% for its entire length along with reshaping the ears, jus to have them to try at some point. it would certainly offer me some latitude when choosing headers in the future. Will let the board know down the road what transpires with the matter of the return and credit.

Nick
 

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