Hi Everyone.
Funny how working on one thing on your Olds can lead to a whole list of new changes you didn't plan on. I'm currently installing UMI's front tubular upper & lower control arms and now realize that the rear lower control arm bolt cannot be removed without taking off the headers.... This leads me to the beginning of my questions. The previous owner built the motor, installed the exhaust etc... The motor is a 455 bored .60 over with an Erson TQ50 cam, 9.5:1 pistons, E series heads with some work done, and balanced rotating assembly. The headers are an unknown brand, but by looking at them, they were massaged A LOT to make them fit. On top of that he added nuts under the motor mounts to hold the engine approximately 5/8" higher for the headers to clear the cross member. This has caused a number of different problems.

I'm going to remove the headers to reinstall the new lower control arms. Since I have to pull the headers, I cannot put back a part I know that isn't right. Also at the same time, I'd like to replace the motor mounts, but I'm struggling to find a clear answer on what to buy.... My Olds is a 1970 Cutlass S that was originally a 350 car (I believe). Many people here on the forums say if it was a 350, leave the 350 mounts when installing a 455... Problem is, I have no idea what combination is in there, and obviously something isn't right. So if I'm starting by buying all new, which mounts would be suggested???

This leads me to my second question.... Many people say on a mild build, just go with manifolds and save the brain damage, others say headers are worth it no matter what!! I'm not sure if its a mild build or something on the bigger side?? People ask me if its fast, and I always tell them.. "Its old car fast". I sold a built Hellcat, and an even more built Audi RS7 to go back to something I could work on and enjoy without a payment, and I have absolutely ZERO regrets. I love my Olds!

I've been looking at ARH Headers, Thorton's Big Block Shorty Headers, and W/Z manifolds? I only want to do this particular job once, but I don't want to spend the money on the ARH headers to only find out my motor isn't even built enough and have a possible scavenging issue or running issues due to the headers. In that same regard, I don't want to choke it with the Shorties or the manifolds if the motor warrants better exhaust flow??

So in summary... Which motor mounts should I be looking at for a 455 with unknown history? And should I be looking at Headers, shorty headers, or manifolds?

Thank you for reading my lengthy, noob questions... Any and all advice would be sincerely appreciated.

 

Headers are not going to negatively impact operation or performance on a mild engine. Don’t stress over this.

 

Must be that time again.

The motor mounts MUST match the frame pads. Without knowing which frame pads are in the car, there is no way to tell yo which motor mounts to get.
When matched properly, the crank centerline ends up in EXACTLY the same place, no matter which 1964-90 Olds motor you have. Note in the second photo below that the 2328 mounts with matching frame pads tucks the mount further under the pan rail and closer to the pan. This opens up a smidge more room for headers, no matter which motor you have. And once again, the only motor mount used in A-body cars was 2261, no matter which engine (330, 350, 400, even 455 in the 68 H/O). The only motor mount used from 1973-90 was 2328, no matter which engine (260, 307, 350, 455, diesel).

 

I think it has been mentioned in the past that Shorty Headers are a waste and to go with the full headers. I put headers on my 69 455 and had no issue, that is no modifications needed. There were 2 difficult spots to get on. Also two places I had to put studs in place of bolts.
Steve

 

Joe I have seen you answer this question and use the photos above many times. Since the crankshaft centerline winds up in the same place with both sets of mounts, why the heck did Olds use two different sets of mounts.

 

Something else I've answered many times...

The original GM motor mounts were simply two metal plates with rubber between them. When the the driver side mount failed, the engine torqued over and the metal rod throttle linkage that GM used in the mid-60s would jam the throttle wide open. The initial reports of Chevys with this problem started in 1968. By 1971 there was a massive recall for this - you can still find Chevys with the retrofitted steel cable that runs from the exhaust manifold to the frame on the driver's side. Olds redesigned the rubber mounts to incorporate an interlocking feature so that even if the rubber failed completely, the interlock would stop the motor from torquing over. This is also why Olds went from a rod-type accelerator linkage to a flexible cable. The initial interlocking redesign of the motor mount resulted in the 2328 style mount, which I believe was pushed down and closer to the pan to make more room for the W/Z manifolds (which were also first used in the 1969 model year). Naturally these were first used on the BBO cars that had a greater chance of breaking a mount. For 1970 Olds came out with an interlocking design for the 2261 mounts for the SBO and slightly changed the frame pads. With the redesigned 1973 A-body cars, Olds just used the 2328 design across the board.

 

Maybe it is my feeble old memory but I don't ever recall seeing that detailed explanation. Thanks for posting it again.

 

I had a broken motor mount on a 63 88 and whenever I made a hard left and stepped on the gas i got the thrill of the throttle being jammed wide open!

 

Memory is the second thing to go, and I can't remember the first...

 

Indeed, Joe provided an excellent write-up...

 

I am also looking for an answer on the header question. I have a 71 Cutlass Supreme conv. Put a 455 in it. Read everything I could find header selection. But no one ever gives a specific set. Only brands. And they all said that them not fitting a Cutlass Supreme is an old wife's tale. Well I purchased a set of Summit brand with the ceramic coating. Slips right in but can't bolt up cause its hitting the proportioning valve. While I could try and make it fit but once I do that my chances of returning them if they still don't fit is slim.

Anyone have a specific set that I won't have to beat on to get to fit?

 

The common resolution with a big block and headers is to relocate the proportoning valve to the top of the frame. Many folks have posted about doing this by simply bending the lines to move the valve.

 

Yup. I've done this many times, but it only works on AT cars. The clutch equalizer is in the way on MT cars. EVERY Olds I've ever owned with headers needed the combo valve moved to clear the headers. The instructions that come with the headers usually tell you this.

 

I have Hooker 1 7/8 primary tube headers on my 69, they are probably 25 years old and still work great. I did have them re-coated about 5 years ago. I remember clearly putting them on, once the starter and oil filter housing were removed the headers took literally an hour to install. They do fit well. I did relocate the distribution block during v the first header install, so figure that into the installation time.

 

I've got a really nice set of long tubes from Hooker. Problem is on my car they are too low. Looks like the drop spindles have to go.