66 GMC Header Installation

[Anthony Fremont]

Ok, I give up. Where can I find the correct V8 motor mount perches for my truck? Someone made these funky adapter plates, but they won't clear my headers. Will the tubular mounts that CPP sells work?

[kevindtimm]

What I can't figure out is why yours are so bad. I have 67-72 mounts on my 62 and they look factory installed.

Bear in mind that whatever you do, there's going to be a lot of fab (frame repair, etc) when you remove those old mounts.

Do you have some other (wider angle, more of the subject) pictures?

[Captainfab]

PM sent....

[Anthony Fremont]

I think that what I have is the V-6 big block mounts that GMC put on and a previous owner rigged this up. I shouldn't have any trouble removing the adapter plates since they are not welded in place.

[kevindtimm]

Here's what my mounts look like (out of the truck)

http://i143.photobucket.com/albums/r...0/P2270067.jpg

[Anthony Fremont]

Originally Posted by kevindtimm

Here's what my mounts look like (out of the truck)

http://i143.photobucket.com/albums/r...0/P2270067.jpg

How close is the #1 exhaust tube to the motor mount in this pic of yours? Did you have to dent the header tube to clear the mount? Can you take a clearer picture of your mount and the rubber? I'm wondering if my clearance problems could be solved by just replacing the rubber piece.

[salazar44]

get the correct mounts at truckandcarshop. they are cheap.

[Anthony Fremont]

Originally Posted by salazar44

get the correct mounts at truckandcarshop. they are cheap.

Went and got a set of V8 mounts locally today. Looks like I already have v8 mounts in my truck it's just that everything is too far back. My engine and tranny need to come forward about 4-5". This means drilling new holes to move the crossmember forward, and then having to fix the emergency brake cables since they seem to depend upon the crossmember being where it is currently. And then there's the little matter of the drive shaft not reaching after that.

This sure seems bizarre. Is it because GMC only did six cylinders? Or did Chevrolet do this kind of stuff too? For example, would a tranny crossmember for a powerglide be mounted in different spots depending upon the engine option?

[kevindtimm]

My motor mounts and headers are 'miles' apart. No interference at all.

I will take clearer pictures tomorrow (had some posted somewhere else, chevytalk maybe but can't find them now).

As far as engine mounting goes, on chevy's the crossmember/tranny goes in the same place all time, regardless of engine, there's more room in front of the v8 than the i6 (IIRC).

Whatever you want pictures of, let me know, I'll happily take them.

[Captainfab]

Originally Posted by Anthony Fremont

Went and got a set of V8 mounts locally today. Looks like I already have v8 mounts in my truck it's just that everything is too far back. My engine and tranny need to come forward about 4-5". This means drilling new holes to move the crossmember forward, and then having to fix the emergency brake cables since they seem to depend upon the crossmember being where it is currently. And then there's the little matter of the drive shaft not reaching after that.

This sure seems bizarre. Is it because GMC only did six cylinders? Or did Chevrolet do this kind of stuff too? For example, would a tranny crossmember for a powerglide be mounted in different spots depending upon the engine option?

Kind of sounds like you got V8 motor mount brackets for a '67-'72. They move the motor forward 3" or so from where the '63-'66 motor mount brackets would be. I've not seen any differences between the Chevy's and GMC's in regards to the motor mount bracket holes in the frame, but then again I haven't dealt much with the V6's. But someone else may chime in that has.

[Anthony Fremont]

Originally Posted by Captainfab

Kind of sounds like you got V8 motor mount brackets for a '67-'72. They move the motor forward 3" or so from where the '63-'66 motor mount brackets would be. I've not seen any differences between the Chevy's and GMC's in regards to the motor mount bracket holes in the frame, but then again I haven't dealt much with the V6's. But someone else may chime in that has.

The mounts I bought aren't exactly like the ones that are already installed, but they are about the same "height". The guy at the truck parts place showed me a 6 cylinder mount and it was much taller than either mine or the ones I bought. It is my understanding that the mount should sit directly on the crossmember, is this correct in all cases? Mine are currently standing on spacers to make up the height difference of being so far back on the crossmember. I guess my main question is, "How is this supposed to look?" Should the mount occupy the front two frame holes or the back two (closest to firewall) on a 66? Can you confirm that there is a difference between a 63-66 and a 67-72 mount?

thanks, I'm really floundering here

[Anthony Fremont]

Originally Posted by kevindtimm

As far as engine mounting goes, on chevy's the crossmember/tranny goes in the same place all time, regardless of engine, there's more room in front of the v8 than the i6 (IIRC).

Thanks! This certainly seems the most sensible way for the factory to have done it. Can anyone else confirm this? If this is the case, then I seem to need motor mounts that use the rear two holes in the frame rails. This is really perplexing.

[Chevy Fleetside]

Here are the best pictures I can show you of when the sb was in my 65 with the stock mounts. This truck is an original 283 truck.

[Anthony Fremont]

I can't tell from the last picture, but does the mount stand directly on the crossmember or is there a spacer under it? Your mounts look pretty similar to the ones I bought, but on opposite sides so that they "reach back" to line up with the engine. The 67 and up trucks that I've seen put the mounts in the front two frame holes and oriented so that the mount "reaches forward" to line up with the engine. I take it your distributor cap clearance was kinda tight (as in you didn't have 6 or 8 inches behind it).

[Chevy Fleetside]

No spacers. There was about 1/2" of clearance for the dist cap. The perches use all of the rear holes. And if you looked at my BB build thread, I now have these.. The one problem I had with them is they moved the engine forward 3/4".. I am keeping my v8 perches just in case I get another truck that needs them. With 2 sb's I just might.

[Chevy Fleetside]

You can ask this guy if these were v8 perches. http://cgi.ebay.com/ebaymotors/1964-...m180250469008& And these are the 67-72 perches and they do look differnt.. http://cgi.ebay.com/ebaymotors/1967-...m360059432956&

[Anthony Fremont]

Originally Posted by Chevy Fleetside

You can ask this guy if these were v8 perches. http://cgi.ebay.com/ebaymotors/1964-...m180250469008& And these are the 67-72 perches and they do look differnt.. http://cgi.ebay.com/ebaymotors/1967-...m360059432956&

The second link looks just like the ones I bought yesterday. Looks like the "expert" I dealt with sold me the wrong ones. No refunds, so I guess I'll be getting a store credit towards a new bumper or something. :-( They'd be fine and give me lots of distributor clearance, but then I'd need to move everything else forward to accomodate them. I think not.....

Thanks for the reply, it's all starting to come together now I think. Once this is all sorted out, I'm thinking it will be good FAQ material.

[Chevy Fleetside]

They should give you your money back if they sold you the wrong ones. He said they were right so you took them. If you told you he wasn't sure and you took them then I could see them not giving you a refund. If he dosn't I wouldn't do business with them anymore, if you can help it that is..

[Anthony Fremont]

Originally Posted by Chevy Fleetside

They should give you your money back if they sold you the wrong ones. He said they were right so you took them. If you told you he wasn't sure and you took them then I could see them not giving you a refund. If he dosn't I wouldn't do business with them anymore, if you can help it that is..

I here you, but we will see. I've been down this road before with suppliers. It's called the golden rule of supply and demand. He who has the gold makes the rules.

I jacked my motor up and took out one of my mounts and its associated spacer and adapter plate. If I take the mount that I bought yesterday and use it on the opposite side, it almost lines up with the mount on the engine. It even stands on the crossmember, but doesn't line up with any existing hole. I guess it's obvious that I have the wrong ones.

[kevindtimm]

On my 62, there were no holes anywhere for side mounts. I measured, aligned, test fit, marked about 5 times before I drilled the first hole.

I only installed one mount at a time (leaving the front U mount in place VERY loosely until I was happy with everything.

That was 2-3 years ago and I couldn't be happier.

[Captainfab]

Originally Posted by Anthony Fremont

The mounts I bought aren't exactly like the ones that are already installed, but they are about the same "height". The guy at the truck parts place showed me a 6 cylinder mount and it was much taller than either mine or the ones I bought. It is my understanding that the mount should sit directly on the crossmember, is this correct in all cases? Mine are currently standing on spacers to make up the height difference of being so far back on the crossmember. I guess my main question is, "How is this supposed to look?" Should the mount occupy the front two frame holes or the back two (closest to firewall) on a 66? Can you confirm that there is a difference between a 63-66 and a 67-72 mount?

thanks, I'm really floundering here

On the top of the frame there are 3 holes. The correct brackets will use the two rear holes on the top of the frame and then down to the rear hole on the crossmember. No spacers or anything, just bolted to the frame and crossmember. I'll see if I can get a pic today of the ones in my '66 C20 with no engine in it.

[Anthony Fremont]

Originally Posted by Captainfab

On the top of the frame there are 3 holes. The correct brackets will use the two rear holes on the top of the frame and then down to the rear hole on the crossmember. No spacers or anything, just bolted to the frame and crossmember. I'll see if I can get a pic today of the ones in my '66 C20 with no engine in it.

Excellent information, thanks!!!! I wonder why CPP and, at least, some other vendors think that everyone can use the same mount from 63-72. I mean the clearance of the later mounts is cool, but not worth the hassle of relocating everything in my case. I really don't need that much tunnel clearance, I'd rather keep the motor where it sits now. I do intend to install the CPP tranny mount and drop-center crossmember later. They're worth the price just for the weight reduction and not having to clean and powdercoat mine.

[joe231]

here is pics of mine. 283 engine
hope they help

[Anthony Fremont]

Thanks for the pics. I now know what I need. Here is a couple of pics of the 67-72 mounts I bought yesterday installed backwards so that I could hang the headers in place temporarily. You can see that they almost line up with the engine part of the mount, but not any holes in the crossmember. They stand the right height so I suppose I could hack them into service by drilling new holes in the crossmember and slotting out the holes in the frame. Just kidding, I'm going to get the right perches. Ignore the electrical tape on the brake line; the previous owner must have fixed a leak.




Glamour shots of the headers tacked in place:





While I'm at it, and I know everyone likes pictures. Here's some pork chops I beautified today:

[joe231]

nice looking meat!!