Anybody ever swap a serpentine setup on to an older block? I am in the middle of swapping in my serpentine belt setup and have come across a problem. The passenger head on my Goodwrench block only has one of the two required accessory bolt holes to mount the serpentine bracket. All other required holes on the block and drivers side head are there. Now - how feasible is it to drill/tap the head while in the car? Has anyone run a serpentine setup with only one of the two upper bolts in place? I think I would be leary of doing this since the heaviest accessory (compressor) resides in this location.

Search for "sofakingdom" because he has written about this before. I believe he said he bolted everything up then removed what was in the way, and drilled/tapped the hole. It usually comes up when someone talks about wanting to run a set of old "double hump" heads with no accessory holes. That's usually a no-no because there is no good place to start from.

I wouldn't be afraid to do it on the heads you have.

Thanks, I just came up with this thread - seems like a common problem/fix to have to drill the head:

http://www.thirdgen.org/techboard/te...ine+head+drill (88 serp. belt setup on early model block)

Anyone know what size drill bit would be required, and what the thread is on these bolts?

Does anyone have any pics handy showing where the steel braces mount for the serpentine setup?

I don't know if this will help because I used a serp setup from a TPI on mine. I had to make a bracket to tie the alternator brace to the intake bolt. Other pic shows lower P/S pump brace and another one I fabed.
EDIT: second picture has the radiator hose gaurd missing.

Sorry Kris, wasn't me... I can speak about why trying to install bolt-hole accessories using stock brackets on no-bolt-hole heads is futile, but not this one.

Take a look behind where the other bolt hole needs to be, and see if there's a lump of metal to drill into right there. If so, then you'll be able to do it. I'd be quite sure it wouldn't be there on older (70s) heads, since they probably weren't aware at the time that 30 years into the future it might be needed; but it might be there on newer castings, just not drilled & tapped.

But, people use that bracket system on those motors all the time, in fact GM sells those replacement motors themselves for such applications; so it's probably OK to use it as is. But I'm no expert on that, don't take my word for it.

I'll have to take a serp bracket and compare it to a head some one of these days and find out what the possibilities are...

It will be fine without drilling and tapping the holes .... but make sure you use all the braces, thos give more then enough strenght to not have that extra bolt.

Does anyone know for sure how many braces there are supposed to be? I have three in total that came with my setup. Mine is from a 91 B-body, but from what I understand, it is the same as an F-body setup.


Supervisor42 - Thanks for those pics - looks like the factory ones pictured are from the alternator to the intake, and the other goes from the back of the PS pump to the manifold. Looks like you had to bend the lifting eye a bit to get that brace in?

I have a third brace - I understand that there is at least one on the A/C compressor?

sofakingdom - yes, there is the flat raised area on the head. It is a Goodwrench block intended for 85 and older applications (hence the lack of the serp accessory hole.

NowTheBadNews - have other done it this way without any problems. After reading some of the threads I found in a search, it sounds like this may lead to cracked brackets.

theres a total of three braces. One goes from back of a/c compressor th a bolt on the exhaust manifold, another goes from back of a/c compressor to the intake manifold. Hower the alternator brace varies from TPI to TBI .. TBI brace goes from back of alternator to an exhaust manifold bolt, TPI I am not sure where it originates but it goes to the intake manifold. ............ I've run one like this with no problems.

I looked at supervisors pictures .... but none of his looks like what I have ever seen except for the alternator brace .... I'm not sure why he has a brace where the power steering pump is because where he bolted it to is not for a brace. It is for mounting the fuel lines ......... Since you are running without the extra bolt I wouldn't rely on homemade braces though LOL.

Right, on the OUTSIDE:

But, is there a BOLT BOSS behind it?

Not all of that flat raised area will hold a bolt. Most of it, is the same thicknes as the rest of the outer water jacket; about 1/8", plus however high the rasied part is (another 1/16" to 1/8" more or less). And of course, if you try to drill in a place like that, you get about 3 threads deep, and then you hit water.

To actually drill for a bolt, there needs to be a lump of metal where the bolt goes for the bolt hole to go INTO, on the INSIDE. It'll be about ¾" deep and the same size around. Pretty big feature, not hard to spot. You can see some of them under the valve covers but some you have to look into the water jacket from underneath.

Thanks. The stud on the back of the PS pump is for fuel lines? My setup is from a B-body, so it sounds like my alt brace will go to the exhaust manifold. You've run yours with the braces, and the missing A/C bolt? How long has it been that way? If the A/C has two braces, I might be ok with that. The brace with the hose protector on it must be for the alternator bracket.

So there is no factory PS brace then correct? I only plan to use the factory braces that came with my setup.


I see - I guess I just assumed if it has the boss on the outside of the head, that there would be the boss on the inside to drill into. Thank you very much for pointing that out - not something you want to find out the hard way! If I can't see it from up top with the valve cover off, I will try to run without the bolt - I'm not removing the head to check (when the heads come off, a different set will be going on )

I had to make the plate on the outside of the P/S bracket to take the place of the top driver's side bolt in the head. The earlier heads I used slope inward and I couldn't move the hole in the bracket because it's down in a "hole".
The 3rd brace doesn't go to the A/C compressor. (I didn't have a picture)
It goes down to the passenger side bracket just below the AIR (smog) pump from the exhaust manifold bolt.
Fresh picture:

Here's a pic of the stock location of the alternator brace on the TPI. You can see why mine is where it is.

Thanks again for the pics. So your setup does not have any braces at the compressor? Both the mounting bolts on my compressor have a threaded stud sticking out the back like they would take a bracket, and some people have mentioned two go on the A/C compressor. Were there different serpentine bracing setups even on the F-bodies? A possible difference in TPI/TBI was mentioned above...

Mine doesn't.
There are probably several different setups in 3rd gens alone, not including other (B?) bodies. That's why I said that my stuff may not be much help.
Here's a better picture of the bracket from the exhaust manifold bolt down to the back of the P/S pump. Remember, this setup was off of a TPI.

Thanks - once I have the brackets mounted I will have to see if I can figure out how my particular braces should mount up. My PS pump does have the stud on the back like your last pic though. My setup is from a 91 B-body - I'll have to pay attention to some if I see any at car shows etc.

Hey 85SS did you ever finish this install? I'm getting ready to do this myself on my goodwrench. I noticed on this motor the flat boss (sofa was talking about) doesn't really go where the stud will, just north of it. On the older head (336) I used to practice on, the flat boss completely covers where the studs goes, but more than that I was able to drill and tap 1 inch before hitting the water jacket. Sofa are you sure the water jacket is only 1/8" back? We only 1/2" worth of threads to do the job, and I'm hoping the goodwrench is similar to the older heads. If not I can just use sealant. Though, all of this isn't necessary according to the GM serpentine kit instructions.

Another question, do you guys think its okay to interchange the brace between TPI and TBI models? I have the latter but can't find a pic or a brace to buy.

I did finish the install, but without drilling/tapping the head. I installed two braces on the compressor though:

-one from the compressor to the front of the intake (factory brace)
-the other was a smog pump to exhaust manifold brace, but with a little massaging of the ends, and a custom length spacer, I was able to use it from the rear of the compressor to the first exhaust manifold stud.

I couldn't use the second factory brace from the rear of the compressor to the 3rd exhaust manifold stud with my g-body headers - but this will work fine on an F-body. I am very comfortable with how solid the whole bracket is with the two braces installed (I think it was actually fine with the one brace), and reading that GM installation procedure takes away whatever worry I may have had left. Thanks for that link!