350 Serpentine belt conversion and intake gasket
 

I know there are a ton of threads concerning serpentine belt conversion and I searched it all before I opened a new thread.

While reading up on installing 350 intake gaskets I found out that the gaskets on engines with a reverse water pump (serpentine setups) had the two rear water ports blocked. I am in the process of putting a new 350 in my 74 GMC truck with a serpentine system. The 74 350 did not have the rear ports blocked. Should I buy the intake gaskets with the rear ports blocked? Is it an issue at all?

I also noticed while digging around that the 99 Suburban with a 350 did not have the rear ports blocked. I might also add that I'm putting an aluminum intake on it.

There has to be someone out there a lot smarter than me that can explain this.

Re: 350 Serpentine belt conversion and intake gasket
 

Welcome to the site. I have an serpentine conversion on my truck. Does the new intake have a water cross over path? If so leave them unplugged. I know mine are not plugged and I run a RPM Air gap intake. Use a nice bead of RTV on both sides of the intake gaskets. Use a very large bead at the front and rear block wall where they match the intake. Use a dap under the corners too. All of the RTV will prevent oil and water leaks. Depending on the intake, you may want to use aircraft forma-a-seal on the bolt threads. The sealer will prevent oil seeping up the bolts onto the intake.

Re: 350 Serpentine belt conversion and intake gasket
 

Most (if not all) aftermarket intakes block off the rear water ports from the heads. Back in the day we used to drill/tap -4 AN fittings and run hose from there to the thormostat housing on both sides to remove steam pockets from the heads on our race motors. I think they are suposed to be blocked otherwise

Re: 350 Serpentine belt conversion and intake gasket
 

Did you mean RTV only on the water ports or on the whole gasket? My concern with RTV on the intake ports is that it would bead up inside the port when bolted together tightly causing a ridge that would create turbolance and hendering flow. I realize this would matter little on 90% of the engines out there.

Welcome to the forum Noel. Perry, FL??? GA??? and I'm sure there are others.

Re: 350 Serpentine belt conversion and intake gasket
 

Only on the water ports. A realy small bead will work. Just make a circle. Use a little dap under the gasket corners where the block, intake, and head meet. I did this on my ZZ4. I have no oil leaks anywhere on my engine.

Re: 350 Serpentine belt conversion and intake gasket
 

That has always been my practice as well, I just read it funny and was curious.

Re: 350 Serpentine belt conversion and intake gasket
 

Thanks everyone for the comments. I checked the intake more closely and found the rear ports are blocked. Newby mistake. I bought the intake gaskets for a 74 which had all the ports open which confused me. I will just use the gasket I bought and get some RTV for the ends and ports holes. Some thread sealer for the bolts as well.

I got my setup from a 99 Suburban because I wanted the A4 AC compressor and the 140 amp alternator. The water pump was a little different too. It has two tubes protruding from the top. One goes to the return line for the heater and the other goes to the radiator. So unless I want to try squeezing a suburban radiator in my 74 I'll just plug the other tube. It goes against my grain. I like doing things right. Jerry rigging is not my thing.

Re: 350 Serpentine belt conversion and intake gasket
 

Here is the progess on the engine so far. Installed the serpentine belt system and rebuilt quadrajet. The serpentine passenger side was a bit of a challenge. The bolt holes did not match up. Lucky for me I have a friend that was a GM engineer. He welded me a bracket that bolted from the intake down to the exhaust manifold. Worked great!

Re: 350 Serpentine belt conversion and intake gasket
 

Are there multiple serpentine bracket set ups? The setup on my motor is a little different. Different brackets and tensioner and idler are swapped.

http://i901.photobucket.com/albums/a...ps4f13ebab.jpg

Re: 350 Serpentine belt conversion and intake gasket
 

Surprised to hear that the bolt holes were off. Everything i have read says it should be a direct swap. Strange. I am getting ready to tackle this on my project as well, but i will be using a newer vortec block.

Re: 350 Serpentine belt conversion and intake gasket
 

Its not quite jerry-rigging, its more like retro-fitting.

I'd stick with the intake gaskets recommended for the intake. In my case, I have a 1986 305 and I happened to have a 1986 TPI manifold. No water crossover in the rear, but it still used the 86 intake gaskets with the crossover ports. I believe GM updated the gaskets in 87 to save on cost, they eliminated iron manifolds with the rear crossover so 2 gasket designs were no longer needed.

Re: 350 Serpentine belt conversion and intake gasket
 

If i'm not mistaken the picture the op posted is from a 96-97 vortec style engine. yes?

Re: 350 Serpentine belt conversion and intake gasket
 

The serpentine system pictured above came off a 1999 Suburban with a 5.7L engine. Same as a 350.The heads are larger than the older 350 with a carburetor because of the fuel injection system I suppose.

Re: 350 Serpentine belt conversion and intake gasket
 

Was wondering if you using the p/s pump from the 99 suburban? Cause I'm doing the same swap now on my 84.

Re: 350 Serpentine belt conversion and intake gasket
 

It's the same Saginaw pump, just the reservoir may be different to fit the bracket. Just swap reservoirs if thats the case.

Re: 350 Serpentine belt conversion and intake gasket
 

Yes I did. Do you need a bracket the one that I talked about above? I can put you in touch with the guy that put mine together.

Re: 350 Serpentine belt conversion and intake gasket
 

I'll let you know. I have summit heads on my motor. So I'll see if it bolt up to the 3 holes.

Re: 350 Serpentine belt conversion and intake gasket
 

What did you do to get the alternator to work?

Re: 350 Serpentine belt conversion and intake gasket
 

The Vortec RH serpentine brackets have provisions for either style of alternator-105A or 140A.

Re: 350 Serpentine belt conversion and intake gasket
 

For folks running the older style serpentine setup who want to run a 140A alternator, I build bracket kits for them.

Re: 350 Serpentine belt conversion and intake gasket
 

Sorry for necrobumping this thread but I'm having similar issues with this same serpentine setup. Do you have any more pictures of that adapter you made for the passenger side bracket