Hi all, i'm building a 383 from a later 98 1pc rms vortec engine. Its going in an 83 Trans Am and i'm sure I saw a youtube video about drilling the waterway to use the bypass hole on the front of the block for the water pump. This is right....right? I didnt dream it did I? Can someone point me in the direction of a video for confirmation please?

Thanks in advance.

Rob

 

Every Vortec block I have had already had the hole and matching hold drilled from the deck surface. In fact my current 383 build will be getting a TBI water pump and the whole accesroy setup spaced out with 1/4" washers to match. My heads have the passageway drilled through the deck surface and a Vortec pump will not cover the passageway making for a massive coolant leak.

 

Many vortec blocks dont have the waterway for a bypass and if you dont run a heater core you can have issues. A simple solution is to install a line between the manifold and the water pump as outlined in the edelbrock install manual for their vortec manifold.

SPECIAL NOTE: This intake manifold is primarily intended for use with Vortec heads on pre-Vortec blocks. 1995 and earlier blocks have the thermostat bypass water passage from the block directly to the water pump through the passenger side water pump mounting flange. If the manifold is used on a 1996 and later Vortec engine that does not have the in-block bypass passage, you must route a thermostat bypass hose from the water bypass port on the front of the manifold to the 5/8” hose nipple on the passenger side of the water pump. The 3/8” pipe to 5/8” hose nipple fitting, hose, and hose clamps are included in the kit. If your engine block has the thermostat bypass passage, use a 3/8” NPT plug supplied in the kit to plug the bypass port in the front of the intake manifold.

https://www.jegs.com/InstallationIns.../350-75164.pdf

 

The 96 vortec I pulled doesn't have the bypass hole but the reman vortec crate I bought does and it is also machined for a mech fuel pump. Both have the same block casting number. You can use a bypass style thermostat or drill a hole in one, another option is to use coolant bypass lines(I suggest small and not the huge 8an many use) from the rear of the intake long as you use an adapter n dump them above the T-stat. The area from two 1/4(4an) lines is about the same as the bypass hole id I think. On one car I blocked the bypass because of using a motor plate and didn't use a bypass thermostat and of course no heater, never had a problem but it didn't see a ton of miles before I tore it down for a wiped cam lobe. It's an old performance trick to plug the bypass so you even the cooling otherwise cylinder 2 gets a bit more, that part of why I prefer to use rear coolant bypass lines.

 

Forgot to mention you can plumb an intake rear bypass line into the suction side of the water pump, I used a single line for that on my C4 corvette.

 

I have drilled many of them, I made a jig to do it. It guides the drill.

 

This is a simple solution

 

The easiest, cleanest and most reliable method is to drill the thermostat with 2 x 1/4" holes. Did it on a Vortec 305 in a 1980 C10. Worked beautifully and no potential to create a future coolant leak. It actually allows the engine to warm up more evenly and hold a far more consistant temperature by never blocking the coolant circulation. It also prevents hot coolant from bypassing the radiator allowing the engine to run cooler on a hot day. In cold weather it took a slight bit longer to warmup but hardly even noticeable unless the truck was sitting at idle.

 

Do you drill the one in the deck surface to meet the hole from the water pump?

 

Old thread but hopefully you guys can help me out as it seems your knowledgeable on the specific subject. Finishing a 383 and my block has the bypass hole on the passenger side of the water pump. I am using AFR Vortec heads and an Edelbrock Vortec base. Being Vortec it has the port in the center of the intake by the thermostat.

I can (should?) use a standard factory style water pump with the extra hole and plug that port on the intake with the block/intake/head combination I am running. I didn't even realize I had this problem until yesterday when I asked what that port was for.

 

I really like your set up and would like to do it on my vortec headed 1980 c3 corvette. I am having trouble finding the brass elbow on the water pump. could you possibly tell me what it is and where to find one? Thanks

 

Most likely this: (or equivalent)
Parker VS209P-8-6 $4.80 Brass Reducing Bushing, MNPT, 1/2" x 3/8" Pipe Size | Zoro.com
Zoro Select 6AFJ7 $2.54 90 Degrees Elbow Hose Clamp, 3/8 in Hose I.D, 3/8 in Thread | Zoro.com

 

It's funny running across this today as I'm in the opposition situation where I have an early GEN1 SBC and I just tapped the passenger-side bypass hole and installed a pipe plug so that it doesn't function.

GM changed to the Vortec style cooling because it just makes more sense and evens out the temperatures between the cylinders better than the early coolant routing.
-I got the Stewart Stage 2 pump that doesn't have a bypass, then tapped and installed a plug in the bypass in the block, and drilled 2 holes in a Robert Shaw style thermostat as the bypass.

I don't like the stock style bypass as Cylinder #2 is already one of the two coolest cylinders and doesn't really need any more coolant flow, so why steal from the other cylinders to give more to cylinder #2?
Also, without the heater bypass active (it's only active on my car in "Heat" or "Defrost" modes, too), the bypass isn't allowing any flow and isn't really a bypass because there's no path to return coolant to the low pressure inlet side of the pump, so.

Adam

 

Hey I know this is an old thread but I have a couple questions as I just ran into this bypass hole issue. I have a 99suburban with 5.7vortec I bought promaxx heads to put on and am now running into the issue of coolant draining out of the bypass hole on the passenger side of the water pump. Can I just plug this hole and go? I would like to use the original style waterpump that does not utilize that bypass hole

 

IIRC the hole is threaded 3/8 NPT. A little sealer and a plug and you should be good to go

 

mine was not threaded, a 3/8 plug seemed to small so I stuck a couple drill bits in to size the hole and was able to fit a 23/64 so I tapped it 7/16 and put a 7/16 plug in with a good amount of sealer. Letting it cure tonight then going to fill her up and finish putting everything back together and see how it goes

 

Nice job no need to drill it out to 3/8 NPT then which is a 37/64 drill before tap

 

1/8" NPT is the correct thread size for that hole.

 

I second this statement, pickup an 1/8 NPT tap and cap. What I had to do on the L31 383 in my Express with Assault heads.