Blocking the bypass hose?

[RET_COP]

Does anyone block the bypass coolant hose and modify the thermostat thus forcing all the coolant in the block at startup through the radiator? Just curious as I have heard of this practice, supposedly it will result in longer warmup times but uniformed cooling?
Lou

[Rick Parker]

Nothing to be gained with conventional 4 bbl manifold.

[Bob In Ct]

The guys in Detroit probably know what they're doing - leave both the thermostat and bypass in place.

BTW, who's favored next Thursday? Go Bears!!

Bob

[JBCOBRA]

I had the bypass corked off. Big mistake. I shifted into 3rd at 7grand and that plug blew out like a Champagne cork! LOL Shot antifreeze everywhere. The stuff blew out of the hoodscoop bigtime. I thought the motor exploded at first. What a mess.

[*13*]

So what are you guys doing when running webers with the dual outlet manifold? No bypass setup unless you do something custom.

[madmaxx]

You want the bypass, why in the hell would you ever want the engine to circulate through the radiator at start-up? You will wear your engine out in 5K miles!!!! It is well known a cold engine wears exponentially faster than a warm. Hot piston and cold cylinder wall means wear. The bypass helps to circulate the coolant in the block, this ensures the uniform engine temp instead of very hot block temp and cooler head temp. It has absolutely no effect on warm up times. Check my recent post on thermostat testing, at once I thought it migh, now I know it does not!!!!

Do exactly opposite of what 99% of people tell you and you will be right 100% of the time. I am the right 1% by the way.

[Caprimaniac]

I've had no troubles without the bypass.
with mechanical or electrical waterpump.

Engine gets warm fast enough, although I do have problems with engine getting a little too cold on the highway. That might be because I do not have an electronic control unit for the water pump. (although it runs with a two stage temerature switch: slow running (1/3 of full) at cold and full when warm.

[madmaxx]

If you are running cool on the freeway it is because of your thermostat. The thermostat determines minimuim operating temp not maximuim. Also remember a thermostat may open at 195F but it will not fully close until 185F.

Now if you have a electric water pump I guess you dont need a thermstat, just shut it off. Outside a race engine how would an electric water pump ever be justified.

By the way 351 blocks have an external hose for the bypass, 302 have the bypass internal to the water pump so from the factory they all have one.

[wanab5150]

Leave it alone......

[bobcowan]

Originally Posted by RET_COP

Does anyone block the bypass coolant hose and modify the thermostat thus forcing all the coolant in the block at startup through the radiator? Just curious as I have heard of this practice, supposedly it will result in longer warmup times but uniformed cooling?
Lou

You need to have water circulating through the block as it's warming up. Otherwise it heatsup unevenly, and you'll get hot spots around the chambers and cold spots around the cylinders.

Race engines can without it, but that's because they don't have a thermostat. That's how the original weber manifolds were built, Y hose and no thermostat.

That's also the reason many cars have trouble keeping warm on the freeway - no thermostat.

[RET_COP]

I read some threads where guys are plugging the bypass and drilling holes in the thermostat to get some water flowing and relieve pressure. That by having the bypass, 20% of the coolant is flowing by the stat. lowering temps.
I have a bypass hose hooked up and plan on leaving that way but I suppose you could play with percentages and temps. by using a restrictor of some sort in the bypass hose instead of drilling holes and plugging hoses.
Lou

[cdnus]

It is not bypassing the stat. It is circulating in the block & heads, equalizing the temp in the engine untill it gets warm enough to open the stat. then it goes through the rad.

[madmaxx]

The only thing you need to read is what I wrote, it is correct. By-pass hose has zero effect on cooling or warming the engine any quicker.

[Barnsnake]

If you are running a thermostat (and you should), without the bypass you can have icewater at the thermostat and steam in the heads. The cooling system needs circulation.

[ponvire09]

Hey I was the first one with the 306 answer, that means I win the motor right????

[DoneByDoug]

Thanks for the info on the bypass. Good stuff

HOWEVER, what's up with your gallery pic of the plug on your heater hose connection just below the bypass?

I sure want to believe you're the 1%. Just curious....

Doug in Louisiana

[Excaliber]

Eh eh, here's to Max.

Got the polish thing down, looking good.
Got the cool pulleys, outstanding.
Got the billet alternator bracket, oh yeah!

Got the funky butt plug in the heater port hose with a couple of screw clamps, wait,,, what the heck???

[Rick Parker]

Madmax, can you explain??

By the way 351 blocks have an external hose for the bypass, 302 have the bypass internal to the water pump so from the factory they all have one.

[bobcowan]

Originally Posted by madmaxx

By the way 351 blocks have an external hose for the bypass, 302 have the bypass internal to the water pump so from the factory they all have one.

I don't thik that's true. the front cover and water pump are the same on both windsor engines. Might be differant for the 351C or M. But there's no 302C or M, so that still doesn't make sense to me.

Originally Posted by DoneByDoug

HOWEVER, what's up with your gallery pic of the plug on your heater hose connection just below the bypass?

The Windsor water pump has two holes, one next to the other. One is for the bypass, and the other is for the heater. Doesn't matter which one you use.

Drilling a hole in the thrmostat base plate is an old trick that's been around since I was kid (like a century or two ago). It's there to allow you to fill the entire cooling system when cold, as air can escape through the hole and out the filler cap.

Without the hole, water will flow from the filler cap, through the radiater, into the lower hose, the water pump, the block, the heads, up to the back of the thermostat. It will stop somewhere in the block or heads, when air pessure builds up enough to hold the water back.

If you set up the hoses and filler correctly, and drill a 1/8" hole at the 12 o'clock position, you won't have any trouble burping the system. It has no discernable impact on the rate of warm up.