[chuckies76ta]

Originally Posted by rolling money pits

I, too, have those Precision head plug things. Was going to tap the xover and run lines there. Then this thread popped up and I thought different.

However, I want to maintain heater core functionality. If I tee the lines in the back, then run through heater core/timing cover like factory, it’ll still help with head cooling?

I would say so, as you’ll be dropping heat off through the heater core. Which in itself is a rad. That’s the way the factory did it anyway in the passenger side head . On another setup, my car I joined both back of heads together, then went to heater core, then to timing cover return.

[Gach]

Originally Posted by chuckies76ta

I used a -8an y splitter. I did not use the heater core.
I came off back of passenger head to the y fitting, took one to crossover and other side of y fitting to water pump return. I wanted the coolant flowing at all times while the engine is running, before thermostat opens

https://www.amazon.ca/BIKING-Fitting...07023500&psc=1

Gotcha… good idea. Yeah I don’t use heater core either. Might try that myself, right now I have the one on timing cover plug off. True IA block takes longer then stock block to heat up, I’ve noticed that to. Thanks for the link

[Dragncar]

Originally Posted by chuckies76ta

Gach, I tried that spacer thing and I didn't like it. I finally removed it and re installed the thermostat. 160*. I took the water lines from the back of the heads to the crossover. I tapped off the passenger side and went to the return on the timing cover that is for the heater core. I also left my bypass on the cross over to timing cover in place. I also have electric fans and a Meziere water pump. I drilled 2 small holes in the thermostat to relieve any air that may be in the system on startup. Car stays at 160 * and on return road is at 170* in 80-90* weather. Been working very nice for us so far.
So on cold start up coolant runs through the bypass and also moves through heater core port on timing cover. I set it up the same way from the factory so coolant is always circulating through the block and heads while thermostat is closed. I use the Napa stainless thermostat for years with no issues.
What's funny about the whole setup is this 505 IA2 take longer to warm up than our previously 468 engine. I think it may have something to do with the Meziere water pump. That pump really moves the coolant. It's the HD pump. I never had a heating issue in any Pontiac engine in all the years doing this stuff, except when I install a Mr. Gasket thermostat and it was sticking on opening.

Can we get a picture of the whole setup ?

[chuckies76ta]

Originally Posted by Gach

Gotcha… good idea. Yeah I don’t use heater core either. Might try that myself, right now I have the one on timing cover plug off. True IA block takes longer then stock block to heat up, I’ve noticed that to. Thanks for the link

So just a thought here Gach. I'm just wondering and learning as I go so,,, If the return from the heater core to the timing cover is blocked, how does coolant circulate in the block if a thermostat is installed? Would it just be returning to the pump through the cross over bypass? and if that was closed off, there would be no circulating coolant when the engine is started?

[chuckies76ta]

Dragncar, Here is a pic of what I did. I just used heater hose for now as it's easier to manipulate. More flexible. I do need to change it up to a better hose. I used an adapter from the 5/8" hose to the 3/4" hose as the nipple on the timing cover is 3/4" hose. It's basically the same as the factory setup with the addition of the hoses to the cross over. I wanted to have a thermostat so the engine would come up to temperature and I also wanted to circulate the coolant in the block as it was warming up before the thermostat opened. I'm basically just following how the engineers did from the factory, with a little mod. Reason being as I like to heat the oil up before running down the track. Does all this make any difference, hell I don't know. All I know for sure is the engine temp has never gone over 170*- 180 * in very hot weather at the track. We've been at the track in 90*F weather and no issues. I also set it up with the electric pump and fans to cool it down in the pits. All my information has come from members on this form who know a hell of a lot more than me.. So Thanks P/Y.

[chuckies76ta]

Here is another pic from a member on this board that was posted.. Very nice setup.

[misterp266]

Originally Posted by chuckies76ta

So just a thought here Gach. I'm just wondering and learning as I go so,,, If the return from the heater core to the timing cover is blocked, how does coolant circulate in the block if a thermostat is installed? Would it just be returning to the pump through the cross over bypass? and if that was closed off, there would be no circulating coolant when the engine is started?

This is important.
You should never have the engine running without the water pump running! Your temperature gauge may show 160* at the crossover but without circulation, it could be 280* or higher at the center exhaust port area.
If you run a thermostat, there has to be a path for coolant to circulate before the thermostat opens. If you eliminate your heater core, the bypass is the only path and it’s quite restrictive. Eliminate that, and there is no path. You can’t run a 55GPM Meziere pump without a path to circulate the coolant.
In a modified engine with a modified coolant system, I would think that a restrictor plate like Gach runs is the way to go. In a daily driven street car, a thermostat would be recommended.

[chuckies76ta]

So that is what I’m alluding to. I have the return on the timing cover plus the by pass working. Thanks

[moneypit]

Lots of good info here! My question is what are the pros and cons of running the lines from the back of the heads above the t-stat or below? Mostly street driven E-headed 467. Passenger side T'd to utilize the heater.
Thanks!

[Formulas]

lines from the back of the head under the thermostat are under control of the thermostat both temperature and total flow

lines from back of head to above the thermostat increase total flow and will flow when the engine or pump is running or pumping, then when the engine reaches temp the stat will regulate overall temp


that is why i went with 2 -6an above the stat because i still wanted the stat to do the heavy work with a little help and that little help is directly and constantly circulating from the back of the engine
also i used these parts because i had them laying around and fit
I like getting into the engineering and making better alot like my work was

[pontbil]

I just used an old thermostat and gutted it. Wehrsmachine.com spacer made in USA

[Gach]

Originally Posted by misterp266

This is important.
You should never have the engine running without the water pump running! Your temperature gauge may show 160* at the crossover but without circulation, it could be 280* or higher at the center exhaust port area.
If you run a thermostat, there has to be a path for coolant to circulate before the thermostat opens. If you eliminate your heater core, the bypass is the only path and it’s quite restrictive. Eliminate that, and there is no path. You can’t run a 55GPM Meziere pump without a path to circulate the coolant.
In a modified engine with a modified coolant system, I would think that a restrictor plate like Gach runs is the way to go. In a daily driven street car, a thermostat would be recommended.

I fire it off today for first time since winter. Finally got garage addition done. I took your advice and turn pump on. Don’t want center exhaust getting to 280 degrees. and having different plug readings. Not much if any take longer to get to 180 degrees.

[Gach]

It works great so I’m not going to mess with putting in the Y and going to timing cover.

[Dragncar]

Originally Posted by Formulas

lines from the back of the head under the thermostat are under control of the thermostat both temperature and total flow

lines from back of head to above the thermostat increase total flow and will flow when the engine or pump is running or pumping, then when the engine reaches temp the stat will regulate overall temp


that is why i went with 2 -6an above the stat because i still wanted the stat to do the heavy work with a little help and that little help is directly and constantly circulating from the back of the engine
also i used these parts because i had them laying around and fit
I like getting into the engineering and making better alot like my work was

OK, so if I run a spacer with 2 NP female threaded holes and run the thermostat in the stock location I will still get some water circulation ( belt driven pump) when the engine fires up through the 2 lines going to the back of the heads.
Then when the thermostat opens I will get even more water circulation.
Correct ?

[242177P]

Originally Posted by Dragncar

OK, so if I run a spacer with 2 NP female threaded holes and run the thermostat in the stock location I will still get some water circulation ( belt driven pump) when the engine fires up through the 2 lines going to the back of the heads.
Then when the thermostat opens I will get even more water circulation.
Correct ?

With just two pickup points, I believe most of the closed
thermostat circulation bypasses the head. Consider the
size of the head's coolant openings versus the space in
the lower water jackets. So it makes a pass through the
block, and the lines provide a convenient exit. 7 and 8
benefit greatly, but the rest are relatively stagnant.

I'd like to experiment with a pair of Bosch 12v coolant
pumps. Draw coolant from the crossover and feed the
rear fittings. Nothing more than endless circulation, but
individual cylinder temps could be more consistent?

[chuckies76ta]

Just a few thoughts. If you run a thermostat, it will not open till it sees it's temperature. So with the thermostat closed, the only path for coolant to circulate is within the block. If you close off the cross over bypass you eliminate a return path for coolant to the water pump. If you close off the heater hose return at the timing cover you eliminate that coolant return to the pump. Now you have no return to the pump with thermostat closed. That is why the thermostat has to be eliminated so there is still coolant flow through the engine. Like mentioned, you could have very high temperatures at the two exhaust ports, cause the coolant is not moving within the block/heads.
It's like what they do with boiler systems. The dedicated circulating pump for the boiler is always moving heated water/ glycol in a loop for the boiler. From there, heated water is moved out in the building through another set of pumps or pump. Point is the water in the boiler loop is never stagnant. it is always moving. Our engines are same. You need flow from the time is it started.
I guess the point were all trying to achieve is stable engine temperature through operation. For myself, I feel the engineers at GM knew what they were doing and it has served engine operation for years. So changing things up somewhat, does it help. I was told by a friend that taking the two coolant lines from the back of the heads to the crossover doesn't do anything. Reason I did it is I figured if one side has more coolant flowing through the heater core, might as well try move coolant on the driver side head.
Now some folks get into moving coolant through the center exhaust ports which I believe is a good thing. I'm not running a turbo car or really high horse power, so for me what I've done is working out really well.

https://forums.maxperformanceinc.com...d.php?t=866093

[Formulas]

Drilling holes in the thermostat body brings coolant past the thermostat when the block crossover bypass is closed or restricted, pretty simple, however i would not engineer a system that can be or is dead headed with the engine driven pump thats where lines from back of heads to above the thermostat comes in it eleviates a dead head condition

and some cars even had a shut off valve to stop hot coolant flow into the heater core during A/C not a problem disableing that path either

[chuckies76ta]

Originally Posted by Formulas

Drilling holes in the thermostat body brings coolant past the thermostat when the block crossover bypass is closed or restricted, pretty simple

Well, simple yes, but your not gonna move much coolant through a couple of small holes.

[Formulas]

Originally Posted by chuckies76ta

Well, simple yes, but your not gonna move much coolant through a couple of small holes.

you dont need much coolant to do that job 2 1/8 - 3/16 holes will bring enough coolant up to the stat plus in my case i did not plug the crossover bypass i reduced it to 1/4 inch so its still doing a job just a lesser degree at that point

basically i reduced not eliminated the amount of water loop circulating in the block via the crossover shifted some of that to holes in the thermostat so it sees block temp and works correctly
then by having lines from back of heads above the stat i pull more coolant directly from the back of the engine
not a wheel reinvented minor tweeks that will work

i experienced more stable temps putting a couple holes in the stat on otherwise stock OE systems regardless of the naysayers

[chuckies76ta]

Originally Posted by Formulas

Drilling holes in the thermostat body brings coolant past the thermostat when the block crossover bypass is closed or restricted, pretty simple, however i would not engineer a system that can be or is dead headed with the engine driven pump thats where lines from back of heads to above the thermostat comes in it eleviates a dead head condition

Ok, I like that idea of moving the coolant above the thermostat.But where is your supply coolant coming from? By pass, heater hose return or both?