Drilling thermostat

adamnreeves · Post by **adamnreeves** » Fri Apr 11, 2008 9:10 pm

I have heard of drilling a 6mm hole at the top of the thermostat, I think this is to keep a little water flowing and to help prevent air locks?

I have the flapper manifold on a later spec 4.6 Gems type engine but with a NAS cover. I am not using a heater matrix. So will only have a header/expansion tank and rad plumbed in.

So drilling the thermostat sounds like a good idea?

ian.stewart · Post by **ian.stewart** » Fri Apr 11, 2008 9:15 pm

Your thermostat is probably allready vented,, take it out and have a look

adamnreeves · Post by **adamnreeves** » Fri Apr 11, 2008 9:39 pm

I shall check tomorrow, hopefully already done so one less job for me. Cheers.

sidecar · Post by **sidecar** » Sat Apr 12, 2008 8:18 am

My stat had one hole in with a funny little bead type think loosely fitted to it. I pulled off the bead and drilled the hole out and two others at 6mm.

I run a 74 degree stat. The motor runs at about 77-82 degrees

The main reason is to the vent air (only one hole needed) but I'm paranoid about overheating my new 4.6 lump so I wanted a bit more flow.

If you watch a stat open in hot water then in my opinon they are still quite restrictive. However some restricton in the outlet is required according to A. Bells tuning book in order to "pack" the coolant round the heads. I guess its a balancing act!

The pressure in the heads is actually highter than the rad cap blow-off pressure due to the restricton.

HTH,

Pete

RoverP6B · Post by **RoverP6B** » Sat Apr 12, 2008 9:27 am

Hello Pete,

I remember the original thermostat fitted into my 3.5 litre engine in the P6B had a jiggle pin, but all subsequent thermostats were pin free.

In my new 4.6, I am using a 74 degree thermostat, along with the largest radiator core that will fit into the available space.

Ron.

sidecar · Post by **sidecar** » Sat Apr 12, 2008 2:19 pm

RoverP6B wrote:Hello Pete,

I remember the original thermostat fitted into my 3.5 litre engine in the P6B had a jiggle pin, but all subsequent thermostats were pin free.

In my new 4.6, I am using a 74 degree thermostat, along with the largest radiator core that will fit into the available space.

Ron.

Hi Ron,

"Jiggle pin".....thats a good word for it! That's what it had until I cut it off!

Cheers,

Pete

adamnreeves · Post by **adamnreeves** » Sat Apr 12, 2008 10:00 pm

Yes my thermostat has this jingle pin. Mine's an 82 centigrade one. Sounds like I need a 74 reading these posts. Another question The thermostat should be installed with this pin at the top but I noticed that it seems to be facing so that the direction of flow would close the pin, I am right that the wax bulb goes inside the manifold.

Post by **katanaman** » Sat Apr 12, 2008 10:47 pm

hundreds of thousands of rv8 engines run perfectly happy with a standard stat. I would advise you run the engine the way its meant to be and if you have problems start changing things. A cold engine doesn't make power, what you have read is someone who has had problems for whatever reason and drilling holes in the stat was a cure albeit a bandage.

Edit.... yes the bulb faces the manifold, the jiggle pin is there to purge air not flow water. Air will flow past it perfectly ok.

adamnreeves · Post by **adamnreeves** » Sun Apr 13, 2008 1:32 am

Cheers that all make sense.

katanaman wrote:hundreds of thousands of rv8 engines run perfectly happy with a standard stat. I would advise you run the engine the way its meant to be and if you have problems start changing things. A cold engine doesn't make power, what you have read is someone who has had problems for whatever reason and drilling holes in the stat was a cure albeit a bandage.

Edit.... yes the bulb faces the manifold, the jiggle pin is there to purge air not flow water. Air will flow past it perfectly ok.

sidecar · Post by **sidecar** » Sun Apr 13, 2008 8:20 am

katanaman wrote:hundreds of thousands of rv8 engines run perfectly happy with a standard stat. I would advise you run the engine the way its meant to be and if you have problems start changing things. A cold engine doesn't make power, what you have read is someone who has had problems for whatever reason and drilling holes in the stat was a cure albeit a bandage.

Edit.... yes the bulb faces the manifold, the jiggle pin is there to purge air not flow water. Air will flow past it perfectly ok.

Rover ran the engines overly hot to get them thought the latest emissons tests, so not really how they were designed to be run.

Post by **katanaman** » Sun Apr 13, 2008 9:46 am

the key word there being latest. These engines have been running since the 60s without holes being drilled all over the stats. The RV8 doesn't inherently have a cooling problem in any form or fashion. They can have problems when transplanted into other cars but its not the engines fault its the installation. In these instances yes drilling holes and all sorts might help but its not something that should be the norm.

sidecar · Post by **sidecar** » Sun Apr 13, 2008 10:04 am

katanaman wrote:the key word there being latest. These engines have been running since the 60s without holes being drilled all over the stats. The RV8 doesn't inherently have a cooling problem in any form or fashion. They can have problems when transplanted into other cars but its not the engines fault its the installation. In these instances yes drilling holes and all sorts might help but its not something that should be the norm.

I see, so in a standard car leave the cooling system standard but in say a Westfield (Like Adam has) the coolant system it may need to be modified

Would you call the Range Rover P38 a "transplant"?

What's more Adam is running a 4.6 lump and I don't care what anyone says, the 4.6 lump IS sensitive to engine temperature in a real bad way!
It needs to be run at round 75-80 degrees and not mega lean either.

Yes you might get a fraction more bore wear but I'd rather have that than a dropped liner!

Adam, you engine spec is virtually the same as mine, V8 Dev stage III heads, Piper 285 cam, etc. If you have not ran ths engine yet then you won't be disappointed when you do, in fact it will be totally mental in your Westy!

If you are running an Edlebrock manifold, I'd do the hole drilling mod to it that has been posted on the forum The stat will then respond much quicker to any rise in engine temperature.

Pete

Post by **katanaman** » Sun Apr 13, 2008 10:28 am

not what I am saying at all! If Adam has got the cooling system right there will be no need to go drilling holes and its definitely not a dead cert he has to do anything. Most of the problems with the 4.6 is the fuelling system being set for low emissions and nothing to do with the actual cooling system. These engines run lean and this is causing localised overheating. I believe he is not going to be running the standard fuel system and all the top tuners state they have had no failed blocks on engines ran with a good fuel system.

In the end you can do what you want, its your engine/car all I am trying to do is stop needless scaremongering on members who might not know any better. As the old saying goes if it isn't broke don't fix it.

adamnreeves · Post by **adamnreeves** » Sun Apr 13, 2008 10:44 am

Same spec as Sidecar's regarding the engine type and cam but I will be running injection and will be using mustang 5.0litre injectors which is about 25% extra flow rate than Rover injectors. I will be using a lambda sensor and megasquirt. I am will using the westfield high efficiency radiator which fits into the nose cone but the core is quite thick and is all ali. I am using a oil cooler also. I am expecting cooling issues as most SEiGHT seem to have but I think in this quandary I will leave as standard and keep a close eye on it on initial start up.

sidecar · Post by **sidecar** » Sun Apr 13, 2008 10:57 am

adamnreeves wrote:Same spec as Sidecar's regarding the engine type and cam but I will be running injection and will be using mustang 5.0litre injectors which is about 25% extra flow rate than Rover injectors. I will be using a lambda sensor and megasquirt. I am will using the westfield high efficiency radiator which fits into the nose cone but the core is quite thick and is all ali. I am using a oil cooler also. I am expecting cooling issues as most SEiGHT seem to have but I think in this quandary I will leave as standard and keep a close eye on it on initial start up.

Good luck with your build, I'm sure that you'll overcome any problems!

You will not be disappointed with the engine!

Pete

(I've decided to put my handbag away!

)