MG Sports Cars

engine swaps and other performance upgrades, plus "factory" and Costello V8s

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ricey
Phil Rice
Chessington Surrey
(33 posts)

Registered:
07/05/2017 02:19AM

Main British Car:
Mgb gt 1975 3.9 rover

v8 cooling 3.9 rover
Posted by: ricey
Date: August 26, 2018 06:49AM

Hi Guys

I have now sorted the build and nearly finished ready to post, but I am overheating just sitting still. its not even off the jack stands!

it is a 3.9 rover on a carb with performer manifold and later front timing cover so it has the higher mount range rover water pump. The plumbing is as follows:

the back of the inlet manifold goes direct to the right hand connection on the heater matrix

the left hand heater matrix comes back and plumbs to the right hand stub at the back of the water pump

the bypass from the thermostat housing at the front of the inlet manifold connects straight to the left hand stub at the back of the water pump.

the radiator is aluminium 2 core from supplier on ebay, dimensionally the same as a mgb v8 rad

it came with a 12 inch electric fan which I have mounted in front of the radiator against the slam panel. it is configured to push air into the engine bay

thermostat is 82 degree with 3 bypass holes drilled in for pre opening flow

i have a expansion tank with pressure cap which is on the inner wing about 2 inches below the top rad hose.

I am running RV8 headers through the inner wings

temp gauge is original smiths capillary attached to the inlet manifold.


so on start up it ticks over with timing circa 6 degrees btdc, it isnt tuned properly yet as cant run it long enough! Within 6 mins of starting the engine hits 90c degrees and thats with the fan running from the very start as I hard wired it to a switch temporarily. the temp will keep going up to over 95c before a bottle out and turn it off. this is with a ambient air temp of 70F and with the bonnet off.

I have pumped hoses to ensure airlocks out and I have an air tit on the top hose which I have bled and the expansion tank is 1/4 full when cold. ALL the hoses are hot with a slight dif between the top and bottom hose but not much. System is not pressured as in a blown head gasket as when running I can still compress hoses.

this is a new build engine and all components are brand new.

Have I got a cheap radiator that hasn't sufficient capacity?
Is the fan cheap and not powerful enough?
Do I need a second fan?

I understand these run hot but if the temp is at 90/95c with no bonnet, fan running, at idle, this cant be right?

any suggestions please

Phil


rficalora
Rob Ficalora
Willis, TX
(2532 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: v8 cooling 3.9 rover
Posted by: rficalora
Date: August 26, 2018 08:28PM

These are all basic, so you're probably way ahead of them, but thought I'd throw them out...

1 - are you sure the temp gauge is reading accurately?

2 - are you sure the thermostat is opening (and in the right way (yours wouldn't be the 1st installed backwards)?

3 - I don't know what timing the 215's need. But retarded timing can cause overheating.

4 - Same with air/fuel - lean mixture can cautoverheating (checked your plugs?)

5. Make sure no trpped air. I had trapped air till I made a cap with a big funnel mounted on top. Ran the car till it heated up and I quit getting air coming out (the funnel was big enough to contain the water even when it got hot.)

6. Fan blowing the right way? Generally a puller fan is more effective but neither will work if blowing the wrong direction. Sometime reversing the polarity will reverse the motor direction. I use a Volvo fan now, but I actually had my original fan in backwards. It was symmetrical so I didn't notice... till the 1st test drive!



Edited 1 time(s). Last edit at 08/26/2018 08:31PM by rficalora.


ricey
Phil Rice
Chessington Surrey
(33 posts)

Registered:
07/05/2017 02:19AM

Main British Car:
Mgb gt 1975 3.9 rover

Re: v8 cooling 3.9 rover
Posted by: ricey
Date: August 27, 2018 06:00AM

Thanks rob,

I looked at the most obvious this morning and took out the thermostat

1. It was 88 rated not 82
2. When I tested it, it didnt open and itís brand new !

So new part ordered will see this week the difference

Cheers


88v8
Ivor Duarte
Gloucestershire UK
(603 posts)

Registered:
02/11/2010 04:29AM

Main British Car:
1974 Land Rover Lightweight V8

Re: v8 cooling 3.9 rover
Posted by: 88v8
Date: August 27, 2018 03:14PM

Your plumbing is correct.
6 btdc should be fine as a starter.
Aly rads are not as good as copper, but it should be OK.
The fan should only run intermittently at idle.
You know stats only open a fraction.

What pressure cap does it have, are you sure it's the right reach.

Ivor


rficalora
Rob Ficalora
Willis, TX
(2532 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: v8 cooling 3.9 rover
Posted by: rficalora
Date: August 27, 2018 03:53PM

Phil - saw your post on the MGE board... while you have the thermostat out, why not try Graham's advice & run it with no thermostat. Won't hurt anything, just shouldn't heat up as quickly. Should be able to tell if the thermostat is your only issue (not opening) or whether you still have other issues causing it to heat (like the procedure being followed not getting all the air out or lean mixture, etc.)


ricey
Phil Rice
Chessington Surrey
(33 posts)

Registered:
07/05/2017 02:19AM

Main British Car:
Mgb gt 1975 3.9 rover

Re: v8 cooling 3.9 rover
Posted by: ricey
Date: August 28, 2018 02:17AM

Rob Iíll do that Iíll run without while I wait for the stat to arrive

Ivor I didnít realise they only open slightly which Is interesting, the pressure cap Iím sure as 1.5 or 1.8 stamped on it. Iím pretty sure itís not letting by on the blow out tube.

What is the suggested cap rating?

Cheers


88v8
Ivor Duarte
Gloucestershire UK
(603 posts)

Registered:
02/11/2010 04:29AM

Main British Car:
1974 Land Rover Lightweight V8

Re: v8 cooling 3.9 rover
Posted by: 88v8
Date: August 28, 2018 04:04AM

15 psi.

Each pound lower reduces the boiling point 3 degrees F.

If yours is stamped 1.4, that could be 1.4 bar which is 20 psi, too high. For the sake of the piddling cost, I'd start with a new cap of known value. Just make sure it's the right reach, no point having the right pressure if it's not in contact with the base of the filler neck.

I inherited the wrong cap with my Rambler (and the wrong timing & mixture) and it boiled over in about 3 minutes from cold.

Ivor



ricey
Phil Rice
Chessington Surrey
(33 posts)

Registered:
07/05/2017 02:19AM

Main British Car:
Mgb gt 1975 3.9 rover

Re: v8 cooling 3.9 rover
Posted by: ricey
Date: August 28, 2018 12:24PM

Right quick update I have progress!

1. first thing we noticed was I had the vac advance for the dizzy connected to the back of the diaphragm not the top. So we reversed this and blocked off the bottom nipple instead. the dif this made was enormous, in that the exhaust headers were no longer running so hot that they were melting the plastic shrouds on the shockers
2. re timed it and connected breather to front of the edolbrock in the middle as Denis suggested. Now ticks over nicely, albiet a bit lumpy but I do have a performance cam in there and it is currently at 6 BTDC with hose disconnected.
3. left the stat out for the time being
4. bled thoroughly

Had it running for over 10 mins with it sat at around 80/85, started creeping up to 90, so turned on the fan and it held it at 90 no problem. ONly issue this is with the bonnet off and stat missing.

With the bonnet on it hits 95 pretty quick with the fan going. However looking at Denis' fan set up he has twin 10" at a guess, and my 12" is not a known brand and i doubt its no where near as affective as a branded fan.

But without the bonnet it now sits at 90 with the fan on with no issues at all.

So, I was going to get two fans to fit at the front and see if that helps and would re fitting the stat help in slowing the water movement down to help cool it?

Also Ivor the cap is 1.3 bar, which google reckons is a tad over 18psi, do you reckon I get a lower cap at the moment based on the all the above


Your opinions please

a very pleased Phil


ex-tyke
Graham Creswick
Chatham, Ontario, Canada
(1025 posts)

Registered:
10/25/2007 11:17AM

Main British Car:
1976 MGB Ford 302

authors avatar
Re: v8 cooling 3.9 rover
Posted by: ex-tyke
Date: August 28, 2018 05:03PM

I've noted your rad /cooling comments and installation photos on the MGEx.
At an idle condition, with the bonnet on, you are getting significant hot air recirculation around the rad.
You need to block off all the areas around the rad - both sides to inner fenders and top of rad to underside of bonnet.....(see attached photos)

MGB rad upper recirc.jpg

MGB rad side recirc.jpg

.and as you have been advised by others, you need to upgrade your fan performance to get more airflow through the core.


rficalora
Rob Ficalora
Willis, TX
(2532 posts)

Registered:
10/24/2007 02:46PM

Main British Car:
'76 MGB w/CB front, Sebring rear, early metal dash Ford 302

authors avatar
Re: v8 cooling 3.9 rover
Posted by: rficalora
Date: August 28, 2018 06:24PM

You are making progress; that is great! Note Graham's advice; it makes a difference. Once you do that, you can progress to ensuring timing and fuel mixtures are good.

On your fan, what gauge wire does it use? Or, what size fuse was specified? A powerful fan will pull serious amps. I don't recall for sure, but believe I have about 10 or 12ga wire and a 30a fuse for the high speed side of my Volvo fan.


ricey
Phil Rice
Chessington Surrey
(33 posts)

Registered:
07/05/2017 02:19AM

Main British Car:
Mgb gt 1975 3.9 rover

Re: v8 cooling 3.9 rover
Posted by: ricey
Date: August 29, 2018 01:54AM

Graham thanks for note on shrouding Iím also running with an MGC fibreglass hood with the front power bulge so I need to look at clearance on that as I could have a sizeable gap above the rad but I will close in the sides properly now.

Rob Iíve found the Volvo fan you discussed on MGE and I reckon Iíll grab that as only £20

Iíve done more replies on MGE for anyone else whose following as well

Iíll come back with an update in a couple of days

Thanks to all

Phil


ricey
Phil Rice
Chessington Surrey
(33 posts)

Registered:
07/05/2017 02:19AM

Main British Car:
Mgb gt 1975 3.9 rover

Re: v8 cooling 3.9 rover
Posted by: ricey
Date: August 30, 2018 01:49AM

Scott gave me a link to Jim Stabes article in here re the Volvo fan which was great.

I am scuppered due to the length of the 3.9 with water pump has pushed the rad hard up against the front crossmember so I canít get the 16Ē Volvo fan down with cutting metal out which I donít want to do.

Kenlowe fit a 10 and 8 to the Mg RV8 which rubs sane set up as I have (sort of), so Iíve plumped for a 12 and 8 off Car Builder Solutions here in the UK (brilliant website) which combined give 1350 cfm

Iíll run the 12 off an 82 water switch and the 8 off a manual override

Plus I need to get used to seeing the temp gauge pretty much at 90/95 and not worry

Should have bits back together over weekend so will post pics and results


88v8
Ivor Duarte
Gloucestershire UK
(603 posts)

Registered:
02/11/2010 04:29AM

Main British Car:
1974 Land Rover Lightweight V8

Re: v8 cooling 3.9 rover
Posted by: 88v8
Date: August 31, 2018 04:24AM

I have just ye olde Kenlowe pusher on my 3.5, complete with widget and variable controller, probably 12", but the rad is bigger.

Switch on at 82 ? I think that's too low, the fan will be coming on all the time. Here's a 90 switch from Demon Tweeks [www.demon-tweeks.com] and here a variable controller [www.carbuildersolutions.com] from Car Builder.
The fan should run as little as possible.

Regarding the rad cap, no harm in going higher if the system doesn't leak. The limitation may be the heater core, don't want that bursting.

It had never occurred to me that air might duck around the rad at idle, I thought that was just a problem at speed. Plenty of scope for air to bypass the rad on my Landy, something for me to look at.

Ivor



Edited 1 time(s). Last edit at 08/31/2018 04:26AM by 88v8.


MG four six eight
Bill Jacobson
Wa state
(281 posts)

Registered:
10/23/2007 02:15AM

Main British Car:
73 MGB Buick 215, Eaton/GM supercharger

Re: v8 cooling 3.9 rover
Posted by: MG four six eight
Date: August 31, 2018 07:26PM

Phil,

Just to add to Rob's comments about wiring and voltage drop to the fan motor. Have you checked to see what your charging system voltage is at idle with the fan running?
Some alternators are better at low RPM charging then others. Ideally you'll want at least 13.5 volts at idle with the fan running as this will spin the fan at it's rated output giving you more air flow.

If you do have low charging voltage at idle and don't want to upgrade the alternator. One possible work around is to install an idle up solenoid (if your carburetted). You would wire it in to the same circuit as the cooling fan motor, so that it increases the idle speed slightly when the fan comes on.

Bill


ricey
Phil Rice
Chessington Surrey
(33 posts)

Registered:
07/05/2017 02:19AM

Main British Car:
Mgb gt 1975 3.9 rover

Re: v8 cooling 3.9 rover
Posted by: ricey
Date: September 02, 2018 02:18AM

All very interesting points

Iíve checked power output and Iím good on the voltage produced by the alternator

Iíve wired up the 12 and 7 inch fans and the amount of air they move is way more than the original ebay cheapy 12Ē so thatís good.

Your right re the 82 fan switch but I am paranoid about overheating. But the 7Ē is on a switch on the dash so is really a back up

Iíll be testing today but still donít have the stat in as missed the courier ! Gutted! But should see an improvement with the better fan

Mixture at tick based on plug colour looks spot on but Iíll get the garage to check when in for MOT next week

Once Iíve got the stat back in Iíll post back

Thanks all of you



ricey
Phil Rice
Chessington Surrey
(33 posts)

Registered:
07/05/2017 02:19AM

Main British Car:
Mgb gt 1975 3.9 rover

Re: v8 cooling 3.9 rover
Posted by: ricey
Date: September 02, 2018 01:53PM

t works !!

1. Still need to fit stat
2. Still need to swap inlet and outlet on heater (thanks mike)

But with new 12Ē it holds at 90 with Bonnet on. If I engage the secondary fan drops to 85

Very happy




I meant to surmise but deleted my ramblings before posting!

For those following on with the same issue, these were my faults as I now see it

1. dodgy thermostat
2. vacuum advance pipe connected to wrong nipple on dizzy causing timing to be sooo far out the headers started melting the shock absorber covers!
3. cheap 12" fan from ebay
4. top heater hose plumbing wrong.

I now have the car moving under its own power pending getting off the drive and to the MOT station over the next couple of days. Being pessimistic I expect a few gremlins and a fail on something.

But hats off to all of you on this site who have built cars the same or more complicated, it is not as easy as the book written 20 years ago suggests, and I have learnt the hard way that doing a conversion like this, on a driveway, with no garage and only mechanical knowledge experienced on Minis 30 years ago is not easy.

I am happy to admit that I probably bit off more than I could chew. Without the knowledge of you guys on this forum, this project would never have got finished.

I wish I had joined earlier and asked more questions about many elements rather than struggling on in the dark.

Well, I've yet to drive it properly god only knows what issues it will give. But for now its off axle stands and not over heating and moving!

Thanks to all of you, and Ill keep you posted


Phil


MGBV8
Carl Floyd
Kingsport, TN
(3450 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
79 MGB, Buick 215

authors avatar
Re: v8 cooling 3.9 rover
Posted by: MGBV8
Date: September 09, 2018 02:35PM

Thanks for the update, Phil. Looks like you got this!


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