Help with cooling

[Steve Senior]

Having great fun with the car now its on the road but it does tend to run a bit warm (100 to 110 deg) when I push it :7

I've done the obvious, checked temp gauge, changes thermostat for one that opens at 82 deg, vent air out of the system. As its a Rover 3.5 with GD 3 core radiator and Clova 14" fan there should be plenty of cooling

Couple of questions
Ian at RPI suggests (among other things) to double check distributor and timing and says "The best ignition timing is as much advance that can be achieved, post detonation ( pinking)" Having always relied on the timing light is pinking easy enough to detect when driving and what am I listening for?
(Static is 8 Deg so it shouldn't be far out)

And secondly
Do the alloy under trays Andy produces for the GD really help direct air through the radiator and improve cooling

Many thanks
Steve

[robert]

Steve

Firstly, ensure there are no air locks in the system, as this will push up the temp.

Secondly, the tray will help as it limits the amount of air the disappears under the car and helps direct the air.

Robert
Forum Admin

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[Steve Senior]

Rob

I've checked and double checked for air locks and found none.
What I have checked today is the timing. I found the engine spot on 8 deg at tickover but only increasing to about 20 deg BTDC at 3500 rpm. This seams a bit low to me.

Steve

[SimonP]

Hi Steve,
You addressed your reply to Rob so I hope you don't mind me butting in!

For your ignition timing, did you check this with or without the vacuum advance line connected? The book usually specifies that timing is set at idle with the vacuum advance disconnected and the line plugged.

Obviously some form of advance is working - I'd expect this to be the mechanical element of the advance (the weights in the distributor).
You can check the vacuum advance easily. If you have a vacuum pump (or can borrow one), great! If not, you can improvise (SUCK!!).
With the cap off the distributor, you should see the plate which the points or pickup is mounted on, rotate as vacuum is applied to the diaphragm on the distributor. If you can't pull a vacuum (ie you can suck air in from somewhere) then the advance diaphragm is faulty.
The drilling in the carburettor venturi which the advance diaphragm is connected to is usually above the throttle butterfly at idle. It is only subjected to venturi vacuum when the throttles are opened a few degrees. It may be possible that you cannot achieve this in the garage without redlining the engine. On the road is much different.
If you have a strong vacuum applied to the distributor diaphragm at idle, it is likely that you have connected the vacuum advance line to the wrong stub on the carb or straight onto the manifold. If you disconnect the vacuum advance line, does the timing retard way too much?

Pinking sounds like a cold diesel engine clattering or as if there are ball bearings floating around in your engine. You will notice it most at medium revs (mechanical advance is fully operated) and light throttle (plenty of vacuum = full vacuum advance). If you think you can detect it, opening the throttle more (less vacuum = less advance) or coming off the throttle (no vacuum advance, hardly any fuel) will stop it.

On the subject of cooling, where is your expansion tank in relation to the radiator top hose connection?
At Duxford I saw a large percentage of cars which had the expansion tank situated level with or below the radiator top hose. The bottom of the tank must be above the top of the top hose in order to keep the system free from air locks. Note how most production cars have a small bore hose that runs from the top radiator hose (or very near by) to the top of the expansion tank in order to easily get rid of any air which may become trapped in the system.

Hope this helps,

Simon

[maxGD059]

Steve
Have you read Snaketorque yet? Theres an excellent article (by my cousin) which may help you.
I had similar problems to you & can possibly help if you're stumped

Richard
(It'll only be a 5 minute job)

[Happy Jim]

Steve,

Have you checked out the RPI site, they recommend up to 38 deg BTDC (with a mallory dual point).

Rgds

Jim

[Steve Senior]

Richard
Yes when I found that article I thought my broblems would be solved. Unfortunately I have already done everything suggested.
Steve

[Steve Senior]

Yes got a check sheet from RPI to check out the ignition system.
I've just sent a question back to them because I have an electronic distributer with an RPI amplifier and it only advances to about 20 deg, still waiting for a reply.
Steve
PS Simon yes I did disconnect the vacuum and plug it and when I suck on the pipe the pickup plate moves

[maxGD059]

Yep this cooling lark can be a pain. I've panelled in the front of my GD, put in a 78 degree thermostat from a TVR & it still ran at around 105-110 after a good thrashing. So, currently I'm running without a thermostat. The draw back is it runs at about 70-75 & gets up to 90 only when idling. I figure that as I rarely drive the car when its really cold then its probably OK. If it weren't such a pain to change the 'stat & rebleed the system, I may have tried something else, but for now I'm still pondering it!

Richard
(It'll only be a 5 minute job)

[Steve Senior]

Richard
Yes did the same as you but when I ran without the thermostat the temp didn't rise above 60 and felt very tight. When I replaced the thermostat it came without a bleed hole so I drilled the largest I could. When I have eliminated all other possibilities I may just drill a few extra holes, but I would prefer to eliminate any potential problems before resorting to this.

Steve

PS are you going to Donnington (I'm there Saturday)