Edelbrock Performer erratic water temperature

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stu60
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Re: Edelbrock Performer erratic water temperature

Post by stu60 »

have a look at this for some ideas. i did the inlet drilling mod with resstrictor in looped heater hose and have no issues since

http://how-to-build-a-pilgrim-sumo.wiki ... e-plumbing

rgds Stuart
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peterc
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Re: Edelbrock Performer erratic water temperature

Post by peterc »

What’s the advantage of that manifold over the Edlebrock performance unit. I have been trying to remember the air flow passages in Edlebrock.
l note that it recommends only a 390 cfm carb which might be for the 215 or 3.5 Litre engine. I thought most Cobras use a 500 cfm carb.
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Homewood
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Re: Edelbrock Performer erratic water temperature

Post by Homewood »

Well after fitting a smaller diameter pulley it started and idled without overheating. On the run it runs cold around 70 degrees but still goes ballistic when slowing down and stopping.

So I am going to drill the thermostat housing, so what size drill bit should I use ?

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Tony
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kdavies3
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Re: Edelbrock Performer erratic water temperature

Post by kdavies3 »

I'd probably tap 1/8" NPT.
Straight drill and tapered tap.
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Stag man
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Re: Edelbrock Performer erratic water temperature

Post by Stag man »

Hi I have overheating issues with my 3.9 r v 8 in my triumph stag running 500 cfm eldelbrock carb and performer manifold. The post ended on June 21 2021.how did you get on with the holes in the manifold problem cured?
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peterc
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Re: Edelbrock Performer erratic water temperature

Post by peterc »

Tony,
Thinking about you tapping the thermostat housing, The only place I can think of available to be tapped would be on the curved body of the thermostat housing which means it’s the outlet side going to the top of the rad via the header tank. E.g. not sensing the water in the head. It would only tell you if the thermostat is sticking.
THe info gained would be at what temp the thermostat has opened at which you can check that in a pan of hot water and watching a thermometer.
I don’t know why some owners have no issues with the Edelbrock manifold and others like us do. I think it is recognised that the temp sensor only records the water exiting No 2 cylinder port. The hot water from all ports has to traverse the manifold to the rear before turning 180 and comes back to the thermostat. Hence the delay in the thermostat opening.
Following advice on another Cobra forum I have drilled a hole through from the thermostat through to both No’s 1 & 2 to bleed water through directly to the stat. This has reduced the variance.
With a 5 mm hole in the stat mine runs happily at 84 C on a cruise but still tends to rise up to 90 on an uphill especially if trying to leave the following car.
I believe that Rover engines are meant to run warm so only 70 degrees is not good.
So long as you can keep the temp below 95 in traffic or going uphill you should be OK.
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Re: Edelbrock Performer erratic water temperature

Post by Homewood »

After drilling two holes 5mm inside the thermostat housing on lhs and rhs as per pilgrim mod it still shoots up to max after slowing down rev it up to drop back. Runs happily at 75 on a run, only when slowing up does it shoot up. Read this on cobra club
Perhaps increasing hole size will help, also have a variable fan switch to fit as my engine seems to run nicely at 75c. Thermostats all checked out. Will fit a 74c thermostat too.

Post by Wilts289 » Sun Mar 30, 2008 5:50 pm

Yes correct manifold outlet fitted with lower bypass pipe below. Manifold mod as follows.lifted from archives

"On the Edel setup, the water from the heads firstly hits the temp sender which only senses the right hand cylinder head temp and then flows to the chamber at the back of the manifold where the heater feed is. It then returns forward to the thermostat plenum chamber to act upon the thermostat. This means that the water is cooled by the charge air flowing thru the manifold before it reaches the thermostat so even though your engine is running hot, the thermostat 'thinks' its cool!! Whats more, the faster you go, the more air the engine takes in and the temperature differential will get bigger. I wired my cooling system up with 7 'K'type thermocouples and a calibrated digital thermometer to find all this out and measured up to 15'C differential between the cylinder head exit temp and the thermostat! I contacted Edelbrock but got no reply. To get around this problem I drilled 2 x 13mm ports internally to allow water from the cylinder head exit ports to allow flow directly to the thermostat plenum chamber and that brought the temperature differential down from 15'C to 2'C, (if you look at an Offy manifold you will see these holes as standard). This also helps with airlocks. as high as possible under the bonnet. "
Made sense to me so I did this before installing it in the 4.2!

What surprises me is how quickly temp goes up and down - 5 seconds from 85 to 105 and only a frew seconds more when it cools down, its as if someone is turning a cold tap on and off!
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peterc
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Re: Edelbrock Performer erratic water temperature

Post by peterc »

Tony,
Truly amazed at the short time it takes to change temperature.
Have you checked that the pump is actually working correctly.
Clutching at straws here but is the impeller clean and rotating correctly?
I know it’s a longer/ more expensive job but taking the pump out to check it or even replace it might provide a substantial part of the problem ?
I had read the comment about 13mm holes but ‘ A ‘ I didn’t have the courage to drill them that big and ‘B ‘ didn’t have a long series drill to do the job. I had a 5mm in stock so used that. Results as advised earlier.
Peter C
Last edited by peterc on Thu Sep 23, 2021 12:17 pm, edited 1 time in total.
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clive
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Re: Edelbrock Performer erratic water temperature

Post by clive »

How effective is the radiator? You might have some blocked water channels which don't allow sufficient cooling when demand is high but are ok in normal situations. You can buy a cheap infra red thermometer which would show hot/cold areas of the rad.
Cheers, Clive.

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Homewood
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Re: Edelbrock Performer erratic water temperature

Post by Homewood »

I would suggest the new water pump works because it would overheat more with higher revs if it was slipping and suspect it would just go hot and stay hot, this zooms up and down in seconds.
New MG V8 radiator so all clear.
I might suggest people with no issues may put their temperature gauge not in the manifold but in the radiator top pipe.
Agree with infra red thermometer it may be my next point of call.
Will fit my variable radiator fan cutout first.
Thanks for all the suggestions.
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