Failed core/freeze plug

[mjheathcote]

I'm currently stripping off my Holley, to fit an insulating spacer and heat shields under the float chambers due to fuel vaporisation issues the last couple of years, I believe due to the increased ethanol in our fuel.
One of the core plugs in the cylinder heads looked a bit discoloured in one corner, so gave it a scrape with a screwdriver and two pin holes appeared with the subsequent coolant dribble!
Engine was cold not under pressure, but if running and then decided to give way, could have been interesting!
Fortunately easy to change in situ.
All the core plugs on the outside still look like new with the plating still shiny.
Will have to see what it's like on the business side of the plug once removed.
Always had approx 50:50 antifreeze/corrosion inhibitor solution, I rebuilt the engine appropriately 25 years ago.
Hope it's a one off as heads off to change them all.

[new to this]

Lucky if you can say that it can be changed with out taking the heads off

Dave

[stagwingnut]

Just out of interest as I run a Holley carb , you say you are fitting an insulator spacer , will you have enough bonnet clearance, as my 14 inch air cleaner does touch the under bonnet insulation pad ?i Regards Graham

[flying farmer]

I usually find the plugs corrode worse around the edges where they are in closest proximity to the alloy. Not that it makes much difference, a leak is still a leak!

[mjheathcote]

I usually find the plugs corrode worse around the edges where they are in closest proximity to the alloy. Not that it makes much difference, a leak is still a leak!

I haven't knocked it out yet, but the pin holes are right in the tight radius.

[mjheathcote]

Just out of interest as I run a Holley carb , you say you are fitting an insulator spacer , will you have enough bonnet clearance, as my 14 inch air cleaner does touch the under bonnet insulation pad ?i Regards Graham

Just.
I don't run a bonnet insulation pad.
The tight points are the front of the air filter and centre.
Using some blutack I have currently 3/8th clearance, I'm adding a 1/4 inch spacer.
This is the thinnest I could find and is basically made up of 3 gaskets and 2 thin plates of aluminium.
This will go on top of my aluminium wedge plate I use to level the Holley.
It's very hard to find anything for the Holley that isn't too thick.
I also bought a sheet of double skinned nimbus aluminium heat shield.
I've cut and formed this as a tight fit around the wedge plate, from the thermostat housing to the distributor.
This to put a heat shield under the float chambers.
I'm hoping this, together with a Holley rebuild kit, will solve my fuel vaporisation issues when in slow/stopped traffic
Never had an issue before they started introducing ethanol into the petrol mix.

[wilf]

You could fit a small electric fan to blow air over the carb? Along the lines of this: https://www.ebay.co.uk/itm/133688078...MAAOSwOEZgSKM-

[022Dave]

Just out of interest as I run a Holley carb , you say you are fitting an insulator spacer , will you have enough bonnet clearance, as my 14 inch air cleaner does touch the under bonnet insulation pad ?i Regards Graham

Hello Graham,

I run a four-barrel Edelbrock, which is broadly similar to the Holley's dimensions. I fitted a heat insulator last year because of the same hot running problems which others have encountered, particularly when driving over the Alps to Italy a few summers ago, and it has proved very effective, particularly improving hot starting. I've also wrapped heat shielding over the fuel lines in the engine bay (the Velcro stuff). I have a bonnet pad fitted, but not the cross bar, and although the air filter touches the pad (not having the bar means the pad sags a little) it isn't a firm contact, and not a problem.

Dave

IMG_0898.HEIC IMG_1738.HEIC IMG_1739.HEIC

[wilf]

If you are not using one already, you can get "dropped base" air filters for Edelbrocks/Holleys, which will lower the top of the filter by 1/2" or more. I have had to use one in the past when I ran out of headroom on another car.

[mjheathcote]

Hello Graham,

I run a four-barrel Edelbrock, which is broadly similar to the Holley's dimensions. I fitted a heat insulator last year because of the same hot running problems which others have encountered, particularly when driving over the Alps to Italy a few summers ago, and it has proved very effective, particularly improving hot starting. I've also wrapped heat shielding over the fuel lines in the engine bay (the Velcro stuff). I have a bonnet pad fitted, but not the cross bar, and although the air filter touches the pad (not having the bar means the pad sags a little) it isn't a firm contact, and not a problem.

Dave

[ATTACH]n819551[/ATTACH] [ATTACH]n819550[/ATTACH] [ATTACH]n819549[/ATTACH]

At least I'm not alone with this problem.

[mjheathcote]

If you are not using one already, you can get "dropped base" air filters for Edelbrocks/Holleys, which will lower the top of the filter by 1/2" or more. I have had to use one in the past when I ran out of headroom on another car.

Yes I'm using a dropped base K&N.

[stagwingnut]

thx guys for the photos and information on the holley , food for thought !! regards graham

[v8ken]

Another way of removing a core plug is to drill a 3mm hole in it ,screw a self tapping screw in and then remove with a claw hammer.

[v8ken]

A few years ago ,when I was convinced the ethanol petrol was causing my hot starting problems,I removed the Strombergs ,serviced them, paying particular attention to the temperature compensators,then whilst checking the operation of the hot air flap on the air intake,noticed it was stuck in the hot position,so renewed the diaphragm and temperature vacuum sensor,I did a thread on here.
since then,moved to Gozo,used it in 40deg c temperatures and had no hot starting issues since,if you don't count the,nearly new coil packing up.

[jbuckl]

It’s important to keep the fuel & air as cool as possible.
triumph did their best for us originally.
after market pancake filters often don’t / cannot suck cool air.
fuel boiling temperatures have reduced over the years, so we also need to mitigate for that.
insulated / modified routing can help on fuel lines.
an electric fan can help cool heat soak after key-off too.
a restricted fuel return to tank can also help as well.