Performer manifold modification

Automania · Post by **Automania** » Sun Dec 16, 2012 8:54 pm

Just read this site, http://how-to-build-a-pilgrim-sumo.wiki ... e-plumbing

Anyone know if this is really needed? It's the only referance I can find on it but I'd rather do it now before the manifold goes on.

ChrisJC · Post by **ChrisJC** » Sun Dec 16, 2012 9:27 pm

If you do it, and it's not necessary, will it be a problem?

Chris.

sidecar · Post by **sidecar** » Sun Dec 16, 2012 9:52 pm

I've done the mod on about 4 manifolds now, my mate's cob was very badly overheating withing 3 miles of starting the engine, the mod totally cured the problem. (It's his wiki site, he nicked the idea of this forum!) I went for bigger holes than the wiki site suggests, about 7mm rather than 4mm.

If you are using one of the blocks that is more prone to 'issues' then it would also be wise to fit a 74 degree thermostat

mgbv8 · Post by **mgbv8** » Sun Dec 16, 2012 10:36 pm

I'm going to be a buzz kill now I guess?

Why not just drill a 4mm hole in the flange of the thermostat and make sure that the stat is fitted so the hole is at the 12 o'clock position in the housing??

Been doing this for years to make sure that the stat has a good flow of water over it from cold and also has the ability to vent air from the block into the rad from a cold start. The air will stay mainly in the rad header where it will be displaced into the exp tank as pressure rises.

Older stats had the jiggle pin hole. Most modern replacements dont have this and are made with a blank flange. The idea of having the hole to make sure you have flow over the temp sensor will only work if the stat has the same sized hole in the flange. If the stat does not have the ability to flow water from cold when its closed the hole in the manifold wont make any difference as the water wont be able to go anywhere?

I dont understand the bit about the restrictor in the line to the expansion tank?

Actually I've just re read and seen the picture. The exp tank has a return line to the engine via the rad. This could lead to a short circuit of water especially when the engine is cold and the stat is closed. This expansion line would only be about 5mm bore on most engines so I cant see why reducing to 3mm would be a benefit. I can see the benefit of it being able to take a constant feed of water from the top of the rad as it would be able to separate some the air from the water until all air had been trapped in the tank.

Why not take the heater feed from the back of the manifold instead of the coolest source of hot water which is from the bottom hose after the rad has done its job?

Surely the best point for the feed line to the exp tank would be from a hole / tapping drilled into the top of the thermostat housing? This would give a pretty quick way of making sure that any air in the system is quickly purged into the exp tank from cold start. This in conjunction with the 3mm restrictor (which on this setup should be in the return leg to the rad) and a 4-5mm hole in the stat flange should give a good solution to making sure that the engine can start from cold, ensure that most of any trapped air is expelled towards the exp tank, and a good supply of water is flowed over the thermostat to make sure that it responds quickly to demand.

If you are using electric fans you should always fit a thermostat that will be wide open before the fans are set to cut in. I used to use an 82C stat with the fans set to cut in at 88-90C. This allowed the fans to operate within the range of 90C to 85C while the stat remained open for full flow through the cooling system so the fans could be most efficient.

These days for racing I use a restrictor in the stat housing which has the same free area as a fully open thermostat. The temp senosr in the top hose does the rest

sidecar · Post by **sidecar** » Mon Dec 17, 2012 5:41 am

The stats that I have fitted have had a hole in them at 12 0 clock, the issue is that due to the design of the manifold you can get area's of coolant that overheat before the coolant around the stat is hot enough to cause it to open. Once it does open then everything is OK. The drilled holes force some of this hot coolant straight into the area behind the stat so that it is not sitting in a pocket of cold coolant.

The restrictor in the header tank (its a header tank on the Sumo Cob replica rather than an expansion tank) is due to the fact that the top bleed pipe is very close to the main radiator feed pipe so some of the coolant ends up taking this route rather than flowing through the rad. The bleed pipe in the Sumo is around 10mm diameter with the smallest section being maybe 6mm. From memory my restrictor is 3mm.

minorv8 · Post by **minorv8** » Mon Dec 17, 2012 6:22 am

I have drilled several holes into the thermostat and never had issues because of the manifold itself. However, due to my radiator being quite low I had to add a couple of hoses to vent the air from high spots to the expansion tank (which is mounted highest in my car). When I fitted a Wilpower manifold I removed one of these vent lines because I though it was no longer needed. I found 5 minutes later that it was indeed needed, the temp hit 110 C in no time (normally 75 C)

Eliot · Post by **Eliot** » Mon Dec 17, 2012 11:10 am

I would suggest that his fans (the cobra) are a little too far away from the radiator. Kempston radiators soldered tubes into my core, so i can bolt it directly to the core:

Going further - few kit cars (mine included) bother to duct the fans around the radiator - but it can make a huge difference. (all OEM's do it)

sidecar · Post by **sidecar** » Mon Dec 17, 2012 11:39 am

Eliot wrote:I would suggest that his fans (the cobra) are a little too far away from the radiator. Kempston radiators soldered tubes into my core, so i can bolt it directly to the core:

Going further - few kit cars (mine included) bother to duct the fans around the radiator - but it can make a huge difference. (all OEM's do it)

The fans that my mate is using are pretty crap anyway! The fans would not switch on anyway when he had the issue because the fan switch was not getting hot due to it being in the rad. The rad was not getting hot due to the stat staying closed.

The way that the engine would overheat was odd, some parts of the coolant system would only be luke warm whilst other bits were too hot and therefore boiling, the resulting steam would then make the system puke coolant out.

Other other thing is that not all cars with this manifold have the issue, my old 3.5 was fine without the mod but maybe that was due to the low temp stat.

I have also tried drilling 4 holes in the stat but I did not like the way that it would take ages to get the engine up to temperature.

mgbv8 · Post by **mgbv8** » Mon Dec 17, 2012 5:22 pm

sidecar wrote:The stats that I have fitted have had a hole in them at 12 0 clock, the issue is that due to the design of the manifold you can get area's of coolant that overheat before the coolant around the stat is hot enough to cause it to open. Once it does open then everything is OK. The drilled holes force some of this hot coolant straight into the area behind the stat so that it is not sitting in a pocket of cold coolant.

The restrictor in the header tank (its a header tank on the Sumo Cob replica rather than an expansion tank) is due to the fact that the top bleed pipe is very close to the main radiator feed pipe so some of the coolant ends up taking this route rather than flowing through the rad. The bleed pipe in the Sumo is around 10mm diameter with the smallest section being maybe 6mm. From memory my restrictor is 3mm.

Ahh!
I see now. So is there some sort of air trap or odd pocket in the manifiold in those areas where it hot spots / has an area of low flow before the stat opens?
Is there a benefit in using a header tank rather than an exp tank?

Perry

sidecar · Post by **sidecar** » Mon Dec 17, 2012 6:39 pm

mgbv8 wrote:
sidecar wrote:The stats that I have fitted have had a hole in them at 12 0 clock, the issue is that due to the design of the manifold you can get area's of coolant that overheat before the coolant around the stat is hot enough to cause it to open. Once it does open then everything is OK. The drilled holes force some of this hot coolant straight into the area behind the stat so that it is not sitting in a pocket of cold coolant.

The restrictor in the header tank (its a header tank on the Sumo Cob replica rather than an expansion tank) is due to the fact that the top bleed pipe is very close to the main radiator feed pipe so some of the coolant ends up taking this route rather than flowing through the rad. The bleed pipe in the Sumo is around 10mm diameter with the smallest section being maybe 6mm. From memory my restrictor is 3mm.
Ahh!
I see now. So is there some sort of air trap or odd pocket in the manifiold in those areas where it hot spots / has an area of low flow before the stat opens?
Is there a benefit in using a header tank rather than an exp tank?

Perry

Hi Perry,

Not sure why Pilgrim went for a header system rather than a system that uses an expansion tank but that's what they decided to do!

I don't think that the tank has anything do do with the manifold issue though, the header issue is probably do do with using a Sierra 2.3 diesel rad fitted up side down!

Your theory of an air pocket is a good one except I don't think it was the case because after one or two overheats within a mile or two the stat would open, the coolant would then flow properly and the engine would run fine for the rest of the day, I would have thought that any air would have then been pushed round into the header tank out of harms way. The engine would be fine for the rest of the day until it was left over night to cool right down. The whole process would then repeat its self!

Someone on this forum years ago did a lot of experiments with thermocouples glued all over his Performer manifold, he had the same issue and came up with the drilling mod!

r2d2hp · Post by **r2d2hp** » Mon Dec 17, 2012 7:01 pm

Hi Pel,

I use a header tank and the in/out pipes are 22mm. I was experiencing overheating as the water was bypassing the radiator so had to add a restrictor in the return to force water to use the radiator.

regards
Reg

RoverP6B · Post by **RoverP6B** » Mon Dec 17, 2012 7:07 pm

sidecar wrote,...

The way that the engine would overheat was odd, some parts of the coolant system would only be luke warm whilst other bits were too hot and therefore boiling, the resulting steam would then make the system puke coolant out.

That to me sounds like the radiator cap is the problem. With a radiator cap that is functioning correctly, as the coolant temperature increases, so it also expands. That is why the hoses become harder with increasing temperature. As the coolant is underpressure from being held captive within a closed system, it is unable to expand to the point that will allow a change of state to occur, ie....change from liquid into gas. Therefore, parts of the system do not boil whilst others remain cool, provided the system is sealed with an effective radiator cap, and of course there are no leaks elsewhere.

If the cap is left off or is defective, then coolant can boil around the passages within the cylinder heads adjacent to the exhaust valves, whilst in other locations the coolant will be at a much lower temperature.

The temperature as measured by the sender is the mean temperature of the entire system. Some areas will be at a higher temperature, others at a lower temperature.

Ron.

sidecar · Post by **sidecar** » Mon Dec 17, 2012 7:43 pm

RoverP6B wrote:sidecar wrote,...
The way that the engine would overheat was odd, some parts of the coolant system would only be luke warm whilst other bits were too hot and therefore boiling, the resulting steam would then make the system puke coolant out.
That to me sounds like the radiator cap is the problem. With a radiator cap that is functioning correctly, as the coolant temperature increases, so it also expands. That is why the hoses become harder with increasing temperature. As the coolant is underpressure from being held captive within a closed system, it is unable to expand to the point that will allow a change of state to occur, ie....change from liquid into gas. Therefore, parts of the system do not boil whilst others remain cool, provided the system is sealed with an effective radiator cap, and of course there are no leaks elsewhere.

If the cap is left off or is defective, then coolant can boil around the passages within the cylinder heads adjacent to the exhaust valves, whilst in other locations the coolant will be at a much lower temperature.

The temperature as measured by the sender is the mean temperature of the entire system. Some areas will be at a higher temperature, others at a lower temperature.

Ron.

Hi Ron,

The blow off pressure of the cap was tested in situ using a foot pump, a pressure gauge and some hose. This was all ages ago, the drilling mod was the thing that fixed the problem.

Cheers,

Pete

mgbv8 · Post by **mgbv8** » Mon Dec 17, 2012 7:58 pm

""after one or two overheats within a mile or two the stat would open, the coolant would then flow properly and the engine would run fine for the rest of the day,""

That was my very first overheat problem with the V8 when I fitted a stat with no hole in it. Back then I didnt know any better and just assumed the pattern part was the same as the old one

RoverP6B · Post by **RoverP6B** » Mon Dec 17, 2012 8:28 pm

Hi Pete,

Yes the trapped air syndrome behind the thermostat without an air release point.

As Perry mentioned, most modern stats don't have the jiggle pin, but many have bleed notches instead. From my own experience I find the latter to be superior in terms of how quickly the system reaches operating temperature in addition to their ability to maintain a much more consistent operating temperature.

Unless a close observation is made, many will not see the notch and therefore drill a hole instead. This is a redundant exercise which only reduces the effective operation of the thermostat, both in terms of reaching operating temperature quickly and then maintaining that temperature consistantly.

The bleed notch can be seen at 12 o'clock

Again at 12 o'clock.

If a stat has no air bleed system at all, then a hole must be drilled on this occasion.

Ron.