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Coolant to heater with Dellorto conversion  Rating:  Rating
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 Posted: 12-22-2006 05:38 pm
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Arvin Appelman
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The inlet manifold that I have doesn't have a fitting for the coolant line to the heater.  It appears that one option is to add one to the firewall end of the manifold but, the casting is rough on that end and should be milled flat before drilling and tapping.  The other option would be to drill and tap the head.  There is a boss just behind the #4 inlet that is part of the outside wall of the waterjacket.  Could I install the fitting in this boss or would it be better to fool with the inlet manifold? 

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 Posted: 12-22-2006 08:38 pm
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John Finch
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I had my Dellorto manifold modified to accept the hose fitting. Works great. Good luck with your project.

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 Posted: 01-07-2007 02:52 pm
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Arvin Appelman
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Has anyone put the heater hose fitting in the head?

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 Posted: 01-07-2007 06:49 pm
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Jensen Healey
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You should hook up your heater hose to the intake manifold as intended by Lotus. Just drill and tap for a common hose fitting from the local hardware store. Why bother milling the surface flat? Thread sealant is all you need for a water tight fitting.

The rear boss on the head was used in later iterations and was connected directly to a fitting on the water pump.

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 Posted: 01-09-2007 06:02 am
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Sylva
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I have a hybred engine, 910 S4 block, cast iron Linners, and a 911 head. I do not have a heater now (track car). But it was fitted to the head. If I had a choice I'd tap into the manifold, for two reasons.

1 You cn get them for 10 $ each, if the tapping it goes wrong,

2 The Lotus conection piece to the head is stell, which rusts when in contact with the alloy head, I've replaced mine with copper.

But in my opionion reason 1 is enough

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 Posted: 01-09-2007 09:01 am
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Harkes
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my hybrid engine has the heater hose fitting in the head near cyl 4 as well and the inlet manifold heater outlet toward interior heating system is plugged.

Despite this set up being the better one to improve the cooling design of the Lotus 907 (came standard on later Lotus engines 910/912), i would not follow this route if your engine is in good shape. If you decide to fit it in the head, be very sure to flush it several times to get rid of debrees from the drilling!! If you are rebuilding your engine then i would recommend this route and have a copper fitting installed as Sylva already suggested!

Quick, safe and easier route is to tap a fitting in the end of the heater outlet of your inlet manifold and connect the hose.

I promised Dan Eiland some pictures of this. I will make a new post for it as soon as i get a chance to get into my garage to make some pictures.

good luck

erik

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 Posted: 01-09-2007 12:38 pm
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Dan Eiland
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Erik,

I just spoke with my machine shop yesterday about this subject and I think I am going to add the fitting to the head. Cleaning the engine is not an issue since the engine is completely apart. Still would like to see how the hose is connected into the heater return to the water pump. I appreciate the suggestion to go with brass or copper for the fitting. My 1994 GMC Suburban has a fitting off the back of the engine similar to the Lotus engine and it was original from the factory done in steel. Thing rusted out twice before I finally told them to install a brass fitting. Seems to have solved that issue.

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 Posted: 01-09-2007 12:56 pm
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Harkes
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Hi Dan,

my hose goes from the fitting at the rear of the head directly to "interior heater INLET". There is NO hose running from the inlet manifold to the interior heater inlet. My inlet manifold is plugged at the end where in stock set-up the hose is supposed to go.

Below the interior heater inlet is the interior heater outlet. I run the stock hose from the heater outlet towards the waterpump.

I have seen photo's of JH owners who have connected the hose from the head (cyl 4) into the stock hose that goes from inlet manifold to interior heater inlet. I understood they used a T-piece with a one way valve. This set-up wasn't recommended by Gary Kemp.

I will soon make pictures for you as promised.

cheers

erik

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 Posted: 01-09-2007 01:26 pm
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Jensen Healey
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If the hose from the head goes directly to the heater inlet it will only cool the #4 cyl. when the heater is ON.

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 Posted: 01-09-2007 11:47 pm
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Dan Eiland
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Erik, I have to agree with Kurt. Unless you have a three way heater valve with a by-pass in it so the water will flow back to the pump when the heater valve is closed it sounds like there is a closed loop, therefore no circulation when the heater valve is closed. Your drawing or pictures may clarify this matter.  

Dan

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 Posted: 01-10-2007 12:50 am
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Mark Rosenbaum
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It's my understanding that Lotus engines with the coolant port in the head at the #4 cylinder use a different water pump with two additional ports.  I presume the second port would be for the car's heater.  However, I've never actually seen one of these water pumps, and have no idea how the two additional ports connect internally, which of course is vital with a double-acting thermostat.

For whatever it's worth, I've attached a picture of one such pump.

Attachment: water pump lotus late #1.jpg (Downloaded 120 times)

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 Posted: 01-10-2007 09:12 am
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Harkes
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Mark,  that is I believe a TURBO waterpump you are showing which are used on the Lotus Turbo engines and the later 912.

The extra nipple provides an extra return flow path back to the waterpump in addition to the one through the intake manifold water passage, which indeed cools the head slightly better.

GGLOTUS quote: "The turbo pump would provide a little extra cooling for a safety margin on hot days. Upgrading to a turbo water pump would be a nice optional extra." unquote.

You guys are right: in my set-up there is no EXTRA cooling near cyl 4 just because of the fitting.. However I do not have the stock 907 2.0L head (which seemingly suffered from a cooling design flaw), but the later modified 2.2L head & 2.2L manifold which has slightly wider water passages and improved cooling design.

Just like in the stock 907 my engine returns the coolant from the head to the inlet manifold water passage towards the pump. As soon as i open the heater valve, then water goes from the rear of the head towards the interior heating system, rather then from the rear of the inlet manifold water passage towards the interior heating system as in stock set up.

According to Garry Kemp an extra return from the rear of the 2.2L head towards a turbo waterpump or in case of 907 towards the hose running from the interior heater to inlet manifold (via a 3-way valve) isn't necessary ...especially not in my climate.

Why have the fitting at the rear of a 2.2L head? If it turns out I need the extra cooling on a hot summer day then i could fairly quickly tap in a fitting at the rear of the inlet manifold, fit the 3-way valve piece and connect the hoses. Having the head drilled to install a fitting there and having it flushed is a lot more work.

It is more likely that on very hot summer days, the engine needs extra cooling when idling in traffic. For this purpose i will soon install an electric fan and replace the original mechanical fan...and as a bonus gain another 5/6 HP :)

When one is rebuilding a stock 907 2.0L head/manifold then i would certainly have the extra fitting at the rear of the head and connect it to the stock heater hose via a three way valve with bypass.

Dan,  I remember you saying that Gary Kemp advised you to open up the water passage near the waterpump in the head a little more, correct? I assume you are rebuilding a stock 907 2.0L engine & head, correct?

I will go into my garage this evening to make the pictures.

 

Last edited on 01-10-2007 09:21 am by Harkes

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 Posted: 01-10-2007 02:03 pm
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Dan Eiland
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Erik, you asked, "Dan,  I remember you saying that Gary Kemp advised you to open up the water passage near the waterpump in the head a little more, correct? I assume you are rebuilding a stock 907 2.0L engine & head, correct?"

The answer to both questions is Yes. Also, I live in a very hot desert climate. June typically runs 30 straight days of 100 plus degree temperatures and does not drop much below 95^ even at night. It can get up to 115^ easily on some summer days around here. I must have as much cooling as possible. I have the three core radiator and will be opening up the water inlet into the block as suggested by Garry. I plan on adding the water port to the back of the head and installing either a brass or copper fitting. If I could find a turbo water pump cheap enough I would go to one for the added cooling. I can use every little bit to keep the engine from overheating in the summer around here. My old Sunbeam Tiger could not be driven past 11:00a.m. around here due to overheating issues. I don't want to run into the same issue with my JH.


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