> Jensen Healey & Jensen GT Tech > Engine & Transmission > Installing M8 restrictor in oil gallery feeding the head |
> Jensen Healey & Jensen GT Tech > Engine & Transmission > Installing M8 restrictor in oil gallery feeding the head |
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Dan Eiland Member
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While rebuilding my engine I thought I would add the M8 restrictor to the oil gallery feeding the head. Problem is, I have know idea where this is located nor where to install the M8 restrictor once I ID the location. Is there an article somewhere with some photos showing this modification to help people like me? I found a write up by Garry Kemp, but there weren't any photos. Any assistance would be greatly appreciated. Greg, you don't happen to know where there is an article with photos do you? |
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Judson Manning Member 
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Dan, You can tap the top of the block where it mates the head and screw in the restrictor there. I use a 3/8" brass screw with a 3/32" hole drilled through it. However, this mod does nothing for you unless several other modifications are made. In fact, you'll burn up your top-end if they aren't made. Judson |
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Jensen Healey Super Moderator 
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You're scaring me Judson! Care to elaborate? Kurt |
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Ron Earp Member 
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My motor is done like that from Judson, as is his own Frankstein beast. Both seem very happy. I want that oil down in the bottom end (with enough in the top end to do the job) where the really expensive stuff is. Plus, maybe end up with less oil pooled all up in the cam towers. After Judson did this on mine, and I thought about it, and compared it to other engine designs/heads, I agree that there is no way the top end needs 50psi of oil through a 1/4" hole, simply is too much. Ron Last edited on 10-23-2006 08:43 pm by Ron Earp |
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Dan Eiland Member
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So where in the top of the block does this go? I see two large openings-one at the front of the block and one at the rear of the block. I'm also with Kurt on this one, what else needs to be done? I'm having dowels added to all ten bolts around the main bearings, then having the block align bored. Without going overkill on a street machine, what else needs to be done? Dan |
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Jensen Healey Super Moderator
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Hi Dan, It's the 1/4" hole next to the #1 cylinder. |
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Dan Eiland Member
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Thanks Kurt, I hadn't even noticed that hole until you told me about it. I thought it was a bolt hole at first glance. I'll have to get some batteries for my digital and take a photo of the culprit and then photograph the restrictor once it is in place. I can only guess the two large holes on the top front and rear of the block are the oil returns to the pan? And I'm still confused over Judson's warning. What other modifications are needed? I noticed too, that Judson uses a 3/32nd inch hole when others have recommended a 1/8th inch hole. Any comments on the size. Does size matter? It looks like there is some kind of brass sleeve inside the hole on my engine. Anyone know what this is for? Dan |
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Harkes Member 
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I'm not sure what Judson is referring to, but Garry Kemp who built my 2.2L engine also built in the oil restrictor to the head. Next to steel cam followers, ported/gas flowed 2.2L head, Garry's own custom 104-like cam and original 107 cam, uprated valves (later lotus or JHPS) etc etc he also fitted an extra cooling outlet near #cyl 4 underneath inlet manifold and plugged the manifold cooling outlet that goes to the interior heating. on later lotus engines this cooling outlet comes standard: 907 engines tend to overheat near #cyl 4 due to a flaw in the cooling flow. The extra cooling outlet there overcomes this issue and may prevent burning up the top end. But Judson may have other mods in mind. My engine also has the lotus x-drilled crank and block has been ten doweled and oil pan has been modified. hope this helps. I can make pictures of the cooling outlet if you want. Good luck and i look forward to see pictures of your great project erik |
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Judson Manning Member
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Keep in mind the MkII head was revised to allow MORE oil to flow to the cam towers (early engines were prone to cam belt failures). As we all know later variants had even more modifications to the cam towers. There is a certain amount of voodoo that goes into making these mods work and you don't want to arbitrarily make them in a vacuum. |
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Jensen Healey Super Moderator
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Indeed, restricting the oil feed to the head seems like a modification for the race track. At constant high revs it solves a problem as discussed in Garry Kemp's letter (tech/ performance mods). What does this do to a street engine that idles for long stretches and never sees 7000 rpm? I used a 3/16 hole when I did the mod but now see I didn't need it at all considering the use the car gets. Kurt |
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Ron Earp Member
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Jensen Healey wrote: What does this do to a street engine that idles for long stretches and never sees 7000 rpm? Probably keeps a lot of excess oil from pooling up in the head and might cut down on the dreaded cam tower leak a bit? I'm sure it won't solve it though, but might help. Ron Last edited on 10-25-2006 04:17 pm by Ron Earp |
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Jensen Healey Super Moderator
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Hi Ron, There's no windage at idle and a lot less oil is being pumped (mine is at 25 psi at 900 rpm idle and the oil pump is spinning at a much slower speed) so there is no pooling issue beyond the normal amount in the exhaust cam cover as I see it. There's plenty of time for the oil to run down the big holes to the sump. For the street driver it's probably better to get an Accusump so you can pre-oil before those 5 second dry start-ups and protect against oil starvation in the occasional long sweeper at 7000 rpm. I have found that I drive my car much more gently after blowing out 2nd gear while showing off. It is getting pretty old and so am I. Kurt |
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Ron Earp Member
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Mine is about 40-50 psi at idle at 900 RPM, runs about 75-80psi at 3000-4000 RPM. Accusump is in and plumbed - hope she does the job. Definitely saved my Z motor before. Ron Last edited on 10-25-2006 09:14 pm by Ron Earp |
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Sylva Member
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Dan My engine was modified by Garry, very well travelled block, made in England, bought in the USA, modified in England and now raced in Malaysia. Any way I have soft copy photo's of Garry's mod and can send them to you, email me at willia@petronas.com.my and I'll send them. My engine also has the oil returns in the head opend up, the returns in the block are 24 mm, the one's in the head are 10. I xrayed my head and then opened up the returns to 24 mm, Regards KElvin |
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