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Valve clearances and Camshafts  Rating:  Rating
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 Posted: 12-31-2006 05:28 pm
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smcmanus
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Both my camshafts are marked with MC25236 and 0351Y and A907E.  Are these correct for this car?

The valve clearances  are:  Intake from .002 to.005, and exhaust from .004 to .009 inches

None of the valves are tight as I can turn the followers easily.  How critical is this on the JH?  Do I have to change out the shims?

I'm afraid I know the answer, but await your guidance.  It seems everything on this car was fiddled with and then put together again to maximize my frustration!  It is one of those projects.

Thanks and have a Happy New Year

Steve

 

 

 

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 Posted: 12-31-2006 06:51 pm
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Ron Mau
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Hi Steve,

The shop manuel lists the clearances for the valves.

Intake  0.005-0.007

Exhaust 0.010-0.012

Lokks like you'll be changing some shims.

Ron Mau

Davenport, IA

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 Posted: 01-01-2007 01:21 am
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Mark Rosenbaum
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Your cams are marked with the correct casting numbers, but that says nothing about the way the cam lobes are ground.  Probably you have the stock JH cams unless there is a stamped number or machined groove present on the front part of either camshaft, just behind the timing gear.  To give you an idea of what to look for, the attached photo shows a couple of type 107 cams, and you can see the 777.... stamped thereon.

With the clearances you mention, I'd be hesitant about driving the car vigorously or for any considerable distance.  While the intakes probably won't cause any immediate problems, the exhaust clearances are far too tight and I'd be very concerned about burning valves.

I suggest checking your feeler gauges with a micrometer to make sure they're actually the thickness marked thereon.  You may get lucky and discover that your gauges are too thick.  Most likely, though, as Ron notes, you'll need to re-shim the engine.  This is an expensive, tedious, and annoying process the first time through, as it is necessary to test-assemble each cam carrier to the head to ensure that its shims are in fact correct.  If you record the shim thickness used at each valve, you can avoid most of that tedium the next time the job needs doing.

 

Attachment: cams type 107 #1.jpg (Downloaded 94 times)

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 Posted: 01-01-2007 03:15 pm
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smcmanus
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I was hoping it was a JH tuner's secret to set the valves tight.  I figured maybe the valve clearances increase as the engine warmed-up.  Oh well.

Can you measure your 107 cam from heel to lobe so I can check mine against it?  As I mentioned, everything on this car has been monkeyed with.  I'm wondering if someone modified it, or maybe just ground the valves when they did the head gasket.

Thanks and have a happy New Year

Steve

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 Posted: 01-01-2007 05:00 pm
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Mark Rosenbaum
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You can determine a cam's nominal lift by measuring the lobe height (the distance from the tip of the cam lobe to the belly of the base circle) and the diameter of the cam's base circle, then subtracting the latter from the former.  By comparing your result to the likely alternatives you may be able to determine which cam grind you have.  For example, I just made some not-very-accurate measurements on two lobes of a stock JH cam, as follows:
Lobe A: lobe height 1.552", base circle 1.210", calculated lift 0.342".
Lobe B: lobe height 1.550", base circle 1.205", calculated lift 0.345".

For 907 engines, the various Lotus-developed cams are listed below.
0.340" - Type C or 101 cam, 907E0101G (stock JH).  No special markings.
0.350" - Type D or 102 cam, 907E0102G.  One groove at front of cam.
0.344" - Type E or 103 cam, 907E0103G.  Two grooves at front of cam.
0.410" - Type 104 cam, 912E0104E.  Marked 444.....
0.378" - Type 107 cam, 912E0107F.  Marked 777.....

In addition to the above, there are many aftermarket cams, mostly for racing of one sort or another:
0.416" - Delta Motorsports' current Type 104 variant
0.361" - Delta Motorsports' current Type 107 variant
0.420" - Dave Smith type DS2
0.420" - Dave Bean Type BLL-104
0.425" - Dave Bean Type BLL-105
0.375" - Dave Bean Type BLL-107
0.360" - Paeco Type JH-7000 Intake Only
0.420" - Paeco Type JH-7000 Exhaust Only
0.370" - Paeco Type JH-7800 Intake and Exhaust
0.415" - Paeco Type JH-8600 Intake and Exhaust


Thanks go to Tim Engel, Garry Kemp, Kurt Housh, and Judson Manning for most of the data presented here.  The photo in the previous posting came from somebody's eBay offering of quite some time ago, not from parts I have on hand.

Attachment: cam measurements.jpg (Downloaded 541 times)

Last edited on 01-01-2007 05:02 pm by Mark Rosenbaum

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 Posted: 01-01-2007 05:55 pm
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smcmanus
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Mark

WOW! Great information.

Thanks

Steve

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 Posted: 01-01-2007 10:55 pm
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smcmanus
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Mark

I mic'd it out and came up with .350 for both the intake and exhaust.  I guess that means I have the type D cams.  Did it come that way from the factory?

I don't know the history of this car. 

Happy New Year

Steve

 

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 Posted: 01-02-2007 12:22 am
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Mark Rosenbaum
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I will again note that the measurements I posted earlier weren't all that accurate -- any or all of the readings I took could easily have been 0.005" or 0.010" off.  Consequently, without proof to the contrary, I'd be inclined to think that your cams are actually Type C's.  Regardless, unless your cams have the groove at the front, they're not real Type D's. 

It's my understanding that as far as anyone has ever been able to document, all JHs came from the factory with Type C cams.  I will note that there's a long-standing rumor that a very few Home Market (UK) cars built early in 1974 had the same Type D cams used in Lotus cars that year, due to an alleged shipping error by Lotus that no one caught until after the cars were sold.  I've never come across any actual proof that this might be true.  However, I do think it's conceivable that Lotus would have deliberately made such an 'error', regardless of contractual obligations to Jensen, if it would have saved them a few bucks in manufacturing costs through not having to custom build a few engines.  In those days, it was often said that when dealing with Colin Chapman, one was always very well advised to count their fingers and their pocket change after shaking hands with the man.

It is also possible that a previous owner installed reground cams at some point in the car's history.  A significant decrease in base circle diameter would be a very good indication of this.  If so, then without some sort of documentation, all you can do is to measure lift versus rotation at many points and compare that information against similar data from possible candidates.  That would be a challenging task.

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 Posted: 01-05-2007 06:55 pm
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smcmanus
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OK, I pulled the intake cam housing after carefully double checking the valve lash.  I find there is a gasket so I called Delta to ask how thick their gaskets are and they told me 15 thousands.  I mic mine and get about 10.  So I guess maybe it crushed to about 10 when installed.  The guy at Delta says I should use gaskets between the cam housing and the head and that it is a bad idea to eliminate the gaskets as the service manual recommends.

Use the gasket or not?

If the gasket maintained .015 thickness, my valves would be close to tolerance.  I suspect the gasket will crush somewhat.  What is the truth? 

If I dry assemble without the gasket I will have no clearance at all so it is pretty hard to accurately measure what size shims I need.  What to do?

Sorry to be such a moron!

Thanks

Steve

 

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 Posted: 01-05-2007 09:18 pm
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Greg Fletcher
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Why would you use the paper gaskets? The gasket was a design flaw from the start. There was Lotus Service Bulletin way back when that clearly states paper gaskets under cam towers will leak (they always do) and to avoid that type of installation. You will never get away from the leaking at this spot if you don't correct it. It's really worth switching over in my opinion if you need to change any of the shims. You must change all the shilms at this point, but if you need to change half of them anyway, it's not like you're saving a lot. I've used Loctite 515 for many years and it has always worked perfectly. It provides a near zero gap and seals from oil leakage as long as it is needed. You can assemble everything dry for a final check and know that you will end up with the same clearance when done. I think shimming the valves is enough trouble without having to figure in additional measurements (which are always approximate).

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 Posted: 01-05-2007 10:33 pm
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smcmanus
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I just came in from dorking around with it.  I dry assembled the exhaust cam after removing the gaskets and cleaning it.  Two of the valves, which previously had .008 clearance, now have nil, but I can turn the lifters.  The one valve which was had .009 has slight clearance, less than 2.  Those with less than 8 were tight.

So I guess it is about 8 thousands difference with no gasket.  Anyone have a shim assortment they can loan me for a couple days?  I'll pay shipping both ways and, of course, pay for the shims I use. 

Why use paper gaskets?  That's why I asked!  The guy at Delta said to use the gaskets but the JH service manual says don't.

Thanks

Steve

 

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 Posted: 01-05-2007 11:07 pm
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Mark Kleimola
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I too am in the process of installing cams and shimming the valves. Since I have switched over from the old base cams to the 107 cams I had, I find I need mostly all new shims.

The new shims I need range from ~.100-.110 (exhaust) to about ~0.110-0.125 (inlet) based on my dry assembly without shims. Are these sizes readily available?  All the shims in my possession range from 0.070 to about 0.095.

Also if by chance someone has some thick ones they would swap for some thin ones 3 thin for 2 thick, or even want to sell, I'm open.

Let me know at mkleimol@comcast.net..
 


Thanks
Mark K

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 Posted: 01-06-2007 12:30 am
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smcmanus
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Let's trade!!!!

I'll bring in the list of shims I've got and let you know.

Steve

 

 

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 Posted: 01-06-2007 02:29 am
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Jensen Healey
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I've found setting the valves a very frustrating process.  The clearances seem to change randomly each time the cam carrier is bolted on. I think it may be related to worn valve stems and used shims.

When the correct clearances are obtained the carrier needs to be removed one last time to apply the Locktite 515. That's usually when the shims fall out on the garage floor. Remember to shove a rag in the oil return hole so the nuts and washers don't fall into the oil pan.

Kurt

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 Posted: 01-06-2007 02:42 am
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jcdean
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http://www.jensenhealey.com/forums/view_topic.php?id=425&forum_id=2

 

Just to remind those who already know and inform the newer members, the shims from the 8 valve SAAB 900 up to 1987 IIRC are a perfect fit. They come in metric sizes and I have ordered them on the internet and purchased them from the local SAAB mechanic. They are a bit cheaper than the Lotus items.

 

Kurt


Copied this from a previous post by Jensen Healey, aka Kurt.  The entire post is worth reading.

 

Joey

Last edited on 01-06-2007 02:45 am by jcdean

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 Posted: 01-06-2007 03:21 am
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Jensen Healey
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Update: SAAB shims are now more expensive than the shims available at the club store. Don't believe everything you read!

Kurt

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 Posted: 01-06-2007 05:02 pm
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smcmanus
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How about this?  I mentioned in a different thread that when I took off the exhaust side cam cover about a quart of oil dumped out.  I didn't get any feedback so I assumed that it was normal.  Maybe not!  The exhaust cam case has the rear oil drain hole blocked with what appears to be epoxy.  What the....? 

In the picture the exhaust cam is closest to the camera and the arrow points at the blob blocking the drain hole.  I scratched it and it is non mettalic; maybe BJ weld or something. 

Am I right in thinking this needs to be removed?

Thanks

Steve

Attachment: jhcamoilhole.jpg (Downloaded 79 times)

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 Posted: 01-06-2007 11:33 pm
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normv
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Steve

I know one of my engine's which was rebuilt under the original warranty in Australia has a Plastic plug in this location and another earlier engine I have doesn't so mabey it was a warranty addition or appeared on later cars as the one which has it to have a proper shaped plastic fitting glued in Looks like it is meant to be there. Many engine use the engine oil to cool the valve springs and stems particularly on the exhaust side so I suggest this is to flood the area with oil for cooling.

Norm

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 Posted: 01-07-2007 03:28 am
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smcmanus
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The goop in the drain hole keeps the oil around the cam (and leaking out of the cover) but does not keep the valve stems or springs in an oil bath.  The drain holes in question are in the cam case, not in the head.  This does not look like something the folks at Lotus would do.  This car has a nice protective coating of oil and was leaking like a sieve.  I wonder if pluggung this hole was an attempt to stem the flow of oil from between the cam case and the head?  There were also ample amounts of blue silicon sealer smeared all over.

Have a nice day

Steve

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 Posted: 03-13-2007 01:17 am
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Dan Eiland
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As a lot of you know I am rebuilding my engine and upgrading at the same time. Today I switched over to the newer style cam carriers which required that I remove ten of the mounting studs which are replaced by star headed bolts. I moved my new cams from my old carriers to the new ones and checked to make sure they were indeed the Delta 104 cams. The base measured 1.065 inches and the lobe height measured 1.481 inches. If I subtract the base for the lobe height I get 0.416 inch lift which corresponds to all the data I have as well as what Mark has already posted. Of course I did find on the end of each cam that they had been stamped with "DELTA 104", so now I know I have the 104 cams with 0.416 lift. I'm now wondering what the clearance should be between the follower and the base of each cam lobe? Should it remain the same as what the book says or does it change with the 104 cams. If it matters I'm also converting to the 2.2L crank. Any assistance would be appreciated.

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