Lotus Europa Community
Lotus Europa Forums => Garage => Topic started by: califkid_66 on Thursday,September 30, 2021, 03:36:11 PM
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im trying to figure out how to adjust my distributor depth if that makes sense
when i had taken apart my crossflow i noticed that the distributor was putting to much pressure on the oil pump gear and the bottom of the gear was rubbing against the block making chips of metal now
what im trying to figure out is do i leave some clearance between the bottom of distributor and drive gear or does the distributor have to push down on the gear cause i know when the engine is turning the cam pushes up the oil pump drive gear and it rubs under the head witch i think is normal or do i have to shim the distributor enough so it pushes it down a bit but not to much to rub under on the block there is no information in my books
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What engine? Renault or Lotus/Ford?
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renault crossflow
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Ok, this is a bit tricky as there normally isn’t an issue. The only thing that springs to mind is that the head has been shaved, and by quite a bit. Solving the issue should be straight forward though. Once the head is in place and torqued down, measure the distance between the upper face of the gear and the top face of the distributor bore in the head. Compare this to distance between the distributor body’s mounting face and the end of the drive. Measure both to tip-off the drive “key” and to just the face of the drive.
Now do the calculations and see how much clearance you have, or haven’t as the case may be. Make up a spacer to lift the distributor the required amount. Important that any significant spacer has a reduced section to positively centre the spacer in the bore, and that the spacer centres on the distributor.
Suggested clearance? It’s an aluminium head and block, so the clearance should grow as the engine warms up. Minimum 0.010 and not too much bigger would be what I would shoot for.
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thanks Jb that’s exactly what i was asking i did measure the depth of the distributor hole where it sits and top of gear did same for distributor
so 0.010 clearance so no pressure on the gear wasn’t sure if the distributor had something to do with aligning the pump gear to the cam
im trying to make sure i don’t leave out any details like you mentioned before some parts are critical like the alignment of the head and other stuff i just wanted to make sure i get it right
thanks again
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Did some online digging as I remember doing this very procedure when assembling Triumph engines. Their spec is 0.005” to 0.007”. So go a little tighter than the 0.010” I recommended upstairs.
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there is something i need to mention when i did the measuring with my calliper i went and took measurement all around in the hole then i turned over the engine and the gear went up in the position it should have been and gave me a different reading a 0.020 difference so im gonna use the reading when the gear is up to adjust the clearance
by the way i didn’t measure in the grooves but on the top of the gear at four different places to make sure it was square and all equal
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When the engine turns, either an upward or a downward pressure will be applied to the drive gear due the cut of gears. So it’s normal for the gear to move if it is not held in position. I would push the drive gear down as far as it will go and then do your measurements.
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ok so when i push it down it goes 0.020 down if i measure from that point and leave a clearance of
0.007 that means the distributor will push down 0.013 on the gear
now the head originally is supposed to be 3.681 i just measured my head 3.605 witch is a difference of 0.074 now my distributor without gasket 3.048 so if i remove 0.074 from 3.048 gives me 2.974
this calculation removes the same amount that was shaved from the head from the distributor shaft
so basically if i shorten the distributor shaft by the same amount that was removed from the head by shimming it it plus a gasket it would be in the right position for the oil pump drive gear
now when i measured my distributor hole wit the gear pushed completely down 3.019 turned the engine and the gear went up and was at 2.999
now acording to my calculations
when engine turns gear is up at 2.999 if you take length of distributor shaft 2.974 that leaves a gap of
0.025 and would be at this position if head would not have been shaved
would this make sense
so my thought is if you just put the distributor in the hole you do not adjust the height it is supposed to be ok so if you remove from the head you remove same amount from distributor by shimming it then it should fall in the right place
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Hmmm . . check my thinking here, but if I recall correctly, as the engine operates, the dizzy gear rises and contacts the underside of the head which limits it's travel. There should be witness marks.
That being the case, the dizzy bore hole height is the determining measurement needed to establish the shim thickness required under the dizzy flange ± the end float desired for the key engagement.
I raise this as a possible concern partly because I don't know the end float spec. on the dizzy shaft.
My expectation is that the dizzy should run freely and is not expected to accept axial thrust from the dizzy gear.
That's the design intention as I see it, but happy to be educated.
Does that make sense?
I can take some measurements from a stock R17-TS crossflow head if needed.
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i checked my crossflow head and i see signs of rubbing the gear does go up when engine turns i tried finding information on adjusting the distributor but since there’s nothing then it’s got to be as simple as putting it in it’s place and should fit ok except if you modified your head
now my new concern since i saw signs of rubbing is lubrications since the gear rubs under the head there is a groove i think it a passage way for oil to lubricate the top of the gear when it’s rubbing against the head
my crossflow head as been shaved and that groove is not there maybe i should have made a groove to help the oil get between the gear and the head
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Should be easy enough to hand form a new groove with a small round file, I reckon.
When you get the spacer made for the dizzy flange, you should be able to install the dizzy and offer up the dizzy drive gear to the head underside and check clearances.
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the head is already installed with new gasket i wouldn’t mind taking it apart but i don’t have another
head gasket
the oil pump gear as grooves right across i think the oil will have access to the top by there
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A suitable spacer should work fine and a better idea that trying to shorten the distributor itself. If you ever replace the head you can just leave the shim out.
What I’m not sure of is what locates the drive gear in the first place? Surely that has also decreased by the same amount …or maybe not. If the head is simply flat then you can shave it to your heart’s content and it makes no difference at all, other than lowering the distributor too far. So, perhaps, the 0.020” movement IS the amount of gear float.
But, if the distributor was been too low for a while, forcing the gear into the block, then it may have “machined” the bore deeper. In which case, a shim UNDER the gear might be required. Just more food for thought.
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for the shim under the gear it slightly rubbed not enough to make a difference
i am positive that the drive gear locates itself automatically in the right position
why
1. there is nothing about adjusting height for distributor
2. the camshaft and the oil gear have to be in the right position for the gears to work without damages
3. i think the oil passage and the rubbing marks on every head i have seen shows that the head is what
positions the gear at the right place
4. i think the distributor only as radial load and not axial as Gavin suggested
5. when i adjusted my valves i turned the engine with the flywheel the oil gear rotated nicely in relation
to the cam gear nicely
6. and finally after all my measurements and calculations i wrote that by shimming the distributor by
the amount that was shaved would leave a 0.025 gap but i noticed a little mistake on my
measurements being that the head was on was hard to take the thickness in a previous post i wrote
my head was 0.3625 and this time i wrote 0.3605 so if i go with the measurements done when the
was not installed that would leave a gap of 0.005 witch is what Jb suggested
i rest my case on these arguments !!!
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Oh . . . that's a bit trickier if the head's already installed.
To measure the bore hole height above the drive gear means ensuring the gear is hard up against the underside of the head.
The only way I can think of is to remove the oil pump and insert a long rod up the spout to keep it in place while you measure.
The drive gear just sits on the oil pump spline in the block. Given the gear is forced upwards during normal running, the limit is where it contacts the underside of the head. I don't think the actual gear float matters. It's always going to be running against the underside of the head no matter how much was skimmed off.
I notice the first pic in Reply #10 shows light witness marks which would seem to confirm califkid's findings about the drive gear being forced down and cutting chips below the gear.
califkid, I reckon you're probably saved yourself some heartache by taking that engine apart.
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thanks im just going to shim under the distributor the amount that was shaved of the head
crossflow head 3.681 my crossflow head 3.625 so 0.056 shim under the distributor should
do the trick
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:-)
Sounds good!
… I think.
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it should be ok it’s a learning curve
while i was at it i noticed witness mark on the distributor witch shows where it was mating with the oil gear
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thanks im just going to shim under the distributor the amount that was shaved of the head
crossflow head 3.681 my crossflow head 3.625 so 0.056 shim under the distributor should
do the trick
Question - has this engine ever actually run without a shim under the dizzy?
I ask because if there's been enough axial load to cut chips under the gear, the situation might have damaged the internals of the distributor similarly.
I've had another bright idea. ::)
Perhaps the dizzy drive gear could be held in place for measuring with a BFMagnet?
I'd still want to measure the actual components.
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… I think.
I could never be accused of that . . .
On my first crossflow, I did a dry build of the head to check something or other and left out the head gasket because It wasn't strictly needed for what I was doing . . might have been valve/piston clearances . . can't remember.
Anyway, I went to turn the crank and heard a strange 'tick' sound and found the crank wouldn't move.
I never figured out what the 'tick' sound was but years later, while doing something else, I discovered part of a gear tooth had broken off the camshaft and was lying under the dizzy gear.
That sounds like empirical evidence the end float of the gear is less than the thickness of the head gasket - ooops. :-[
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i don’t know looks like the block ran had glitter in oil and oil was used but top end did not seem to have run carburetor freshly rebuilt never had fuel head unbolted and came off very easily as if it was just installed the head gasket looked old the pistons were very clean no carbon
pretty hard to tell when you don’t have the history
for the dizzy i not going to use it it came from a fuego
im just gonna continue working on it im not in a hurry i just want to make sure im doing everything right