The Lotus Cars Community banner

1 - 20 of 21 Posts

·
Registered
Joined
·
860 Posts
Discussion Starter #1
I am in the process of doing a complete service "c" on my Esprit. As part of the timing and v-belt change, I am changing the cam pulleys to the green dot 104 degree MOP pulleys. When installing these pulleys, is it advisable to put a dab of blue loctite on the threads?
 

·
Registered
Joined
·
1,293 Posts
There is actually an oilway blanking grub screw in the center of the camshaft threaded hole and for that reason some people put a little silicone in the threaded hole to make sure it stays sealed. I usually do that when I rebuild an engine.

Do one or the other. I use loctite on just about every critical fastener unless it's specifically stated to be fitted dry or with oiled threads.

The green dot cam pulleys were originally spec'd on early Lotus 9XX engines and give 4 more degrees advance to the cam timing than the stock blue dot pulleys. Lotus retarded the cam timing for emissions purposes in the later engines. Green are 104 MOP and Blue are 100 MOP. Switching to the green dot gives a little performance boost at the expense of increased emissions.
 

·
Registered
Joined
·
113 Posts
Im still confused. I have a 2001 v8 and i recently did the cam belts and cam seals (had to remove cam sprokets aka cam pulleys) and they dont have keys and move freely. So how would changing the cam pulleys advance timing if you can essentially set it yourself? Sorry for sounding naiive but i am unaware of this

And to the OP, i did use loctite on the bolts
 

·
Registered
Joined
·
860 Posts
Discussion Starter #5
These cam pulleys are for the 910 series engines. As Jim stated, lotus retarded the cam events so that the engines would get some egr-like emissions compliance. It was a cheap solution and lotus didn't have to add An egr to the engines.
 

·
Registered
Joined
·
113 Posts
For 4 cyl. Got it. Thanks

But still quadcam, use locTite. I used red loctite heavy duty. Oil does circulate around the sprockets and last thing you want is an oil leak.
 

·
Registered
Joined
·
860 Posts
Discussion Starter #7
Jim, great info About the oil passageway in the cam. I noticed oil leaked out the front of the cam when I pulled the bolt out. It seemed like their were bits of plastic in the cam snout when the bolt came out. Can you tell me more about the "grub screw?"
 

·
Registered
Joined
·
860 Posts
Discussion Starter #8
I found the grub screw in the service manual. I guess grub screw is Britsh for setscrew. It doesn't say much about it the manual though..... just says that there is one in there.
 

·
Registered
Joined
·
1,293 Posts
If you have seen some evidence of oil in the hole, then best to clean it well and seal with silicone. I wouldn't try to get the grub screw out if you don't have to. It's easy to strip and you'd then have to pull the cam tower to fix it.
 

·
Registered
Joined
·
184 Posts
FWIW, I recently did this, along with a few other turbo-to-port intake tweaks to get better breathing and the differnce is surprisingly good on my 89 non-SE. I don't know how much is cam gears vs. the other stuff, but i suspect the gears are a large part of it. After pushing it progressively harder for a week or so after finishing all the work, when I finally went full-on, I was impressed. From a rolling start, when I punched it in 1st, it spun the tires all the way until I shifted around 7K. I thought it might just be the road I was on, but I've done it again on a few roads. I think the extra torque from the 104 gears is large part of the reason. As a side benefit, it sounds a little throatier/less sewing machine-like now. None of my other recent changes would account for that. For anyone considering the gear change, while it's obviously not neccessary, it's pretty damn cool and, at least in my experience, a very nice upgrade...and it's how Lotus would have done it if it hadn't been for regulatory compliance. I thought it might be worth sharing my results for folks wondering if it's worth while.
 

·
Registered
Joined
·
860 Posts
Discussion Starter #11
dalefield,

I recently heard an S4 with a stock cat and no muffler. He had the performed the green dot cam pulley change. With no muffler, you could really hear a difference in the exhaust note from the cam timing change. Hearing that car inspired me to get off my ass and do the cam belt and pulley change. I've hads the parts for several months.....just didn't want to dive into the project.

I haven't had a chance to work on the Esprit for the last 2 days. I should be able to finish it all up this weekend. I'm looking forward to feeling/hearing the difference from the new pulleys.
 

·
Registered
Joined
·
184 Posts
Hearing that car inspired me to get off my ass and do the cam belt and pulley change. I've hads the parts for several months.....just didn't want to dive into the project.
I think you'll be pretty happy with it. For all the other stuff we do (myself included) to tweak performance, when we haven't done this yet, it's kind of silly in hindsight. This is so easy (at least for the mechanically inclined) and such low hanging fruit that it should be at or near the top of the pick list.

I hope you get similar results!
 

·
Registered
Joined
·
1,231 Posts
:clap:

Nice to hear this! I just finished a rebuild of my '89 non-SE and that work included the green dots, Al B.'s custom header, and a high-flow cat. I'm almost ready to put it back on the road and this is great to hear. I have started the motor (still working on a few transmission pieces) and it does sound very nice with the new engine parts.
 

·
Registered
Joined
·
514 Posts
I'm a little late to this conversation, but...

The 910 cam pulleys butt up against a shoulder on the cam, and are securely clamped by the bolt, so there's no need for Loctite between the pulley and shaft journal (to the contrary, apply a film of Anti-Seize there). But DO seal the threads & bore against oil leakage using silicone sealant (RTV).

If you are starting from scratch with the cams out of the engine, then remove the grub screw located down in the bottom of the pulley screw hole. Clean out all the old silicone sealant, then back-flush the cam bore to make certain all silicone debris is removed. A stray chunk of silicone can easily block an oil passage, leading to bearing failure and expensive repairs. Flush, use a small bore gun barrel cleaning brush, flush again on a paranoid scale.

During assembly, pre-coat the grub screw threads with silicone, then install into the dry threaded hole and tighten securely. "Dry threaded hole", such that any silicone oozing out of the threads during installation will come back into the threaded bore, and NOT into the cam's oil bore. Using a small, slender art brush, paint the end of the grub screw with a coat of silicone sealant and allow it to cure. Then paint the threads (bore & screw) and fill the bottom of the bore with silicone.

Lightly coat the pulley bore and cam journal with Anti-Seize, and wipe off all excess... leave only a film. Install the pulleys, carefully noting which side should face forward on each cam, and tap them back securely against the shoulder on the cam.

Install the thick retaining washer, and run the bolt in as a trial fit, noting whether or not it stops properly due to bottoming out, or due to hydraulic lock with the silicone packed in the bottom of the bore. A slow tightening should cause excess silicone to ooze out past the threads. When you're sure the bolt has bottomed, remove it and clean up any mess that oozed out. Be prompt... don't let the silicone set-up.

Then re-install and torque to 25 lbs-ft. Allow plenty of time (24 hours minimum) for the silicone to cure before starting the engine.

*~*~*
If you're simply R&R'ing the pulleys, pick as much old silicone out of the threads as possible... male and female. If the joint was previously oil-tight, then don't clean the mass of silicone out of the bottom of the bore... if it ain't broke, don't fix it. Just clean the threads, male & female, re-coat with silicone, and re-install.

However, if the joint was a leaker, then clean all the way down to the grub screw and start over. Just be paranoid-certain that no silicone debris gets pushed into the cam's oil bore. If in doubt, remove the cam and flush the bore.

*~*~*
The auxiliary pulley butts up against a thin wire circlip, and is no where near as solid as the cam pulleys. Here, use a little low-medium strength blue Loctite 242 Threadlocker in the pulley bore/ shaft journal. Full coverage isn't required, just a little. Apply it to the back end of the bore such that the shaft pushes it forward through the bore when the pulley is installed. Wipe off any excess. Don't apply it to the shaft, then push it back with the pulley, or you risk contaminating the lip seal with Loctite. Apply a small dab on the screw threads and tighten.

*~*~*

Properly installed, the cam pulleys should come off with little effort next time. Hand wiggling, maybe a little lite tapping, but a puller shouldn't be required. Certainly no heat/ propane torch.

However, the auxiliary pulley, with the blue Loctite, won't just come off easily. And even though low-medium strength Loctite is used, there's enough surface area in the bore to require a pretty heavy pull with a 3-jaw puller, along with some heat. Don't do it cold with brute force. The pulley is aluminum, and it's easy to break the spokes if you get to carried away with the puller.

Instead, remove the bolt and retaining washer, and re-install the bolt to give the puller screw a surface to push against (DO NOT run the puller screw directly against the end of the aux shaft/ threaded hole !!).

Install the puller and apply a good load without going nutz. Then heat the pulley's hub area with a propane torch, taking care not to heat-damage the lip-seal directly behind the pulley. Wrap the shaft/ seal area behind the pulley with wet rags to protect the seal, then aim the flame at the pulley hub area only, working from behind the pulley and aiming the flame forward. Watch for the pulley to move a wee bit when the Loctite gets hot enough to let go, then pull it the rest of the way off. It's hot, wear gloves.

It's best to put the puller's jaws through the spoke holes, and hook them directly onto the hub. That takes all the pulling loads off the spokes, and minimizes the chances of breaking the pulley. With enough heat to kill the Loctite, you can get away with pulling on the pulley's rim most of the time. It's just that 'once' that can ruin your day.

A small 3-jaw puller will fit between the pulley and the Esprit's firewall, but it does need to be a small puller. A typical 3" puller fits, but brands vary, so shop for the smaller end of the range.

Regards,
Tim Engel
Lotus Owners Oftha North (LOON)
 

·
Registered
Joined
·
480 Posts
I am considering upgrading to green dot pulleys when I put a HSN HTD cam belt on my soon arriving 95 S4. It looks like it still had the ORIGINAL cam belt on it, so no driving until it is done.

It does not 'advance' the cam timing per say, it corrects it. The cams are ground with a 104 mop, the 100 and 110 mop pulleys were for meeting polution specs, that retarding the cam timing.

I'm sure it should increase power having correct timing, I am just wondering since that would probably increase efficiency, if it might actually help on fuel mileage. On my original in the day 77 Esprit S1, getting rid of the polution crap, retiming the cams to correct timing, and recurving the distributor, the mileage went from 27mpg to 33mpg.

I emailed Garry Kemp for his thoughts on the matter, and will probably have a response tomorrow.

Brian
 

·
Registered
Joined
·
514 Posts
(Snip)... It does not 'advance' the cam timing per say, it corrects it. The cams are ground with a 104 mop, the 100 and 110 mop pulleys were for meeting polution specs, that retarding the cam timing.

I'm sure it should increase power having correct timing, I am just wondering since that would probably increase efficiency, if it might actually help on fuel mileage. On my original in the day 77 Esprit S1, getting rid of the polution crap, retiming the cams to correct timing, and recurving the distributor, the mileage went from 27mpg to 33mpg.(Snip)...
Putting the red dot 110 MOP pulley on the intake retards it 6 degrees. The blue dot 100 MOP pulley is a bit of an oddball in that it's really a 97 MOP, just rounded up... all the other pulleys are as marked. Anyway... putting the blue dot pulley on the exhaust retards it 7 degrees.

With the 104/ 104 cam timing, the engine will feel more urgent and have better off-boost power and throttle response. As for improved gas mileage, well yes, if you drive like economy is a priority. However, if you drive in a spirited manner that allows you to feel the improvement, economy isn't really an issue. Put your foot in it, and it will drink guzzle regardless of the cam timing.

Regards,
Tim Engel
 

·
Registered
Joined
·
480 Posts
Totally agree Tim, thanks for your input!!!

Once Garry emails, I will also post over his viewpoint from the other side of the pond. I am interested on what he has to say too.

With me, being retired now, every penny counts. I loved that 33mpg on my original, bought new S1. I want to be able to take off on a thousand mile trip when I want, and get there with enough money for food.

On this S4, being one of the most original S4 cars out there (even still has the factory exhaust, zero mods, < 18k miles), I am not going to modify it for another 30-50hp, and drop the fuel consumption by 10mpg, does not make rational sense to me in these days and times. It will be quick enough to be entertaining, and will get my wife and I to wal-mart in a flash! :)

My S1 project, however, will be more balls to the wall, it will not be the 'trip' car, I expect to make at least 225hp, NA, and I bet I still retain around 28mpg on it from my build specifications I came up with. That is another story for another time.

Each to his own, however. That is what this hobby is all about.

Best Regards,

Brian
 

·
Registered
Joined
·
860 Posts
Discussion Starter #18
Brian,

As Tim said, you really feel the difference off idle. IMO, the car doesn't feel like it is struggling to leave a stoplight anymore. Other than that, I don't feel a difference with these 104 cam pulleys. there is a nice lope at idle though.
 

·
Registered
Joined
·
480 Posts
Well Quad, if it helps the lope at idle, I am all for it! I love that musical cam sound that repeats itself.

Garry seems to say all se/s4's had 110/100 apparently both sides of the pond -

"I have never tried the pulley change in isolation – I avoid working on cars if possible, so usually I get the engine sent to me and I send it back dynoed, the “federal” timing of 110/100 is emission related and the early Euro cars ran with the 104 / 104. I believe all SE / S4’s and the 110/100 timing. I think the difference will be exactly as you say, but I doubt the difference will be huge – 107 cams are quite mild. You know on the S4 you get a “free” 104 pulley – the oil pump pulley is a 104 and can be swapped with one of the cam pulleys, so you will only need a single 104 pulley if you do want to change."

Brian
 

·
Registered
Joined
·
860 Posts
Discussion Starter #20
even the SEs came with a green dot on the oil pump. So, you are right.... you only have to purchase one green dot cam pulley.
 
1 - 20 of 21 Posts
Top