Jump to content
alexmillikan

L20b Front Cover Issues

Recommended Posts

Hi guys I'm in the middle of rebuilding my L20b and have run into an issue with the front cover distributor/oil pump shaft bung that is cast into the front cover, mine is worn quite a bit I don't think it would bind or back out of the oil pump, but it worries me. Wanted to see if anyone here has had similiar issues and what they have done to fix it. I have searched for L series 4cyl front covers but haven't found anything for sale.

  • Like 1

Share this post


Link to post

Is it just scored up a little, or is there actually slop in it ?

If just a little scoring, I've saved them by applying a thick coat of moly , then honing it enough to get an un-scored shaft to slide in, and turn freely.

But I'm set-up to do my own engine coatings.

If the hole actually worn so much that it clunks around in the hole, it's scrap, as most likely is the crank gear, and oil shaft.

Gears don't like to be run only partially engaged.

 

I think you should just find another.

And unfortunately, the L20b is longer than any other L-series, so it will have to be from another L20b.

  • Like 2

Share this post


Link to post

Thats a good reason to do an engine swap I say

  • Like 1

Share this post


Link to post

Yeah I just got a 32/36 I'm waiting to find a good deal on some used side drafts before I go that route. Do you have any leads on headers besides the ones on eBay from California datsun?

Share this post


Link to post

Make sure you replace the front seal on what ever you get.

  • Like 1

Share this post


Link to post

Header not needed. Stay with stock manifold.

  • Like 2

Share this post


Link to post

I don't know what type of exhaust manifold a 76 has. The preferred ones would be the non smog(non injection port) L16 manifold froma 510 or 521

Datzenmike has photos but ones need a Y pipe and if not made.

 

The Header you mention will fit and ez to install but best to have poweder coated ans fit is so so on these as could be a leaker and it not ceramic coated turns in to a rust eye sore in 6 months

Share this post


Link to post

If the wear in the spindle guide is only on the thrust surface, not in the bore, then you could machine/grind/sand it flat and use a distributor shim to take up the play. We did this on L series race engines (if a distributor was used) to take up the play to stabilize the ignition timing.

 

Here are some dist shims - https://www.summitracing.com/search/product-line/moroso-distributor-shim-kits

 

Obviously you want the correct inner diameter.

 

Good L headers are expensive and hard to find. The best come from Nissan Motorsports, but finding one for a 620 is going to be harder than the needle in the haystack. They made them a long time ago. The name of the man who builds them has slipped my mind, but he still does make headers. It's not Ed Pink, it's...? If anyone can remember his name, that's your best bet.

 

If you have $1500 to spend on a header, just about any good custom fab shop can build you a nice one. Hell, I'll build you one.

  • Like 2

Share this post


Link to post

The '76 will have the co-joined intake and exhaust. It uses exhaust heat to warm the underside of the intake. If you remove the exhaust manifold, you will have a huge hole in the bottom of the intake. Besides, the L20B exhausts are 4 into one and a single down pipe. I guess the simplest thing would be to find an L16 or L18 intake and exhaust manifold and swap it on. It's the 4 into two (cast iron header) with a two into one down pipe. You will need to get a down pipe that will work on it or make one. There's a bit more to it but preferable to an expensive short lived header who's basic advantage on a stock engine is lighter weight. California Datsun???? never heard anything good about them yet. 

 

A stock engine, tell the truth, you won't notice a thing doing any of this. Get a larger turbo muffler instead. 

  • Like 2

Share this post


Link to post

Thank you for all the responses!! Didn't expect to hear from all of the Datsun experts so quickly. And yes Datzen Mike I have the conjoined intake and exhaust I am going to sand blast the intake and exhaust and am in the process of getting rid the tube near the bottom of the manifold and the air injectors I plan on welding the holes shut or if the threads are any good putting brass plugs in. As well as making a block off plate for the intake. Stoffregen thank you I didn't think of that, I contacted an eBay seller and was able to find a cover for sale but I think that would be a great way to fix my issue, at first I thought something was missing between the surfaces like there should be a bearing in there. I'm not sure why it ate into the cover whether it be lack of lubrication or misalignment of the gear on the crank. I didn't notice any wear on the worm gears though. I appreciate the offer on the header but I'm not ready to spend quite that much on a header but also not okay with the quality of eBay ones so i guess I will be sticking with the manifold

  • Like 1

Share this post


Link to post

Also Mike, I have a l16 intake I plan on porting out (later on when I switch exhaust manifolds) and I saw a post where you said you drilled the holes in your head for coolant, is this a necessity for the fuel to atomize correctly in the intake or just good for when the engine is warming up? And the head you drilled was a u67 right?

  • Like 1

Share this post


Link to post

Somewhere in another thread here on Ratsun, someone posted a pic of a plug that fits directly into the air injection port holes. I think it was DanielC and it was a Volkswagen part.

 

Don't try to weld the manifold holes. The weld will likely not stick. Instead, cut the tubes off close to the nut and weld the tubes closed.

 

The wear in the cover can come from the crank pulley bolt coming loose, and then everything walks around inside causing the spindle to bounce up and down. If you see no other wear inside there, then it's likely someone fixed that stuff before, but failed to notice the wear in the cover.

  • Like 1

Share this post


Link to post

They are VW oil drain plugs IIRC. dat521gatherer was the one reporting that.

  • Like 1

Share this post


Link to post

The hard part is getting them out. Soak with kroil or wd-40 ect. Work them back and forth little by little. If the head gets rounded pound a 12 point socket that's slightly smaller than the head onto it. If the head breaks off just drill it out and tap it. I forget the size.

 

SANY5620.jpg

 

SANY6041.jpg

 

KGrHqJioE2LQFFV4OBNjQUKkhCQ0_12.jpg

Share this post


Link to post

Well if you have the stock joined intake there is no need to drill the head as the intake does not flow coolant through it. The whole point of the coolant flow is to warm it faster when the air is cold and cool it when it's very hot out. The hot exhaust will bake the intake. Coolant flow here will actually cool it. The intent is to provide a more regulated intake air temperature over a wider range of outside temperatures. The engine performs more predictably when very cold or extremely hot out.

  • Like 1

Share this post


Link to post

The hard part is getting them out. Soak with kroil or wd-40 ect. Work them back and forth little by little. If the head gets rounded pound a 12 point socket that's slightly smaller than the head onto it. If the head breaks off just drill it out and tap it. I forget the size.

 

 

 

 

 

KGrHqJioE2LQFFV4OBNjQUKkhCQ0_12.jpg

 

Man the size/part is the most important thing.  Try and remember kind sir.  

Share this post


Link to post

Heat is going to be your friend in getting those nuts out. Welding the nut closed will provide enough heat to break them loose, but then if you've welded the head closed, you don't need to remove them.

Share this post


Link to post

Stock manifold good for 192hp.

Works great on my setup.

 

PM me for a timing cover.

Share this post


Link to post

Added a few new pics to the folder https://drive.google.com/open?id=1xOO9FazmwTxgcAMs-HKIo5JaI4SXlpEm

 

So I got another front cover from eBay and the thrust area for the oil pump shaft is good but it has a dowel pin broken off for the water pump does anyone think this could cause issues or just put it together as is? (Pics are in the link) I also added some pics of my exhaust manifold the PO did a somewhat subpar job plugging the holes for the air tubes but they don't appear to have been leaking at all. I was going to cut what the PO did off and just fill it with weld but if you guys don't think it will stick very well I will just leave it alone.

Share this post


Link to post

At least the hole is still mostly there. Clean the hole out really good, make sure the pin is clean. Stuff it back in the hole with some JB weld, then mount a pump on it while it dries. Remove the pump and sand the surface clean. Done.

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

By using this site, you agree to our Terms of Use.