Some simple '74 l20b questions

[frank88]

Hi guys,

 

I have a few questions about my l20b, as I prepare to fit my R1 carbs. As I'm in the UK, and it's a classic vehicle I can remove all the emissions stuff so I'm doing that at the same time.

 

I've removed this now but is this the 'Altitude correction compressor'?

 

 

Presumably this is a fuel pressure regulator? I'm going to run a motorbike pump or a pump and regulator near the tank so I want to remove this. Why is it attached to the block? Can I just blank it off? Also I know I'm going to sort that copper pipe!

 

I'm going to remove the carb, Inlet and exhaust manifold, is the thermostat attached to that setup and hence why you have to drain the coolant first? Can I block the pipes that come from the thermostat apart from the one to the rad obviously? Sorry, this is the most amature question!

 

Finally, van I remove the smog pump with the rad still in place?

 

Thanks,

Frank

Edited April 18, 2019 by frank88

[metalmonkey47]

9 hours ago, frank88 said:

Presumably this is a fuel pressure regulator? I'm going to run a motorbike pump or a pump and regulator near the tank so I want to remove this. Why is it attached to the block? Can I just blank it off? Also I know I'm going to sort that copper pipe!

 

 

I'm going to remove the carb, Inlet and exhaust manifold, is the thermostat attached to that setup and hence why you have to drain the coolant first? Can I block the pipes that come from the thermostat apart from the one to the rad obviously? Sorry, this is the most amature question!

 

Cannot believe no one has responded to this yet. 

That 'thing' on the side of the cylinder head that you call a regulator is a mechanical fuel pump. If you're installing an aftermarket electronic pump and regulator you can remove that pump but you'll need to make a block off plate.

 

Also, if you're removing the carb and intake manifold you might as well go ahead and drain the radiator of coolant at that point. The thermostat housing is not part of the intake manifold assembly BUT if I recall properly, the intake manifold on your '74 is watercooled and will have ports on the cylinder head for coolant. You'll be loosing coolant either way.

[Stoffregen Motorsports]

Can of worms time...

 

While you're in there, you may as well remove the thermostat housing from the head take it apart, clean it up and reinstall it with a new thermostat. I know, don't fix what ain't broke, but it is right there. Just try not to break the bolts holding it to the head and the bolts holding the outlet to the t-stat housing. If they don't come free right away, hit it with some heat and penetrating oil. While it is off the motor, take this time to plug any un-used holes with pipe plugs.

 

Same goes for the water inlet under the fuel pump. If you're deleting the water pipes (nice copper pipe by the way...), you may as well remove the inlet, clean it and seal up the outlet that you're not using anymore. You can do this with a small pipe tap and tapered plug, or with JB weld, or...if you know someone with a TIG welder, have it welded shut.

[datzenmike]

You want to preserve the by pass hose/copper pipe from the thermostat housing down to the lower rad hose inlet to the timing cover. Even if you close off the Y to the intake. The thermostat housing is on the side of the head and needs the small flow of coolant past it so the thermostat can sample the hot water inside the engine. Without the by pass the engine can over heat while the thermostat is bathed in cooler stagnant water. Definitely get rid of the copper pipe and just use a suitable hose.

 

That is not an L series fuel pump. They are at least twice the size and this one may not be capable of proper delivery to the R-1 carbs. An electric should be around 3 PSI.

 

The altitude compensator would be in the air filter housing and only on California models or higher altitude states.

 

 

This looks like (but not sure) the fuel shut off. This is used to open the circuit to the idle cut solenoid which will shut off fuel to the idle circuit during high RPM deceleration. During deceleration the idle fuel would simply be sucked out the exhaust. This would save gas even. High intake vacuum turns it on and when lower speeds and vacuum returns it turns off allowing normal idle. '78 California models had this and ALL 620s had it in '79.

[banzai510(hainz)]

this is me.

On the stat housing and cover you got to be careful. I seen alot of bolts break, I would find soem spares while your at it. I persoanlly would not revove the housing from the head. The stat cover most likely is rusted in there also. but be nice to put a new stat in there.

I have cracked 2 since owning Datsuns most time taking the sender out.  I just get spares or new housings when possible

[datzenmike]

This.

 

If not leaking, leave it. I had a broken rear bolt, and you know the long front one in the housing that corrodes solid and snaps off? I had to cut into the housing with an angle grinder to get if off. Replaced the housing with a spare and lots of anti seize on the bolts.

 

 

[frank88]

1 hour ago, metalmonkey47 said:

 

Cannot believe no one has responded to this yet.

This is why I love Ratsun, outrage that no one has responded in 10 hours despite the time difference 😂😂

 

Thanks for all the help guys.

 

So moving forward, I'm going to remove the fuel pump and sort out a blank.

 

Bit confused about what to leave or delete in terms of coolant hoses but I'll get some better pics and sort that out in this thread later.

 

I'll try and get a spare thermostat but in the meantime I'll leave as is for now.

 

Mike, mine is a cali model but a 74. Was searching through my manual for that bit and the altitude thing was the closest I could get but didn't look right. Either way it's now gone!

[datzenmike]

1 hour ago, frank88 said:

This is why I love Ratsun, outrage that no one has responded in 10 hours despite the time difference 😂😂

 

 

 

Yeah, it was 1:30 my time when you posted and I was up past 10 the night before and slept in till 8? Usually on line by 5:20 but try to read and respond. MM is on the east coast so 2-3 hours ahead of me. We were all sleepin' in...

[frank88]

Right, I've gotten a bit further. Is this manifold of any use? One of the studs in that cover plate has sheared which is annoying. If not, what are my options?

 

https://imgur.com/gallery/KQYVyP1

 

Also, any tips on getting the three nut off to free the bottom of the manifold from the exhaust?

[Rat-a-tat-Dat]

Nothing wrong with the manifold, it's OEM and works. If removing any emission control apparatus then you can remove the tube assembly and plug all four holes, plus the one attached to the large outlet end.

 

If you have access to a welder, you can place a nut over the broken stud and weld it in place. Once cooled, remove it like any bolt. Be sure to use plenty of penetrant and take your time. You may need to heat the manifold a couple of times if it resists.

[banzai510(hainz)]

PB Blaster. or acetone mix with auto trans fluid. soak the bolts and use antiseize next time.

 

be honest if you don't have to break them loose ,dont

[frank88]

Couple more questions, how do I go about plugging the coolant holes in the head and what is the big tube and can i/how do I plug it?

 

Also is there a good trick for getting the studs out of the manifold where it attaches to the downpipe?

 

Thanks

[Stoffregen Motorsports]

Heat and WD40.

 

Heat it with a torch. Not overly hot, but maybe a couple hundred degrees. Enough so that when you squirt the ,metal with the WD40, it smokes like hell. After you've soaked the studs, try right away to break them free. If they don't budge, squirt them down good and walk away until it cools down, then try to remove them.

 

Hitting the manifold around the stud with a hammer may also help to loosen them up.

 

If they break...not the end of the world. Sucks, yeah, but nothing a grinder, centerpunch, drill and tap won't fix.

[Crashtd420]

2 hours ago, frank88 said:

Couple more questions, how do I go about plugging the coolant holes in the head and what is the big tube and can i/how do I plug it?

 

Also is there a good trick for getting the studs out of the manifold where it attaches to the downpipe?

 

Thanks

 

Dont plug the big tube, that's your crank case breather ... it should be connected to you intake with a PVC valve .....

But I just looked back and saw the mention of r1 carbs so just put a breather filter on it....

 

I think the best way to plug the coolant holes Is to drill and tap it for an npt plug, not sure what size the coolant holes are... measure and use the closest size plug.... 

[banzai510(hainz)]

use 1/4inch pipe plugs.They are not really a 1/4 inch its the tool. But I think if you can find a 1/4 plug its tapered to find what a 1/4 inch plug uses for a thread tool.  I had a drill and tap kit. but my head I had drill to a 1/4 size holt to run a water line as I went to stock intake but the head was orginal had not holes as it was a Japan spec head.

 

your head is already the stock large hole so maybe a drill size might not be need but just the tap.

 

Use a shorter tap as a long one will hit the other side.

Youl have to do this a few times till you get the plug to fit flush.if too tight then reuse the tap till the plug get tight when its flush to be perfect

 

https://www.fairburyfastener.com/xdims_plug_pressure.htm

 

https://www.grainger.com/product/5RLG0?cm_mmc=PPC:+MSN+PLA&s_kwcid=AL!2966!10!8973609678!1102900016376&ef_id=XJ1JqQAAAHnaTjrH:20190425231607:s

Edited April 25, 2019 by banzai510(hainz)

[datzenmike]

4 hours ago, frank88 said:

Couple more questions, how do I go about plugging the coolant holes in the head and what is the big tube and can i/how do I plug it?

 

 

 

The intake and gasket will seal over the coolant holes so don't even bother to close them off. If you are going to use the coolant intake keep these open and use it.

 

Never plug the block vent. Keep it connected to the PCV valve system. It keeps your oil and inside the engine cleaner longer. 

 

Try loosening after running the engine when they are hot. They get very hot so they will rust (oxidize) much faster than anything else. Chances are good that they will snap off. Once the exhaust is off it's easy enough to work on. If there is a nub sticking up, heat around it till the manifold is orange and it will twist out with vice grips. Replace with stainless studs and nuts and coat with anti-seize.

[Stoffregen Motorsports]

I like to plug the holes even when using a non-stock manifold. Having them plugged makes it easier to remove the intake for maintenance, mods, etc.

[frank88]

Cheers for all the input guys, really appreciated.

 

So the coolant holes are 11.6mm so I'm going to drill to 11.8mm and tap it to 1/4 BSP and fit a plug. I like the idea of it being done so no leaks.

 

As in fitting the r1 carbs, and mine was a cali model I'm ditching all emissions stuff for better or worse so going to get a catch can for the block and cam cover breathes. Shame the block vent is so huge 

[Stoffregen Motorsports]

BSPT plugs with the taper, right?

 

There used to be a brass plug that tapped into place, but I haven't seen those in years.

[frank88]

Ah no I wasnt going to use the tapered ones. Should I? They require a smaller than 11.6mm pilot so I'd be looking at drilling it out to over 12.5mm for the next size up.

 

I was planning on running the tap in so far and trying the plug just until its flush/just past flush. Then use ptfe tape or lsx gel when I put it in. It's only hot water after all so plumbing stuff should be fine right!?

[Crashtd420]

I think either would work but I believe the taper one does seal better.

I think you would be fine taping the existing hole without drilling for a the 1/4 bspt.... you are only talking .4mm which is only .015 bigger.... with the bspt being tapered that shouldn't matter....

[wayno]

I don't think it was mentioned yet, but that is a 1978/79 W58 head(smog head), don't know for sure but I think that is a U67 exhaust manifold that had the intake connected to it so the coolant passages in the head were not even functioning, you have a mix-match of parts there, several different years, it's kinda hard for you to figure out what is going on unless you know you engines.

Is that exhaust manifold where that plate is going to get in the way of the R1 carbs, if that plate is close or in the way I would try to find an early L16 exhaust manifold with or without the smog stuff if possible.

The plus is you have a w58 head(open/closed chamber??) which has the large intake ports and large valves, the U67 head is the same but is open chamber, but it doesn't have them coolant holes unless someone drilled them, and it has square exhaust ports???

 

[datzenmike]

First of all you don't need to plug those coolant lines. The exhaust manifold in the picture is from a U67 head L20B. These are co-joined intake and exhaust and do not use the coolant holes. Yours doesn't and it never leaked and won't leak. The non coolant intake will block it off and the gasket seal it. Don't waste your time drilling and tapping. 

 

Second this is an L20B engine and the '74 620 used an L18 so it's been swapped.

 

Third. That is definitely a round exhaust port W58 head from a '78-'80 L20B. Maybe entire engine is a '78 or newer.

 

 Forth. Here's my home made R-1 intake. It's 1/2" thick so it's the same height as the exhaust flange and the bolts will clamp properly. No coolant hole. 

 

[frank88]

Def a W58 head yea.

 

Interesting info. So okay I'll concede, I dont need to plug the holes!

 

I would love a simple l16/18 non smog manifold but I certainly wont be finding one here in the UK so just going to bolt the plate on and use the one I have.

 

Am I the only one that finds it odd that the intake is held on with two bolts on top and none underneath!?

[wayno]

My point was that the U67 exhaust manifold has a square port exhaust, but your W58 head is a round port exhaust, that exhaust manifold was never meant or made to be on the head, it will likely have exhaust leaks at the head/manifold area as either the head or the manifold don't match the gasket, I don't remember for sure which gasket should be used, but square port type gasket I think, I believe the round port gasket will leak the moment the engine is started.