New to me L20b + Dual Mikunis + Racer Brown Cam

[d.p]

I recently bought an L20b, U60 head with a racer brown cam, (ss-54 110), dual Mikuni 40s, pertronix dizzy and other aftermarket internals (valve spring retainers not sure what else).   Engine came out of a 510 but I believe it was originally out of a 74 610 based on the straight vent pipe.   I know nothing about the PO or what they did or didn't do to it.  The guy I bought it from swapped an S2000 motor into the 510 any didn't have any knowledge of it either.   

 

Pressure plate and clutch have seen better days so I am going to replace those and whatever else I need to do.  I would like to freshen up this engine before I drop it into my 521 but not exactly sure on what to do.  The head has been shaved and measures just under 4" so I am not sure it can be taken down anymore.  Crank pulley has a ton of notches on it and the block only has the single pointer on the alternator side, nothing on the drivers side (sawtooth supposed to be there?).  At TDC#1 it lines up with a notch on the pulley so I marked that and now trying to figure out what to do next besides take the head off.  If it were a stock block with stock internals thats one thing, but it isn't so not sure how to proceed.  

 

 

 

 

 

 

Edited July 17, 2019 by d.p

[datzenmike]

4 hours ago, d.p said:

   If it were a stock block with stock internals thats one thing, but it isn't so not sure how to proceed.  

 

Same thing as a stock engine. Cam lobes may be higher, maybe different lash pads and springs/retainers  but go together same as stock. Cam and crank sprockets and chain and guides and oiling is the same. Head bolts on exactly the same and are stock L series not studs. A head gasket is a head gasket. May have forged pistons but pistons are pistons. My have longer or shorter rods but rods are rods. Bearings are all the same and so is the crank and all bolt on the same. The point is some things may be changed but they go on exactly the same.

 

 

SS 54 110 looks like 0.480" lift and 236 degrees duration which I assume is measured at 0.050" lift as the stock L20B cam is 248 degrees duration and probably isn't. Stock L20B lift is 0.413" 

[Stoffregen Motorsports]

If you're serious about doing this freshen up yourself, there are a few tools you should have:

 

-  dial indicator on a vise grip base (also known as a brake rotor runout gauge) for checking cam timing, TDC and crank thrust end play

-  piston ring compressor and dead-blow hammer for installing pistons into the block

-  dial bore gauge for measuring the cylinders and the rod and main bearing bores

-  various micrometers for measuring crank journals and pistons

-  straight edge for checking head and block surfaces

- heavy sanding block and emery paper for cleaning those surfaces

- valve spring compressor

 

Mostly, just pay attention to the disassembly. Check the cam timing before you remove it so you know a ballpark of where to put it back. Don't throw anything away, including the head gasket, rings, bearings, etc until the engine is built. There can be telltale signs in all of those parts as to how the engine was treated, and you can also use them as an ordering guide for new parts. Also, check the wipe pattern on the rockers before disassembly. This will help you set the lash pad thickness in the event that you have the valves done.

 

Of course, this all assumes that the engine was properly built in the first place.

 

A machine shop can do all the measuring for you on the crank and block, but I would still invest the $100 in a brake rotor runout gauge and learn how to set the cam timing using the split overlap method. Google it. It's way easier than using a degree wheel.

 

[Stoffregen Motorsports]

Also, depending on what pistons are in there, you may need to fit and file the rings. A cheap ring grinder can be purchased anywhere that sells engine supplies.

 

You'll also need feeler gauges and a good torque wrench, but I'm sure you already knew that.

 

BTW- from what I could see of your pics, it looks like the head bolts are the good ones, so if they are in good shape, re-use them. If the head has been cut, sometimes the head bolts bottom out in the block, so pay attention to the head bolt washers. If there are more than one on any bolt, it's because the head has been cut and be sure to put them back in the same spot upon reassembly.

Edited July 19, 2019 by Stoffregen Motorsports

[banzai510(hainz)]

I say

Pressure wash and install the distributor correct and put the carbs on and yourll rolling in 1or 2 days  DONE!!!!!!!!!!!!!!!!!!

[john510]

I agree with Hainz.Clean it up and run it before tearing it apart.With those upgraded parts chances are whoever built that motor did a decent job.

[Stoffregen Motorsports]

It looks pretty old, like maybe from the 90's. Those aluminum spring retainers were very common back then.

[d.p]

No idea how long since it's been touched and I don't want to drop it in without knowing what is inside it.  I was wondering where those spring retainers were from?  Head has been cut and I would be surprised if there isn't aftermarket pistons in it.  Meaning why would they go through all that trouble with the head and not do anything to the bottom end?  At the very least the head is going to come off and the carbs are going to get rebuilt.  There is some question about what or where the dizzy came from as well.  

 

You can see here its been cut to allow for more advance I guess?  It was advanced all the way when I took it off.  

 

 

 

[wayno]

I suspect the plate was cut because they didn't want to take the time to drop the oil pump to re-clock the distributor drive and set it up properly.

I also believe that the U60 head was shaved that far to up the compression because it has stock dished pistons, if it had aftermarket pistons it would not have needed to be shaved as they would have bought the pistons to match the head, not shave the head to match the pistons, but I am just guessing.

 

[d.p]

Just now, wayno said:

I suspect the plate was cut because they didn't want to take the time to drop the oil pump to re-clock the distributor drive and set it up properly.

I also believe that the U60 head was shaved that far to up the compression because it has stock dished pistons, if it had aftermarket pistons it would not have needed to be shaved as they would have bought the pistons to match the head, not shave the head to match the pistons, but I am just guessing.

 

 

Maybe but it really doesn't take long to drop the spindle and turn it but who really knows.

 

 Did you see my most recent measurement?  I didn't ZERO out my caliper the first time so the head is really 4.217" vs the 3.9" I had thought. 

 

[datzenmike]

This is the problem with two posts about the same thing. Someone on one has question already discussed and answered on the other. There's a good chance of duplication of effort.

 

Would you like the other post merged into this one?

[wayno]

Yes I seen the measurement, I don't get that deep into my builds, I have never measured a head in my life, I have never seen the need to, a head is a head, what counts to me is what head it is, a 219 head is closed chamber with big 1.5" intake ports and large valves, a U67 head(U60 is the same) is an open chamber head with big intake ports and large valves, the W53 head is usually a closed chamber head although I have an open chamber one, they have medium valves and small intake ports, the A87 head is either open or closed with small or large intakes depending on the head as a few A87 heads have a 219 on the front of the head, this is all I need to know, if I plan on buying a head I look to see if any of the head designation letter/number has been shaved off, if it has I do not buy the head.

I have had a few W53 closed chamber heads made into a 219 race head, I do this because I want it to breath on the freeway using a stock cam with my dual SUs, I use stock cams because I want my engines to have torque/grunt, hot cams do not have grunt as they sacrifice grunt for more HP, I don't drive around above 4000rpms so I see no need for a hot cam, my trucks go plenty fast, I broke my Datsun 521 speedo needle off breaking in my LZ23, I took it up to 6000rpms once and then let off, when I looked at the speedo the needle was gone.

 

Edited July 20, 2019 by wayno

[john510]

2 hours ago, d.p said:

No idea how long since it's been touched and I don't want to drop it in without knowing what is inside it.  I was wondering where those spring retainers were from?  Head has been cut and I would be surprised if there isn't aftermarket pistons in it.  Meaning why would they go through all that trouble with the head and not do anything to the bottom end?  At the very least the head is going to come off and the carbs are going to get rebuilt.  There is some question about what or where the dizzy came from as well.  

 

You can see here its been cut to allow for more advance I guess?  It was advanced all the way when I took it off.  

 

 

 

An L series bottom end is pretty tough stock.Not really necessary to do anything unless it's a full on race engine.

[banzai510(hainz)]

Most bottom ends are stock.Its the head cam carbs that make the HP. these in my opinion. well on pump gas

[Stoffregen Motorsports]

20 hours ago, wayno said:

I have never measured a head in my life, I have never seen the need to,  if I plan on buying a head I look to see if any of the head designation letter/number has been shaved off, if it has I do not buy the head.

 

 

This subject has been shrouded in mystery for decades. Casting shift over years of production can cause the casting number location to move slightly. Some factory stock heads have a third of the digits cut off. You should always measure a head (if you are looking to buy) because of this. Just because the numbers look cut, doesn't mean the head has been.

[Stoffregen Motorsports]

22 hours ago, d.p said:

No idea how long since it's been touched and I don't want to drop it in without knowing what is inside it.  I was wondering where those spring retainers were from?  Head has been cut and I would be surprised if there isn't aftermarket pistons in it.  Meaning why would they go through all that trouble with the head and not do anything to the bottom end?  At the very least the head is going to come off and the carbs are going.  to get rebuiltThere is some question about what or where the dizzy came from as well.  

 

You can see here its been cut to allow for more advance I guess?  It was advanced all the way when I took it off.  

 

 

 

It's likely the distributor stand and plate don't match and they cut the slot to get the phasing back to stock. Someone other than the engine builder probably did this.

 

Your game plan is good. Take the head off and have a look. At the very least, have a valve job done, replace the stem seals and maybe the springs (or have them checked). You can tell a lot about the bottom end by inspecting the bores. If you see any sign of scratching in the bores, the rings are likely trashed or broken. If the scratches are deep enough, boring the block to the next piston size may be the only way to get the scratches out...but we're getting ahead of ourselves here.

[Stoffregen Motorsports]

20 hours ago, datzenmike said:

This is the problem with two posts about the same thing. Someone on one has question already discussed and answered on the other. There's a good chance of duplication of effort.

 

Would you like the other post merged into this one?

Yeah, I didn't even realize he had another post going on this topic.

[d.p]

Yeah that other topic is my truck thread.  I figure the overlap a little but no big deal.  Ill try to keep all the technical shit on this engine in this thread alone.  

 

Like you said Stoffgren no harm in taking the head off to see whats doing.  Its like christmas present, could go either way! 

 

I could also see carbon build up on the valve stems looking through the intake and exhaust ports so I would like to get that cleaned up.  Are some valve stem seals better than others?  with my current head I used the ones that came with the Felrpo gasket kit but no idea if they were/are any good.   I figure remove the head, get a look at the bottom end and then go from there. 

 

My "How to rebuild Datsun and Nissan OHC engines" book showed up today so I figure I get some light reading in before bed tonight.   

 

 

[Stoffregen Motorsports]

That book still has a lot of valuable information, even 30 years later.

 

The OEM black rubber stem seals seal the best, and they are very similar to what normally comes in the box gasket sets. They seal well. They do get hard and crack eventually, but we're talking a decade or more here.

[d.p]

Took the head off and this is what I got..there was anti-sieze on the head bolts and everything came apart super easy.  A lot easier than my L16 at least.    Appreciate any input as to what is doing with the block and what not.  

 

Head gasket was completely gone around the front of the TC, what would cause that?   

 

 

 

 

 

 

 

Block:

 

 

 

 

 

 

 

[wayno]

Looks like a stock L block with dished pistons to me, the head looks like an open chamber U67(U60), nothing special there either, I can see why they shaved the head, to get the compression up.

The front of the head gasket may have been removed to install the front cover without having to remove the oil pan or head and then they just squeezed a lot of gasket maker in between.

There appears to have been lot of short cuts taken on this engine, shaving the head, no gasket between the timing cover and head, cut distributor bracket instead of dropping the oil pump and timing the distributor properly, maybe the wrong distributor or wrong pedestal for that distributor, you called it, tearing it down was likely the right decision.

 

[Stoffregen Motorsports]

I see a "100" stamped in the pistons, probably .040" over. The valves don't look sunk into the valve seats, so you're probably good there. Bores look good from the pics. Can you feel any scratches with your fingernail?

[d.p]

Yeah no biggie for me take the head off, like I said my engine is fine in my truck so I am in no rush to drop this one in.   I figure I can take my time with it, clean it up, fix what needs to be fixed then have it ready to drop in whenever that will be. 

 

They are stamped "100" and I couldn't feel anything with my nail when I was looking yesterday.  Will double check today.  At this point should I be looking to do anything to the block?  I am going to drop the head off to get cleaned up and valve job if needed.   Also going to have the Mikunis rebuilt and cleaned up, but other than that not sure what else to do?  

Edited July 26, 2019 by d.p

[banzai510(hainz)]

YOu got to many threads going on this as I just responded to the last one.

 

I hope you taking it to the right guy to do the head. One needs to put the valves rockers out and put back from where they come from. be honest I don't trust some of these guys. Lash pads could be different size ect….. Before you know it your 800$ into a motor that MAYBE needed a  60$ headgasket.

 

get some carb cleaner and toothbrush and clean it up and ROLL IT!!!!!!!!!!!!!

 

 

Carbs rebuilt means they replace the needle valve and accel pump and just the gaskets. If carbs are not dirty then they most likely are OK.as the gaskets are not leaking.  Then you have to set set up everything to get the synce and idle right. Just bolt the fuckers On your truck and youll figure it out if they good or bad in one day.