Yet Another 'Building an L28' Thread

[DOOM]

I’m hoping to make a mild street L28 with an N42/N42 head and block combination taking advantage of the 400cc for a wider powerband with added torque. Also trying to keep parts costs down using as many stock parts as possible and assembling it myself. Using flattop pistons instead of the dished ones to up the comp ratio, as the block has minimal bore wear they will remain 86mm, bores receiving a hone. However the block deck does require a shave creating an issue of keeping the dynamic compression ratio (DCR) and static compression ratio (SCR) within usable street ratios along with quench distance. Playing around with various engine calculators (AtlanticZ, OZDat and Wallace Racing DCR calculator) I found the 2.0mm Kameari headgasket (90.5mm bore) will help keep compression manageable, 9.1 SCR and 7.9 DCR respectively on a stock block deck height, but the deck needs to shaved. I am not certain how much the block deck will need to be shaved; estimating a 0.5mm shave this increases both compression ratios and lowers the quench distance by removing deck height. So should invest in a cam with a later intake close (to lower DCR (a mild kit from here: http://www.thezstore.com/page/TZS/PROD/classic12e03/10-2000 )) or is there another way around this? I’ve read of others using the same combination with good success staying away from detonation.

 

I’d be looking to get machining done at Chris Milton engines in SA. Also the engine had not been opened before, still retaining standard main journal and crank pin journal bearings. The crank journals were in as new condition. A head bolt did snap off due being rusted in the deck, with serious rust build up around it necessitating the head shave. For fuel delivery I’m aiming to use triple Webers/Minkunis/Solexes. This is my first engine build, yes this is my second topic in a week. Use engine building terminology if I don’t understand it I’ll google it. I own ‘How to Modify’ and ‘How to Rebuild’ by Honsowetz and Monroe. Any tips/help is appreciated a lot.

 

[d3c0y]

I personally think you are getting wound up over nothing, 9:1 isn't that high even on a street car. My engine runs 11:1 on pump 98, albeit with a big cam.

 

 

Sounds to me like you are just rebuilding a stock L28 rather than doing an engine 'build'. Put a big cam in it just for the reason it makes more HP.

[Riceburner]

You should be able to assemble it by yourself using those books, I did with my L28 with tips from PMC. Just make sure you get everything balanced together, go with a genuine Nissan head gasket and use ARP head studs.

[DOOM]

Alright big cam and flattops it is.

[Zedman240®]

I'd be buying the valvetrain hardware that PMC swear by.. You haven't really said anything about valve gear in your post but I'd be asking even more questions about whats the best to use nad what works.

[gav240z]

Hey Doom, good timing I am in the middle of an engine tear down and now trying to decide on what path to take with my build. I want to do as much of the build myself as possible.

 

I'm looking to build a stroker so use LD28 crank, L14 or L24 rods (depends on piston choices I have available), Triple Mikuni's, N42 head (F54 block cause that is what I have, will probably go to 89mm on the bore but not going to push it to have 0.1 of a litre more capacity) and valve train wise I still don't know what to use yet.

 

I heard bad things about Schneider cams when I posted the cam shaft kit I had on here a while ago, but James Flett said he's used them without issue. So just goes to show everyone has their own choices and preferences when it comes to these things.

 

From what I've learnt and read over the years, selection of the correct camshaft and engine head work is critical to getting the right performance from your motor for it's application.

 

In particular it's not the size of the ports, but their shape, most gains seem to be found around the underside of the valves (the angles here) and the seat area. Also I think on the L-series heads the valve stem area is also quite an impediment to flow so re-shaping that area can help reduce unwanted turbulence.

 

A couple of articles I read last night were talking about looking at the head's CFM and matching a camshaft to suit, it really is about experimenting with what works and doesn't on a dyno I think.

 

I didn't have too much issue getting my motor apart - I really thought the stuck piston was going to give me grief but everything came apart relatively easily and no broken bolts or rusted ones thankfully.

 

 

[DOOM]

I'm going to stay away from stroker's, too much money no denying the power. So really I should be paying attention to valve train, I've been reading up a lot on these engines and I have been told that the power is in the head. I might stay away from any head porting/reshaping to keep costs down (and P plates). Is it true that I need to replace rocker arms when changing cams? Zedman what are the parts PMC swears by?

[dazzed]

I think you forgot something vital??/ oil pick up ??/

front  sump or rear

[DOOM]

No I haven't forgotten, I just can't bloody get a front sump.

[dazzed]

No I haven't forgotten, I just can't bloody get a front sump.

yeas there a bit rare but if you are doing a full rebuild just drill the block for the front sump pickup and block of the other one, you will have to remove the oil gallery plus to remove any swarf and is wise to do regardless

[DOOM]

yeas there a bit rare but if you are doing a full rebuild just drill the block for the front sump pickup and block of the other one, you will have to remove the oil gallery plus to remove any swarf and is wise to do regardless

 

I'm sorry but what does 'remove the gallery' exactly mean? I know what one is, but where is the one that needs to be removed in relation to the new dipstick and pickup location? Do I need to fill it up, or block off? Obviously there is more work than a simple sump swap and oil pickup extension.

[PB260Z]

I'm sorry but what does 'remove the gallery' exactly mean? I know what one is, but where is the one that needs to be removed in relation to the new dipstick and pickup location? Do I need to fill it up, or block off? Obviously there is more work than a simple sump swap and oil pickup extension.

 

The reference is to removing the oil gallery plugs (typed as plus in the post) once these are removed you can flush the oil gallery (or internally cast oil passage).

 

https://www.google.com.au/#q=oil+galley+plug

 

Cheers

[DOOM]

The reference is to removing the oil gallery plugs (typed as plus in the post) once these are removed you can flush the oil gallery (or internally cast oil passage).

 

https://www.google.com.au/#q=oil+galley+plug

 

Cheers

 

Sorry now I get it, I thought dazzed meant I had to remove a whole section of oil gallery.

[PB260Z]

Sorry now I get it, I thought dazzed meant I had to remove a whole section of oil gallery.

 

Yeah, I thought as much. Always better to ask the question than make a mistake 

[1600dave]

Oil gallery plugs are located as in the pics below, standard they are just a solid plug bashed into the block. Drill them out carefully, then tap the existing hole with a tap to suit a tapered, threaded plug (I can't remember if I used BSP or NPT plugs, would have to look at the taps). Careful with the one in the front of the block, there is an oilway intersecting the main oil gallery just inside, you don't want the plug to block this or your #1 bearing won't be happy. I had to turn the plug down in length to get it to clear.

 

I run 10.4 compression in my L-series without dramas on 98 fuel.

 

 

 

 

 

 

[dat2kman]

Do what Dave1600 did.

You are way overthinking your comp ratios.

Yes flat tops, longer 133 mm rods, a low cost piston look at Isuzu G200 units, and machine top off to suit final deck height.

Use regular type head gasket, no need for MLS or big bore /oversize type gasket,

 

If you want to chase higher comp on a n42 head, either a heavy shave ( 2-3 mm) and fit the twin gear timing chain tensioner setup,

Or, weld it up,.

 

Yes the PMC /Les sourced upper head stuff is better than the rest out there, and fairly easy to get.

[dazzed]

I'm sorry but what does 'remove the gallery' exactly mean? I know what one is, but where is the one that needs to be removed in relation to the new dipstick and pickup location? Do I need to fill it up, or block off? Obviously there is more work than a simple sump swap and oil pickup extension.

  my mistake apologies didnt do a spell check, redrilling the block also requires redrilling a hole straight through the oil gallery at the front of the block but dosnt restrict oil flow to the mains, drilling has to be precise an accurate, just measure off your front sump L24 motor for a guide

 

[gav240z]

Sorry guys but why are we blocking off this orifice? Or are we just using a threaded screw for easier removal later than the stock plug?

 

Since it is related any tips for removing the freeze / welsh / coolant plugs? I have tried a hammer and punch but I think mine are rusted in nicely. So thinking of drilling a hole then inserting a slide hammer to pull them out? Just want to be careful not to damage cylinder bores on other side.

[Enzo]

Hi Gav,

          Just started pulling down my L28 yesterday. The factory welch plugs have a sealant on them. Use your hammer and punch or a screw driver and hit on one side in the recess. The plug is tight so hit a few times if needed. When it starts to turn use pliers or just lever it out.

David

[gav240z]

Thanks mate, yeah I started to do that but the punch just started to go through the plug (as in a hole in it) as oppose to push it to 1 side. Will give it some thought.

[1600dave]

Sorry guys but why are we blocking off this orifice?

 

Its a hangover from the manufacturing process - they drill right through the block and then just blank off the ends with soft, bashed in interference fit plugs. There's quite a few oil galleries in the motor likes this (ie the head has a similar one from front to back, and one coming in from the side).

 

I drilled the old plugs out so I could clean the oil galleries right out (I used long, thin bottle brush types cleaners, have heard of people using rifle cleaners) to make sure it was free of 40 years of sludge, plus the engine I rebuilt had scored bearings and cam, indicating the possibility of loose bits of metal / grit being in the engine. Without removing these plugs, you cant get in to clean the galleries thoroughly.

 

Tapping and using a removable tapered plug is just one way to block the galleries again and is easily removed and replaced if / when  the engine gets its next rebuild. I have them all through my engine, including the crank.

[1600dave]

For stubborn welsh plugs, I use a very large diameter punch - something like a big-ish bolt (cut the thread off, leaving just the plain shank) and hit on the edge of the lip of the welsh plug. Once it starts to spin, its easy to remove.

 

The large diameter is so you don't risk scratching the block like you may if you use a standard, small diameter punch, potentially causing a spot that may leak. Not likely, but better to be safe than sorry.

[gav240z]

Awesome info Dave, I had scored bottom end bearings (scratch lines in them) so something foreign / contaminated oil was running through the motor. So I'll need to clean everything out as suggested. I'll let Doom have his thread back lol..

[dat2kman]

Not all the oil passes through a filter, the blocks run a bypass, so yes, any crud left in after a rebuild, or other bits of "stuff" will eventually find its way between two bits of metal bearings, or, block a oil feed hole.

 

Now, re drill and tapping the main oil gallery, take carefull note of the very small oil feed hole right at the end of the large gallery.

Do not screw a full size plug in, to be flush with the block end face, as this will block THAT oil feed hole.

Modify the screw in plug, file a bit off each side, you dont need a full depth Allen wrench hole.

 

The next oil feed hole, is the one on top of block, this needs drilling out as it feeds oil up into head.

Combined with the L28T high vol pump, this ensures more oil up top.

[ZED83]

Hay Gav this is what you'll need to do to your block if you are thinking about building a stroker with the LD-28 crank you have. This gives reasurance the oil gallery plugs won't be pushed out under higher oil pressures. The other one you wan't to tap is the oil filter bypass ball bearing for the reason you don't loose oil pressure. So pull it out an put tap in there to.