l20b build

[spdcrazy]

I apologize for posting what i'm sure is overlapping on many other threads, but there is just to many variables for me to figure out what I need/want to go with. I have an.... assortment.... of engine parts, just trying to find the best combo of them for my desires. It'll be going back in my 521 with a 5spd and factory 4.375 gears. I want a daily driver truck with compression around 9.5 or so max. keep in mind this truck is in Denver, mile high city. plan on using my 32/36 for the moment

 

my parts list includes

 

L20b block with unk bore, and unk knocky knocky inside,

l20b block freshly rebuilt, pistons stamped .75, also these pistons are slightly dished, not flat

A87 head (unk if open or closed at this time)

associated cam for that head, has a stamp of 3 on it if that helps

w58 or 53 head (has the emission sleeves in the ports)

associated cam for that head. has a stamp of 5 (iirc)

matchbox dizzy

cast exhaust with split at the flange

 

 

I think the plan is to have the a87 head port matched for the exh and intake,

44mm 280z intake valves

then installed on the L20b block

 

questions are

 

l20b block with pistons stamped .75 means what for my overall bore?

 

I was told the cam in the w53 or 58 is a factory l20b cam, and therefore is more desirable in the a87 head as it wasn't a l20b head, is this correct and why?

 

Any way to calc compression with my couple of options as listed here? if so, teach me your calcs so I can do this on my own later?

 

anything else I should be looking into without getting crazy on the fiances? this was not an intentional engine build, just happened to let go at a time I wasn't piss poor for once!

 

thanks for the input in advance

[Doctor510]

questions are

 

l20b block with pistons stamped .75 means what for my overall bore?

 

Means that it has been bored +0.030"

[spdcrazy]

And the doc comes to the rescue again!

 

What's your thoughts on the compression expected if I continue with it?

[datzenmike]

If boring the block the machinist will measure them and bore accordingly.

 

Stock L20B with open chamber head is 8.4 compression. Closed chamber head... 8.9

A 1mm bore increase is 8.55 and 9.06 so... slightly under these.

 

L20B cams have two square bumps across from each other between cylinders 2 and 3.

[banzai510(hainz)]

I woould get a real cam in there if your going to do all this work on this head. Or do a spare head and bolt on later than worry about a L20b cam

 

I think youll notice more power just by bolting on a 38/38 Weber than a L20b Cam

[spdcrazy]

All of this makes sense. But for now, with what I have, is it worth swapping the L20 came into the a87? Is it really a better cam? (Yes I plan to change up carbing and such at a later time

[banzai510(hainz)]

if the cam comes with the same exact rocker arms from the same spot. then maybe

 

Personally if both heads are together why part them out to get 1 working when you have 2 good heads already. extra work for a extra .020 lift if  that

 

 

if L20 head just bolt the hole head on there and you have the cam and the L20 usually has bigger intake ports anyways(1.375 I think)

 

. Thats compression shit is overrated.. Between my L16 and L18 I never could tell the difference. You are starting out already better than me with a L20.   Most different I ever felt was bolting a 38/38 on my L motor or a Twin sidedraft set up.

 

bore out to the next avail size if the bore is BAD , If not bad just rering it.  Then make sure they have pistons for that size.

 

 

 

I do prefer a closed chamber head . Esp if running a dwon draft as open heads will have run on. Might not with a sidedraft set up.

 

 

this is all just my opinion

[datzenmike]

Pretty sure the A87 has the same L20B cam in them. Look on middle of camshaft for a square bump on each side. Probably has U60 cast into it also.

 

L20B cam has 0.413 lift. L16's are 0.390 - ISH?

[flatcat19]

Why try to make a better mousetrap if the current one works?

 

 

See if either your W58 or A87 are closed chamber.

Then see if it/they are flat.

 

Put em together, run it.

 

 

Of the combinations you have there is nothing crazy that's going to create a large enough difference to put too much thought into it.

[spdcrazy]

I don't think my a87 has the square bumps on it. my w58 however does. no reason to not swap them out and still have two usable heads tho correct? giving me the best of my avail options?

[flatcat19]

I don't think my a87 has the square bumps on it. my w58 however does. no reason to not swap them out and still have two usable heads tho correct? giving me the best of my avail options?

The cam installed in either of your heads is minimal.

 

One being closed would be a greater find.

 

 

If you feel the need to have that cam in whichever head, already said above, make sure to swap rocker arms too...and...very important...install rocker arms in exact spot they came from from the other head.

[datzenmike]

The A87 has smaller (narrower) intake ports than the W58 so I see no sense putting larger intake valves into it without opening them out also. 

 

No need to ask, just swap the W58 cam and rockers as a set keeping the rockers in the order they were on the W58. In other words... keep the rockers on the same lobes of the cam.

 

The ideal head would be a U67. It's basically a W58 but with square exhaust ports (good for use with 4 into 2 L16 cast exhaust manifold) without the exhaust liners. (but I digress)

[spdcrazy]

so should I be looking into bigger valves in the w58 head? with the l20b cam that is already installed.

[flatcat19]

No.

[datzenmike]

The W58 has round exhaust ports and while they will work if using an earlier square port L16 exhaust manifold it's not exactly perfect. In addition the W58 has exhaust liners. Has no effect at most RPMs but it is an obstruction to good flow.

 

The A87 head would be the best choice if you put larger valves in it and the W58 cam and rockers (just keep the rockers in order) and port the intake runners out for better flow. Definitely gasket match the head and gasket match the intake.

 

If your exhaust has the smog pump air lines, remove them and weld the holes up.

[spdcrazy]

exactly my plan.

 

thanks to all for the info!

 

as usual, i'm way overthinking this. but I have a direction now!

[banzai510(hainz)]

i WOULD JUST MATCHPORT THE  INTAKE TO THE HEAD AND OPEN UP THE THROAT TO THE INTAK MANIFOLD FOR THE TOP

[KoHeartsGPA]

Jeebus.....don't over think this, I've got an W58 with intake port matched to a cannon single side draft intake manifold, if the carb is tuned properly, it will rock.

 

 

 

[flatcat19]

Jeebus.....don't over think this, I've got an W58 CLOSED CHAMBER HEAD with intake port matched to a cannon single side draft intake manifold, if the carb is tuned properly, it will rock.

 

Fixed.

[KoHeartsGPA]

:thumbup:

[Stoffregen Motorsports]

Has anybody mentioned lash pads? To be sure you get the proper rocker geometry, use the lash pads that are installed with the cam.

 

Installing big valves is not an easy modification. Probably close to $1000 to get that done right.

[flatcat19]

And...with $1000...better bang for the buck is to just go KA.

 

 

Maybe more than $1000, I know.

But building a proper L ain't cheap and still won't net a huge gain.

[datzenmike]

anything else I should be looking into without getting crazy on the fiances? this was not an intentional engine build, just happened to let go at a time I wasn't piss poor for once!

 

thanks for the input in advance

 

Best bang for the buck is mix 'n match heads and parts and forget the larger valves. It isn't going to make much difference on a stock engine. L heads breath just fine. 

[scooter]

Has anybody mentioned lash pads? To be sure you get the proper rocker geometry, use the lash pads that are installed with the cam.

 

Installing big valves is not an easy modification. Probably close to $1000 to get that done right.

 

Thick lash pads are getting hard to find, a solution ive come up with is to use manley 8mm valve stem caps under the lash pads. They are cupped and go over the valve tip to keep them there. They are close to the keepers but they dont touch. Ive buzzed mine to 7500 lots with no problems so far. These will raise your pad height up another 80 thou so keep in mind this isnt a good idea with stock retainers.

 

Stroff is right about the valves. Ferreas are around 40 bucks a valve, x8 then new valve seats, guides, valve springs and retainers... Adds up fast.

[banzai510(hainz)]

scooter you have photos of these mods