L20b in my '68 510 sits a TINY bit too high

[AZhitman]

Hi guys - Looking for some assistance from the pros.  My L20b sits a little too high in the engine bay.  I have about 3/4" clearance (pan to crossmember).  Is that about right?

 

What's the best way to drop it a little?  

 

Thanks in advance.  :)

[Laecaon]

How thick are your motor mounts?

[AZhitman]

They're stock.

[Dat Lurka]

From what I think I know, the L20b sits higher because it is a taller block. It can have a breather clearance issue in some datsuns.

[ggzilla]

Yes, L20B is 19mm taller.

 

But it should sit the same distance from the crossmember as the L16.

[Tristin]

.75in sounds about right... That's about where my L16 sits. What is making you think it's high? Is it hitting your hood?- what part?

[hobbes_the_cat]

All my 510's that had L20b swaps rubbed the hood at the front of the cam cover. A thin pieces of foam or hood insulation can stop any noise or rubbing on the underside of the hood. I have never lowered the motor but if you have room below that should work.

[gearboxx70]

A hammer would work too. If it doesn't, you'll need to get a bigger hammer.

 

Oh, and the best piece of advice I can give is "don't take advice from a carpenter".

[Sealik]

A hammer would work too. If it doesn't, you'll need to get a bigger hammer.

 

Oh, and the best piece of advice I can give is "don't take advice from a carpenter".

 

 

Oh really....

Better a carpenter than someone doing time at 'Taco Bell'................. :fu:

[Tristin]

I wonder if there's a market for billet mounts to lower the engine.... Hmmmm

[john510]

I recently did the L-20b swap.I tried new motor mounts from Beck Arnley.The oil pan was about 3/4 of an inch above the crossmember,everything looked good until i tried to close the hood.It hit the valvecover.I put the original stock mounts back in.Now the oil pan is about a 1/4 inch above the crossmember and the valve cover doesnt hit the hood.Maybe you dont have the original Nissan factory mounts ?

[Colbino]

I too have this problem. Spoke to a number of other dime owners at shows with the L20b and none of them knew what I was talking about - which I thought was odd.

 

I have nissan L16 mounts and engine brackets, but still have the issues with the hood hitting. I've come across posts where people have ovaled out the holes on the engine bracket (block side) to lower the motor down towards the crossmember, but I have yet to attempt this myself.

[Dat Lurka]

Make a hood scoop.

[Boaty]

Oy. I've seen this pop up so many times now.

You probably aren't using L16 engine brackets & mounts, you're probably using L20B Truck/HL mounts. Use the stock L16 brackets & mounts and it'll fix your problem. The L20B is going to sit higher than the L16 did, but everything from the block deck down should be identical in fitment. Make sure you're using the L16 oil pan & pickup tube (however I don't think you'd have anything else on there or it wouldn't fit at all.)

 

No need for custom mounts or anything like that, you simply need 510/L16 brackets & isolators.

Steve

[Boaty]

By the way, the hood clearance thing.. you should half at minimum a half of an inch of clearance between the hood and the valve cover in the front if you're doing it right. Might be closer to 5/8" - 3/4" or so but they should definitely NOT be kissing each other in there. Make sure you have the tilt correct too - I'm not sure if you can mix and match each side, but the mounts are different I believe. The engine should tilt to the passenger side not the driver's side, and should not be pointing straight up. Look at any L-motor install and you'll see what I mean. I can't remember if you can reverse it or not but you have to have your tilt correct. The clearance between crossmember and oil pan should be the same on either side and not closer on one side.

FWIW When I did my L20B swap, I had to have the engine on the hoist with the engine mounts hooked up to the crossmember, and the brackets unbolted from the block. I had to slowly lower the block, aligning it as I went, so that the engine slid down into position so I could get both of the bolts into the block for the brackets. I could not for the life of me do it the other way around and lower the engine in and then bolt the isolators to the crossmember. Could never get it to line up, and you aren't going go overpower a good rubber isolator with a screwdriver well enough to fit two M8's in.

Oh and be sure not to strip anything out while you're in there. ;)

[NICKLE&DIME]

Different sizes of isolators is one thing. Bought a new set and my engine sat high. Had to use some old ones that were

fair condition, an old dimer said that it also depends on the way the tranny sits, and like boaty mentioned the tilt of

the block. Need to oval the bolt holes on the mounts. Proflex over on the realm did a slight mod with his nos mounts to get

his l20 to fit.

[AZhitman]

I'm using the L16 brackets, and brand new, OEM isolators.

 

I should clarify - I'm not hitting the hood (although the VC is *real* close)... I have a strut tower brace that needs about 1/4" more clearance to fit perfectly.

 

Engine has the proper "tilt" and such.  Maybe I'll try making the mount holes oval and pick up a little more "drop".

 

Are the L16 (510) isolators different from the L20b (620) isolators?  That could be part of the issue, I suppose - I can't be positive which ones I used (although I'm pretty sure they were 510 units).

[Ranman72]

I used stock 510 motor mounts the l16 510 oil pan the metal motor mounts off the L16 an experimental Engineering tranny crossmember on my 68 510 and have no clearance issues

I have heard of this from many sources but a friend of mine has done many L20b's and has never had an issue he always uses nissan parts when available Maybe after market mounts are thicker 

[AZhitman]

Like I said, these are OEM.

 

As in, original, 10-digit part number, made by Nissan, still-in-the-packaging, leftover motor mounts.  :)

[Laecaon]

And this is why I asked how thick they were.

 

620 mounts are thicker... or at least the drivers side I believe.

[Dattokai]

My L20b hits the hood of my 510.

I know my problem though, I have truck mounts.

I didn't do the swap though, my 510 came like this.

[AZhitman]

Gotcha - Gonna measure, brb.

 

OK, the "pad" of each isolator is 1" thick.

 

The distance from the crossmember to the center point of the upper motor mount bolt (driver's side) is 8.5".

 

(Passenger side is obscured by the oil filter, of course).

[ggzilla]

620 motor mounts are 2 mm taller than 510 motor mounts. Left and Right are slightly different, so some run two left side isolators, others use Left and Right as Datsun intended.

[AZhitman]

I'll check out my 620 isolators tomorrow and compare them.

[john510]

Gotcha - Gonna measure, brb.

 

OK, the "pad" of each isolator is 1" thick.

 

The distance from the crossmember to the center point of the upper motor mount bolt (driver's side) is 8.5".

 

(Passenger side is obscured by the oil filter, of course).

I went out and measured my motor mounts,the Beck Arnley mounts are 1" thick at the rubber,stock ones 3/4".Doesnt seem like much but i couldnt get the thick ones to work.