Snacks going square????

[jrock4224]

so my l 16 that iu pulled out has a square port exhaust manifold .....but my l20 has a round port exhaust.... hmmmmm any thoughts ..... been done or should I clean up the round port manifold and put it on there ....

[Phixius]

square port mani on a round port head = good to go.  but not round port mani on squard port head...

[jrock4224]

yeah u told me that last night ..... just brainstorming

[Eagle_Adam]

ive pulled apart RUNNING motors that had square on round and vise verse.

 

It will run either way

 

 

 

BUT

 

 

best scenario is to keep them shape matched  

[izzo]

round into square.  doesn't work good square into round mani, at all. gasket is fucked, doesn't seal up right on the ports alone.

[Silky_Johnson]

Get a U67 from the junkyard, mount it on the L20B, and use the L16 exhaust manifold.  Or if you want a cammed A87 peanut head with U67 size valves, square port exhaust, and 1.5" port matched intake, I'll sell it to you...

[jrock4224]

for 1 .00

[jrock4224]

I think I will just switch to the 620 manifold that had round ports and hop it donesnt interfere with any of my high tech shitz going on under the hood...I get what frank is saying that round port head will flow freelyish into a square port exhaust...I would imagine the other way round it gets weird ... but other then some turbulence on the round head to the square port I don't see why it wouldn't work unless it doesn't seal worth a beans ..

[Silky_Johnson]

for 1 .00

 

Don't you think we should maybe ask for more than $1.00?  $1.00 isn't exactly a lot of money these days...

 

http://www.youtube.com/watch?v=-DJtHL3NV1o

[jrock4224]

ok 10.00...... I upped my offer 1000 percent

[Silky_Johnson]

You drive a hard bargain...

[Eagle_Adam]

$11.00 and ill buy you a beer..... 

[datzenmike]

so my l 16 that iu pulled out has a square port exhaust manifold .....but my l20 has a round port exhaust.... hmmmmm any thoughts ..... been done or should I clean up the round port manifold and put it on there ....

.

Your W58 head will work fine into an L16 square port exhaust manifold. Use square port gasket.

[bananahamuck]

Aesthetically  the square port exhaust looks way better.. use it

 

Round port exhaust mani looks blob-ish ,, if you put it on you will hate the look of it..

[jrock4224]

damn I got round port gasket .... I guess I will buy one ...

 

eagle adam gets a bonus point ....11.00 is actually a 1000 percent of my original offer...

[datzenmike]

The round port exhaust, hell even the square port exhaust used on the L20Bs is just a 4 into 1 and not at all the sleek header-like L16 4 into 2 into 1

[datsunaholic]

It's actually a fallacy that a square port manifold will work fine on a round port head.   True, Square-port head into round port manifold is WORSE, but the 2 types do NOT overlap properly no matter which way you do it:

 

 

 

 

That's what came off my '76 620.  At some point in its past someone stuck a 200SX engine in it with a roundport W58 peanut head.  Kept the original square '76 manifolds.  Notice the carbon fouling on the manifolds?  That's where the round ports of the head line up with the square ports on the manifold.  I will note that it did have the round gasket, which didn't help matters, but it's quite clear the ports aren't exactly lined up.

 

So, you'll get excessive backpressure, horrendous flow, and the gasket won't live as long.  Going the other way is a lot worse, though- it will burn out the gasket even faster, and the backpressure tends to lead to burnt valves.

[jrock4224]

well right now im running a square to round ....witthhe new motor and its has no leaks not sure about flow but for now it works,,.,,

[jrock4224]

I need that square port manifold pictured...that has the three bolt lower flange .... that's exactly what I need to make it work good so im looking for a 76 620 manifold I guess..... to get the swaurae ports like my a87 head im now running

[Eagle_Adam]

I has one......

 

 

 

Its urs 

[jrock4224]

three bolt collector square port ?

[Eagle_Adam]

yup

[Eagle_Adam]

one day young grass hoppa you will learn to check my parts stash before putting the wrong part on...

 

 

 

coulda dropped it off when i was there ;) 

[Eagle_Adam]

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