L20b cam

[620fever]

So I have to replace a head gasket for an L20b motor in a 77 620, and since I would like to switch the stock cam with a bigger after market one, I'm debating whether I should do it now. In any case I wanted to get some opinions of which cam would work best for what I want, which is a basic street motor that's going to be reliable but will offer a bit more performance than stock. I have a weber 32/36 I'll be running and everything else will be stock, I will probably invest in headers at some point. Thanks guys.

[nismo dr]

First, what head do you have? A big cam isn't going to do much but suck gas and make it crappy to drive unless you are going to do more than "headers".

[nismo dr]

In any case I wanted to get some opinions of which cam would work best for what I want, which is a basic street motor that's going to be reliable but will offer a bit more performance than stock.

 

 

old saying: "cheap, fast, reliable.... pick two"

[datzenmike]

The '77 came with the intake and exhaust bolted together allowing hot exhaust to warm the underside of the intake manifold. This gave a faster warm up and helped evaporate the fuel when the engine and outside air was cold. So if going to a header you are going to have to find an earlier L18 or L16 intake which is separate. I don't care for these as they have smaller diameter runners for use on a larger L20B. What I would do is find one from a '78-'80 car or truck. They are larger and separate.

 

Now the header... H-m-m-m-m not a lot of good I can say about them I'm afraid. This is something done by racers who spend any amount of money go to a lot of trouble and put up with a lot for a few extra hp on a full out race prepared motor (without muffler) to give them any advantage over the competition. On the street, (with muffler) any extra hp isn't in the range where you drive the vast majority of the time. If you spend about $100 on a header, you are paying about $20 per hp., and I think 5 hp is rather generous on a stock two liter motor. The stock exhaust is more than adequate so any increase will be well up in the rpm range. For your $100 you get to spend a weekend installing it. Now, assuming you didn't have to hammer a dent in one of the pipes to clear the torsion bar and your intake went on and bolted down without a vacuum leak, you didn't break anything removing the motor mount to tilt the motor over to install it, you now have to put up with increased noise level in cab so say goodbye to formally great sounding $2,200 sound system, increased under hood and floor temps causing hard restarts on warm days, header flange to down pipe bolts constantly coming loose/gasket leaking, in 6 months your $100 header is rusty and looks like shit. (not that anybody can see it anyway) Usually long before it gets rusty you wish you had the stock system back on there but that would take another weekend to put on, another gasket and repairing your (once perfectly good) exhaust pipe, even if you could find your exhaust manifold you think you threw away.

 

Here's what to do: Find an L18 or L16 exhaust manifold. It's the closest thing to a cast iron header. Will perfectly fit your U67 head is quiet, never wears out and does not leak, hell you don't even have to move the motor to get it in. You will need to have a muffler shop make you a new two into one down pipe and mate to your pipe. These come up for sale every now and then I got mine for $15 I think.

 

 

 

 

 

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[620fever]

Thanks for replies. I've seen discussions on using the exhaust manifold from L16's or L18's and I would definitely consider that my only issue was paying for the custom exhaust you'd need after installing the manifold, but after thinking about it some more it probably wouldn't cost a whole lot more than a decent ceramic coated header.

 

As for the cam I am cost conscious but I'm not against paying more money for a cam that can offer more hp and provide reliability, I just don't care to build a full out race motor so I'm not looking for the biggest. I honestly don't know what kind of head I have I'll have to check, I am completely new to the world of Datsun and have read that the peanut heads are decent, I just need to spend a bit more time researching. Thanks again guys, if you have any more input as far as types of cams paired with fairly stock heads that I might be able to find I'd love to hear your opinions.

[ggzilla]

The manifold is $20 at pick-n-pull, while a decent ceramic-coated header is $350. The manifold works better and doesn't leak at the gasket flange.

 

L20B comes with a decent cam, but a higher lift will work a bit better. Call Isdenderian or Delta Cams and they will custom-grind a better cam for about $120.

[EricJB]

I've been looking for a GOOD header for awhile now. All I can find on the internet is that Pacesetter POS that I already have. Does anyone have a source for something like 1 5/8 to 1 3/4 primaries about 30 inches long;that will fit a 521.

 

(L20b)

 

Ya I know Its a tall order.

[banzai510(hainz)]

Doesnt frank in Everett have a L16 manifold? Key is the Y pipe to pass over the Torsion bar.

Headers that your looking for in that length have to be Torsion bar specific.

 

or Top End Performance short tube header that needs a ceramic coating

[EricJB]

The top end performance header is a Pacesetter. The Stock manifold was designed so well, and the available headers are designed so poorly. A shorty header is not going to out perform a stock manifold. If someone made long tube or a Tri Y, than it would be worth swapping out.

[banzai510(hainz)]

the Top End Header is a Trimill out of Los Angeles. they make lots of VW stuff. Dont know if they make Pacesetter.

 

The short header clears the torsion bars. and also is a universal fit as when a L20 gets installed it raises the y pipe up 3/4 inch.

Its good to get rid of the nasty L20 exhaust manifold full of emission stuff.

 

Most L16 manifolds people dont sell the correct Y pipe as they are differnt from the 510 ones as the torsion bar gets in the way(521)

 

I have a L16 manifold but has a 510 Y pipe has a broken stud

 

 

Most L16/18 long tube headers will hit ther floor on a 510 with a L20 so I assume the same with a truck or torsion bar proplems

[Radim]

I have a Hooker longtube header on my 620 w/ L20B... No clearance issues.

[banzai510(hainz)]

I have a Hooker longtube header on my 620 w/ L20B... No clearance issues.

 

 

does it hang low?? a lowered truck example

[crackerjack69]

I have an un-identified header on my 72 620 w/ L16. Came from PO that way. Makes my exhaust hang below the scrubline of the truck, so whenever I bottom out it's the first to hit. Kinda upsets me, I'll prolly see it in my rearview mirror one day. It's got some battle scars. Something I've learned from skate boarding: The ground is hard, lol. The truck sounds real good, and no exhaust leaks that I know of. Nice to know that the stock L16 bit is good though. To the OP, I'm working on getting a gnarly cam in my truck and am real excited. I say go for it, and I'll be looking forward to hearing how yours goes! Search "Phlebmaster's 620" on youtube, that's the cam I'm putting in :) Sounds great.

[EricJB]

the Top End Header is a Trimill out of Los Angeles. they make lots of VW stuff. Dont know if they make Pacesetter.

 

You are correct Sir.I bought mine a million years ago when I worked at Bow Wow in Seattle. We sold S @ S, and Tbird for the VW's, and pacesetter for the others.

 

I forgot that I ordered it from Trimill hoping it was better than the Pacesetter.It seemed to be a lot thicker than most of the pacesetter stuff, but looked the same.

 

Man I'm gettin old.