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Closed chamber hp gains?


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#1 KamakSun

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Posted 07 September 2017 - 02:49 PM

Hi fellow ratsunners,

I just dropped a stock closed chamber head off to an engine rebuilder. The machinist said that not a lot of gains are to be had unless the head is ported, valves and springs changed and a hotter cam installed. Is this correct?

Additionally, he wants me to switch to headers and this board told me to keep the cast manifold.

Thank you,

Kamaksun

#2 Skib

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Posted 07 September 2017 - 03:01 PM

does he know much about Datsuns?

the old style L16 mani flows like a tube header without the exhaust leaks of a lot of them out there.


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#3 KamakSun

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Posted 07 September 2017 - 03:04 PM

He does. I gave him my mikuni manifold to match to. Photos of the exhaust options are in my previous posts.

#4 kelowg

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Posted 07 September 2017 - 03:04 PM

Closed camb can help stop pinging. But yes the full benefit would need those mods.



#5 banzai510(hainz)

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Posted 07 September 2017 - 03:42 PM

closed chamber is better. less pinging than a open chamber.

 

 

yes side drafts carb and cam and porting. $$$$$$$ for a extra 4 to 20 hp

 

 

Fuck the header. cast manifold will last forever.


Throw on some Weber sidedrafts, Rising Sun hood.... call it good

#6 G-Duax

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Posted 07 September 2017 - 04:05 PM

My header has lasted at least 20 years......



#7 racerx

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Posted 07 September 2017 - 04:07 PM

Hi fellow ratsunners,

I just dropped a stock closed chamber head off to an engine rebuilder. The machinist said that not a lot of gains are to be had unless the head is ported, valves and springs changed and a hotter cam installed. Is this correct?

Additionally, he wants me to switch to headers and this board told me to keep the cast manifold.

Thank you,

Kamaksun

, he could just be biased and used to putting headers on his cars. A friend of mine and go fishing a lot and he swears up and down about lures being more effective than bait. I told him that lures have its place like bait. If its windy you will have a hard time casting lures. Anywho, stay with stock exaust and 2 inch pipe w turbo mufflers is good to go.

#8 datzenmike

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Posted 07 September 2017 - 04:52 PM

The closed chamber head only works properly if you have flattop pistons. This gives you maximum quench and swirl to homogenize the mixture and reduce hot spots. If you have any dish (usually L16s are 7cc) it does very little. The L16SSS and L18SSS had flattops.

 

There are several closed chamber heads but if you have the L16 or L18SSS head there is no need to port as they are already at 1.5" intake.

 

 

L16SSS compression is............... 9.29

L16 with stock head..................... 8.58

L16 with closed chamber head.... 8.21.... this is because the closed chamber head is larger than the stock head. You are going to lose power here. Does your machinist know this???? You may be able to mill the head down to get some of the compression back but you are starting in the hole.


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#9 KamakSun

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Posted 07 September 2017 - 05:02 PM

Domed piston l20b, u67 closed chamber head. Machinist is going to mill it carefully to ensure valve clearance

#10 KamakSun

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Posted 07 September 2017 - 05:03 PM

Ok I'll come clean, monte at machine tech in Oceanside CA

#11 Crashtd420

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Posted 07 September 2017 - 05:39 PM

Have you done the math for compression ratio? Flat tops are probably better than dome unless you want the higher comprssion ratio and extra effort....
Also for reference I have 84mm dome piston in my l16 with a closed chamber w53 head.... I had do so a considerable amount of work to clearance the walls of the combustion area so the piston wouldn't contact the head, I even run a .05 shim on my spark plugs . I ended up at 10.7 to 1
I also am stuck running 93 octain...
Just look at the end result, and your buget.what are you trying to do with this motor? That should determine what need...

#12 Crashtd420

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Posted 07 September 2017 - 05:41 PM

Domed piston l20b, u67 closed chamber head. Machinist is going to mill it carefully to ensure valve clearance


What do they plan on milling?
Head or the piston?

#13 datzenmike

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Posted 07 September 2017 - 05:54 PM

Domed piston l20b, u67 closed chamber head. Machinist is going to mill it carefully to ensure valve clearance

 

All I had to go on was the 510. Any more missing info??

 

 

There are no closed chamber U67 heads.

 

Are you now going to say it was custom welded up???


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#14 KamakSun

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Posted 07 September 2017 - 07:08 PM

No, I'll follow up. But it is definitely closed chamber

#15 KamakSun

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Posted 07 September 2017 - 07:11 PM

A87, I stand corrected. Just had to check the receipt from the rebuilder

#16 datzenmike

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Posted 07 September 2017 - 07:11 PM

It happens. A good head.


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#17 KamakSun

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Posted 07 September 2017 - 07:13 PM

<a href="http://s557.photobuc...wshzg.jpg.html"target="_blank"><img src="http://i557.photobucket.com/albums/ss11/briankamak/69%20Datsun%20510/6D26C118-8FA4-43DA-BEB0-7CA6F7906517_zpss0gwshzg.jpg" border="0" alt=" photo 6D26C118-8FA4-43DA-BEB0-7CA6F7906517_zpss0gwshzg.jpg"></a>

#18 KamakSun

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Posted 07 September 2017 - 07:14 PM

6D26C118-8FA4-43DA-BEB0-7CA6F7906517_zps

#19 KamakSun

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Posted 07 September 2017 - 07:14 PM

Photo of the receipt, I forgot that this is ratsun

#20 KamakSun

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Posted 07 September 2017 - 07:19 PM

Norris can with a 327 stamp on it