Victor,
I'm quoting from the "Datsun Competition Preparation Manual" by Bob Sharp
Racing, regarding a 1600 engine. If you do this, you're on your own. Keep
in mind that Bob Sharp specified these mods as part of a coordinated set of
changes to the carbs. Namely cutting down the carb throttle shafts and
butterflys, needle and dashpot oil changes. And a bunch of other tricks to
the engine. Personally, I don't think it's worth the trouble, unless you go
the whole distance and make major mods elsewhere as Bob Sharp recommends.
And it sounds scary to perform.
"... Match the intake and exhaust manifolds to the cylinder head ports.
Place the manifold gasket to the head and scribe the outline of the ports.
Next, place it against the intake and exhaust manifolds and check for
alignment. Any necessary grinding can be done with a high-speed hand
grinder. Remove the locating rings from the intake manifold and discard.
Open the intake ports in the cylinder head to 1 7/16" on the 1600 model.
One-third into the port, taper-down gradually 1/16" to ensure that you
don't grind through the wall into the bolt hole. On the exhaust ports in
the cylinder head, merely grind away the rough castings and polish -
without opening or increasing the basic stock dimensions."
Fred - So.SF
----------
> From: Victor Laury <vlaury@earthlink.net>
> To: datsun-roadsters@autox.team.net
> Subject: Smooth breathing?
> Date: Tuesday, March 02, 1999 8:19 PM
>
> Roadsterites,
>
> I recently purchased a used SU set with manifold and air cleaner from
Dave
> Murphy. I sent the carbs and hardware off to Scott of Ztherapy to perform
> his restoration magic. I took the manifold to a local shop that blasts
whole
> car bodies with plastic media and now I have this beautiful, clean
manifold.
>
> The casting is very rough. I wouldn't mind smoothing out the exterior for
> appearance sake (I know, not a "stock" appearance) But it's the interior
> that concerns me. The interior is rough and the bores are at least a 32th
> smaller than the phenolitic blocks.
>
> Does anybody know if there is an advantage to spending some time
smoothing
> the passages and porting them to match the blocks?
>
> Eastwood sells a kit for this purpose and it might make a good "watch TV
> after dinner" project <single men don't get yelled at for making a mess!
and
> as sick as it might sound, I miss getting yelled at!
>
> Victor Laury
> 70 2000
> Los Angeles
>
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