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Re: manifold preheat

To: "Roadster List" <datsun-roadsters@autox.team.net>
Subject: Re: manifold preheat
From: Ronnie Day <ronday@home.com>
Date: Mon, 22 Jan 2001 19:47:46 -0600
>The time the fuel charge spends in the manifold
>is not enough to significantly warm the mix, but believe it or not, you
>may start 'icing up' on a drive at 40-50 degrees outside temperature if
>you don't preheat the manifold walls. (Icing up is when you freeze moisture
>to the manifold walls, restricting the passages to the point of stalling the
>engine. Evaporating gasoline gets COLD).

When we lived in Hawaii in the mid '70s, one of my proudest automotive 
acquisitions was a Warneford (Australian, I think) manifold for a single 
side draft twin throat carb. I used it with a 42 DCOE (yes, a 42) on an 
L-16 that had been massaged a bit. OEM head, but with Z-Valves, Norris 
cam (around 260 degree if I remember correctly) and the head ports 
matched to the intake. Never did get it to really work right due to the 
terrible mixture distribution, but the final nail in that particular 
coffin's lid came after we moved back to San Antonio in the summer of '75.

I finally found some knowledgeable guys at a BAP in Houston and we got it 
running as well as it could, then in October we had our first cold spell. 
I hoped in the car and it ran fine until shortly after I pulled onto the 
freeway. Within a mile or so it felt like the car just ran out of gas. 
Pulling off onto the shoulder I popped the hood and was more than a 
little surprised to see gasoline icicles hanging from the airhorns (for 
some dumb reason I'd left the filters off, too). Yes, the manifold had a 
hot water bypass built into it so there was not manifold or carburetor 
heat. True story. I put a slightly modified OEM Hitachi on the car and it 
worked fine. Probably better than the Weber.

BTW, do you know the difference between a Fairy Tale and a Sea Story? The 
Fairy Tale begins, "Once upon a time..." while the Sea Story starts, "Now 
this ain't no BS!"

FWIW,
Ron

Ronnie Day
ronday@home.com
Dallas/Ft. Worth
'71 510 2-dr (Prepared Class Autocrosser)
'73 510 2-dr (Street Toy)

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