The intake heat issue is a common topic in the Inliners newsletter Tech Q &
A section.
The consensus is that for a street engine, heat to the intake is the single
best thing you can do for better driveability and economy. Apparently
Clifford has acknowledged this with their recent line of water-heated inlet
manifolds.
I had a similar setup to the one you describe, and it suffered from off-idle
stumbles and lousy MPG until I ran heat to the intake. After doing so, I was
able to drop down several main jet sizes and tune for a leaner idle mixture.
And this was in Florida, where cold starting was seldom an issue. Without
intake heat, the fuel mixture won't stay vaporized, so you get uneven
distribution and end up over-jetting to compensate.
If the Offy has a heat riser flange (most do), make a plate from 1/4"
aluminum and run copper tube from the headers, then connect with pipe
fittings. Not pretty but it will sure help. Some guys have drilled new
fittings in the rear of the headers so the tubes aren't so obvious. There is
no advantage to connecting the header sections together, other than possibly
reducing noise a little.
You will probably get conflicting answers to the intake heat question. Why
not just put it tgether with no heat and see how it runs. All applications
are different and you may be happy with it as is. Let the list know the
results.
There are many different vacuum advance cans with various profiles depending
on the donor engine. An adjustable advance will allow you to tailor the
point at which engine vacuum asks for more advance. But it may be fine with
the can that's in it, I'd try it as is. Any differences will be very subtle.
Jack / Winter Park FL
----- Original Message -----
From: <MPHUDAK@aol.com>
To: <oletrucks@autox.team.net>
Sent: Friday, December 24, 1999 8:25 PM
Subject: [oletrucks] To heat the intake or not to heat the intake
> OK everyone, i need some advice. I am to the point of installing the offy
> intake (1x2) and the fenton headers on my 235. Question, do i need to
heat
> the intake, if so how. I know there are holes in the exhaust manifold
that i
> have been told i need to link together. Is this true? I'm running
patricks
> mild cam, can't remember off the top what grind it is. Also, i have a
> stovebolt modified HEI distributor w/non adjustable vaccum advance. Do i
> need to switch to the adjustable or am i fine with the non adjustable?
Many
> thanks to all responses. Happy Holidays to all.
>
> Hudak
> 2-54 3100
> 57 3100
> oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
>
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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