Maurice,
Thanks for the input. I'll question Duane (my mechanic) about the
difference in flange size, etc.
How did you come up with a 2.5 liter engine with a manifold that was
too small for the carbs? Are HD 8's larger than ZS 175's (which is
what I would expect to find on a TR6).
I guess I figured that the adapter (to fit between the new carb and
old manifold) which lowers each carb, would also taper down from the
larger bore to the smaller, as well as present new, appropriately
sized flanges
Duane is extremely meticulous, in my experience, and I'd be surprised
if he hadn't considered this issue--but I WILL ask him!
BTW, did those HD 8's present any sort of clearance problem with the
GT6 bonnet?
Thanks,
John Donohoe
'70 GT6+ (holding my breath for those 175's)
---Maurice Dykes <mhdykes@thinkage.on.ca> wrote:
>
> At 03:07 PM 11/18/98 , john donohoe wrote:
> >I plan on upgrading to freshly rebuilt 175's, and we will fabricate
an
> >adapter to go between the carb and manifold which offsets the carb to
> >clear the bonnet as required.
> >
> >If anyone has already done this, let me know! And if not, let me know
> >if you're interested in an adapter "kit" of your own!
>
> Hi John,
>
> When I converted to HD 8's in my 2.5 GT6 I didn't bother with the
> adapter route. If you look at your intake manifold you will notice the
> skinny runners leading up to flange plus the flange itself is not
quite
> big enough to mate with larger carbs.
>
> Any porting with this manifold would have resulted in breaking through
> the manifold's tube wall.
>
> This I solved by getting a welder friend to add gobs of aluminum to
the
> underside of the skinny tubes next to the flange and to fill in all
the
> hollow areas. Then he built up the surface area of the flange's
mating
> surface to accommodate the 4 bolt pattern. He also filled in the old
> carb mounting holes.
>
> At this stage it looked pretty ugly but I took a hand grinder (dremmel
> tool?) to the new aluminum and smoothed it off, then opened up the
> ports and finally had a machine shop resurface the flange and drill
> new carb mounting holes.
>
> End result was an intake manifold that flowed much nicer than an
> adapter mated to a small bore inlet. Total cost $60.
>
> -Maurice
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