Re: Two barrel TBI must have a flaw, I give up.

[olbap <olbap@mail.mia.bellsouth.net>]

At 11:07 PM 6/1/00 -0400, you wrote:
>The reason I asked about the height above the manifold, is that
>with a 2bbl, the air flow can slam into the bottom of the plenum.
>(high velocity air stream).


Yeah this is what I had hypothesized was theproblem in my first post.. but
ive done some more tuning, and maybe not

>It can help to space the tbi up a bit.

True, hood clearance is a problem though

>
>The air director things are important on the tbi's. Bruce has
>covered this in detail, so I'll just brief it. Notice that a stock
>tbi air cleaner has a metal ring the diameter of the tbi top.
>This ring extends toward the top of the cleaner, with a gap
>at the top. This forms the air-flow into a column that flows
>down past the injectors, drawing the fuel with it.


Wow, ok now this might be a problem.. seems that early on in my TBI wars I
saw that setup as a huge restriction, i thought that thing inside theair
cleaner was a silencer (and the fact that there was like barely an inch from
thelid didnt look like ithelped) So I removed it
later on I got an open element, then I saw that gold iridite spacer ring as
a restriction, since it seemed to shroud the tbi forcing air around the
injector tops, so I tossed it, and got a non drop open element which fit
wonderfully with a 3" element and exposed the tbi.. which to me seemed like
it would flow a whole hell of alot more. 

and ive seen some mention of what bruce went over with regards to the air
cleaner in the archives. So I take it, if I went back to the drop base
aircleaner with the spacer ring Id be better off then? I guess its the same
idea as a velocity stack.

Ill file this under well intentioned dumb moves of mine.. and all this time
I thought I had seriously improved my setup (it actually was .3 faster if
that means anything, probably mostly cause ofjust being an open element as
opposed to that really tiny single snorkle and pathetic filter)

>
>Check out the basic stuff, take a deep breath, then start
>over. The carb test was good, you can now concentrate
>on the tbi.

I am, i was having evil thoughts of going to the "dark side" but I now
believe there is yet hope.

>By-the-way, what ecm are you using?

im using the 8746, similar to the 7747


Pablo

>
>BobR.
>
>
>olbap wrote:
>
>> At 07:44 AM 6/1/00 -0400, you wrote:
>> >
>> >Those numbers sound about right. Remember that they are 2-bbl numbers
>> >at 3"hg, 4bbl's are rated at 1.5" hg.
>> >
>> >Not being able to look at the car, this can be tough. There are so many
>> >little things that can get ya'. Like, are the throttle blades all the
way open
>> >when the go pedal is down? Do you have the 'air-directors' on the
>> >tbi? How high off the manifold is the tbi?
>> >
>>
>> Im pretty sure the throttle blades are opening up all the way, now the "air
>> directors"  I dont know about, I probably call them those ----- thingies.
>>
>> The TBI is off the manifold mounting flange about 3/8 (because of the
adapter)
>>
>> Played with the fuel some more tonight, held everything constant except for
>> bpw as per a members reccomendation, i could get it really rich on the top
>> but the power was just not there i mean it took a year to rev from 4000 to
>> 5000 and the sound the engine was making was not pretty
>>
>> Pablo
>>
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