Re: [OMC-Boats] Dwell/tach

From: Lee Shuster <lks@...>
Date: Sun, 13 Sep 2009 11:10:30 -0600

The motor mounts wouldn't be your biggest headache expense in
switching to a SB Chevy. One of the single biggest expenses would
switching over to the different OMC log style manifolds for the Chevy.

But depending on what your source of a SB Chevy was, say former OMC
marine application, you might luck out and get everything.

I would say your chances of finding a 66-67 Buick intermediate of full-
size with a 340 would be pretty good. Then it's pretty straight-
forward swap with what you already have with your 300.

Most of the factory 4-V 340's used Carter carbs and did run a pretty
high compression ratio. Retro fitting a Q-Jet to a 340 might require
modifying the squarebore intake.

But even a properly set up 2-V on a 340 would be a economical, very
torquey upgrade.

On Sep 12, 2009, at 6:41 PM, Justin DeSantis wrote:

> Cool. Now all I need is to find a 340 Buick and a Qudra Jet. I don't
> really want to move the motor mounts so I'm going to stay away from
> the 350 Chevy.
>> Electric stringers will designed to safely take 350-400 ft-lbs of
>> torque and
>> stay under 5000 rpm. One could fairly safely accommodate a 260-290
>> hp small
>> block.
>> A Quadra-Jet 4-barrel on a 340 Buick or a 350 Chevy would be ideal
>> without
>> getting crazy. OMC installed the 351-W ford which they
>> conservatively rated
>> at 235 hp.
>> Lee
>> On Sep 12, 2009, at 8:54 AM, BC Howk wrote:
>> some history for your buick should give you some idea about HP
>> gains and
>> torque (I did not realize the buick nail head and the aluminium
>> rover V8
>> were related, interesting)
>> Did a quick search for 4bbl intake does not seem to be an easy item
>> to run
>> across, apparently origional buick 4bbl intakes were
>> aluminium......aftermarket doesnt seem to have much for the 300 and
>> 340
>> (tons of stuff for the 350 and big block buicks)but if you did some
>> research
>> and hunting I bet you could come up with some good performance
>> enhancements
>> for what you have.
>> Lee swapped in a small block chevy into his sportsman, take a look
>> at his
>> web site he goes into a lot of detail
>> if you went on the road of swapping in a small block chevy (like a
>> 350),
>> well you could just go NUTS with aftermarket performance stuff if you
>> wanted. The only question would be how much HP would the old electric
>> stringer actually take....
>> Cheers,
>> B.C.
>> On Sep 11, 2009, Justin DeSantis <duc1098desmo@...> wrote:
>> I hadn't planned on adjusting the timing. Just checking it while I
>> was
>> poking around in there. Once I get in and look around, I'll let you
>> know if I have more questions. Good to know about the Buick 340. Any
>> idea of the horsepower increase if I performed said swap? What about
>> other GM small blocks?
>> And while we're talking, let me run a few other things by you. I
>> spoke
>> with a marine mechanic today, he gave me some info on the stringers,
>> but it's been so long since he's actually worked on one, I wanted to
>> make sure he was remembering correctly. Because he said a few things
>> that are in direct contradiction with the owners manual for my boat.
>> First, we we're talking about oil. I told him I used type C or
>> Premium
>> (in OMC speak) fluid in the lower and upper gear case. He told me I
>> goofed. He said they use Type C in the lower gear case, and high vis
>> in the upper gear case and tilt motor gear case. When I told him the
>> manual said to use type C in those, he told me I must have read
>> wrong.
>> Well I checked, and I was right, they call for type c in all those
>> places. Should I be using Hi vis? He also said there is oil in the
>> intermediate that needs to be changed. I can't find any mention of
>> this in the manual.
>> One more thing, this guy told me changing out the impeller requires
>> the outdrive to come off the boat before I remove the lower unit.
>> Said
>> I'd damage it if I removed it without first removing the outdrive
>> from
>> the intermediate. Now, I know this guy, and he knows his stuff. But
>> they stopped working on stringers years ago, so it wouldn't shock me
>> if he's wrong on some of this. Once I get my service manual, I'l' be
>> golden, but until then, I'm flying blind. No biggie though, I don't
>> plan on replacing the impeller until winter. This year, I'm storing
>> the boat in my mother in laws garage so I can get some projects done
>> on it over the winter. (Let me tell you, it's going to be a real feat
>> to get it into her garage. The garage is big enough, but the location
>> will make it tricky to get a boat in. I'll take pictures of that
>> fiasco.)
>> Thanks for all the info.
>> On Sat, Sep 12, 2009 at 12:03 AM, Lee Shuster (lib1) <lib1@...
>> >
>> wrote:
>>> NO, you're describing a SECONDARY HV INDUCTIVE pickup designed to
>>> sense
>>> pulse firing off No.1 cylinder. I'm not surprised that's what you
>>> are more
>>> familiar with. These induction pickups are also commonly used on
>>> timing
>>> lights as well.
>>> NOTE: I"M Pretty sure that's NOT what you have with the RAC If it
>>> has
>>> the common red and black alligator clips.
>>> This RAC tach/dwell PROBABLY hooks up to one of (two) the small
>>> threaded
>>> terminals on the COIL. The coil has THREE CONNECTIONS.
>>> 1) HV SECONDARY which sends high voltage spark to the center
>>> distributor
>>> terminal. IGNORE
>>> 2) + IGN (PRIMARY) Voltage from the ballast resistor (small threaded
>>> terminal) IGNORE
>>> 3) - (PRIMARY) voltage small lead to distributor and lead to tach
>>> (Small
>>> threaded terminal) HOOK UP THE RED TACH LEAD HERE. Connect the
>>> lead to any common ground.
>>> THERE"S NO Timing "port" like you're used to viewing on motorcycles.
>>> Instead
>>> there will be timing "marks" on the rotating damper which is
>>> connected to
>>> the front crankshaft. There will be a static pointer. Point your
>>> timing
>>> light at the pointer when the engine is running (follow the manual
>>> instructions to adjust timing). The distributor will mechanically
>>> advance
>>> the timing over 20 degrees as you increase the RPMs up to roughly
>>> 2750 to
>>> 3000 RPM. It's not recommended you alter ign timing, until you
>>> checked
>>> compression, gapped the plugs, checked spark plug HT wire
>>> resistance/HV,
>>> set
>>> the points & dwell.
>>> Have fun. BTW, I researched the Buick V8 faimly a little more. The
>>> 300
>>> shares pretty much everything with the 340 and would be a no-
>>> brainer bolt
>>> in. The 350 Buick shares very little, I'm not sure exhaust
>>> manifolds would
>>> swap over.
>>> On Sep 11, 2009, at 8:00 PM, Justin DeSantis wrote:
>>>> Cool, I'm looking forward to hooking it up and comparing it's
>>>> accuracy
>>>> to my other 2 tachs. Hopefully it's correct. You just clipping it
>>>> on
>>>> to the outside of the plug wire like a modern tach, or does it
>>>> require
>>>> some special hook-up procedure. One more question where is the
>>>> port to
>>>> inspect timing? (I ordered a service manual. Not here yet.)
>>>> On Fri, Sep 11, 2009 at 8:47 PM, Lee Shuster <lks@...>
>>>> wrote:
>>>>> I've got one of those old-school RAC's too. Pretty common back
>>>>> in the
>>>>> sixties.
>>>>> Simple to hook it:
>>>>> 1) You connect the Red side to the (-) coil primary (same
>>>>> terminal which
>>>>> has
>>>>> the lead to your distributor points.
>>>>> 2) Then the other side is connected to a good engine ground.
>>>>> Should have a switch to change from 6 to 8 cyl. (4 cyl used 1/2
>>>>> the 8
>>>>> cyl
>>>>> reading).
>>>>> On Sep 11, 2009, at 5:45 PM, Justin DeSantis wrote:
>>>>>> Hey gang. I borrowed a dwell meter and tach combo from a
>>>>>> friend. I
>>>>>> can't for the life of me figure out how to use it as a tach
>>>>>> though.
>>>>>> It's an old RAC dwell/tach. all it has is red and black alligator
>>>>>> clips. Other tachs I've used just go to the spark plug cable, one
>>>>>> wire. How does this thing hook up for use as a tach? One lead
>>>>>> to the
>>>>>> spark plug, one to the battery negative? I know how to use it as
>>>>>> dwell, but not as tach. Anyone use one of these old beasts?
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Received on Sunday, 13 September 2009

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