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K&B 3.5 engine

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K&B 3.5 engine

Old 08-01-2010, 11:01 AM
  #1  
neverthought
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Default K&B 3.5 engine

Hi all,

I have a K&B 3.5 engine modified with tune pipe, it looks like I'm missing the tail piece. The large part of the exaust is 4.25" long (fron U elbow) and the outlet is 3/8" (10mm) ID. Anyonw know what the outlet size for a 3.5 should be? Also there is a conection in the engine block (looks like and is the same size as the water cool conections on the head) and I have a conection on the muffler (for the gas tank I guess) anybody know what the conection on the block is for?

Any help would be greatly appriciated,
Thanks,
Pete
Old 08-01-2010, 11:18 AM
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Dan S
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Default RE: K&B 3.5 engine

Can you put some pics up, please.

Dan
Old 08-01-2010, 11:31 AM
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neverthought
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Default RE: K&B 3.5 engine

I knew you would ask for pics, this is my first time uploading pics, hope this works.
Rgds,
Pete

Also, in the middle pic notice a corner broke off on the mounting plate, anybody know where I can find a new plate?
Thanks.

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Old 08-01-2010, 12:06 PM
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rcguy1411
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Default RE: K&B 3.5 engine

some guys ran the pressure tap off the block to the fuel tank instead of off the pipe i used this setup when i ran a 7.5 k&b with an exhaust throttle
Old 08-01-2010, 12:41 PM
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neverthought
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Default RE: K&B 3.5 engine

What do I do if I have both? plug one up? if so how?
Thanks,
Pete
Old 08-01-2010, 12:42 PM
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neverthought
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Default RE: K&B 3.5 engine

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Old 08-01-2010, 01:29 PM
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Ron Olson
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Default RE: K&B 3.5 engine

What you've got there appears to new a later model of the Irwin quiet pipe. He tried 2 different outlets on the pipe, one with a tiny stinger and the other has 3 slits in the bottom of the muffled area.
The two pieces that I think that you're typing about should be one for the tank pressure fitting and the other is for bolting on a bracket to hold the pipe in place.
The OB motor mount looks like a Prather. Man, I hated those things! A Du-Bro or Octura is much easier to use.
Old 08-01-2010, 03:33 PM
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Default RE: K&B 3.5 engine

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Ron,

Thanks for the reply, If you look closely you will see a brass nipple on the header (for tank pressure I assume) and if you look at the pic showing the motor mount that you hated so much (thanks, I will buy the du-bro!) above on the engine block there is an aluminum nipple like the brass ones.
Which one should I use and what do I do with the one I'm not going to use?
Thanks,
Pete

Old 08-01-2010, 04:44 PM
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rcguy1411
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Default RE: K&B 3.5 engine

if you use the fitting on the pipe just put a bolt in the one on the crankcase but make shure it isn t to long if you use the one one the case plug the one with a pice ot tubing with a bolt in it or put a screw inthe pipe
Old 08-01-2010, 04:54 PM
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neverthought
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Default RE: K&B 3.5 engine

Is one better than the other?
Old 08-01-2010, 06:08 PM
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Default RE: K&B 3.5 engine

As already stated, the nipple on the case is used for throttle exhaust. If going with a carb, use the pressure from the pipe. Looking at the pics again, the pressure nipple has to be on the pipe, not the header. Place the nipple near (just after it) the first weld on the flat portion. The other one, get some JB Weld and get that hole plugged.

If you want one of those mounts to replace the broken one, pm me your snail addy. Got plenty of those around that I'm no longer using. Might even have a Dubro mount system that won't be used either.
Old 08-01-2010, 10:27 PM
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neverthought
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Default RE: K&B 3.5 engine

How about the size of the inside diameter of the tune pipe outlet, any idea what it should be?
Old 08-02-2010, 03:04 AM
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ob nut
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Default RE: K&B 3.5 engine

I can check some of the outlet ID's of the pipes I have when I get home today.. Night shift sucks!
Old 08-02-2010, 05:15 PM
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ob nut
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Default RE: K&B 3.5 engine

Ok. My pipes are from .325 to .380 +\- a couple thousandth. Digi stopped working and rely on these old eyes ain't what they used to be. LOL
Old 08-02-2010, 09:43 PM
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neverthought
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Default RE: K&B 3.5 engine

That a great starting point.
Thanks very much>
Pete
Old 08-03-2010, 03:00 AM
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Default RE: K&B 3.5 engine

The pipe you have there is a Garcia Mini Marine 3.5 outboard pipe with the stinger broke off.
Lee Garcia made about a zillion different 3.5 outboard pipes but 95% of them ended up with about a .312" I.D. stinger internal diameter.
Lee used to make his stingers about 2-1/2" long and he inserted the stinger down inside the center of the pipe about an inch before welding.
The internal stinger inserted down inside the pipe effectively made the pipe a "quiet pipe" and it did not affect the performance of the pipe one little bit......
Mount the pipe pressure tap anywhere on the flat section of the pipe between the cones and take off or plug the pressure tap that is on the header.
If you don't have access to a TIG to weld up the hole just slip a piece of fuel tubing over the tap with a screw in the end of it to plug the hole.
Plug the pressure tap hole in the crankcase the same way......
You have to be an old guy like me to remember Garcia pipes.....Lee dissappeared off the boating scene about 15-20 years ago.Garcia pipes were made in SoCal....
Garcia pipes were good pipes.....you will be happy with the way it runs....Rod Geraghty
Old 08-03-2010, 11:26 AM
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neverthought
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Default RE: K&B 3.5 engine

Great info, I'm setting it up as we speek.
Thank you very much.
Regards,
pete

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