dmaxx3500

anybody got any tricks for drilling a transom for tail pipes,id like to only drill it 1 time,not 6,,any templates i can make or mearsurements i should be using

737jetmech

Depends on your drives/exhaust set-up ... Hardin marine has a dimension chart on there site for standard bravo set-up. All dimensions are taken from crank shaft centerline .

tips : measure twice ... maybe 3 times and cut once.

CcanDo

Does the transom have present holes for the tail pipes ?

whatabout1

I used 4" PVC pipe to mock it up. You can cut and trim until it is just right.
PVC is cheaper then stainless so if you cut to short just grab another piece.

That's if the motors and headers are in.

I then outlined where the pipe was contacting the transom and drilled a 1/4 hole in the center (from inside to out)
Trying to drill at the angled the pipes touched the transom.

Used the mockups to have the tail pipes made up at the correct droop and length.
(the 'X' was set high for extension boxes and standard pipes would have exited too high on the transom)

Then put a longer 1/4" pilot drill in my hole saw, fed it in at the correct angle (drill not running).
Braced drill on 2x4 so I don't break my wrists and drilled away. Drilled from outside to in.

All 4 holes were spot on. It was a 34' scarab twin 468 w/ blowers & stellings.

dmaxx3500

sorry,
1 no holes in transom
2 stainless marine headers and full tailpipes
3 yes engs ang headers are already installed
4 tailpipes are clamp on to headers and are 1 piece thru transom

whatabout1

Yep, I would cut PVC the same as the pipes.
You will have to shorten but it should line right where the SS pipes would.

Some use cardboard tubes but I think it doesn't cut as nice as PVC.

Good luck ! I was sweeting bullets when I punched the first 4 1/2" hole !!!!!

dmaxx3500

yep,i haven't done any in 10 years,and i thought maybe there were some tricks i forgot,i'll try the pvc,thanks