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New to me 86 Formula 242ls

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Old 07-27-2015 | 07:27 AM
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Default New to me 86 Formula 242ls

Just picked up an 86 Formula 242ls, its only a SBC alpha one but its a great improvement over my last boat. Its pretty clean needs a few little things but runs great and takes the water like a barge!!! I see most SBC 242 guys aren't happy with the speed..... mine came with a SS 17p prop I though it wasn't getting up to RPM..... I tried an alum 15p I get 45mph.............. but after verifying with a timing light we learned that the tach was wrong, at 4300 on my tach I am seeing more like 4900-5100 RPM. I am going to put the 17p SS back and see what that's like?? I do like the holeshot from the 15p though lol.....
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Old 07-27-2015 | 07:29 AM
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Looks good! Nice tow rig too!

Time for a Vortec 350 build!
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Old 07-27-2015 | 07:35 AM
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Thanks! Gotta figure out if I want a 96+ 5.7 or a BBC?
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Old 07-27-2015 | 08:00 AM
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Is the tach a Medallion brand? They always seem to read low. There is an adjustment on the back that takes a small screwdriver. Its very sensitive, but mine was off by about 900 rpms. I got it adjusted so its now accurate.

I would stick with a 350 if you are keeping the alpha. Vortec 350s will make 350-375 horse quite easily if built correctly.
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Old 07-27-2015 | 08:35 AM
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Thanks! I'll look not sure what brand? I'd like to keep the 350.... I think a 350-375hp 350 would be a nice improvement. I'm sure the "stock" 350 I have now has barely 260hp? Its a Napa Marine reman.
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Old 07-27-2015 | 09:24 AM
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Originally Posted by Mr Maine
Is the tach a Medallion brand? They always seem to read low. There is an adjustment on the back that takes a small screwdriver. Its very sensitive, but mine was off by about 900 rpms. I got it adjusted so its now accurate.

I would stick with a 350 if you are keeping the alpha. Vortec 350s will make 350-375 horse quite easily if built correctly.


Anyone have any input on this setup??? With a 96+ Vortec, I'd have the heads cleaned up too.

http://www.compperformancegroupstore...de=RLERCAMXMAR
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Old 07-27-2015 | 03:33 PM
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Take it from me I had an 86 242ls, I went from the stock 260/350 that ran 45 mph with 19 pitch prop, to the vortec style 350 which ran 54 mph with a 21 pitch mirage plus and wasn't happy with the results. If your going to invest the money the only way to go is BBC and bravo. My last combo was a 509 BBC with a bravo swap that got me into the 70's with a labbed 23 mirage plus with about 525 hp. Search my screen name to find threads about the swap and info.

Last edited by 86242ls; 07-27-2015 at 03:35 PM.
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Old 07-27-2015 | 05:06 PM
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Originally Posted by 86242ls
Take it from me I had an 86 242ls, I went from the stock 260/350 that ran 45 mph with 19 pitch prop, to the vortec style 350 which ran 54 mph with a 21 pitch mirage plus and wasn't happy with the results. If your going to invest the money the only way to go is BBC and bravo. My last combo was a 509 BBC with a bravo swap that got me into the 70's with a labbed 23 mirage plus with about 525 hp. Search my screen name to find threads about the swap and info.
Big block Bravo is a little pricey for me, if I can get 55ish out of it I'll be happy. Maybe someday I'd upgrade but to keep a reasonable budget on this one, I appreciate the info though. How were you only running 45 with a 19? I can see 45 with a 15p alum prop.... Boat came with a 17 I was going to go back to it now that I know the tach is off..... I was hoping to see an improvement over my 45mph top speed?
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Old 07-27-2015 | 05:08 PM
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Would the stock BBC be a better option than a 350hp vortec?
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Old 07-27-2015 | 05:15 PM
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its a big heavy stout riding 50 mph boat. Enjoy it for what it is.

You want to feel like you are going fast ?

Go out in some big waves and play Johnny Offshore Racer.

40 mph in some 3 to 5s will make you feel like you are going 80
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