Johnson 235, Lower unit replacement with v-8, what sould the Compression #'s be

[sschlachta]

I have a 1985 Johnson 235 on a Wellcraft 24'8" openfisherman. Are there any things I should keep tabs on since this is an older motor?<br /><br />I recently replaced the lower unit with a comercial v-6 (v-8) lower are there any concerns I should have about this? <br /><br />Are there any differences in gear ratio between the v-6 and v-8 lowers?<br /><br />What are the max WOT that I should run at?<br /><br />I am currently using a raker offshore SS 4 blade at 14 or 14.5 by 17 and crusing ~40 at 5200, does this sound right?<br /><br />What is the fuel comsuption for the engine?<br /><br />What is the prop shaft horespower rating for this motor?

 

[Solittle]

Re: Johnson 235, Lower unit replacement with v-8, what sould the Compression #'s

Re: Johnson 235, Lower unit replacement with v-8, what sould the Compression #'s

Old 235 - My guess is that you are set about right. You did not give us rpm at WOT but 40 mph at 5200 seems OK. I'll let someone who knows your motor tell you what the WOT should be but I'd guess 5500 rpm. I run 34 mph at 4200 rpm on a 23' Wellcraft 23' CC with twin V4 Sea Drives.<br /><br />If you keep you foot out of the throttle and cruise at 4000-4500 your fuel consumption will drop markedly.

 

[Reel Appeal]

Re: Johnson 235, Lower unit replacement with v-8, what sould the Compression #'s

Re: Johnson 235, Lower unit replacement with v-8, what sould the Compression #'s

old 235,<br /> I have heard of powerhead/blown head gasket problems occasionally with these.I would not be too concerned,just don't run it at WOT for extended periods of time.If you are equipped with VRO oil injection,keep an eye on it(oil tank levels),otherwise 50:1 mix.The L/U you installed is a little beefier,not sure about gear ratio changes,should be ok to use....Your prop size should be 15X17.Your speed and rpm's sound about right although a four-bladed prop is unnecessary unless you water-ski.Four blades are better for hole shots(quick acceleration).Better suited for bass boats.Your motor is rated for 235 horsepower@WOT(Full throttle).Fuel consumption is different with every boat.The heavier boat with a deep V hull will use more fuel than a lighter boat with a semi-V,etc. etc. You will have to find out what is "normal fuel consumption" for your rig.Good luck

 

[sschlachta]

Re: Johnson 235, Lower unit replacement with v-8, what sould the Compression #'s

Re: Johnson 235, Lower unit replacement with v-8, what sould the Compression #'s

Thanks all for the information. <br /><br />I am going for a test run this weekend and will retest both props that I have the 15x17 SS and the 4 blade raker SS. Both props seemed to perform very similar except the 4 blade is a little better out of the hole.<br /><br />I will post results after this weekend.