4 blade ss 23p 52 mph w.o.t

[vortec4.3]

my boats 17ft 350 vortec lt4 cam .elder rock cab 1409,est ignition ,timing @total 30* drive unit 1.5 alpha1,I was test drive today , the boat hit 52 wot @ 4000 rpm,i think I did not had right prop, or some thing set up not right, would some one help, because I look over online I saw one guys had same engine like me but I run 64mph.thanks

 

[MikDee]

Re: 4 blade ss 23p 52 mph w.o.t

That sounds like a bit too much total advance to me? 350's with a Thunderbolt IV, or 5, usually only run 22-24* total advance.

 

[steelespike]

Re: 4 blade ss 23p 52 mph w.o.t

What year is your boat and motor?
You may want to check the timing advance as MikDee suggests.
Also a 4 blade prop isn't the best choice for top end speed.Just changing to a same model 3 blade
should add about 200 rpm and perhaps reach 54 or 55 mph.Is your speed by gps.
Is the other boat and motor exactly like yours?Same gear ratio? What prop are they running.
Is their speed by gps?

 

[vortec4.3]

Re: 4 blade ss 23p 52 mph w.o.t

What year is your boat and motor?
You may want to check the timing advance as MikDee suggests.
Also a 4 blade prop isn't the best choice for top end speed.Just changing to a same model 3 blade
should add about 200 rpm and perhaps reach 54 or 55 mph.Is your speed by gps.
Is the other boat and motor exactly like yours?Same gear ratio? What prop are they running.
Is their speed by gps?

the boats 91 with mod vortec 350 ....I read speed on boats,rpm read on boats.i run solar ss 23p

 

[funk6294]

Re: 4 blade ss 23p 52 mph w.o.t

When you installed the lt4 cam did you have the heads reworked for the additional lift? The stock heads are not real happy with much lift over stock. Additionally the stock vortec springs are pretty weak which could provide problems controlling the valves with the new cam. I just went through this building the motors on my current project. Also with respect to the comments on the tb iv curve, the 22-24 degrees is what the box ads. Typically the vortec engine takes just about 32 degrees total. So take the curve from the ignition plus the advave from positioning the dist and that gives total. The fact you can't pull to rpm means either the tune is off of the prop is too big.

 

[vortec4.3]

Re: 4 blade ss 23p 52 mph w.o.t

yes I had head work I used beehive springs (16pcs set) and comp 787-16 I also cut seal down with comp tool. I think I got wrong total timing,or cheape fuel

 

[funk6294]

Re: 4 blade ss 23p 52 mph w.o.t

Any progress?

 

[vortec4.3]

Re: 4 blade ss 23p 52 mph w.o.t

I think I got wrong timing, I just buy new timing light with dial ,and I re timing today check it only show 5* INITIAL TIMING and I move it to 10* and I got total 32*to 34* at over 3000rpm I remove 87 fuel out of the tank and put 91 fuel in tank .I did not take the boat out to the lake ,on Sunday this week I will try it , I may get 3 blade 23p mirage ....thanks you very much, this is my first boat it had long story,i spend too much time on it