Ringing the HP out of a 5.7 vortec roller cam motor got a couple questions?

[tfmech]

The boat is a 89 baja 210 sport motor is a 2005 5.7 hooked to a gen 2 alpha drive. I know I am going to have to be nice to the alpha drive to get it to live but the boat is pretty light, got a drive shower on it. The motor is a stock low hours 4 bolt 5.7 has vortec heads and is a factory roller cam motor. I has a high rise intake with a quadrajet on it still. I just ordered the cam for it will be here tomorrow going to beehive springs to accommodate the lift. cam is 212 intake and 218 exhaust at 50 with .488 int .495 exhaust lift with a 112 lobe separation to so we don't get reversion. Exhaust is glenwood manifolds with stainless highflow risers turn downs and 4 inch out the back with no muffler inserts. Motor is out of the boat almost disassembled for cam installation.

​Here are the questions I have:

​1. I am dumping the Q Jet and installing a 650 DP holley for carburation it has J tubes but it was originally a car carb ( I know) does anyone have some setup specs I should start with like jet sizes go a little richer or leaner then stock. Power valve size to start with if different then stock 6.5 or if I need one at all in a boat.

​2. Thunder bolt ignition is hitting the scrap bin too going to MSD 6 box with MSD distributer. Question is on the curve and how much max advance was thinking about starting at 36 max and get it all in by 3000 if it dosent ping give it maybe 38 or so. Motor is set to spin 5200 with a cleaver prop on it.

3. What is the stock compression on a 2005 260 HP 5.7 as that is what the motor started life as?

​Thanks for the help

 

[Scott Danforth]

With a 715cfm vac secondary i was running 78 primary jets, 98 secondary jets, #35 power valve.

The DP not needed on a small block as you may run into issues about 3500 rpm. You can change the secondary squirt cam

The XM270HR cam you have listed is a good choice, however unless you pulled the motor apart and throw away the stock GM pistons for propper Vortec pistons (d-shapped dish) you wont see much in a gain.

Add a 2" phenolic spacer

No more than 34 degrees advance needed. 12 degrees base timing

 

[tfmech]

With a 715cfm vac secondary i was running 78 primary jets, 98 secondary jets, #35 power valve.

The DP not needed on a small block as you may run into issues about 3500 rpm. You can change the secondary squirt cam

The XM270HR cam you have listed is a good choice, however unless you pulled the motor apart and throw away the stock GM pistons for propper Vortec pistons (d-shapped dish) you wont see much in a gain.

Add a 2" phenolic spacer

No more than 34 degrees advance needed. 12 degrees base timing

I already own the dp can go vacuum if it will be better, as far as pistons I can pull the heads and put pistons in if I need to, I havent pulled the heads, and is why I was asking the compression, what is the stock compression on it.

 

[tfmech]

Any idea on cam color for secondaries if I do keep the dp

 

[Scott Danforth]

your stock compression is 9.4:1

your already starting with 290-300 hp at the crank to get 260hp at the prop. the cam will get you about another 30 hp max. if you want more out of it, you will need a piston change for better quench. then while your at it, probably ad a bit of stroke

as far as the secondary squirt cam, you would have to put it together and play with it. my guess is drop it down to a .018 discharge nozzle, maybe a pink cam

http://documents.holley.com/99-41141-100.pdf

BTW, you wont gain any performance with the MSD box over the Thunderbolt ignition. you simply loose the shift interupt switch which is a no-no on an alpha drive. stick with the TB5 or switch drives to a cone clutch drive such as the bravo or the VP

 

[tfmech]

your stock compression is 9.4:1

your already starting with 290-300 hp at the crank to get 260hp at the prop. the cam will get you about another 30 hp max. if you want more out of it, you will need a piston change for better quench. then while your at it, probably ad a bit of stroke

as far as the secondary squirt cam, you would have to put it together and play with it. my guess is drop it down to a .018 discharge nozzle, maybe a pink cam

http://documents.holley.com/99-41141-100.pdf

BTW, you wont gain any performance with the MSD box over the Thunderbolt ignition. you simply loose the shift interupt switch which is a no-no on an alpha drive. stick with the TB5 or switch drives to a cone clutch drive such as the bravo or the VP

I was figuring about 30 hp out of the cam and sounding a little meaner . Thanks for the info on the carb.

If I stick with the thunderbolt 5 ignition is any of the control modules better for hp then the other. What's the timing curve on them?

 

[Scott Danforth]

the timing curves are published. the SBC/bbc curve is base plus 18. the curve is best for marine applications

 

[tfmech]

the timing curves are published. the SBC/bbc curve is base plus 18. the curve is best for marine applications

Alright guess I have some more questions about the tb5 ignition. Looks like if you lock it out it has a the 18 degree standard timing curve with non of the rest of the stuff or just set the timing and let it do it's thing helping Accel and watching knock and all.

My question is what about the Rev limiter on the 5.7 alpha is that it kicks in about 4950 or so I'm looking for 5200 any way around the Rev limiter on the tb5?

 

[Scott Danforth]

Remember the stock drive is not set up for high RPM

 

[tfmech]

Remember the stock drive is not set up for high RPM

Guess that's a no on getting around the limiter?

There are a ton of alpha drives getting spun faster then 4950 probably way North of 5000 and still alive tb4 didn't even have limiter except for a couple of them. If or when the alpha breaks it will get a bravo till then we are going to give the gen two a stress test.

So what are the best options looking at some the diagrams msd shows to use the white wire through the shift interrupt switch. What about max volt, anything use the stock distributer maybe dig up a old crane hi-6m they have way to run the interrupt switch?

 

[Scott Danforth]

30hp isnt much of an increase in HP. If your motor pulls 4800 now, the cam will get you to about 5000 rpm.

I would get the boat running and out on the water before throwing money away on an MSD box.

Unless you pull the motor apart and change pistons, rebalance the motor, etc, you wont be going over 5000 rpm anyway.

 

[Rick Stephens]

Nothing beats torque on a boat. Skip all the funky stuff with a SBC and drop an 8.1L in it. Go Bravo now. Swing a real prop and go boating at real speeds. If that isn't likely, then stroke your 5.7 and up the prop. Spending $$ on RPMs on a boat motor is not all its cracked up to be. Increasing cam overlap will just accomplish reversion and a broken motor when it sucks water at idle..

 

[tfmech]

The boat will be back together the end of next week. I would go the rest of the motor and change pistons and have it balanced and all but I just don't think it is going to need it to get it where I want it to be. We were comparing it to dyno pulls on simular small block boat motors they have built the engine shop the other day. It looks like it is going to have right around 375hp or a little more and whole lot of grunt right around 3500-4000 and still have pretty good numbers out to about just above 5000.

​I am looking to get it right around 75 mph as I think from the bit I had it out it is probably going to run out of hull much above that. Maybe more but as it did have a pretty good hook forming in the left side of the hull that is getting fixed right now that was trying to suck the hull down in the mid range. I maybe wrong and am getting ready to find out but I don't think 5200 is going to be hard on a stock small block bottom end especially since the boat is pretty light and by the time it sees the 5200 the hull will already be up on top of the water. I could always put the high speed retard box on it start pulling some timeing on the top end if you really think it is going to pound the bearing out of it and chunk a rod at 5200


This was memorial day weekend
https://www.youtube.com/watch?v=aqX7uXpcTGI

​I guess my question still from before is MSD pretty much the only good way to go or if I am going to do it anyway. Old HI-6M or Max volt any good?

​Thanks for the help

 

[tfmech]

Nothing beats torque on a boat. Skip all the funky stuff with a SBC and drop an 8.1L in it. Go Bravo now. Swing a real prop and go boating at real speeds. If that isn't likely, then stroke your 5.7 and up the prop. Spending $$ on RPMs on a boat motor is not all its cracked up to be. Increasing cam overlap will just accomplish reversion and a broken motor when it sucks water at idle..

​may go big block someday probably will not be in this boat go with something bigger so it can handle all I want to throw at it. It is swinging a pretty healthy prop right now even before new cam and all video was with a 24 pitch mercury racing 4 blade Bravo 1 I also have a mercury racing cleaver for it. If it dosent do what I want I may put the stroker kit it this winter.

 

[tfmech]

Alright past weather it should be done or why I am going there or if I have the ability to make it happen or if I know what I am doing or no.

The question still at hand is sense the thunderbolt 5 ignition has a rev limiter that is not able to bypass. What is the best option for ignition to get it past 5000 is it msd,maxvolt, old crane tb4..........?

 

[Scott06]

Heard good thing here about the Delco system, which doesn't appear to have a rev limiter. These comments are more from a cheaper than TBV replacement parts standpoint than a performance standpoint. Also can take the shift interrupt you need girl the alpha.

 

[Scott Danforth]

Alright past weather it should be done or why I am going there or if I have the ability to make it happen or if I know what I am doing or no.

The question still at hand is sense the thunderbolt 5 ignition has a rev limiter that is not able to bypass. What is the best option for ignition to get it past 5000 is it msd,maxvolt, old crane tb4..........?

A mere cam change wont get you past 5000 RPM unless you hit a wave and unload the drive. Thats when you want the rev limiter, because when you hit the water and instantly load the drive is when the alpha drive goes bang.

Put boat in water and run it. I doubt you hit the rev limiter

 

[tfmech]

A mere cam change wont get you past 5000 RPM unless you hit a wave and unload the drive. Thats when you want the rev limiter, because when you hit the water and instantly load the drive is when the alpha drive goes bang.

Put boat in water and run it. I doubt you hit the rev limiter

I don't think you understand it is going past 5000 whether you think it will it should or if you think it has the torque or hp to do it, or maybe I am not telling you everything about the motor. So since it is going there obviously it needs spark past 4950 that the tb5 will supply. It will have a Rev limiter just will be where I want it.

So I ask again what is the best performing and most reliable high performance ignition option for a boat small block that will supply spark above 4950. Anyone use a DUI hei, msd, Delco hei, old crane?

 

[Scott Danforth]

No Title

Im running a Mallory dizzy, however i dont have to worry about a shift interupt with my drive.

What ever you use, make sure its marine rated, and for the alpha drive, has a shift interupt

 

[alldodge]

Its about an even split between MSD and DUI at OSO