Early style head swap for Vortech? Need help please.
 

Hi all... I'm new to the make my boat go a bit faster world. I can't seem to get any straight answers from any one...Water jackets on early "69-85" and late model "86-up" the same? Can I ditch the vortech heads and intake on my 89 5.7 for early style heads and manifold? Any cooling issues? What about valve train geometry? I was planing on the following up grades to speed things up.
1. Through hull exhaust.
2. Good after-market heads "Dart Iron Eagle"
3. Cam and Manifold to match heads
4. MSD ignition
5. Drive shower
6. 14 3/4 x 23 prop

Any susgestions would be great.
Thanks again. :D

Re: Early style head swap for Vortech? Need help please.
 

No problem swapping the heads and intake. Water passages are the same.

Just remember that the Vortec intake uses a different bolt pattern than the older style (no center bolts).
Actually there are three bolt patterns for the intake. Don't know the manufacturing year but just before the Vortec heads came out the center two intake bolts were drilled on a different angel (straight up, vertical) than the years preceding (perpendicular to intake surface). Be sure you have the correct intake for the heads.

BTW what's wrong with the Vortec heads?
There are many SBC engines making 425+ HP with the Vortec heads. All they need is a little modification to allow a higher lift cam. The Vortec heads also make great torque.

Re: Early style head swap for Vortech? Need help please.
 

Try this thread, it may be helpful
http://www.offshoreonly.com/forums/s...ad.php?t=93389
Bob

Re: Early style head swap for Vortech? Need help please.
 

Thank you much for the quick reply. I have other questions. Do people start a new thread for each question?

Re: Early style head swap for Vortech? Need help please.
 

Not necessary, just add them to this thread if you wish.
If they are on different topics I might consider starting a new one. It'll get more attention that way too.

Bring'em on!

Let me ask a few questions of you:
What boat?
How big?
Type of drive? Alpha or Bravo?
What cam kit did you have in mind?
What intake were you planning?
Carb?
Changing exhaust?
What prop are running now? Need make, model, and pitch.

Re: Early style head swap for Vortech? Need help please.
 

Thanks Iggy, It's a 1989 IMP 23' with a alpha drive. I don't want to convert to a Bravo "$$". So i was going to put a new set of upper gears, 1.34:1 this i was told is good way of keeping it together, also a drive shower. I do not hole shot the boat ever time I move it if ever " that should help too." The prop now is a 4 blade 14 1/2 X18 SS. As for the intake and cam, I'm looking at the Edelbrock performer RPM package. D234/[email protected] L.539/548 hydraulic roller 1500-6500. I was going to degree the cam to bring down the red line to 5800. 6500 will cook the alpha iv been told. They also have a non roller that is D234/[email protected] and lift is 488/510. A classic 650 Holley vac secondaries will do. Don't for get a MSD to fire this pig up. I want to move prop size to a 14 3/4X23. And finely to let it breath, exhaust straight thought transom. " need advise on best parts for that too"

Thank you
Rob

Re: Early style head swap for Vortech? Need help please.
 

You currently have an 18" pitch prop on it now?
Sounds a bit low for the boat. I have a 1988 21' Formula with a 270hp 350 MAG and an Alpha drive (1.5:1) and I'm spinning a 21" Laser II. Also have a 21" Mirage as a spare.
Is it possible you already have the 1:34:1 gears?

Before you go buying parts you should pick up a copy of "Small-Block Chevy Marine Performance" by Dennis Moore. www.mooreperformance.org
This book will help you pick the right parts.

Re: Early style head swap for Vortech? Need help please.
 

Ok, I went to Edelbrock's site and looked up the cams your considering.
According to Dennis Moore's book the cam you're thinking about is too big for a 350. Crane Cams makes a similar grind and Dennis states that this cam should "only be used in a 383 to 406 in. SBC".
Look at the Chevy p/n 24502586 and Crane p/n 109631.

Re: Early style head swap for Vortech? Need help please.
 

Hey Iggy, your 100% right about the cam, that would be the best choice.

The GLM exhaust is the ticket as well, nice separation of ports into upper riser and very well built all with a reasonable price.

I checked the prop today, it's like I said. I top out around 40mph @4700rpm. I can't check the gears unless I count the gear teeth. What prop would you recommend?

One last thought is, wouldn't I be better off putting a Whipple or Procharger with 5-7lbs of boost and call it a day? "no other mods except exhaust and ignition."
Thanks
Rob

Re: Early style head swap for Vortech? Need help please.
 

Hmmmm......at 4700/4800 rpm I'm moving at 58-60mph.
You must have a heavy hull. Or does an extra 2 feet of length make that much difference?

Have you tried a different prop just to see what happens? Maybe a 21" 3 blade?
Write down the serial number off the upper gearcase and go to Mercury's Parts Express web site. Enter the S/N and I believe it will tell you what ratio the drive originally came with. Mercuy Parts Express

Tossing a blower onto the stock engine could result in a trashed motor. I don't know how many hours you have on it but without rebuilding it with the proper parts a blower will tear it apart.
If you want to keep the bottom end as is then a cam, heads, intake, ignition, and exhaust is about all you can do. Even then, depending on how worn out the cylinders are, you may not get the full potential out of it without a full rebuild.

Re: Early style head swap for Vortech? Need help please.
 

Yea, it's heavy. But what a nice ride. That is why i want a few more Hp, to get it up to 50 or so.
How much power can i put through an alpha one? I will check mercs site for the gears. but I'm pretty sure the only came with 1:50-1.
I have most of the parts for a nice 383. But I figured the drive could not handle it.
Thank you so much for all your input, this is a great site with nice people. I'v ben reading the tech board like mad, learning allot.

P.S Nice quote.

Re: Early style head swap for Vortech? Need help please.
 

I had a searay 207, 21 foot 1985 bow rider. Not sure how much weight, but a very heavy boat. It came with a 305- ran about 40mph. I put a 260 hp 350 in it and it ran 45. The problem was when I loaded the boat with 8 healthy friends and wanted to ski, it almost wouldn't get on plane. I built a supercharged engine for it, 350, using a 144 b+m blower, way more trouble than it was worth.put 1.34 gears in the top end- bad move, get the heavy duty 1.50 gears from merc.I finally built a 383 stroker and wow, perfection! With this engine, it leaps onto plane even fully loaded with people, accelerates hard, idles great, it completely transformed the boat.My 383 dynoed at 400 hp, 430 ft.# of torque. drive died after 2nd season, thats when I put in the heavy duty gear set. 4 seasons later, still runs fine.I will do the occassional hole shot, but usually roll on the throttle. Stay with naturally aspirated- you can build all the hp an alpha can take without the expense and complexity of a blower set up with a 383 and it will run forever!

Re: Early style head swap for Vortech? Need help please.
 

I forgot to mention, I have a friend who also built a 383 using the vortec heads that were on his 1999 350, and it made more hp and torque than my engine that had canfield aluminum heads, stay with the vortec heads and spend your money on a good steel crank and rods. Also, with the 383, my searay ran 58 mph on gps, lightly loaded.

Re: Early style head swap for Vortech? Need help please.
 

Why do you feel the 1.34 will be a bad move? Is it a RPM isssue or will the motor be under to much load for the torque the engine puts out? I'm all ready to do a 383, It's the drive thats freaking me out. I don't have the cash to do a bravo.

Thanks

Re: Early style head swap for Vortech? Need help please.
 

The boat is listed as a 24.5 foot but I keep calling it 23 foot. My last boat was a 23'

Re: Early style head swap for Vortech? Need help please.
 

Sorry about not getting back to you right away, to use a 1.34 gear set you will need way more hp than the alpha can take, or you will need about a 7 pitch prop! With a 383 and about 400hp, with 1.5 gears, you will probably only need a 21 pitch 4 blade for your size boat. I had great success with the revolution by mercury- it really helped the prop stop blowing out in turns and on hard acceleration. Hope this helps. Rick.

Re: Early style head swap for Vortech? Need help please.
 

Hi Rick, I think that would be the best set-up. I posted another thread about the gear ratio. Every one made it very clear that this was not a good idea. This is such a great board! You guy have saved me so much time and money. Can't thank you guys enough.

I think the 383 will be the ticket along with the 1.50 HD. I will take it easy on it. If it breaks it breaks. "I have sea tow and a radio" Im going to start putting the pieces together this weekend. I'm new to the make the boat faster and I can't believe the power it takes to gain a few mph. It's so different from the muscle car world I'm use to.

The next question I have is what about fresh water cooling. I have raw water now and I wanted a "full system" if i was to put a fresh motor in it. If I sell the boat I can always pull the motor and drop it in my Tahoe. Can they take the heat of 400-hp? I would like to do this since I could then take advantage of aluminum heads and intakes along with longer engine life and rust free exhaust manifolds. What do ya think?

Thanks
Rob

Re: Early style head swap for Vortech? Need help please.
 

I don't know the specs of the second cam that was recommended, but the performer RPM cam you first mentioned is a crappy choice for a boat. You must have a flat torque curve or you'll never get it out of the hole, or if you do, it still won't accelerate worth a darn.

A 383 is a nice choice as it gives a good torque boost.
Combine that with a "normal" performer intake and a cam with around 220 degrees duration @ 050. Your boat is heavy and needs grunt. You'll get it with that combo.

4700rpm 1.5 gears and an 18"pitch prop sound about right. Without doing anything to your motor, I believe a 21" prop will put you at 4200rpm and about the same speed. A 19 pitch prop maybe 4500rpm and a little faster speed.

Be aware that this hull and power combo will never see more than 55 unless you plan to throw a lot of money at it (not recommended).

Re: Early style head swap for Vortech? Need help please.
 

I ran raw water cooling, and in the searay, at full throttle the engine temps would start to climb. I chased this problem for a couple of years and finally decided that the alpha drive was not really designed to go 60 mph. At 55 it would run all day, above that, it would start to warm up. I ended up getting rid of the boat and getting a nova, but I think the fix would have been to run a thru- hull water pick up and a bravo sea water pump. As far as closed cooling, I don't have any expierience with it, I ran raw water and had no issues with corrosion, running aluminum heads and intake, but I never ran in salt, and the boat only stayed in the water for a week at a time once a year on vacation. Always pulled the boat out after every use when not on vacation. Mcollinstn is way off on your est. top speed, I would guess it at 54.8. Just kidding, I think he is dead on, I've read a lot of his posts, listen to what he has to say, his info comes from hard work and experience. As far as cams I used a crane cam, I think the number ended in 831 but I'm not sure, would have to look it up. Easy to go too big with cams and carbs in a boat.I used a sea demon 650 and felt it was fine, good throttle response, amazing acceleration over stock.