1990 5.7 vortec head swap

[powerhaulic]

I have done quite a bit of searching here and am still looking for some answers.

I need to know the cam specs for the production cam in my 1990 5.7
I have a new set of vortec 062 heads from GMPP, an intake i got @ swap meet.
I want to use a set of comp 1.6 magnum rockers instead of a cam swap.
I will be physically checking retainer to seal clearance, but need the cam specs so I can figure the additional lift for the rockers.

I have the valve covers off and it has a set of 217 heads which are listed as having 64cc chambers, so compression will be the same.

The engine is OC775*** which comes up as a model 457B100CR, parts list says cam #431-5943.
The engine is a flat tappet motor as I can see down from the valve cover.

The boat is a Sea Ray 210 with only 210hr, and runs very well. 1/2 tank fuel and myself solo will run 50-51 with 19p quicksilver stainless and 1.5 drive @ 48-4900.
So with a bit more power and a 21p prop should give me a nice increase.
I figure between the heads and rockers 50ish hp increase

Thanks for any help

 

[Scott Danforth]

Re: 1990 5.7 vortec head swap

start by reading here http://forums.iboats.com/volvo-pent...-into-performance-upgrades-aq271c-503800.html

your compression ratio will increase from your current heads

 

[powerhaulic]

Re: 1990 5.7 vortec head swap

start by reading here http://forums.iboats.com/volvo-pent...-into-performance-upgrades-aq271c-503800.html

your compression ratio will increase from your current heads

Both heads are 64cc, there will be no increase??

 

[Scott Danforth]

Re: 1990 5.7 vortec head swap

the vortec heads are closer to 62cc if you actually measure them.

 

[powerhaulic]

Re: 1990 5.7 vortec head swap

the vortec heads are closer to 62cc if you actually measure them.

I'll take the 2cc change if it pans out that way. will still be under 10:1

I'd still need the cam specs tho, I believe it is a bit hotter than what u have listed for your stock engine.

this is a 1990 so it is machined for a roller setup, confirmed by eye :joyous:

 

[Scott Danforth]

Re: 1990 5.7 vortec head swap

all I could find was the 1988 350 mag cam info

Merc P/N 431-5943
GM P/N 340284
Flat lifter (non-roller)

Duration at .050 - 200 intake
212 exhaust

Lift at valve - .400 intake
.410 exhaust

Lobe centerline - intake 108 deg ATDC
exhaust 112 deg BTDC

Lobe seperation angle - 110 deg

I doubt the specs changed much for the roller you have. I still would swap the cam myself.

 

[Walt T]

Re: 1990 5.7 vortec head swap

Doing all that won't give you a "Nice" increase. DO NOT change rockers to 1.6 without knowing exactly what is going on inside that motor with all the changes. Don't get me wrong I'm not saying there wont be a power increase. I'm saying there won't be enough to make a difference if there is any. Any power increase can come at the expense of low end torque if you don't know exactly what you're doing. You need to know what pistons are in there first. The casting number off the heads will tell you exactly what heads you have. There are different Vortec heads with different valve sizes, springs, stem lengths and chamber volumes. One cam or one rocker does not fit all. If 1.6 rockers were so great why wouldn't they be used in the first place?

Go online to Chevy cylinder head Identification - Small block casting numbers and check the heads first. CC the heads to verify they haven't been modified too much. If you insist on trying 1.6 rockers, then you WILL check piston to valve clearance in every cylinder and you will not take shortcuts. DO NOT take anyone's word for it that "they'll be fine" You wouldn't take a persons word for what spark plug is best for your motor when they don't know what car you have right? That's whats happening here. Yes, Vortec heads are great and they can give a pretty good HP increase. They are designed to be run with specific cams with an entire valve train to match. It's pointless to do all this work and only do half of it. Sorry, I don't mean to **** anyone off or flame anybody but you're going about this all wrong. This is just my opinion of course and you're free to try whatever you like. Do the math homework first, it can prevent a lot of grief.

Here is some fantastic information on Chevy heads: A Guide to Vortec vs OE Small Block Chevy Heads | OneDirt

I'm curious though, why do you want to know what cam is in there now? It's not a Vortec cam that much we know. Knowing the extra lift doesn't give you piston to valve clearance. 50 hp increase isn't possible this way. Even if you achieved that it will be above 5000 rpms which is useless. Increasing lift will help low end torque in theory but can negatively affect top end. You need duration for that. Here's what happens when you do what you are thinking; Higher lift at lower rpms work okay with everything else being stock. However at 5000 rpms the springs are pushed well past what they are designed for and all sorts of bad things happen. Valves now "float" when they didnt before simply because the springs can't react fast enough as they weren't intended to be used this way. Floating valves hit pistons. maybe very little at first but enough to cause slight ridges in the soft piston. Those ridges then concentrate heat lines and eventually can melt and a hole is formed. The very first thing you'll notice however is a loss of power from the original set up. It all has to work together.

 

[Walt T]

Re: 1990 5.7 vortec head swap

Ya know what guys, Its easy for me to sit here on my high horse and be a nattering nabob of negativism when a guy simply wants a little more power and is smart enough to ask questions. I should at least offer solutions instead of just shattering his dreams of winning the IHBA title.
The one thing Powerhaulic did do right was procure Vortec heads. We don't know valve sizes or anything but he can check those casting numbers out. I will assume you can't easily change the camshaft without pulling the motor out of the boat which is common. The number one thing that will get you more power is increasing compression. Smaller chamber sizes do this. So does milling heads. Vortec heads can really wake up a stock engine this way. Pull the heads off, and I imagine the pistons will have valve reliefs in them. If they're flat well then maybe you can't mill them without a camshaft. Take the Vortec heads to a machinist and talk to the man. He or she can make a good recommendation as to how much to take off the heads and safely retain clearance. Show the machinist a picture of the pistons. They'll know what you have. Let them know what you want to do rockers or cam wise. They'll know you're not an expert so don't try to impress them. My guess is for now to use the stock cam setup, and check clearances once the heads are milled. They may say use the 1.6s but they'll explain it wont get you more speed.
Don't allow them to port the Vortecs. The Vortec port design is beautiful as it is, leave it alone.

Trust me when I tell you you will have more top end power with the stock 1.5 rockers. The 1.6s are great for pulling skiiers and stuff, but with a stock cam, not so good for top end. Your machinist may disagree and make a good recommendation for springs, etc. I would trust but verify the clearances.
By the way 50 mph is pretty darn good for your Sea Ray. That's a heavy deep V hull and takes a lot of power to move it that fast. I have a 22 foot cuddy with a Volvo DP 5.7. 45-48 gps was about all it would do with all the junk and people in it. I built a stroker motor for it with stock heads and a specific cam and it will overwhelm the 23" aluminum props on there now. These are perfect for towing kids around so thats what I use. The stainless 25" get me 53 mph at 5200 and the engine just keeps climbing but I can feel the power slipping away above that. I have a set of Vortec heads I plan on installing, but the flat top pistons will require a custom cam grind and the lobes have to be ground to allow the rod caps to clear the cam. I like to think I'm am expert at this high performance stuff but even I have to research this Vortec stuff. I do have a roller cam in there now, and I can easily change cams and heads with my engine access. The point I am making is not to brag but to point out what can be done if it's all built to work together. Please ask questions and I will do my best not to ridicule you and give you my divorce lawyer's number as you'll be needing it once you discover you can watch ball games unmolested in the garage when the family thinks you're "taking precision measurements" out there. Yep, precision measuring of the actual volume of beer in a 12 0z can. It actually does vary. Use a CC syringe to draw it out and 'precisionly' measure it.

Sorry for the long posts I know I get carried away. As for all you poor guys who read all this hoping for something funny concerning wives, beer, recliners in the garage, sorry but the dog is seriously wanting to go outside.

 

[powerhaulic]

Re: 1990 5.7 vortec head swap

Walt,
I understand very well where u are coming from.
I am positive the pistons are slight dish 4 relief pieces.
I got the boat from original owner, and the paint is on every bolt on the engine. I broke the paint on the carb bolts when i serviced the Q-jet.
It has 217 heads which are the crate non swirl port heads with 64cc chambers. So compression will remain basically the same.
I picked up a nice marine (brass lined) hi-rise alu intake @ a swap meet and am planning to convert the Q-jet to elect. choke as vortec manifolds have no exhaust crossover for choke heat. (have several parts carbs)
I wanted to know cam specs so i can figure retainer to seal clearence in the vortec heads w/1.6 rockers, and then determine if i am changing springs on these new not reman heads
I do not plan to do a cam swap, but if I do I would not bother to reinstall a flat tappet cam. The block in this boat is machined for production roller cam, so that is the route I would go if I were to do a cam swap.
So it comes back to retainer to seal clearance and ease of upgrade.

I am not intimidated by the labor to accomplish any of this or go deeper, as i am an ASE master tech.
I was simply looking for some help with details from people who have been here before.

Thanks

 

[FreeBeeTony]

Re: 1990 5.7 vortec head swap

I would stick with the 1.5 rocker and replace the cam with a roller. If you're going to fool with the bottom end I'd build a simple stroker....just my $0.02.

 

[NHGuy]

Re: 1990 5.7 vortec head swap

Boat motors have different stresses than car motors. I would ask the guys on offshore only and speedwake what they think of 1.6 rockers.
Myself, I'd get a marine grind cam package from Comp and put it together with the 1.5's since it's been tested that way. If you decide to do the bottom end, get pistons with a dish under the combustion chamber and flat under the rest of the surface. That will get you great quench for even combustion. You want .038 for a quench value. Old style circular dished pistons don't have good quench, so I hope you find flat tops in there. That's what the picture looks like in Mercruiser's manual, but who know what was installed.
Boat engines cool well so a nice tight quench will promote good combustion. ie. resist detonation. It can be done without super high compression ratios or timing advance. Boats run at high loads most of the time so it's not like a car that just bolts to red line and then lets off the gas. A 9.2 or 9.4 CR might be good since there's no knock sensor to save you if you go too big.
The block you have can come with flat or roller lifters. A roller upgrade can be done without block machine work as I understand it. Vortec heads don't offer a lot of lift so see what you can do with the parts you want. You can work the Vortecs to get your preferred lift though, as you are aware. Another consideration is that the exhaust risers are close to the valve covers and you can't always put big covers on to clear a tall valve train.
If you get a comp marine cam they give you the valve lift values and a recipe of needed parts like springs, lifters, retainers and keepers to use. From that you can figure what, if any machine work to do on the Vortecs.
BTW I just took a look at Mercruiser's parts list. They use the same Mercruiser part # for my cam with the early non vortec heads as they use for the 97 flat tappet motor which does have vortecs.
I have been researching cams this winter and have not seen any cam companies specifying whether their grinds are specific or even preferable for one head or the other.

Here's a discussion about strokers for marine. Turning a 350 into a 383 stroker

 

[Walt T]

Re: 1990 5.7 vortec head swap

ASE master tech kind of explains a bit. Keep in mind boats aren't like cars. They don't respond to a 30 hp increase like a car will. Boats are shoving aside a massive amount of water weight just to move at a lousy 30 mph. Cars are rolling down a road with only friction and drag so any increase in HP is felt easily. A boat is like a truck towing a massive 5th wheeler with a huge drag coefficient uphill in second gear. A small increase in HP doesn't make a difference in this case. To make a difference and actually be able to turn a steeper pitch prop you need 75-100 hp for a boat like yours. That's only at 5000 rpm. You still want to be able to tow skiiers and play all day long with that same motor so you need some serious torque to go with it. That's why the guys have mentioned stoker motor which I agree with. Or drop in a 454 which STILL wont get you to a steeper prop!! It is SO difficult to build to turn a steeper prop you have no idea! It can't be done with just a cam or heads. However I am wholeheartedly behind your ideas with the Vortec and would really like to read the results when you do it. Mill the heads or not, let us or me know what was done and the results. Hopefully you'll prove me wrong. Wouldn't be the first time. Heck I was wrong when I told em Nixon was just a fill in for the real crook but that's what they all said anyway. Of course they also say I'm an excitable boy who needs lawyers guns and money.

 

[Scott Danforth]

Re: 1990 5.7 vortec head swap

FWIW comp cams recommended the 1.52 rockers when I talked to them.

 

[NHGuy]

Re: 1990 5.7 vortec head swap

Or, to answer your actual question! According to Mercruiser the cam lifts your intake valves .394", and the exhaust .404" with stock 1.5 rockers. The intake lobes are .263" and the exhaust are .269". So 1.6 rockers will get you .421 intake and .430 exhaust. Not crazy lift values, the marine cam I want lifts higher than that with 1.5 rockers.

 

[blaneym]

Re: 1990 5.7 vortec head swap

Walt,
I understand very well where u are coming from.
I am positive the pistons are slight dish 4 relief pieces.
I got the boat from original owner, and the paint is on every bolt on the engine. I broke the paint on the carb bolts when i serviced the Q-jet.
It has 217 heads which are the crate non swirl port heads with 64cc chambers. So compression will remain basically the same.
I picked up a nice marine (brass lined) hi-rise alu intake @ a swap meet and am planning to convert the Q-jet to elect. choke as vortec manifolds have no exhaust crossover for choke heat. (have several parts carbs)
I wanted to know cam specs so i can figure retainer to seal clearence in the vortec heads w/1.6 rockers, and then determine if i am changing springs on these new not reman heads
I do not plan to do a cam swap, but if I do I would not bother to reinstall a flat tappet cam. The block in this boat is machined for production roller cam, so that is the route I would go if I were to do a cam swap.
So it comes back to retainer to seal clearance and ease of upgrade.

I am not intimidated by the labor to accomplish any of this or go deeper, as i am an ASE master tech.
I was simply looking for some help with details from people who have been here before.

Thanks

You may want to consider changing to a marine Holley carburetor too...
I know some people like Quadrajunks, and don't get me wrong because I've built them for street strip cars, trucks, and marine usage but they need the bottom of the main jet wells and well plugs epoxied so they can't leak, and there used to be and hopfully still is a gasket kit that has a thick gasket for that area, but I prefer the tuneability and better performance that I can get out of the property cfm square bore Holley. I and my Fiancee' picked up 4 mph with our Quadrant to Holley swap and can't hardly wait to see how much more performance we get when we change to the dual plane aluminum high rise intake I've chosen to match my Holley carburetor instead of using an adapter. Our boat is a 22' Regal Valante' (cuddy; not open bow) with a switch from a 17* pitch aluminum to a 19° stainless steel prop and now will hit 50 mph (actual GPS readings repeatedly) . We are planning more changes too.