5.7 vortec conversion

[ckgreenman]

I'm looking at replacing my engine (1996 Merc 350 Magnum Alpha 1) and was curious what all it would take to convert it over to vortec heads (mine are pre vortec with center bolt valve covers). I know the intake needs to be changed but other than that, is there anything else I need to consider? Is it worth it?

Thanks

 

[FreeBeeTony]

Re: 5.7 vortec conversion

As far as I know it's just the intake and heads.......I did it.

Just make sure you get an intake that matches your carb.........

 

[ckgreenman]

Re: 5.7 vortec conversion

As far as I know it's just the intake and heads.......I did it.

Just make sure you get an intake that matches your carb.........

Pfft. Technically the carb doesn't match the manifold now. Spread bore manifold and square bore carb. Both the carb and manifold are factory.

 

[FreeBeeTony]

Re: 5.7 vortec conversion

Pfft. Technically the carb doesn't match the manifold now. Spread bore manifold and square bore carb. Both the carb and manifold are factory.

So now maybe is the time to get an intake to match your carb.........

 

[John_S]

Re: 5.7 vortec conversion

I did the conversion on my '96 1/2 5.7L 2brl, a few years ago. Off the top of my head, here is what you are going to need. All the old parts can be sold on ebay.

- Vortec Heads
- Ext reach plugs
- Head Gaskets
- Exhaust Gasket
- Intake Manifold
- Intake gasket
- Intake mounting bolts
- 4brl Carb
- Carb gasket
- Throttle Bracket
- Fuel Line

If you already have a 4brl, you will just need new gasket and some carb tuning. Any bracktry that attaches to your current intake bolts might need new mounting or slight modification.

At prop HP will be around 280. I came from 210, so definitly an improvement. Make sure your bottom end is good repair. Wasting money if it is worn out.

 

[ckgreenman]

Re: 5.7 vortec conversion

I did the conversion on my '96 1/2 5.7L 2brl, a few years ago. Off the top of my head, here is what you are going to need. All the old parts can be sold on ebay.

- Vortec Heads
- Ext reach plugs
- Head Gaskets
- Exhaust Gasket
- Intake Manifold
- Intake gasket
- Intake mounting bolts
- 4brl Carb
- Carb gasket
- Throttle Bracket
- Fuel Line

If you already have a 4brl, you will just need new gasket and some carb tuning. Any bracktry that attaches to your current intake bolts might need new mounting or slight modification.

At prop HP will be around 280. I came from 210, so definitly an improvement. Make sure your bottom end is good repair. Wasting money if it is worn out.

Cool thanks. I already have the 4bbl carb and IIRC there wasn't anything attached to the center bolts on the intake. As far as the rest of the intake bolts, Do they have the same spacing as the 12 bolt manifold? If so that should make bolting stuff back on easier.

What exactly do you mean by ext reach plugs?

So now maybe is the time to get an intake to match your carb.........

hehehe. yeah.

 

[FreeBeeTony]

Re: 5.7 vortec conversion

Cool thanks. I already have the 4bbl carb and IIRC there wasn't anything attached to the center bolts on the intake.

Could this have been part of the problem as to why the other engine failed?

 

[ckgreenman]

Re: 5.7 vortec conversion

Could this have been part of the problem as to why the other engine failed?

Not sure I follow. There were bolts there but no brackets were attached.

 

[FreeBeeTony]

Re: 5.7 vortec conversion

OK......I thought there weren't even bolts installed........I misunderstood you.

 

[John_S]

Re: 5.7 vortec conversion

Cool thanks. I already have the 4bbl carb and IIRC there wasn't anything attached to the center bolts on the intake. As far as the rest of the intake bolts, Do they have the same spacing as the 12 bolt manifold? If so that should make bolting stuff back on easier.

What exactly do you mean by ext reach plugs?

I don't know if they have the same spacing but the vortec intake takes a special bolt and torque value and sequence. I do not have any bracketry attached to mine. The only thing I remember moving was the coil, which now attaches via a bolt in the end back of one of the heads.

Vortec heads take a different plug which has longer threads and extended tip. I'd have to go look that up for the specific one. (? NGK BP6EFS? or AC equivelent)

 

[FreeBeeTony]

Re: 5.7 vortec conversion

Ac Mr43lts

 

[ckgreenman]

Re: 5.7 vortec conversion

I don't know if they have the same spacing but the vortec intake takes a special bolt and torque value and sequence. I do not have any bracketry attached to mine. The only thing I remember moving was the coil, which now attaches via a bolt in the end back of one of the heads.

Vortec heads take a different plug which has longer threads and extended tip. I'd have to go look that up for the specific one. (? NGK BP6EFS? or AC equivelent)

The only things bolted to the manifold were the lifting brackets and maybe the coil like you mentioned. Shouldn't bee too hard to put back as long as I can get the right stud that allows me to bolt stuff back on.

Ac Mr43lts

Awesome. Thanks.

 

[180shabah]

Re: 5.7 vortec conversion

Don't forget, you can't reuse your old rockers.

self-aligning vs non self-aligning. Small detail, but it akes a big difference

 

[John_S]

Re: 5.7 vortec conversion

Don't forget, you can't reuse your old rockers.

self-aligning vs non self-aligning. Small detail, but it akes a big difference

His heads should have self-aligners. Mine did. I think that change happened in early 90's.

 

[ckgreenman]

Re: 5.7 vortec conversion

His heads should have self-aligners. Mine did. I think that change happened in early 90's.

Hehehe I never knew there was a difference until I cracked my engine open a couple weeks ago. Both were 193 heads. One had guides and the other had the self aligning rockers..

I've got to get new heads anyway so I'll make sure I get the right style rockers if they don't already come with them.

 

[betayv]

Re: 5.7 vortec conversion

hi there I been reading here trying to learn what type of heads are you using for that and how much did you paid for them are the heads marine app or automotive if they automotive thanks.

 

[ckgreenman]

Re: 5.7 vortec conversion

hi there I been reading here trying to learn what type of heads are you using for that and how much did you paid for them are the heads marine app or automotive if they automotive thanks.

Who is this question directed towards?

 

[180shabah]

Re: 5.7 vortec conversion

hi there I been reading here trying to learn what type of heads are you using for that and how much did you paid for them are the heads marine app or automotive if they automotive thanks.

GM didn't make car heads and marins heads, they just built heads and they went wherever.... I picked up a set of 4.3 vortec heads off of a wrecked low miles blazer for $50, assembled minus the rockers. Of course that deal is only good if I ever get them on the boat. Just hard to talk myself into pulling the engine for an upgrade, when it runs just fine as is.

 

[LS1_SE7EN]

Re: 5.7 vortec conversion

Did the cam have to be changed? or was it as straight forward as heads/intake (w/ supporting parts for the change over)?

 

[180shabah]

Re: 5.7 vortec conversion

The vortec haeds don't allow as much lift (.488 max IIRC), but if you are running the stock cam, or any cam that doesn't excede .488 (at the valve, not lobe) then no need to change it.