Roller tip rockers on 95 4.3, to do or not to do?

[mattb100]

I had manifolds leak this summer and replaced them, everything seems OK. I began to wonder what the cylinders might look like so I decided to tear down top end this winter and check things out. A comp check before dis-assembly showed 160 psi on 1,3,4,5 and 180 on 2,6 seems OK but I still wanted to visually inspect cylinder conditions and check heads. My plan is for an edelbrock intake,( I installed an Edelbrock 600 carb this year), a basic head rebuild/valve job, and i can get a set of stamped steel roller tipped rockers for free. Any pros or cons to installing these. I believe they are 1.6 ratio. Thanks to all. Matt.

 

[Lager]

From what I read, the original ratio rocker is 1.5. Increasing it to 1.6 will give you a little more valve lift but nothing drastic and in the auto 4.3 engine, thats worth about 8 HP or so. The roller tip supposedly frees up drag, but its nothing your going to notice. If they are free, i would use them. They dont cost a whole lot, you can buy them for less then $100. If you are just planning on pulling the heads and rebuilding them and if you have access to a die grinder and some carbide bits, I would do a port match from intake to exhaust, maybe smooth the intake and exhaust ports of casting flash. Be careful what intake you buy,boats need low end grunt to get them going out the hole

 

[Lager]

This might help.http://forums.iboats.com/forum/engi...graded-to-a-4bbl-carb-on-their-mercruiser-4-3

 

[NHGuy]

Yes, use them. I did a higher lift cam with 1.5 ratio roller rockers and ended up with lift like you will get with 1.6's. The engine runs nicely. Your engine has the same bore and stroke as mine so you can expect similar results.
As far as porting, make it very minor. Maybe a little unshrouding near the valves. If you match the intake ports don't go bigger all the way through. You want to hourglass them so there is the same inside cross section area. Smoothing but retaining the original cross section size is supposed to produce a venturi effect. That's the phenomena of air rushing faster as it passes through a smaller opening. It's to retain or enhance your holeshot by maximizing your torque.
The lift and the reduced friction of the roller tips will be a help whenever the engine runs. Should get you some horses at upper rpm. But saving your torque is important.

 

[Volphin]

I went with Comp Cams Magnum roller tips @ 1.6 with a custom cam grind. Be aware that you will need 3/8 studs in true Vortec heads. I had my Vortec heads drilled and tapped for them. Are your heads Vortec or standard? The old standard heads, come with 3/8 studs as std equipment.

If I had the heads off, I'd swap em for Vortecs if you don't have them. Much better flow and smaller, kidney shaped combustion chamber... 64cc or so.

The eddy manifold you will need will be the 2114 for Vortec or the 2111 non Vortec.

 

[mattb100]

I think there was an earlier version of "vortec" heads. It has vortec 3 bolt valve covers but it will use the 2111 manifold, like first gen SBCs. I have not pulled heads yet, boat is all original. If cylinders check ok i will stop here, if not ?? It is supposed to be 50 this weekend, probably head out to the barn and get them pulled. Thanks All, for info, opinion and links.

 

[NHGuy]

Oh, that's right. Check the part # on your heads and see if they are Vortec. Vortec's will probably need machining to allow the greater lift of the 1.6 ratio rockers. As well as the correct studs.

 

[Bondo]

Oh, that's right. Check the part # on your heads and see if they are Vortec. Vortec's will probably need machining to allow the greater lift of the 1.6 ratio rockers. As well as the correct studs.

Ayuh,.... Just count the intake bolts,...

An 8 bolt intake is Vortec heads,...
A 12 bolt intake is Pre-vortec heads,....