Offshoreonly.com - New guy with 383 and cam questions

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Quote:

Originally Posted by NHGuy (Post 4744583)

i like a lot of your design but I do have a suggestion. I'd recommend bigger intake runners. I'd do 195s to 215s. Your boat will take off fine even with the lessened low end of the big runner heads. it's a lighter 20 footer. A 383 will spin up so far you won't be able to keep it wide open. You are going to have to learn to drive it at scary fast speeds
I think you ought to look into external hydraulic steering.

These heads listed below are from Sierra Marine Mfg # 18-4503. I doubt they actually produce them. I think all the numbers look good for what I am doing here. Only thing I am not sure of if my exhaust will bolt right up. Vortec or non Vortec. I don't know if exhaust is the same.

As far as driving scary fast speeds I don't plan to keep it WOT across the lake. Although you never know. I don't want to kill myself.

185cc intake runner/ 62cc exhaust runner
72cc combustion chambers
2.02 intake/1.60 exhaust stainless steel valves
5 angle valve seat cut
Double drilled intake mounting for either standard 12 bolt GM intake or late model 8 bolt Vortec intake
Accepts both perimeter or center bolt valve covers
Fits 5.7 & 6.2L small block GM V-8 applications
Cast Iron
Corrosion resistance heavy-duty cast iron castings suitable for saltwater usage

Those are EQ (Engine Quest) cylinder heads. You can get them from many places including engine builders, which I’d suggest you do so you know the valve springs are set up right snd valve job done correctly. Also guide clearance of course.

Quote:

Originally Posted by NautiStrokinRat (Post 4744624)

I'll 2nd or 3rd that XM 270 HR cam as it is very nice grind indeed. It's good for avoiding reversion, has lots of torque and idles extremely well. Go with the roller, you won't be sorry. I've used it in a small block stroker 383 and big block stroker 496 with great results. The lifters get a little pricey but you can't go wrong. If you need good cam recommendations ask for Gabby at Comp and he'll take care of you.

This is the cam and roller kit I am probably going to order. SK12-417-8 Its a retro roller lifter with cam and timing gear. It includes the 270 cam

Quote:

Originally Posted by traviar (Post 4744728)

This is the cam and roller kit I am probably going to order. SK12-417-8 Its a retro roller lifter with cam and timing gear. It includes the 270 cam

Tried one of those in a 383 sbc, Dart 200 cc heads, it was done at 5100 rpm, and it was in a 20 ft Glastron

Isn't that all I want or a few hundred RPM more? Are you saying that was not a good combo?

Quote:

Originally Posted by GPM (Post 4744764)

Tried one of those in a 383 sbc, Dart 200 cc heads, it was done at 5100 rpm, and it was in a 20 ft Glastron

Yup, exactly. many of found 5k -5200 in 383’s. 5200 - 5400 in 350’s.

Quote:

Originally Posted by traviar (Post 4744768)

Isn't that all I want or a few hundred RPM more? Are you saying that was not a good combo?

Just my opinion, after spending all of the money to go to a 383, seems like you're leaving a lot on the table, definately do what you want.

Quote:

Originally Posted by GPM (Post 4744764)

Tried one of those in a 383 sbc, Dart 200 cc heads, it was done at 5100 rpm, and it was in a 20 ft Glastron

Maybe this will help the OP.

How fast did it go this way ?

▲▲▲▲▲▲▲▲▲▲ Yeah how fast did that go? I'm not trying to push my family boat to 80MPH. haha

Rotating assembly will be here tomorrow! I was going to order my cam today. XM270 but Scat said since its a 383 it has to be a smaller diameter cam or custom ground or #2 and maybe #6 main caps I think they said would hit. Is this common with a 383? My machine shop asked me to check before ordering my cam. Anyway comp cams said they will do that so I am waiting on a call back from the tech there I spoke to.

Yes, on 383’s because the extra stroke Hits rod bolts, yes, for many rod designs. You can either get rods that don’t do this or get reduced base circle cam. Make sure your engine machine shop advises you on this, which it sounds they sre doing.