Mercuryfan3

I am hoping that some off the knowledgeable people on this forum can help my with my half finished 383 stroker build.

I am in the process of building a 383 stroker for my 21ft Wellcraft.
My goal is to build a 400 hp or slightly more small block with a reasonably decent idle.
What i have so far is the following:

2 bolt 1998 vortec roller block
Eagle 3.750 cast crank
dss racing forged pistons with 1.425 compression height , -5cc eyebrows and total seal rings.
eagle rods 5.7 inch
edelbrock performer rpm or airgap (have both)
670 holley marine carb (new)
msd ready to run distr.
i have a set of new aluminium glm tuned port manifolds
Block is zero decked and bored and rotating assy is balanced.


I am going to run this through a 1.50 bravo xr
I know its not a race boat but id love a healthy strong running small block.

I,d like some advise on
the following
camshaft (comp xm270 or 276) reversion??
heads, i need something with 75 or 76 cc comb chambers to keep the flat tops under 10 to 1 cr.
and exhaust risers, i need to run through prop in the marina, captains call side exit.
Any insight would be very welcome.

SB

iTrader: (1)

270HR has been a great cam for 383's.
Pick your fav cy head - AFR/Brodix/EQ/etc Last few years lots have loved the Profiler sbc for the $$$.
GLM exhaust will usually require a length of inner pipe welded on. See search for Ryan00TJ threads on this. He had this set up (like many others)with that cam first in his 383 and then I believe I believe, closer to 240 at .050" with this set up. Lightweight 20ft boat that hauled azz. Near 80. Had Alpha SS and AFR heads though.

NHGuy

Yup, I have a virgin deck with flat tops and 76cc dart iron eagle heads. So My pistons are .025 in the hole. I calculated 9.9:1 static compression. But the DCR is a nice low 8 something or so. It's very lively. Has not been to the dynamometer.
Find some heads with 180 to 195 cc runners. With your zero deck block you can do a .038 to .048 head gasket and get your CR down plus great quench. Your boat is light enough to take off fine without using tiny intake runners like I started off with. My engine had been running out of breath around 5000 rpm so I opened up the runners over the winter.

Mercuryfan3

So i cant find any affordable 75 or 76 cc chamber 180 ccintake runner hads other than the afrs.
the iron eagle 76ccs have 165 runners so these are to small.
The block is already zeroed so i cant mount anything smaller as these pistons should give me 10.37cr with a 70cc head, i suppose that is with 9.025 std deck height.

i have looked so much that the numbers start spinning in my head.

i,am now leaning towards the xm 276hr but i want good low and mid range as this is where the engine spends most of its time.

so what is your thought about using the 75cc/180 afr heads with a 270 or 276 xm camshaft?

Trash

I'm running the 165 runner Darts on a a 377. I would not toss them off the list just yet. You could run them as is or open them up a little if needed. I've gone north of 5500 rpm with those heads.

SB

iTrader: (1)

If you are going aluminum, Brodix and I'd bet others offer a 76cc CNC combustion chamber option. These typically cost $150-$200 per head.

As far as cast iron 76cc heads, my brain comes up empty (which it is anyway ) but I'll do some digging when I have a chance.

Mercuryfan3

You dont happen to know a part number for these 75cc brodix heads? I cant find them on the site.

SB

iTrader: (1)

No. I think the IK's and RR's, or just Race Rites have this option. Been a while since I looked at them. Give'm a call.

NHGuy

I had a minute. The AFR head is your best move. $1515 bare, $1717 assembled, Pairs, Gulp. Either buy them assembled or get your own valves and springs. Make sure that if you get a higher lift cam that you have a tall enough valve for the spring you will use. I got so close to coil bind that I had my spring pockets cut, which took extra time and $

This gets 9.7835 cr with a .045 gasket that has 4.10 diameter.

I prefer to buy springs and cam as a set, But you don't have to. i also use short travel lifters because I want to avoid lifter pump up on long higher rpm runs.

GPM

***