vortec heads on sbc 400
im wondering what i kind of gains and compression i could get out of running a set of 350 vortec heads on my sbc400. its got 4 valve relief flat tops, comp 270 cam .470 lift, 224 duration, full length headers, running a performer intake which id still run for the vortec style heads, customized 650 double pumper. the current heads are 882 heads that have been pocket ported, triple angle valve job, and decked. will vortec heads be able to handle my cam lift, and could i still run it on 93 octane gas? how much hp could i gain
You will be running at least 10.75 to 11 to one. You will gain of bunch of HP by better flow and more compression. If your gear ratio allows, you will be able to take advantage of a bigger cam. BUT the heads will have to be modified to accept the springs for that cam and to have adequate guide-to-retainer clearance. The Performer intake will also be a choke point for the heads. You may also want a bigger carb.
I dont think the regular style performer will bolt up to the vortec heads. You will need the vortec specific performer. The vortec manifold has 8 bolt holes instead of 12 I believe.
Stock vortecs are supposed to be able to handle .475 lift, but I have heard mixed opinions about that.
Here is a similar build for vortec heads on a 400 but has a tad bigger cam and bigger carb. http://www.chevyhiperformance.com/te.../148_0306_406/
Stock Vortecs will just handle .455".
Modified ones with better springs and
the guides cut down to handle somewhat
over .550 can be had from hi po Chevy
dealers like Sallee Chevrolet.
Chev also makes a high perf iron Vortec
sbc head with 200cc or so intake ports (the
production stockers are just 170cc) and
a thicker deck to prevent the cracking
that frequently occurs in stock production
pieces. They also have larger valves, etc.
However, you're talking the same price
as Edelbrock's excellent Vortec alum
heads, which will flow better and are
of course lighter.
For intake you'd definitely want the
Vortec Performer RPM (or Air Gap if
you just drive in only warm weather or
live WAY down South).
Go to the Silvolite / Keith Black pistons
website, they have a compression
calculator that factors in head cc's etc.
You just need to know your piston's
compression height spec.
For some interesting sbc combo's, incl
406s etc, check these pages out
http://www.chevyhiperformance.com/te.../148_0306_406/ (that one is a real monster)
thanks fellas, i planned on using the vortec style intake because i know mine wouldnt work on those heads. it sounds like id have to do a fair deal of machine work to get these heads to work. i have these vortecs just laying around at the house, but would it be better just to go with a set of world motown heads? anyone ever use them?
I picked up a set of the vortec heads in a trade. had my machine shop do the required mods, added a air gap and not looked back. lots of good power for cheap.
how much did the mods cost, like getting the spring seats bigger to run stiffer valves, will cast iron heads hold up to 11.1 compression? my rear gear is 3.73 with a locker
Thanks Macx! So, now here is the question, how streetable is this cam?
GMPP HOT hydraulic roller, with 0.525/0.525 in. of lift and 218°/228° of duration @ 0.050 in. of lift.
I'm looking for a Cam for a 383 but to be honest, as I said in one of my other posts, I don't know anything about them.
It depends a lot on what your idea of
Do you mind or want, or don't want,
just a little bit of a lopey idle.
Do you do most of your driving in
the 1500 to 2500 or 3000 range,
or do you keep the rpms up a
little higher, like 2000 & up.
And of course, you have to build
the rest of the motor to match
the cam, or vice versa.
220 @ 050 in a 350 is a good street
performance cam that will have just
a little bit of a ragtged edge but will
still be plenty driveable.
Above that and you start getting a
little more ragged, but you've got
33 cubes more, so that'll soak up
about 5 degrees more @ 050 and
run the same.
If you look thru the dyno tests
on that Ryan's carpage, here's
all on 383's, most with quite
good heads (AFRs mostly,
but you can also see that
the Vortecs are VERY little
behind the AFRs on similar
Also, your torque peak is
a good clue as to how
it will run in the lower
4000 rpm torque peak is
a great high performance
cam that will still run pretty
nice on the street.
For a daily driver, I'd be
cautious about going with
a combo that has a torque
peak much above that.
Actually, a torque peak of 3500 to 4000
works really well, and will give you
a tad more in the lower rpm ranges
and be a bit smoother.
So - here's some comparisons:
again, all with 383's & good heads
230/236 duration, torque peak at 4000
of 500 lbs! Peak hp at 5500 of 490.
That's a stout motor! Also notice
the fairly wide spread between the
torque and hp peaks. That cam will
not be real peaky, so will have a
nice wide torque curve, with good
lower rpm torque. At least in that
combo. You could put that cam in
a motor with worse heads/intake,
and it would run rough and be
weak on the lower end.
218/223 @ 050 - 470 lbs at 3500
440hp @ 5000
Another stout combo with great
low/mid range torque, just not
quite as much hp or torque cuz
the peaks are at a lower rpm than
the one above. Should rev
nicely to over 5500 - heck of
a nice street torque curve and
you don't have to wear your
motor out or break it revving
it high to get the power.
Notice that one is close to the
GM Hot Cam.
In contrast, there's one with 230
@ 050 & the torque peak is
515 but it's at 4500, and the
hp is 470 but at 5500.
Getting a bit on the ragged side
in lower rpm.
There are some dyno tests with
the GM hot cam, & they do pretty
well, but comparable tests with
Comp Cams hydr rollers, the
XE series, seem to usually do
a little better on both torque
& hp with similar specs.
Some good Comp hydr roller cams
would be the XR276HR with 1900 to 5600
rpm range with a 350, so take 200 to
300 off that for a 383.
The one above is the XR282HR,
getting a little ragged.
There's a Magnum hydr roller,.
the 280HR that has just about
identical specs to the GM hot cam
and the rpm range is 2000 to 5500
on a 350, so should be a
great street cam for a 383.
Lunati also has some super cams.
That last link about the 406 that
puts out monster torque has a
cam about the same duration
but around 470 lift.
Take a look at the Lunati 54743 with
a range of 1800 to 5800 in a 350,
or the one just under that.
It's as important to match your combo
With any of those cams, incl the Hot Cam,
and your Vortec heads, be sure to run
an Edelbrock Performer RPM intake and
about a 750 carb and 1-5/8 headers.
With those heads you should be able
to run near 9.5 compression on 91 octane.
Read that 406 article, they used Vortecs
and see what they ran for compression
and spark advance. That same setup
in your 383 should only be ~20 lbs tq
and 20 hp less than that 406, and that
would do any street machine proud.
It would probly have 200+ higher tq
and rpm peaks cuz of your fewer cubes.
But - ask around a lot with reputable
hi perf shops that build good motors,
and talk to cam manufcturers.
Then fit the combo to your driving style
and vehicle gearing and weight.
A good combo can go 1 step milder
cam than a person might think and
have just as much power and be
Good luck! Have fun with it.
Thinking back QUITE a few years to some cars I drove
in my real hot rod days, here's some observations:
Far & away the fastest was a 66 426 street hemi
with 3:54 gears. Not real good out of the hole
cuz I couldn't get a whole lot for tire in the
fenders, but it was brutal for torque. The
torque peak was relatively low for that level
of an engine at slightly over 4,000. During
daily driving it ran as smooth as my dad's
Chrysler 413 used to, and had torque at
any rpm range, even off idle.
Somewhat of an opposite was a 67
Camaro SS 397/375 hp with 3:73's.
That was exactly the same as a
427/425 hp except a smaller bore,
had the same cam, rectangular
port heads, etc. Fairly high rpm
for a street engine, but a real
blast to drive. Torque peak was
probly closer to 4500 if not even
a little higher, and I seldom drove
it under 2000 rpm, but that wasn't
a problem. It really liked to rev,
and it was "pretty snappy" from
like 3000 on up, and not bad really
even around 2500.
Not as "smooth" as the hemi at
lower rpms, but I'd get a
real neat kick in the pants
feeling whenever I stepped
on it, instant response.
It definitely had a bit more of
an edge than the Hemi, but
that wasn't a problem. Great
So - again - how do you
like to drive, how heavy is
your vehicle, what gears
do you have?
BTW - the Camaro was quicker
than the hemi to maybe 70 or 80 mph
but after that the hemi would
run and hide from it.
Even with a fairly mild cam,
the hemi would pull 7200 in 4th
gear with 3:54's and 29"
diameter tires. From 40 to
over 130 it would pin me right
back in the seat, and it topped
out at about 172 in that configuration.
;-)))))) Now THAT's the "good old days"!
For some background, the gears I'm using are stock 3.73's. The Transmission is a non-electronic controled 700R4 that's currently hooked to bone stock 305 (1984 Trans AM). The motor completely runs out of gas around 4500 RPM which is where the tranny likes to shift (runs to 4500, sits there a few seconds, then shifts...really annoying). However, thanks to a Transkit from B&M I can take that manual all the way to 5500 but the current 305 doesn't like that at all and really has no power over that magic 4500 mark. WIth over drive, I'm running 70mph at 2600rpm...not too bad if you ask me.
What I want to shoot for in the 383 is a red line around 5500 but i want it to pull all the way through it. I get really sick of running out of power before the red line. I've got a 67 Camaro that would pull until the engine explodes (bought it that way, no Idea what type of cam is in it). I'd like to hit 400hp, but anything more than 440 is really way more than I was looking for...though in the words of my idol... "Oh, oh oh..MORE POWER!!" So if I "accidentally" hit 450 I won't complain to much. My checkbook might from running through a tank of gas every third day, but eh...what's the price of power?
The motor itself is a 2000 Chevy 350 that was overheated once and is in the shop right now getting checked for cracks and for the forseeable future, if it's ok, will be my daily driver (just bought a house only money I have left is what I set aside for this project) Pending the out come of the crack check, I have tapped Jegs for their Edelbrock vortec intake (carborated) and I plan on using my current 4bbl Rochester which from what I've been reading on this site is a really good carborator if it will fit on that intake. I just need to get it rebuilt and tuned for the new motor. I also don't know if the mounts will be correct or if I"ll need an adapter kit or not. The intake is supposed to run (Idle to 5500) which would fit right where I need it and matched to the right cam, would be perfect (Or so I'm told by the experts here).
The heads are the original Vortec 1.94/1.56 heads from the motor (L31?? I don't know). I plan on porting and polishing them as well however one of the guys I work with said that some people have problems with the Vortec's when they try that. I honestly don't know since this is the first engine I've ever worked on. I really do appreciate the comments. And thanks for all the help!
350 heads on a 400
I didn't see where it was mentioned above but you will have to drill steam holes in the 350 heads before you put them on a 400, I learned this the hard way on one of my 400 engines,thinking a small block is a small block, maybe the 350 vortec heads already have the steam holes ,,I don't know, easy to find out by placeing the head gasket on them that goes to the 400, if the holes aren't drilled it's going to run hot and something is going to crack sooner or later, I found this out from a Napa machineist when I took the 350 heads in for a valve job, he called me up and told me the heads were cracked in several places and showed me where the holes needed to be drilled in the next set I put on the 400
The need for a vortec intake, vortec rockers, and vortec valve covers make them expensive to use if you already have a good intake, rockers and valve covers. Plus the machine work is not chicken feed.
You would do better just to get a set of 200cc Dart iron eagles or something similar.
Your Performer intake (if it's a Performer versus a
Performer RPM) will do fine up thru about 5,500
like it says (remember that's on a 350 so you'll see
a little shorter rpm curve & lower torque peak on
a larger 383), but a Performer RPM is stronger from maybe
around 3000 up esp. on a 383 and only loses a very few ponies
to a regular Perf under that, and the extra cubes of
a 383 will magnify that somewhat. You'd be stretching
to get your 400hp + out of a regular Performer and would be
in danger of having to use too big of a cam for the intake
which would weaken your lower end quite a bit - then
your intake would fall off just after your cam gets into
its best rpm range. Net result, a weaker overall engine
than if you used a smaller cam.
A regular Performer is more suited to cams in the up to 215 intake
duration range (without looking) - check Edelbrock's
Performer cam specs which is the matching cam.
On a 383, that regular Performer intake will torque peak
maybe before 3500, and the Perf RPM would peak
a little higher plus generate more torque above 3000
or so, extending the whole torque curve higher -
basically continuing it as much as 700 rpm or more
over where the regular Perf starts to drop off.
Then look at their Perf RPM cams, although they tend
to be just slightly long on duration, you can see what
they consider to be a match to that RPM intake.
Your gearing should be really good, but you'll need
to beef that 700R4 some eventually and get at least
a 2500 stall converter. I've done a bunch of research
on the auto OD's and will post some links later so
you can read up on them. If you do a fair amount
of freeway driving, 2500 @ 70 can get just a bit
tiresome cuz you'd be up around 3000 to hit closer to 80.
I've got 3:55's with fairly tall tires (16.5" diameter,
255x50x17) and I run 2500 at close to 80.)
Your 383 will be a torque motor versus an rpm
motor, and it's usually more productive to let
the torque pull the car rather than rpms, cuz
in a torque motor you run out of the peak
torque rpm envelope quicker, so deeper gears
really don't do as well as gears more in the
mid 3's, - so you might want to consider
using a 220 to 225 cam and an RPM intake
to extend the rpm of your "power curve envelope"
up another 500 rpm plus. Would be a better
match for those gears. Plus the R4 has a real
deep 1st gear, so you'd rev thru it very quickly
and wouldn't be taking advantage of the
torque to accelerate the car unless your
engine will stay in that best rpm envelope
longer, like legitimately thru 5500. Just becuz
an engine will feel like it's pulling thru a
certain rpm point doesn't mean it's making
rpms more than it's making torque, in other
words is on the downslope of both the torque
AND hp curves. You want basically to shift at or
just past your hp peak which will bring it
down to about your torque peak. That's
your best acceleration rpm envelope.
Or you could use taller tires, which give you a
longer foot print and more traction out of the
hole anyway - that's the cheapest way to "change gears"
Remember - you've got to match everything to the
same basic rpm range. So with a Perf intake, I'd
stay around 215 intake duration max. You'd be like
gangbusters up to 4500 and would pull thru 5500,
but a Perf RPM and cam in the 220 to 225 duration
would get you probly 30 more tq & hp and at an
extended rpm range - like you say "pull well thru
the 5500" point and still be in the fat part of the hp curve.
All those cam & intake descriptions are for a 350 inch
engine, you've got to remember that the ranges and
peaks will be around 500 lower on a 383.
I'll also link some more articles later today that
I have on 383's with Vortecs - so you can see
how they're built and what their power curves are.
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