1991tealRSt-topGuy

yeah, i know, i'm building a 305, shame on me

anyways,

LT4 heads
LT4 carb manifold
LT4 hot cam
aprox 9.5:1 compression

is this too much for a 305? i understand that its a relatively small engine, but i assume the LT4 heads would help it reach better volumetric efficiency to warrant the cam

am i on a good track here, or am i just brain dead?

RB83L69

Why?

For what you'd spend getting a set of those heads, you could have a nice 350 short block instead. Plus, you might have a hard time coming up with a "LT4 carb intake", since the LT4 didn't have a distributor, and didn't come with a carb. And there's lots better cams in the world than that one, which is optimized for FI not carb applications.

All in all, sounds like not a good plan to me. Very very poor ratios when you measure it by way of results per $$$$$, and results per hassle.

1991tealRSt-topGuy

ok, thanx man

but they do indeed make a LT4 intake for carbs

go to www.paceparts.com if you'd like to see it


i have a 350 i am building for my other camaro, in my situation, either i use the 305 or the car goes to the junkyard and i have nothing

i fully 100% understand that i will get better results with a 350
i'm not that brain dead.........my parents on the otherhand, well, they are........now maybe you understand where i am coming from



(hint: my parents did not want me to buy a project car because they were afraid THEIR house was gonna turn into a junkyard, low and behold i have a 350, 700R4, 4 tires, TPI system, 3 sets of heads, set of pistons, torque converter, flywheel, and lots of other parts stuffed into my garage.......so if i tell them i am buying another engine.....................hehe, now i know you get the picture)

F-BIRD'88

1. Lt4 and lt1 heads cannot be used on a 305 block.
Lt4 motors hae a different reversed coolin water jacket system.
Not going to happen.
2. while these heads flow quite well, the port volume is much bigger then a typical 305 type head.
Not a good match.

But your in luck. Instead of useing LT-4 heads, use the next best thing.
That is a set of vortec heads. The vortec ports are very simular
in design to the LT-4, flow just as good, and are smaller/better
for a 305. Think of the vortecs as a gen 1 block version of the
LT-4 head.
All your other parts would work well with them too.
You'll need a vortec manifold.
If you want an aluminum version of this head then use the
Edelbrock E-TEC 170 head.

www.edelbrock.com
...

1991tealRSt-topGuy

ok, whats the best way for me to calculate whether certain heads are too large or not?

F-BIRD'88

There is no easy calculation that I know of to calculate the
speed of the air in a intake port for particular motor/ head.

It can be calculated, but not easily. (for you)
More flow generaly means more horsepower and more rpm.
But if the port is too big to get the "more flow" then the speed
of the air in the port is slower/ relative to rpm/ cubic in.
Meaning a big head may cause the airlflow to be lazy, especially at low rpm.
Makeing horsepower is about getting more air into and outof a motor. Fast moving air tends to pack in to the cylinder during
the intake stroke. (Inertia)

It is the flow, speed and density and time(ing) of the air movement into a cylinder that desides how well it will be filled
(volumetric efficiency). Power output is directly tied to this.
Maximizing volumetric efficiency for certain size motor over a certain rpm range is a balanceing act between
air flow, air speed (velocity) port tuning length and air density.
And valve timing. On a car with tuned headers the exhaust
tuning and timing and flow pulses are used to aid intake air filling too.
(exhaust scavageing)

A 305 would have to rev quite high to cause the air in a big LT-4 port to be @speed or have enough velocity.
For good street use with a rpm range of say 2500 6000 rpm
a good breathing smaller sized port would work better.
Like a vortec port. 170cc vs 210cc for the lt-4.
The lt4 is better suited to a street 350 or 383.

The 170cc vortec port is still quite bigger and flows much better than a stock 305 head port. You'll make lots of power and torque.

You could build a powerful motor with a 305 and a big 210cc port head like the LT-4,, BUT It would be a real high rpm motor
requireing long cam timing, short high rpm tuned intake runners
high compression ratio. Peak horsepower and torque would be at a much higher rpm. low rpm torque and responce would be lazy. This would require a high rear gear ratio, high rpm and
a high stall speed converter in an automatic.
Very high rpm motors are more expensive to build and don't
make good street use motors.

Dan88IrocZ

There is nothing wrong with building a 305. Why build a 350 when you can build a 400 for about the same price?

Plus, nothing brings more joy to my face when I spank a Mustang or beat another 5.7 and I say it's a 305.

1991tealRSt-topGuy

thanx man, some of the points you made i was already aware of, but you did tell me some things that i was pondering

honestly, i cant afford to keep 2 cars on the road, so i was contemplating more a faster, higher end car.........


i've been talking with some local people and they have given me some ideas also

one important question: whats the max RPM you would take a factory shortblock to? 6000 RPM?

F-BIRD'88

6000+/- rpm is a good limit for a factory short block.
The valve train , valvefloat rpm is usually the limiting factor.
I would not build for much more than 6500 rpm,,, tops.
You can make tons of power within these limits.
You only need to rev a motor to peak horsepower rpm or a little beyond for best acceleration between gears.
Many (most) inexperienced people rev a motor too high.

RPM costs $money$

FrozenFirebird

Ive been thinkin about building up my stock 305 roller block lately too...I just think it would be cool to go with a different route than 350, granted you will get more power out of a 350....
But with the right setup you should see some impressive results on the 305.. This is what my setup is going to look like
(In theory)

LO3 Roller Short Block
L-31 Vortec Heads w/screw in studs and guide plates
981 Comp Springs 1.5:1 Roller rockers
9.3 comp ratio (Heads milled down to 58cc)
XR258 Comp Roller Cam
Performer Vortec Intake
625 cfm Road Demon
68460 Headman Full Length Headers

Anyone offer some input on this combination?

on a side note, if you do go with vortec heads, dont expect to just bolt them on and go, you will have to have the heads reworked if you want anything more than .460 lift...You will also want to get the "push-out" rocker arm studs removed in favor of screw in and guide plates so you can go with non-self aligning rocker arms.

1991tealRSt-topGuy

cool, so i can base my power range from about 3000-6000 RPM because i never installed my 2500 RPM stall converter yet
i am also planning on a 4.10 rear

1991tealRSt-topGuy

well, i used the blue racer program and they gave me a great recomendation

thanx F-BIRD88