suggest about porting heads

[cerryblazer]

Hello guys!
I must remove heads from my '81 k5 Blazer 305 engine, 'cause i must replace old lifters with new ones OE.
I'm thinking that it could be a good thing check-out heads for crack or damage and doing "porting heads".
With "porting heads" process, which other process it's important?
if i improve air flowing, intake manifold must be replaced with better new?
or for example with new exhaust manifold?
If air runs better but it's blocked by tight exhaust manifold, i think could be just an hald good job.

Thanks guys for attention.
Fabio

 

[toomany]

The lifters can be replaced with the heads still on the motor, only need to remove the intake manifold.

Porting a set of stock 305 heads would be polishing a turd. Could you gain some improvement, yes. Is it worth the effort, not really. There is a good chance they are probably cracked too. Late 70's through late '80's small block heads aren't the best castings from the factory. You would see more gains from a set of Vortec heads (and the matching intake). I'd look into these if yours come back cracked.

Better bang for the buck would be a set of headers and some better flowing exhaust. Or an intake/carb upgrade.

 

[76zimmer]

better yet, replace with a 350 Vortec engine.

 

[cerryblazer]

thanks for answers guys!
about exhasut system, i removed cataltytic converter and i changed muffler, but replacing heads with Vortec heads, i must replace carb too and intake manifold?
how much Vortec heads?

 

[Corey 78K5]

Don't waste your time with a 305, they are boat anchors. Get a 350 instead.

 

[76zimmer]

thanks for answers guys!
about exhasut system, i removed cataltytic converter and i changed muffler, but replacing heads with Vortec heads, i must replace carb too and intake manifold?
how much Vortec heads?

Is that Monza Italy your from?

If your engine is an 81, I really wouldn't put money into it unless absolutely necessary. Start saving for a Vortec 350, minus the intake system, or a 80-95 350 and put the Vortec 350 heads on it.Then get an aftermarket manifold (Edlebrock performer Vortec) to put your quad on. You might have to open the jets a couple thousandths to accomodate.

Intake:

Chevrolet 262-400 Small-Block V8
PERFORMER EPS VORTEC (idle-5500 rpm)
Now available for small-block Chevys with Vortec or Edelbrock E-Tec cylinder heads, the Performer EPS dual-plane manifold is optimized to deliver superior performance with Edelbrock square-bore Performer Series or Thunder Series AVS carburetors. The runner design is "tuned" for peak torque around 3500 rpm on a 350-inch engine and it?s ideal for power from off- idle to 5500 rpm. Dyno tests showed gains averaging 5+ ft/lbs. of torque from 3000 to 4500 rpm for more performance where you need it most. Match with a dependable Edelbrock square-bore carburetor for maximum performance gains. Will not fit under stock Corvette hood.

ApplicationsPart #Performer EPS manifold for Small-Block Chevy Vortec (non-EGR)#2716*Performer EPS manifold for Small-Block Chevy Vortec w/ Polished finish (non-EGR)#27161*Performer EPS manifold for Small-Block Chevy Vortec w/ EnduraShine finish (non-EGR)#27164* Carburetor Recommendations: Edelbrock Thunder Series AVS or Performer Series carb, 500-650 cfm (see Carbs & Accessories),use bracket #8031 or #8036 for 1972-78

Installation Notes: Recommended intake gasket: Edelbrock #7235. Manifold ht: A-3.96", B-5.08". Port exit is 2.05" tall with slanted side walls. see A/B Measurements.

 

[cerryblazer]

yeah i'm from Monza north Italy and surely you can understand how hard is to find good stuff and suggests here

so definitly is not good tune-up or just replace some part on 305 engine without wasting time?!

the problem is to find a Vortec engine in Italy without spending 5.000 euro!

i must get something throught internet but shipping is mad about big items

 

[wasted wages]

Seeing that you don't have access to a lot of engines and parts, I would get a good set of intake gaskets and "gasket port" the heads and intake manifold...would give you slight gains, but it is better than nothing...

basically you would match the ports to the size of the intake gasket and blend the ports back into the heads and intake..just a good basic clean up of the ports.

 

[cerryblazer]

sure!
i have a lot of book about porting head
and usually i use tool like dremel and others

 

[76zimmer]

You have a lot of stroke on that engine, but not much bore, so you can't really get a lot of airflow through it. Would it be cost prohibitive to get a Performer intake manifold to you from the US?
I have one that would work on that engine, and would let it go to ya for 50$ US, plus shipping to you.

 

[cerryblazer]

the problem is not intake manifold but headers or big items.

for example i found exhaust parts for $.80$ but shipping was $.250!

 

[76zimmer]

OUCH....that sucks bigtime.