305 head flow possibilities?

[F-BIRD'88]

.
"There is nothing stock about a stock car.

[vortecpro]

.
"There is nothing stock about a stock car.

Basic engine design/car design put into practice, its more a mind set than anything else. Some people would try and portray it as "magic" its not, its about common sense and doing the work, and of course spending the money. I find most a fair amount of people who race this type of car are CK righters/bubble packers. Back to the 305 stocker engine, I doubt they make more than 420 STP corrected power, although they do it with NHRA legal port volumes, 1.845 intakes, stock type factory intakes, copy of stock pistons, factory cam lift, and Q-Jet. I believe the 1986 305 NHRA stock Camaro G/SA has been as fast as high 10.50s, impressive performance.

[jeff swisher]

I have never cracked a 305 head..I have got some that were cracked but got all kinds of heads that were cracked so that is just what happens when people do not watch temps and timing I assume.

I have ran 305 heads on my 350's since the 90's and well over 400,000 miles on some 1.72 valve heads that were on a 305" that never gave up.

Why do I run them??
Because the old double humps were all used up and needed guides 90% of the time and i wanted a small chamber inexpensive head that would get the job done.
INEXPENSIVE was key in my book.
25-50 for a set of them that had good guides and no cracks and only needed valves lapped hard to say no to that.
I spend some time porting them but any head i use will get ported..I do it myself and have about 25 bucks tied up in porting supplies for a pair of heads.

Now we are up to 75 bucks. add 80 to that for machined for screw in studs and guide plates will cost you some also.
Add 100 for studs and guide plates
$255 in them so far. Then springs and I like the Beehive Pac springs now.
That is a cost you will pay for on any head.

I use the stock valves.

Go run 12's with old school cam and cheap heads and drive it for 100,000 miles or more and no worries.
Not that aftermarket iron heads have a worry factor.

I usually port heads for my buddies for 200-250 or I trade it out in labor or goodies.
So my friends are not into the heads for very much.

[jeff swisher]

Basic engine design/car design put into practice, its more a mind set than anything else. Some people would try and portray it as "magic" its not, its about common sense and doing the work, and of course spending the money. I find most a fair amount of people who race this type of car are CK righters/bubble packers. Back to the 305 stocker engine, I doubt they make more than 420 STP corrected power, although they do it with NHRA legal port volumes, 1.845 intakes, stock type factory intakes, copy of stock pistons, factory cam lift, and Q-Jet. I believe the 1986 305 NHRA stock Camaro G/SA has been as fast as high 10.50s, impressive performance.

I wish there was a like button.
I tested 3 intakes on a 305 headed 350 ..the marine intake a Q jet iron, a plenum ported Iron Qjet car intake, the Performer rpm square bore.
2 carbs tested on all 3 intakes 4779 much modified and a 750 Q jet.
At the rear wheels the marine intake was 30HP less than the RPM intake and the Ported Car Iron intake was 10HP down vs the RPM intake.

Q jet made 10 more HP on the Q jet manifolds than the Holley 4779.
But the 4779 made 10 More hp on the RPM intake than the Q jet which put it at the win.
Do not dismiss the Q jet on a spread bore intake.

[vortecpro]

Although I understand what Randy331 is saying, I also think playing with production cheap parts can be very enjoyable for myself. When you get into a higher HP/RPM application you don't want your very worked heads break-in, but in Jeffs application I think the parts he uses are just fine. But again I'am bias I like to work with junk......

[gmrocket]

We are sticking with the 305 turds for now. It's getting the 1.84"s because I have them. He needs to save his money for other things that will be costly, like a Ford rear , custom driveshaft, custom rad, probably an electric water pump, headers and exhaust, rims and tires.

I also told him this thing is not going on the road until it has a cage in it...more money for that.

It's a lite little car so it's not gonna need much to make it go. It's easy enough to upgrade the heads after it's all sorted out and running. These things are suppose to be about 2260lbs with no a/c or other options?

I can see these small valve 305 heads are horrible on the intake bowls..that's an easy fix with the 1.84's

He's learning as we go..I'll do one port/bowl. He will do the rest.

To offset the cost the great running rotary and 5 speed tranny in it is on eBay and kijiji...

[tchapps88]

I seen the brzezinski article on losing flow with 1.94 valves but i was curious about what if a person put 8mm liners in a 305 head and used 1.89 and 1.55 valves out of an early 4.8 or 5.3 head?

[jeff swisher]

I do not think it is needed really.
The little heads make good power and will flat Rev despite what you read on the internet.
Do not build the engine tight .. there is power in a looser engine.
.003" piston to wall clearance with cast piston will rev quicker and higher than .0015".
Talking old school long skirt fat ring pistons.

Been there and tried that.
I have had the 268H cam custom ground on a 106LSA and it would rev to 7200 rpm before valve float running 1.25" springs set up at 80 psi seat pressure.

That combo with the 601 head and 1.84-1.50 valve has taken my old truck to 165MPH on a wheel dyno and 150 on asphalt at
6500 rpm.. more left in it.
Step up the cam and revs are about the same but more power past the peak.

I flowed 1.94 and 1.84 valves I got 4 more cfm from the 1.94 but chamber was larger and I feel still not large enough.
Valve job was probably not optimized either.. I did not do it.

I built a 357" with ported Vortecs 906 heads with 1.94-1.50 valves and the 305 heads out flowed them on the exhaust side, 305 heads were down 20-25 cfm on the intake side.
I ran a roller cam 228@ .050 .492" lift on a 110 lsa with the vortec head engine.
The engine did not feel any more powerful than the smaller chamber 305 head 350" with 280H magnum cam 230@ .050 .480" lift on a 110 LSA.
Would I do another Vortec head build NO.
Would I do another 305 head build Yes.

The Vortec head engine is in my 47 dodge truck and it is 400 lbs lighter than my 57 with the 305 heads.
The 57 chevy out runs the truck.
There is a gear difference though Truck has 3.25 gear and car has 3.70.
From a roll or a dig the 57 wins.
NO Tunnel-rams for the Vortec head either If you like Tunnel-rams.

[randy331]

Well,...at least all that was validated on a BUTT dyno. LOL

Randy

[jeff swisher]

Calibrated Butt dyno. Not correct to sea level though.

I did have the 57 engine in the 47 truck for over 6 years with different cams in it. and a 385" stroker and a 327" engine.
The stroker felt better than all of them and had 305 1.84-1.50 heads on it also.
The 327 got the 1.94-1.50 valved 305 heads same casting in all engines #601.
The 327 was a slug. I left it in there for 2 days and pulled it out and it has sat on the floor ever since.
It got the 280H cam in it.. but as we know a flat top in a 327 does not make as much compression as a longer stroke deal.
The little engine really needed much more compression.
The 385 was 11.9 compression and the 350 is 10.8

[F-BIRD'88]

Jeff has the best stories and analysis.
Just saying....

[randy331]

The "stories" and "analysis" would get debunked on a real engine dyno.

If you built a 350 with 305 heads and it beat one you did with vortec heads, you did something horribly wrong.

Randy

[midnightbluS10]

I seen the brzezinski article on losing flow with 1.94 valves but i was curious about what if a person put 8mm liners in a 305 head and used 1.89 and 1.55 valves out of an early 4.8 or 5.3 head?

I think the valve he used in his test was actually a 1.90 valve, IIRC.

Edit: it was

Test head: ‘450 casting number Chevy 305 head with “UnderCover Porting”.

Air flow with 1.84″ valve. Ferrea # F5060.
.200 126
.300 173
.400 206
.500 212
.600 213

After the head was flow tested with the 1.84″ valve, we machined the valve seat to accept a 1.900″ valve. If all you look at the high end flow numbers, you would think that the larger valve was a improvement. However, the small improvement at .500″ and .600″ lift was more than offset by a sizeable reduction below that point.

Air Flow with a 1.900″ valve Ferrea #F5072.
.200 124 -3
.300 170 -3
.400 198 -8
.500 214 +2
.600 215 +2

https://www.castheads.com/cylinder-head ... 305-heads/

[F-BIRD'88]

Re that: when you go from a 1.84 to a 1.94 valve the chamber needs to be opened up around the new larger valve so the air can get around the opening valve.
Deshrouded"
Now flow test it.
Its all about context...
Yup when you dobthat to a 305 head casting the chamber volume gets a bit bigger.
Eg:
A 58cc head ends up about 62 cc
You can mill it then to adjust...

Hot rodding the sbc 305 head is a great way for your son to do and learn these basics..

[jeff swisher]

Did you read what was stated.
"After the head was flow tested with the 1.84″ valve, we machined the valve seat to accept a 1.900″ valve."

Why would you only machine the valve seat then install a larger valve???
You also need to open up the bowl rework the short turn and then massage the chamber.
If I had a flow bench I would probably be able to get much more from my junker 305 heads.. but as it is now I must pay 40 bucks each time I have 1 intake and 1 exhaust port flowed.
I have spent a few hundred having heads flowed.
I mostly spend money and time on removing head and re-tweaking the port job and reinstall head and test in car.
Gaskets you know.

I did have some wheel dyno time with my 47 dodge and my 57 chevy with different heads and cams.
The 268H on a 106LSA made more power than the Vortec head engine and roller cam below 4500rpm.
Past 4500 the Vortec came in.

28 More hp from the Vortec head and roller cam than the 268h on a 106 and 305 heads.. at the wheels uncorrected.

I was saying my current cam the larger 280H seems to feel stronger..I have not had it on the dyno with that 280 cam.
I guess I need to make another trip to the wheel dyno.

Wheel dyno graph here. post 8
http://nastyz28.com/threads/vortec-head ... re.319793/