SpeedTalk Store - Opinion Columns

350 vortec heads on a 305

General engine tech -- Drag Racing to Circle Track

Moderator: Team

350 vortec heads on a 305

Postby 19chevy85 » Mon Apr 16, 2012 11:58 am

im building the first motor for my self. im 17 and trying to hear what people will say about what im trying to build. i got a 305 block and 350 vortec heads. i heard a 305 heads was a 58cc chamber head and the vortec heads was a 64cc head. so what i have done to bump my compressin back up is put flat top piston heads in it with a mild comp cam. this motor will be going in a 1985 c10 with a granny 3 speed. so if yall wouldnt mind if you could give me some advice for this. cause the truck will be getting drove to college 319 miles away and i want it to be dependable. not to hoped up but just a little more then stock
19chevy85
 

Re: 350 vortec heads on a 305

Postby rfoll » Mon Apr 16, 2012 1:19 pm

Vortec heads have no provision for carb heat, no heat riser ports. If you live where it gets cold it will matter. Carb icing will stop your car and make you wait for it to melt. With no heat riser, no hot air choke, which is likely what you have if you are using a stock carb. The vortec heads tend to make the engine run cooler, agravating the problem. If you need to address this , I can post details on how to overcome these issues.
So much to do, so little time...
rfoll
Guru
Guru
 
Posts: 1146
Joined: Mon Jan 11, 2010 12:44 pm
Location: St. Helens, OR

Re: 350 vortec heads on a 305

Postby 19chevy85 » Mon Apr 16, 2012 2:57 pm

im running a 650 holly with a edelbrock performer intake and cam that is at a 480 lift and like a 250 duration is what the engine shop said.
19chevy85
 

Re: 350 vortec heads on a 305

Postby 19chevy85 » Mon Apr 16, 2012 5:11 pm

Could any one tell me my compression ratio or least give me a idea of what it would be with this set up
19chevy85
 

Re: 350 vortec heads on a 305

Postby rfoll » Mon Apr 16, 2012 8:25 pm

If you have a manifold to fit the stock heads, it won't work on the vortec heads. At 480 lift, your cam is more like 230 degrees of duration, probably too much for a 305. A Melling MTC-1, (204/214 @ .050), would be a better choice. You could add 10 degrees, ( 214/224), and probably be OK, but the lower rpm is going to get softer. Not all 305 heads are 58cc, I have several sets at 64 cc. Depending on gasket thickness, flat top pistons will be close to 9:1 with 64 cc heads, closer to 10:1 with 58 cc heads.
So much to do, so little time...
rfoll
Guru
Guru
 
Posts: 1146
Joined: Mon Jan 11, 2010 12:44 pm
Location: St. Helens, OR

Re: 350 vortec heads on a 305

Postby 19chevy85 » Mon Apr 16, 2012 8:58 pm

Your probably right on the cam. I know he said that it is a 480 lift. But I'm going with headers. I just would like to tell a night and day difference between a stock 305 and this 305
19chevy85
 

Re: 350 vortec heads on a 305

Postby F-BIRD'88 » Mon Apr 16, 2012 9:49 pm

College should be your priority. The price of a gallon of gas is not going to get any cheaper.
Increasing the horsepower of your 305 will not get you back and forth to school any faster or cheaper.

Creating more horsepower requires burning more fuel.

I'd keep it real simple for now. Have the L-31 (062-906 ) vortec heads shaved down aprox .040 to .050" to reduce the chamber volume. Install on the flat top piston 305, using a shim style .015" head gasket (felpro 1094)

Do not use a big cam in it.

Buy a near stock short duration cam or use the stock 305 cam again.
Find a mild cam with 195 to 204 intake duration .400 to .430" lift.
Dual plane vortec intake manifold.

Any big cam used in a 305 .(480" lift) will need a very high rear gear ratio to realize the high rpm power gain.

Unless you ware going to swap gears, do not use a big cam in your 305.
The taller the truck tires the more gear it will want, or it will be a slug.

When you graduate from college and get a paying job you can get more serious on the power.
Last edited by F-BIRD'88 on Mon Apr 16, 2012 9:57 pm, edited 1 time in total.
F-BIRD'88
Guru
Guru
 
Posts: 2318
Joined: Tue Mar 27, 2007 5:56 pm
Location: Ontario, Canada

Re: 350 vortec heads on a 305

Postby 19chevy85 » Mon Apr 16, 2012 9:55 pm

Do I have to shave my block to or will it be fine to just shave the heads and will I need new push rods
19chevy85
 

Re: 350 vortec heads on a 305

Postby F-BIRD'88 » Mon Apr 16, 2012 10:01 pm

19chevy85 wrote:Do I have to shave my block to or will it be fine to just shave the heads and will I need new push rods


nay be , but not nesssessairily if you keep things simple. are the block decks reasonabily flat now? You need to define the result you want to end up with and your budget.

Stock truck gears + truck tires+ ='s keep the cam small.
F-BIRD'88
Guru
Guru
 
Posts: 2318
Joined: Tue Mar 27, 2007 5:56 pm
Location: Ontario, Canada

Re: 350 vortec heads on a 305

Postby ProPower engines » Mon Apr 16, 2012 10:27 pm

F-Birds right. The 305 don't want a big cam. as suggested the Melling MTC-1 is the best choice for economy and torque. Do not be stupid and let some one talk you into more cam for the lumpy idle. It sounds mean but don't run like it in a daily driver. That way the rest of the valve train don't need to be improved with more money> Stock rockers will work just fine.
The intake choice is a good one but the carb design is not clear. Vacuum secondaries or mechanical??
Keeping it around 9.0-1 will allow you to use regular pump gas thus saving you money. Hard to say at this point what you will end up with without all the rest of the details like what the deck heights are what gasket thickness is and the actual cyl. head chamber volumes are.
Headers again a good choice but what is the rest of the system consist of??
What ign system are you usingetc etc etc............... you see where this is going. More Accurate Details are required.
Real Race Cars Don't Have Doors
ProPower engines
Guru
Guru
 
Posts: 5340
Joined: Sun Jan 21, 2007 1:16 pm
Location: VICTORIA BC CANADA

Re: 350 vortec heads on a 305

Postby 19chevy85 » Tue Apr 17, 2012 1:03 pm

I just got me some msd spark plug wires and a msd distributor. I have a mechanical 2nd linkage on the card. But what other things could I do on the out side of the motor to help. And will a 350 crank work in my 305
19chevy85
 

Re: 350 vortec heads on a 305

Postby Rizzle » Tue Apr 17, 2012 3:34 pm

19chevy85 wrote:. And will a 350 crank work in my 305


It will fit, the only difference will be the balance being off, its the same stroke, so theres absolutely no point in doing it.
I know its late for you, but doing a carbed 4.8/5.3 swap should be considered long before hopping up a 305 should be, if theres a reason that you'd want to stay with less cubes. A STOCK 5.3 would meet your 300hp.

Yeroon
Rizzle
Expert
Expert
 
Posts: 571
Joined: Mon Feb 04, 2008 10:34 pm
Location: St. Catharines, Ont

Re: 350 vortec heads on a 305

Postby rfoll » Tue Apr 17, 2012 8:18 pm

Changing to a 350 and the additional 50 or so ft. lbs. of torque will make it easier to achieve the HP goal, and probably get better fuel economy than a 305 at the same HP level. Much cheaper to build as well. What's with the 300 number? Build the motor on a plan to improve things, like pocket porting, headers, good ignition, good intake and carb. The power will happen as a result of the improvements, the economy will improve, and it doesn't matter what the HP number is. Tell everyone it makes 300 HP if it sounds good. Every motor I have built for fuel economy has experienced a significant improvement in power.
So much to do, so little time...
rfoll
Guru
Guru
 
Posts: 1146
Joined: Mon Jan 11, 2010 12:44 pm
Location: St. Helens, OR

Re: 350 vortec heads on a 305

Postby 19chevy85 » Tue Apr 17, 2012 8:47 pm

Yes sir. This is just my first motor on building. I guess my head just aint set like a true engine builder. I will learn as time goes on. But I just hope it is a improvement compared to the stock 305
19chevy85
 

Re: 350 vortec heads on a 305

Postby MileHighMan » Tue Apr 17, 2012 10:19 pm

F-BIRD'88 wrote:College should be your priority. The price of a gallon of gas is not going to get any cheaper.
Increasing the horsepower of your 305 will not get you back and forth to school any faster or cheaper.

Creating more horsepower requires burning more fuel.

I'd keep it real simple for now. Have the L-31 (062-906 ) vortec heads shaved down aprox .040 to .050" to reduce the chamber volume. Install on the flat top piston 305, using a shim style .015" head gasket (felpro 1094)

Do not use a big cam in it.

Buy a near stock short duration cam or use the stock 305 cam again.
Find a mild cam with 195 to 204 intake duration .400 to .430" lift.
Dual plane vortec intake manifold.

Any big cam used in a 305 .(480" lift) will need a very high rear gear ratio to realize the high rpm power gain.

Unless you ware going to swap gears, do not use a big cam in your 305.
The taller the truck tires the more gear it will want, or it will be a slug.

When you graduate from college and get a paying job you can get more serious on the power.





1985 your gonna want to listen to F-bird 88 on this one.......GET YOUR COLLEGE EDUCATION FIRST........Take our advice...While racing is fun,,,,RETIREMENT IS A DIFFERRENT STORY.......I sure had fun,,but now I gotta pay the bills..you don't get any younger.......Dan.
MileHighMan
Expert
Expert
 
Posts: 982
Joined: Mon Aug 07, 2006 9:31 am
Location: usa

Next

Return to Engine Tech

Who is online

Users browsing this forum: benno318, bimbleuk, Google [Bot], John Wallace, leahymtsps, lukester, thedynoguy, Yahoo [Bot] and 21 guests