I have a 350 with a set of 416 heads on it. How much power would I gain switching to a set of 906 vortecs? I know I need a different manifold. Just curious if the power gain would be decent. Thanks

 

If the 416 heads are stock and unported, then you could gain as much as 30 to 40 horsepower depending on the combination the Vortec heads are going on.

Stock 416 heads are poor performers.
If they are ported correctly then it would be a very close call between them and stock Vortecs.

 

They are stock. I was just going to throw them on while im building my stroker motor this year. Im poor so i cant get all the parts for the other motor at once lol. I think ill throw these heads on then. Thanks

The cam is a lunati backet master 2 480 lift
00010LK

I guess it should run ok, for one summer lol

 

vortecs are the best stock gm head. hands down.

 

rubberman here is my engine setup

350sbc +.040
345 pistons...1.56 piston pin height
recon gm rods with arp bolts
decked .015"
f/pro #1094 head gaskets
# 882 heads... cut .005"
ported polished with 1.94/1.60 valves
edelbrock rpm manifold
287/214/.443"lift/1.6:1 r/r(/473" lift at valve

using dyno 2003 engine program comes out o approx. 9.6:1 comp ratio
approx. 400/400 motor power under 6000rpm

also under $1000 to put it all together

if u are using the "305" heads which i believe you are .. my suggestion
would have to square them and put the bigger valves in with back cut stems in... seeing since they are 1.84/1.50 and the valve seats r probably worn the c/c wil most like ly be about 58-60cc's afterward a plus .100" valve height woud be more efficient to use with roller rockers and a beehive spring to give the added lift for future cam upgrades.stepped headers will be of great benefit.
unless you plan on using it at the track considerably then the 900-4800rpm range is were u will be pushing most of you time, with the occasional blast to 5400-5700rpm range which will not gain u any more just keep your engine in the proper power band range for shifting

 

While I basically agree with what you have said, I feel a need to throw in some corrections for others who may be reading.

First is that you should never put in bigger valves with no other changes to match the valves. Putting a larger obstruction into the same size hole does not improve flow, and when you increase valve size in the smaller 305 chamber the shrouding increases dramatically.

I like to upgrade the valves in 305 heads to 2.00"/1.55" (LSX type - see links in sig.), which is much bigger, but I also do the complementary porting, open up the throat area under the seats to around 90% of the valve diameter, and also lay back the chamber walls in certain areas to reshape it and reduce valve shrouding.

 

horrible advice.... He's got vortecs sitting there... Huge waste of time and money to modify those 416 heads... If he can port, then porting and good valve job would be good... no need for big valve when they're not the restriction... And that engine of urs would be LUCKY to make 320hp let a lone anywhere near 400...that cam only makes 320hp in the edelbrock engines...

 

NO SBC should ever use +.100" valves, even if you do get longer pushrods. You still end up with valvetrain issues. And generally they're not even necessary, just use some plus fifty retainers and some plus fifty locks with some full roller rockers. you can get to .700" valve lift without =.100" valves, so forget that they even exist.

 

If the guy has Vortecs then he should use those, hands down, but if he can't afford the Vortec base then he should port and polish the 416 heads, IF he is going to do a home port/polish, since it's way cheaper. It seems the 416 heads are decent heads, with porting and polishing done to them.

My only question about the 416 heads is about a 305 sbc and cc quench, as far as cutting away the combustion chamber walls for valve shrouding reduction.

Should a guy scribe the cutting area using the exact gasket he is going to run, or should he scribe it using an actual 305 bore head gasket? My confusion comes when I think about getting the heads milled, so as not to lose compression, then that changes the combustion chambers, once again, and the gasket still won't match the darn things.

It seems there is no way to keep higher compression and also totally eliminate that extra space that will occur between the bottom of the head and the deck, when a larger bore head gasket is used.

???

 

Use the actual cylinder bores to scribe on the heads, not the gaskets.

Deshrouding 305 heads does not cause a significant loss of compression. You shouldn't be removing that much material.

 

im kinda old school. what models do i find vortec heads on. i want a set for my 350 build.

 

96+ trucks

 

I agree. If you want to big-valve 305 heads for use on a 350, then find a bare block, put the 305 heads on without any head gaskets, and scribe the heads to match the cylinders.
Then when the machine shop cuts the seats for the larger valves, they can do a sweeper cut for de-shrouding. They'll adjust it to match your scribe lines.
When I do this, I find it adds less than 6 cc. If I then mill the heads 0.030", that fixes the cc issue.
And if you're getting the seats cut for larger valves, they should be starting with the 3-angle valve job first. It should be angles of 30/45/60 degrees, because air flows over a 15-degree angle as though it were a perfect radius. But by 20 degrees, there's turbulence. That's why we like increments of 15.
After the 3-angle, they should follow that up with a 75 degree bowl hog. If they don't have one, then you're at the wrong machine shop. This should be adjusted for the deepest possible cut possible while still being high enough to leave the 60 degree cut about 0.055-0.060" wide.
This bowl hog does 85% of your porting for you. It does in seconds what would take you hours. And your results wouldn't be as good that way.
Then the sweeper / de-shrouding cut comes last.
Then pay, take the heads home, and just blend the 75 cut into the ports. Just radius any abrupt edges, taper the exhaust guides, and polish the exhaust ports. Then take the heads back for the shop to finish their work.
For 416 and 081 heads, get these: http://www.competitionproducts.com/S...ductinfo/8430/ before the shop starts on the heads. Also before they start the 3-angle, have them put a small 30-degree back cut on each and every one of these valves. Then they can set the 3-angle cutter to match.
That's the right way for the average person to get the best possible bang-for-the-buck from production iron heads, Vortec or otherwise.