On a Lo3 will any vortec heads work with the right intake?

 

Well yes they will but make sure they are vortec heads. The heads will need to be milled to keep from loosing compression in a big way, and remember the valve guides will only handle 460 lift.



Brian Felts

 

Thanks for the help..how many cc are vortec heads are they all 64cc because that would require a lot of milling to get to the LO3 55cc & can you put .050 longer valves in to retain proper geometry after milling and be able to use a .473 lift cam?

 

Well I was using flat top pistons and milled .025 and got 9.5 to 1 . However if you do not change pistons you will need to take .035 to get it down to where you want it. Your maching shop will be able to tell you the exact measurements. The valve guides will only hold 460 lift (I found this out the hard way with my lt4 cam).

I had no geometry problems with the Mill job. I did not fix the guides the first time so we broke them all with the LT4 cam (476 I 488 E with 1.6 rockers) and the Edelbrock for the vortech heads works very well.


Brian

 

thanks for the help Brian. Do you know what the cc size is on vortec and are they all the same. I have speedpro .030 cast pistons in the block now a .030 size bore would raise compression a little too would'nt it. I do know that 58cc L98 heads even have to be milled .035 to match a 305 LO3 chamber size of 55cc.how did you cure your lift problem because I will be using a .473 cam?

 

305 heads are 58cc's, not 55cc's. Also, Vortec heads are all supposed to be 64cc's but they've been measured around 61cc's. Why not just get a 350 engine instead of trying to make these 350 heads work on your 305?

 

the 305 is already started, beside that it's a lot harder to find a 350 roller block,if built the same a 350 will give 10-15 more HP. so I figured I have a 305 roller block, I'll go w/that. but in the F-notes article hot rod did they said that a LO3 has 55cc heads, they used 58cc heads off a vette and had to mill to 55cc to retain compression.

 

Yeah the alum. l98 heads are 58 cc your 305 heads are 58cc. I was getting around 325hp and about the same number of torque with my setup. Yeah a 350 would be great but if you are building a 305 I am living proof you can make that bad boy scream!!!!!!!!! Then take bets on your casting ###


Brian

 

They will work. I don't know or particularly care what the compression ratio is but at WOT it run's strong.

I did change the springs and space the retainers up .050 to get clearance for an LT4 cam with .480 lift

Later

 

which head is better in your opinions-The L98 alum vette heads or a vortec set,I'm looking for a very strong low end and midrange . I don't do a lot of 5000rpm driving but I want some top end. I would be very happy with 300-325 HP and a somewhat flat torque curve 300-330 lbs.I've got a short block .030 over with a .473/212 @ .050 cam 111LS. What should I get? It's not a 350 but it will make me happy if it hits 300hp

 

So what exactly need to be done to be able to run a high lift cam on the Vortecs besides new springs? Just new valve guides? How are the new guides different from the ones that won't work? Did stock Vortecs come with screw in studs?

 

i am thinkin of goin with the same set up but i wasn't gonna bother millin the heads cause i figure no matter wut they are still better then the stock TBI heads. what do u think u will run with your combo

 

I hate to through a wrench in to the pot here but GM made 350 vortec engines before 96 that were tbi's. The good heads came on the 96 and later vortec engines with sfi. Make sure if you buy used heads that they have the correct part number and like JP said, kedney shaped combustion chambers. I could be wrong but I don't think so.

Steve

 

The guy at P.A.W. was telling me this saying Vortec started when they changed the center intake bolt angle in 1987. That might be true, but in todays world, not 1987, 1996+ L31 and L30 heads are the "Vortecs". Their fame and popularity has pretty much secured the title exclusively for the heads for Gen 1 blocks.

 

L03's come with flat tops stock, so I'm confused by that statement?

 

Tas, I hope we all know what a true vortec head is, but as we see many questions on this subject it is entirely posible for someone to get taken by a unknowledgable person thinking he is selling vortec heads and could be but off the early vortec motor not an L31. We're all here to learn and help others so the more we know how to spot the real thing the more we know how to spot a fake.

Knowledge is power.

Steve

 

Yes the LO3 does have flat top pistons however the Vortec heads are 64cc and the 305 heads are 58cc. you MUST mill them or you will end up with a 8.5 to 1 CR and that would not be good.


Brian

 

you don't have to mill them. Of course it would be better if you did, but if you don't, you'll still get an awesome improvement over L03 heads.

 

I would hate to think I was dropping compression just to save $50.00 there is a chart out there that shows the raise in HP per point raise in Compression......I am thinking its 10hp but I will have to get back on that.


Brian

 

A lot of people don't want to mill them because they want to use them on a 350 block later.

 

That is true................I can see where you are coming from. I just can't see if you are building a 305 (I did and loved it) why you would drop your compression lower than a LG4. If you are running Nitrous it is very good idea. I Had built a 300 + hp 305 and it would RUN like many Mustang owners only wish. I did keep the C/R at 9.5 with the heads milles to 58cc.


Brian

 

Steve, you lost me about the pre 96 vortec motors. My dad has a 95 suburban and it's TBI, got the funky 2 stud, 2 wingnut air cleaner and that's a 350. I'm pretty sure there weren't any pre 96 vortec motors. I think the 4.3L vortec motor cam out a year before the small block versions but again I really don't have a clue. I just know 96+ vortec heads are what you want.
What were the head casting numbers?
Brian, I'm going to jet over to your place tomorrow. I'll call you either later tonight or in the morning. Kyle said he was going to talk to you about it.
I really want to see your 350 and Kyles TTA. If my car is in a good mood (sure it will be ) I'll give you a ride. The last time you were in my car it was running SO SO SO lean that it was backfiring through the intake and didn't pull past 3000rpm, lol.
You're getting a new custom eprom tomorrow with weather permitting . You never got back to me about if you had excel on the desktop!?

 

They called them "VORTEC" a long time before '96. The v8's and the v6's. My brother's '93 4.3 has vortec on the engine somewhere.

Think about it. They still call the new LS1 based engines "VORTEC" they call the 2.2 in the s10 "VORTEC". It's no different than the one in my '90 cavalier except for the cam and the injection system.

 

JP, I think Keith said it better, the only thing vortec about a pre96 vortev engine was the name with the exception of the 4.3L V6. i think they put a special CPI fuel injection system on them in the early 90's. Of coarse I could always be wrong.

Steve

 

My brother's says vortec, but i think it's just the same old 4.3 as always. He's got the same TBI we do. Maybe a different unit, not sure. It looks about the same.