Motorheads...Need help with Vortec style heads, can they just be swapped?

[firstgear]

one of the intake manifolds I am considering for my '60 vette only works with Vortec style heads. I have a mid 70's 350cuin motor that has been turned into a 383 stroker with stock heads.

I have found some Vortec heads at Summit

Brand: Summit
Product Line: Summit Performance Vortec Cylinder Heads
Cylinder Head Style: Assembled
Cylinder Head Material: Cast iron
Cylinder Head Finish: Natural
Combustion Chamber Volume (cc): 67
CNC Machined Combustion Chamber: No
Intake Runner Volume (cc): 170cc
CNC Machined Intake Runner: No
CNC Machined Exhaust Runner: No
Intake Port Location: Standard
Exhaust Port Shape: Square
Exhaust Port Location: Standard
Spark Plug Style: Straight
Intake Valves Included: Yes
Intake Valve Diameter (in): 1.940 in.
Exhaust Valves Included: Yes
Exhaust Valve Diameter (in): 1.500 in.
Valve Springs Included: Yes
Maximum Valve Lift (in): 0.520 in.
Outside Diameter of Outer Spring (in): 1.250 in.
Damper Spring Included: Yes
Number of Springs Per Valve: Single
Retainers Included: Yes
Retainer Material: Steel
Locks Included: Yes
Lock Style: 7 degree
Valve Stem Seals Included: Yes
Valve Stem Seal Style: Umbrella
Rocker Arm Studs Included: Yes
Rocker Arm Nut Thread Size: 3/8-24 in.
Rocker Arms Included: No
Rocker Arm Nuts Included: No
Guideplates Included: No
Valve Cover Mounting Style: Centerbolt
Accessory Bolt Holes Drilled: Yes
Valve Guides Included: Yes
Valve Guide Material: Bronze
Valve Seats Machined: Yes
Valve Seat Machine Style: 3-angle
Valve Seat Material: Ductile iron
Steam Holes Drilled: No
Oiling Style: Through pushrod
Machined for O-Ring: No
Heat Crossover: No
Quantity: Sold individually.
Notes: Features ductile iron seats on exhaust ports only for use with unleaded gas. Machine work must be done to accommodate guideplates.

Cylinder Head, Vortec, Cast Iron, Assembled, 67cc Chamber, 170cc Intake Runner, Chevy, Small Block, Each


Will I be able to just take my old heads off and put these on and still use my rocker arms and push rods? Or do I need to invest in new there as well? I am trying to get a handle on how much this conversion will cost and the heads are required to make the EFI that I am looking at work.

There must be some motorheads out there that will know.....

note, my maximum lift of my cam is about .484 , so the valve springs will be fine from what I can tell.

thanks, Herb

 

[bossvette]

they should work, altho I would prefer guideplates for the pushrods. One thing you might want to check is if they require self aligning rockers some of the newer heads do; I ran into that with my YT with a set of later 305 heads. the Vortec heads are supposed to work real well out of the box.

 

[Mac]

If you're swapping heads, why not go the full nine yards? Get a roller cam with matching hardware. You've already got the top end apart. The cost of freshening up the cam to make the most of those new heads won't be significant.

-Mac

 

[firstgear]

If you're swapping heads, why not go the full nine yards? Get a roller cam with matching hardware. You've already got the top end apart. The cost of freshening up the cam to make the most of those new heads won't be significant.

-Mac

sorry, not sure what a roller cam will do...don't know that much about it....when the motor was rebuilt I had the builder put a new cam and pieces in, so I am trying to not get into a massive teardown and taking out brand new parts.

If i had thought at the start about going EFI, then perhaps that would have led me down a different path. So unless there is a big advantage, I will probably keep what is there.

Good suggestion, but trying to not toos more money out than I already have.....

 

[firstgear]

they should work, altho I would prefer guideplates for the pushrods. One thing you might want to check is if they require self aligning rockers some of the newer heads do; I ran into that with my YT with a set of later 305 heads. the Vortec heads are supposed to work real well out of the box.

Craig, what do guideplates do?

The questions I am asking should clue you in, that I really don't know much if anything about this....

Herb

 

[bossvette]

Craig, what do guideplates do?

The questions I am asking should clue you in, that I really don't know much if anything about this....

Herb

Guideplates "guide" the pushrods to better line up the rocker arms and tips of the valve. What EFI are you going with is it user programable? What cam are you running EFI likes its vacuum and if you are running a cam that is designed for a carb with a longer duration the vacuum might not be high enough for good drivability.

generally an engine is built so all components work together cam, heads, intake and exhaust then you have to take the drivetrain into consideration.

It happens all the time people put a bigger cam or carb on the car and it runs worse then before.:W

just in general the "Vortec" head is one of the best cast iron head out of the box it is was designed for better economy but ended up making better power also
the Wife is calling we will be heading East to this event in a little bit so I have to go.
See Ya
Craig sr.

 

[firstgear]

Intake @cam .310 @ valve .465
Exhaust @cam .325 @valve .488
Rocker arm ratio 1.5

Intake duration 290
Exhaust duration 300

I don't think this is a radical cam at all, it is supposed to be a mild cam.

The EFI system I am lokoing at is supposed to be very similar in controls and behavior as the RAM JET from GM. In fact the manual they use is the Ram Jet manual, and after talking to the guy at Arizona Speed and Marine, it sounds like it is a very near duplicate, but it looks like a polished version of the original FI unit on the C1's.

How do I know if the cam creates enough vacuum BEFORE I try to fire it up?

 

[bossvette]

contact the maker of the EFI and ask if it will work with that cam give the brand and specks they should know if it will work or not.

I am running an Isky roller cam in my 76 with these numbers
I 265 deg .485 lift 217deg @.050
E 272 deg .505 lift 225 deg @ .050
cverlap of 44.5 degrees, it was designed for TPI

 

[firstgear]

contact the maker of the EFI and ask if it will work with that cam give the brand and specks they should know if it will work or not.

I am running an Isky roller cam in my 76 with these numbers
I 265 deg .485 lift 217deg @.050
E 272 deg .505 lift 225 deg @ .050
cverlap of 44.5 degrees, it was designed for TPI

this cam at 0.050 is intake 224 duration, exhaust 234 duration

I will check with the EFI guy....thanks

 

[JohnGrawcock]

Warning

There are two major differences that you should be aware of before changing to Vortec head.

1. The heads have a different intake manifold and valve cover bolt patterns than your original heads. You'll need a Vortec specific intake. The valve covers are the center bolt type.

2. With a 67cc camber iron head on a 383 your compression ratio might be too high for pump gas. I'd run though the calculations to make sure the combo results in less than 9:1 before you spend any money on parts.

 

[firstgear]

There are two major differences that you should be aware of before changing to Vortec head.

1. The heads have a different intake manifold and valve cover bolt patterns than your original heads. You'll need a Vortec specific intake. The valve covers are the center bolt type. Yes, the intake is why I would be changing, I am looking at EFI that requires a Vortec style head.

2. With a 67cc camber iron head on a 383 your compression ratio might be too high for pump gas. I'd run though the calculations to make sure the combo results in less than 9:1 before you spend any money on parts. The heads I have now are 76cc, trying to find heads that are 76cc in a Vortec style I have found are nearly impossible, if not impossible. I will have to check out what my compression would be. What is the most compression that I could run and still get away with pump gas? 93 octane?

I filled my answers and other questions in above.

other thoughts or comments?

 

[Stan's Customs]

....compression you can run depends on the piston deck height and the type piston you use. Some times you can actually stop pinging by raising compression......Here is an old article in Chevy High Performance mag on "Quench Quest" for information on that subject, it works. http://www.chevyhiperformance.com/techarticles/94138/

A roller cam for the application is much better. It allows you to roll over the cam humps and will allow much steeper ramps on the cam ..therefore better cam grind selections. More horsepower with less lope and more vacuum to oversimplify...generally because of broader duration capabilities.

This also would be more easily accomplished with a later model block that already had the machine bosses and holes drilled for the roller retainers in place....Or a Vortec motor for instance. 1998 was the last year for that 350 block I believe.

Can you run the cam and pistons you already have...absolute maybe. Will it clatter (ping)? Too many unknowns here...most noteably the exact deck height and piston configuration. Cam shaft choice will be Ok ...but isn't the best, in my view. You will have great heads without a cam that was really meant for the Vortec's tall intake runners flow characteristics ....(i.e. Duration improvements mostly, that are available with a roller cam).

Sounds like you've changed your mind in mid stream. Perhaps selling the good carbureted motor combination you have and building a stock Vortec engine would be a consideration...it'll perform much better. Then the fuel system you are considering will work as it should too...

Like the man said... many improvements made to these engines just hurt performance....it's a matter of everything working together, the little things that make the great motors.

Big carbs and wrong cams have made junk out of more engines than they have improved.....mismatching parts generally just cost horsepower and efficiency.

Not what we want to hear when we have already spent money ...and you can put something together that will be OK.... but is OK what these cars are about...? I would stay with the original plan... or start over with a new one.

 

[Tom Bryant]

Love those Arizona Speed and Marine FI units. It uses a [FONT=arial, helvetica]Delphi MEFI 4 ECU and sets up and tunes like a production GM EFI. I think it's the same control that comes with the Ram Jet 350 crate engine.

My opinion is that if you are going to spend the big bucks, and these units are salty, for one of these, then use the camshaft that Arizona Speed and Marine recommends as a match to the EFI. You will be a lot happier in the long run.Your current cam specs don't sound too EFI friendly. Sure you are taking out new parts but if they don't work well with your EFI then it really doesn't make any dif.

The thing that makes a Vortech head a Vortech is the combustion chamber shape and the as cast super flowing ports. But even more is that they were original equipment on the L31 Vortech light truck engine that was used from the late '90s until the SB2 took over. The reason you can't find any reference to Vortech heads from other sources is because Vortech is a registered trademark of General Motors Corp. T[/FONT][FONT=arial, helvetica]h[/FONT][FONT=arial, helvetica]e heads from Summit are GM pieces or at least start that way so they retain the name. Most of the features of the Vortech heads like the fast burn combustion chamber can now be found on most of the aftermarket street heads currently available. The Edelbrock Performer series heads went to the fast burn chamber shape a couple of years ago. Also Air Flow Research and Racing Head Service have them. Probably Dart and others as well in their street lines. The big benefit of the fast burn chamber is that it is more pump gas friendly. You can run more compression and timing (or lower octane fuel) with this head before you experience pinging. Many of the aftermarket heads are available in both aluminum and iron and in several combustion chamber sizes and port volume so you can match them to your engine.

The GM Vortechs are a bargain right out of the box but if you need a larger chamber to keep your compression ratio in line then an aftermarket head may be just the ticket. Plus most of the aftermarket heads have dual valve cover bolt patterns so you can use your old style valve covers or new center bolt styles.

The bottom line is that the EFI, heads and cam all have to work together to make a happy package.

[/FONT]

 

[JohnGrawcock]

I filled my answers and other questions in above.

other thoughts or comments?

For premium pump gas (92-93 octane) you typically want to stay below 9:1 for iron heads and 10:1 for aluminum. You'll still need to watch the ignition curve.

It's definitely overkill and there may be better choices but, one head that would definitely be safe from a compression standpoint is the AFR 195. It's an aluminum CNC ported head with a 74cc chamber. I don't know for certain that it will mate with a Vortec intake, but the last couple of lines in the description on the following page make me think there is a version of it that does. Check it out.
http://www.jegs.com/webapp/wcs/stores/servlet/CategoryDisplay?storeId=10001&catalogId=10002&catalogIdentifier=Jegs_Direct&categoryId=26569&parentCategoryId=10187

Ultimately, I'd talk to the head and cam manufactures for advice on picking the correct matching components.

 

[JohnGrawcock]

firstgear,

Any advice from the pros on this yet?

 

[firstgear]

firstgear,

Any advice from the pros on this yet?

I have decided it is a no go.....biggest problem I seem to run into is the head volume. my heads are 76cc combustion chambers. Most (certainly not all) that are available are 64cc which will take my compression ratio outside the realm of pump gas, or make it so close that it might be marginal.

There are some heads out there that are 74cc combustion chambers that might work, but at a minimum there are a number of rocker arm guides and such that would also have to be added.

Bottom line, if I had put the motor together from the very begining with this in mind, the motor would still be a 383 stroker but the stroke/piston and such would have been planned to obtain the right copmpression ratio while at the same time using the Vortec style heads.

I have abandoned this approach and I am now looking at other types of fuel injection systems, none as flashy as the one up above that looks like an old time polished FI, but EFI none the less.

I have found one that will work with my type of heads, but the next thing you find out is that these EFI units want a certain amount of vacuum in them and a mid to high range cam may not provide that vacuum that is needed and soon you find out there is a problem there,.

I am looking at a unit made by Accel now, but the cam they speicfy is for Gen II SBC, not Gen I. So now I need to find out if I find a cam with the same kind of specs that they are talking about, would that work. So at a minimum, I might be changing the cam as well as the intake to get EFI.

That is where I am now....trying to sort out what will work and what won't work. I figure it is easiest to change the cam now while the motor is on the frame and no body to crawl over than to try and do it later when the car is all put back together. I have some time as I am still fussing with the exhaust system, so while that is going on I am using this time to sort through the intake.

I really would like to go EFI, but if I don't then I will use the brand new spanking Holley 650 I have along with intake and proceed as to the original plan.

Stay tuned....I am sure there is more to follow yet on this subject!

Herb

 

[bossvette]

Herb
If you go with Edelbrocks E-tec in Aluminum you can handle more compression, I have Brodix heads on my 383 and they have small chambers. The Vortec style heads have an improved combustion chamber and remember most EFI's have computer controlled ignition and Knock sensors.
Craig sr
BTW if you are changing heads its a small step to swap the cam.

 

[firstgear]

Herb
If you go with Edelbrocks E-tec in Aluminum you can handle more compression

why is that? How much more compression can I handle? I had called and talked to the shop that built my motor and asked them and they said it would generate too much compression...but that was the easy answer. The guy that owned the shop has retired and his assistant now owns the place and while the assistant is the one that built the motor, they do so many motors that I doubt he can remember the details of what he put in it....never mind even remember me.....short of taking everything apart, is there any way I can figure out what I have to determine what compression ratio I really have now and then I can back calculate what I might have with different heads....I really want to find a way to make this work, but I don't have enough knowledge to go outon a limb like this by myself and the cost for a wrong guess on my part is so great, it is better to avoid than jump head first in and not know how deep the water might be.....hence my reluctance to jump.....so I need some help sorting this out....

 

[Tom Bryant]

When he built your engine didn't you get an invoice with everything on it?

As John said above you can run a point higher compression ratio with aluminum heads. That is due to the greater heat transfer properties of aluminum. I fact, with everything else being the same you need to increase CR by 1 point to keep the same power output if you switch from iron heads to nearly identical head made from aluminum. The fast burn chamber also allows you to run an higher CR before you get into problems with pump gas. That's why Craig said you can handle more compression with the Edelbrock E-Tecs. You get both aluminum and the fast burn chamber design. With the EFI computer calling the shots you will be able to run a lot more squeeze than you think.

Also you can't just try to find a cam with the same specs because roller profiles are different than flat tappets. I'd call Accell and ask for a specific recomendation for your engine. Then bring up the aluminum head question too and see what they think.

 

[firstgear]

When he built your engine didn't you get an invoice with everything on it?.

Yes, I was thinking of that last night...I need to look...it is somewhere around here.....I have stock rods, they used the rods from the 350....I have a photo of the new pistons, so I think I can back myself into what they were if I need to.

Also you can't just try to find a cam with the same specs because roller profiles are different than flat tappets. I'd call Accell and ask for a specific recomendation for your engine. Then bring up the aluminum head question too and see what they think.

I have sent an email to Accel to ask some of these very questions.....I will follow up on the Al heads as well.......nothing is ever easy.....