Vortec Heads - Port & Polish Gain...
#1
Member
Thread Starter
Join Date: May 2002
Location: SE Pennsylvania
Posts: 432
Likes: 0
Received 0 Likes
on
0 Posts
Car: 1986 Trans Am
Engine: 350 W/Plenty of Mods
Transmission: T5
Vortec Heads - Port & Polish Gain...
Ok, I have a set of vortec heads, and am looking to get them ported and polished. What kind of HP gain am I looking at in doing this, and is it really that benneficial? Also, i want to put 1.6 roller rockers on and i know that in order to do that I need to have the valve seats ground out and I need bigger springs. Anything else I need to do other than that, and can anyone reccomend good springs with a comp cams XE cam .487 - .490 cam? Anyone have any suggestions to anything else? Thanks
#2
Supreme Member
Join Date: Apr 2001
Location: USA
Posts: 4,969
Likes: 0
Received 0 Likes
on
0 Posts
Car: yy wife, crazy.
Engine: 350, Vortecs, 650DP
Transmission: TH-350
Axle/Gears: 8.5", 3.42
I've got a scan of a flow chart by David Vizard somewhere. I think if you click on the link for my exhaust clip, you'll find it in the folders somewhere.
I'll try and find it first.
I'll try and find it first.
#3
Supreme Member
Join Date: Jul 1999
Location: Loveland, OH, US
Posts: 18,457
Likes: 0
Received 14 Likes
on
14 Posts
Car: 4
Engine: 6
Transmission: 5
If you want to use that XE274 with 1.6 rockers, you need at least 986 springs, and it might not be a bad idea to step up to 987s, especially if you're going to be running it past 6000 RPM. Same price, a little better spring.
#4
Supreme Member
Join Date: Apr 2001
Location: USA
Posts: 4,969
Likes: 0
Received 0 Likes
on
0 Posts
Car: yy wife, crazy.
Engine: 350, Vortecs, 650DP
Transmission: TH-350
Axle/Gears: 8.5", 3.42
OK...... here it is. I had to upload it. I must have removed it from Yahoo.
BTW, you gotta be a member of Yahoo to see it.
Vortec
BTW, you gotta be a member of Yahoo to see it.
Vortec
Last edited by AJ_92RS; 02-20-2003 at 04:18 PM.
#5
Supreme Member
I would leave the intake port as is and port and polish the exhaust port for this motor.
The stock vortec port and 1.94" valve is hard to beat as it comes.
porting will only help at real high lift. which you don't have.
Just do the exhaust ports and set the springs, guides and
studs up for your new cam.
Use a thin head gasket to help maximize your final cr with your "base crate motor" (dished pistons)
The stock vortec port and 1.94" valve is hard to beat as it comes.
porting will only help at real high lift. which you don't have.
Just do the exhaust ports and set the springs, guides and
studs up for your new cam.
Use a thin head gasket to help maximize your final cr with your "base crate motor" (dished pistons)
#6
Supreme Member
Join Date: Jan 2002
Location: Valley of the Sun
Posts: 3,852
Likes: 0
Received 0 Likes
on
0 Posts
Car: 82 Z28
Engine: Al LT1 headed LG4 305
Transmission: TH350
Axle/Gears: 3.73 posi with spacer
Porting or other mods to the bowls and runners has been shown to hurt flow!
#7
Supreme Member
Join Date: Apr 2001
Location: USA
Posts: 4,969
Likes: 0
Received 0 Likes
on
0 Posts
Car: yy wife, crazy.
Engine: 350, Vortecs, 650DP
Transmission: TH-350
Axle/Gears: 8.5", 3.42
If you look at that chart I showed (or buy the book) you'll see that just doing pocket porting (bowl blending) does very little to the Vortec heads.
IMHO, I'd agree with ME Leigh that you'd be better off not messing with them due to chancing amature mistakes, like nicking the valve seats, or hitting a water passage. But that's me.
The ONLY thing I'd do is back cut that valves 30*. That's been shown to help. Although word around the water cooler is GM now sells them that way. You'd have to ask (Scoggin-Dickey or Jim Pace Performance Parts) if the ones you're buying are that way.
IMHO, I'd agree with ME Leigh that you'd be better off not messing with them due to chancing amature mistakes, like nicking the valve seats, or hitting a water passage. But that's me.
The ONLY thing I'd do is back cut that valves 30*. That's been shown to help. Although word around the water cooler is GM now sells them that way. You'd have to ask (Scoggin-Dickey or Jim Pace Performance Parts) if the ones you're buying are that way.
Trending Topics
#8
with the xe 274h and the re done vortecs it should make peak right around 5900....go to the car craft website and look for a backissue on this buildup called "400hp vortec engine"
this is the same motor i am building and it made 442hp@5900 and 452ft lbs at 4400rpms
this is the same motor i am building and it made 442hp@5900 and 452ft lbs at 4400rpms
#9
Supreme Member
Join Date: Mar 2001
Location: Monticello, IN USA
Posts: 1,346
Likes: 0
Received 2 Likes
on
2 Posts
Car: 1991 Z-28
Engine: 350
Transmission: T-5 (gonna buy the farm)
Hey AJ_92RS,
Do you have a bigger version of that article? I can't read any of it. Or if you know what issue of mag it came form, I could look it up on the net.
Thanks,
Do you have a bigger version of that article? I can't read any of it. Or if you know what issue of mag it came form, I could look it up on the net.
Thanks,
#10
Supreme Member
Join Date: Apr 2001
Location: USA
Posts: 4,969
Likes: 0
Received 0 Likes
on
0 Posts
Car: yy wife, crazy.
Engine: 350, Vortecs, 650DP
Transmission: TH-350
Axle/Gears: 8.5", 3.42
Originally posted by johnsjj2
Hey AJ_92RS,
Do you have a bigger version of that article? I can't read any of it. Or if you know what issue of mag it came form, I could look it up on the net.
Thanks,
Hey AJ_92RS,
Do you have a bigger version of that article? I can't read any of it. Or if you know what issue of mag it came form, I could look it up on the net.
Thanks,
Doing that fills my 17" flat screen. Granted it's a bit fuzzy, but legible.
Thread
Thread Starter
Forum
Replies
Last Post
84z96L31vortec
Tech / General Engine
7
08-20-2017 12:16 AM
L98GTA87
Engine/Drivetrain/Suspension Wanted
1
08-11-2015 06:55 PM
84z96L31vortec
North East Region
1
08-10-2015 08:27 PM