Looking for advice on headers and plug angle?
Thread Starter
Advanced
Joined: Jan 2014
Posts: 77
Likes: 8
From: Muskegon Michigan
Looking for advice on headers and plug angle?
I am getting things together for my Alum head roller cam update to my 1980 L48 for this off season (Michigan winter). I plan on going to a roller cam in the .500" range and some 180cc alum heads. I figured while I had it apart I also would replace my old tired/ rusty headers. I am looking for advice on a good fitting long tube header that comes in either ceramic coat or stainless. Also on that point I have the option of either straight plug or angled plug heads and I'm not sure which way to go or what the pros and cons of the 2 types are. One more related question is with 1.5 to 1 roller rockers will I have to go to tall valve covers with this set up? All advice will be appreciated as always. I have gotten some great advice from all the expertise on this forum, you all have helped me tremendously with this project. Thanks Gil
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
I'd go with Hedmann ceramic coated long tube headers and straight plug heads. Less issues with clearance between the headers and plugs. If you are running flat-top pistons, straight or angled no real advantage:
https://www.hotrod.com/articles/ccrp...tion-chambers/
Plus, with angled, you will have to spend more on headers to get the clearance.
https://www.hotrod.com/articles/ccrp...tion-chambers/
Plus, with angled, you will have to spend more on headers to get the clearance.
Last edited by TedH; Aug 26, 2018 at 08:44 AM. Reason: clarification
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
I am getting things together for my Alum head roller cam update to my 1980 L48 for this off season (Michigan winter). I plan on going to a roller cam in the .500" range and some 180cc alum heads. I figured while I had it apart I also would replace my old tired/ rusty headers. I am looking for advice on a good fitting long tube header that comes in either ceramic coat or stainless. Also on that point I have the option of either straight plug or angled plug heads and I'm not sure which way to go or what the pros and cons of the 2 types are. One more related question is with 1.5 to 1 roller rockers will I have to go to tall valve covers with this set up? All advice will be appreciated as always. I have gotten some great advice from all the expertise on this forum, you all have helped me tremendously with this project. Thanks Gil
1.5:1 rockers are the stock ratio. You shouldn't need tall valve covers unless you purchase some of the roller rocker arms.
Craig
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,443
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
It has been my experience with lots of different heads that I has nothing to do with the angle of the plug per say, but the actual casting placement of the plug in relationship to the exhaust ports
I had 186 heads with 1 5/8th headman headers then 292 angle plug hooker SC headers 1 3/4. Then I went to dart. .600 raised port angle plugs. Never a problem and then I bought AFR and it is hard to even install the plugs and I had to dent my headers for the plug wires so for great flow it came at a small cost.
to me heads are a lifetime purchase and can be used on many future motor combinations. So my advice is to think about that 383, 400, or 427 coming up next
I had 186 heads with 1 5/8th headman headers then 292 angle plug hooker SC headers 1 3/4. Then I went to dart. .600 raised port angle plugs. Never a problem and then I bought AFR and it is hard to even install the plugs and I had to dent my headers for the plug wires so for great flow it came at a small cost.
to me heads are a lifetime purchase and can be used on many future motor combinations. So my advice is to think about that 383, 400, or 427 coming up next
Le Mans Master
Joined: Mar 2004
Posts: 7,423
Likes: 1,458
From: Little Rock AR
My $.02 is straight plug heads will work and fit straight plug headers. You have one less thing to deal with now and down the road. Might cost a few HP ....but not much.
The roller rockers frequently need tall valve covers. There are some locknuts that allow short covers with roller rockers but not as common. It can be done. I have used (like) the cast steel roller tips and they will fit without modifications, but the spring loads you need are likely too high for those rockers.
My $.04 - Angle plug heads and roller rockers have their place. If you were needing every last 10 HP you want to look for it. If you have no rules restrictions, more cubes is a better way to get there. Blower is a close second behind cubes. (maybe do all three
)
Truth - If you were REALLY needing every last HP with no restrictions, LS based motor makes it much easier than a Gen 1. I have both, and each have their place.
The roller rockers frequently need tall valve covers. There are some locknuts that allow short covers with roller rockers but not as common. It can be done. I have used (like) the cast steel roller tips and they will fit without modifications, but the spring loads you need are likely too high for those rockers.
My $.04 - Angle plug heads and roller rockers have their place. If you were needing every last 10 HP you want to look for it. If you have no rules restrictions, more cubes is a better way to get there. Blower is a close second behind cubes. (maybe do all three
)Truth - If you were REALLY needing every last HP with no restrictions, LS based motor makes it much easier than a Gen 1. I have both, and each have their place.
Thread Starter
Advanced
Joined: Jan 2014
Posts: 77
Likes: 8
From: Muskegon Michigan
My $.02 is straight plug heads will work and fit straight plug headers. You have one less thing to deal with now and down the road. Might cost a few HP ....but not much.
The roller rockers frequently need tall valve covers. There are some locknuts that allow short covers with roller rockers but not as common. It can be done. I have used (like) the cast steel roller tips and they will fit without modifications, but the spring loads you need are likely too high for those rockers.
My $.04 - Angle plug heads and roller rockers have their place. If you were needing every last 10 HP you want to look for it. If you have no rules restrictions, more cubes is a better way to get there. Blower is a close second behind cubes. (maybe do all three )
Truth - If you were REALLY needing every last HP with no restrictions, LS based motor makes it much easier than a Gen 1. I have both, and each have their place.
The roller rockers frequently need tall valve covers. There are some locknuts that allow short covers with roller rockers but not as common. It can be done. I have used (like) the cast steel roller tips and they will fit without modifications, but the spring loads you need are likely too high for those rockers.
My $.04 - Angle plug heads and roller rockers have their place. If you were needing every last 10 HP you want to look for it. If you have no rules restrictions, more cubes is a better way to get there. Blower is a close second behind cubes. (maybe do all three
)Truth - If you were REALLY needing every last HP with no restrictions, LS based motor makes it much easier than a Gen 1. I have both, and each have their place.
Pro
Joined: May 2016
Posts: 708
Likes: 149
From: Minnesota
I would stick with your plan as-is, go with straight plugs and I went with Doug's Headers (ceramic coated) and they fit beautifully with plenty of boot clearance, etc. I have read lots of good feedback on Hooker and Doug's. Good idea on AFR 180's ... whatever you do, avoid the Dart SHP (I am running them, they made decent power, but struggled with pushrod geometry and interference -- BS for new heads that you spend this kind of money on). I used a Howard's roller (I know there are various out there) and very happy with the motor.
Thread Starter
Advanced
Joined: Jan 2014
Posts: 77
Likes: 8
From: Muskegon Michigan
I would stick with your plan as-is, go with straight plugs and I went with Doug's Headers (ceramic coated) and they fit beautifully with plenty of boot clearance, etc. I have read lots of good feedback on Hooker and Doug's. Good idea on AFR 180's ... whatever you do, avoid the Dart SHP (I am running them, they made decent power, but struggled with pushrod geometry and interference -- BS for new heads that you spend this kind of money on). I used a Howard's roller (I know there are various out there) and very happy with the motor.
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Dr. Detroit
Joined: Mar 2012
Posts: 10,090
Likes: 4,015
From: New Braunfels Texas
Straight plug. There has never been a shred of evidence supporting angle plug designs..........especially now with the kidney bean fast burn chambers that most manufactures use now.
I have Dart Pro 1 Platinums on my 72' with straight plug and a 30 year old pair of Hedman Headers.....everything fits perfect and easily accessible.
I have run Comp Pro Magnum roller rockers with stock LT-1 valve covers as the body of these rockers is relatively small. If using a Scorpion or Lunati rocker with a big fat body.....you will need extra thick valve cover gaskets. It is hit or miss whether or not you will have to remove the dripper tabs on the inside of the covers as this is dictated more by the length of the pushrod which will raise or lower the whole rocker and poly lock. My rollers fit on my flat tappet deal......but roller stuff is taller. It also depends on what heads you buy....the AFR has a really high valve cover rail.......the Dart does too but not so much. You will have to mock it up and see.
Jebby
I have Dart Pro 1 Platinums on my 72' with straight plug and a 30 year old pair of Hedman Headers.....everything fits perfect and easily accessible.
I have run Comp Pro Magnum roller rockers with stock LT-1 valve covers as the body of these rockers is relatively small. If using a Scorpion or Lunati rocker with a big fat body.....you will need extra thick valve cover gaskets. It is hit or miss whether or not you will have to remove the dripper tabs on the inside of the covers as this is dictated more by the length of the pushrod which will raise or lower the whole rocker and poly lock. My rollers fit on my flat tappet deal......but roller stuff is taller. It also depends on what heads you buy....the AFR has a really high valve cover rail.......the Dart does too but not so much. You will have to mock it up and see.
Jebby
Last edited by Jebbysan; Aug 26, 2018 at 03:27 PM.
Le Mans Master
Joined: Aug 2010
Posts: 5,339
Likes: 546
From: Central Texas
Thanks Joe, I plan on a Howards roller set up for mine something in the neighborhood of .485 to .500" lift. My L48 had a complete and well done rebuilt shortly before I bought the car so I am just making changes to the cam heads and valve train for now. I plan on staying with my Edelbrock performer intake and holley 750 as well. I may give you a holler for advice as I go thru this as it appears our goals and builds will be very similar. Gil
Burning Brakes
Joined: May 2018
Posts: 797
Likes: 156
From: England AR
I have the Super Comp Side exhaust with angle plugs and I love em, I doubt they do anything for my HP and honestly I don't care if they did or didn't... having them angle away from the center primaries makes life sooooo much easier when doing plugs and wires
Melting Slicks
Joined: May 2012
Posts: 2,192
Likes: 343
From: Allenton Wisconsin
I used Harlan Sharps 1.5 to 1 roller rockers under the stock tin painted valve covers on my 69 and also under stock C4 84 magnesium valve covers mounted on Dart Pro 1s. T
Last edited by terrys6t8roadster; Aug 27, 2018 at 06:44 AM.