Exhaust manifolds for an L31 swap from 350? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

msg · 12-20-2019, 04:20 PM

I am swapping out the 350 engine I had on my 66 C10 for a new L31 Vortec and the rusty headers are bugging me. I think they will fit the new engine but Im not sure I want to run them. I thought for a start just hook them up and get things running, maybe have them sandblasted and coated. I called around and got a quote for ceramic coating them for $265 a pair. I guess I could wirebrush and use some spray can VHT and let it ride, but Im not writing off stock exhaust manifolds if I knew which to get. I will have a 700r4 trans once I get it all assembled. I dont race the truck just cruising around so unless the gas mileage is improved much with headers I think Id rather have the stock manifolds. Which manifolds are the ones to get? Here is a pic of what the headers looked like on the 350 I pulled.

chevy_mike · 12-21-2019, 03:23 PM

I used these on my '65 panel and they worked great! Fit perfect and looked good and best thing, they are cheap being ceramic coated.

https://www.summitracing.com/parts/sum-g9200s/overview/

msg · 12-21-2019, 06:16 PM

Thanks for that Mike! Im tempted to drop the headers and do this.

**LostMy65** · 12-21-2019, 09:11 PM

Quote:

Originally Posted by chevy_mike

I used these on my '65 panel and they worked great! Fit perfect and looked good and best thing, they are cheap being ceramic coated.

https://www.summitracing.com/parts/sum-g9200s/overview/

Very nice.

**MikeN** · 12-21-2019, 09:19 PM

The stock-type rams horn manifolds, either natural or coated, are the way to go. Have them on my 64 C10 and my 65 Impala. The coated ones above look super nice. No leaks, fit great, quiet, etc.

**Captainfab** · 12-21-2019, 10:26 PM

Before you pull the trigger on those exhaust manifolds, you might want to verify that they will work with the centerbolt valve covers that are on the L31 350.

msg · 12-22-2019, 12:05 AM

Thanks for the word of caution Captain, Ill look into it.

**The Rocknrod** · 12-22-2019, 10:12 AM

Quote:

Originally Posted by Captainfab

Before you pull the trigger on those exhaust manifolds, you might want to verify that they will work with the centerbolt valve covers that are on the L31 350.

What have you heard?
Thats a killer price listed above, also the hedman units with the 3/8" flange and coated would be nice. About double the cost though.

What gets in the way?
Oh I just looked - http://67-72chevytrucks.com/vboard/s...d.php?t=759196

b454rat · 12-22-2019, 10:14 AM

Iv'e read somewhere that the Vortec heads have a different shaped exhaust port, almost like a D shape.

msg · 12-22-2019, 10:48 AM

That link Rocknrod listed is saying the bolt holes arent centered on the exhaust ports causing a mismatch. I have to believe that is correct info, but when I put the pics from summits site of the engine I bought and that exhaust port they look centered to me. Pics arent always right, and Im probably looking at it wrong though.

**The Rocknrod** · 12-22-2019, 04:50 PM

The bolt holes "look" lower to me in that pic. What's the link?

msg · 12-22-2019, 05:13 PM

Heres the engine I bought
https://www.summitracing.com/parts/NAL-12681432

and the manifold I used in that comparison pic
https://www.summitracing.com/parts/sum-g9200s/overview/

**bhap** · 01-15-2020, 06:52 PM

Have you had a chance to match the Vortec heads to the Rams Horn manifolds? I'm thinking of doing a similar setup so would like to hear how yours is going.

Thanks

gulfcoast66 · 01-16-2020, 08:34 AM

D-Ports on the Vortecl31 Heads and Square Ports on the Ram Horns...

msg · 01-17-2020, 06:40 PM

I wish I was at the point of install on the engine, still getting the brake lines worked out first. But hopefully it wont be long now. The gasket on the engine looks like this

msg · 01-17-2020, 06:42 PM

The same gasket on the manifold looks like this. I am no expert but I think this would work.

**Captainfab** · 01-17-2020, 10:50 PM

I don't see why that won't work. Exhaust manifold ports are seldom a perfect match to the head ports.

**The Rocknrod** · 01-18-2020, 01:23 PM

That's a great pic MSD (both of them). Thanks for that.

52 gimmy · 01-22-2020, 01:27 PM

They will work. I have used them before on the centerbolt heads. No issues

**MikeN** · 01-23-2020, 10:29 AM

I didn't clarify in my first post above - my Impala has a 355 SBC with EngineQuest (EQ) heads, which are new castings that are basically exact copies of the GM Vortec castings. I have the inexpensive Dorman (Chinese) reproduction 2.5" rams horn manifolds on it. They look great and work great with the Vortec-style heads.

Off-topic, but anyone building a performance engine should research the EQ heads. They are really nice heads, and a great value.

12-20-2019, 04:20 PM	#1
msg Registered User Join Date: Feb 2013 Location: GA Posts: 1,313	Exhaust manifolds for an L31 swap from 350? I am swapping out the 350 engine I had on my 66 C10 for a new L31 Vortec and the rusty headers are bugging me. I think they will fit the new engine but Im not sure I want to run them. I thought for a start just hook them up and get things running, maybe have them sandblasted and coated. I called around and got a quote for ceramic coating them for $265 a pair. I guess I could wirebrush and use some spray can VHT and let it ride, but Im not writing off stock exhaust manifolds if I knew which to get. I will have a 700r4 trans once I get it all assembled. I dont race the truck just cruising around so unless the gas mileage is improved much with headers I think Id rather have the stock manifolds. Which manifolds are the ones to get? Here is a pic of what the headers looked like on the 350 I pulled. Attached Images __________________ Progress thread for my 66 http://67-72chevytrucks.com/vboard/s...d.php?t=623848

12-21-2019, 03:23 PM	#2
chevy_mike Never Ending Projects Join Date: Jul 2006 Location: San Diego, CA Posts: 3,836	Re: Exhaust manifolds for an L31 swap from 350? I used these on my '65 panel and they worked great! Fit perfect and looked good and best thing, they are cheap being ceramic coated. https://www.summitracing.com/parts/sum-g9200s/overview/ Attached Images __________________ . 1965 C10 Panel, Tiki Express http://www.67-72chevytrucks.com/vboa...d.php?t=506580 SOLD 1968 Chevy C10, Long, Fleetside, Hot Rod Hauler http://67-72chevytrucks.com/vboard/s...d.php?t=313233 SOLD 1965 Chevy C10, Long, Fleetside, Hot Rod C10 http://67-72chevytrucks.com/vboard/s...d.php?t=415702 SOLD We were given two ears and one mouth for a reason... listen twice as much and speak half as often...

12-21-2019, 06:16 PM	#3
msg Registered User Join Date: Feb 2013 Location: GA Posts: 1,313	Re: Exhaust manifolds for an L31 swap from 350? Thanks for that Mike! Im tempted to drop the headers and do this. __________________ Progress thread for my 66 http://67-72chevytrucks.com/vboard/s...d.php?t=623848

12-21-2019, 09:19 PM	#5
MikeN Senior Member Join Date: Oct 2007 Location: Marietta, GA Posts: 776	Re: Exhaust manifolds for an L31 swap from 350? The stock-type rams horn manifolds, either natural or coated, are the way to go. Have them on my 64 C10 and my 65 Impala. The coated ones above look super nice. No leaks, fit great, quiet, etc.

12-21-2019, 10:26 PM	#6
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,246	Re: Exhaust manifolds for an L31 swap from 350? Before you pull the trigger on those exhaust manifolds, you might want to verify that they will work with the centerbolt valve covers that are on the L31 350. __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE

12-22-2019, 12:05 AM	#7
msg Registered User Join Date: Feb 2013 Location: GA Posts: 1,313	Re: Exhaust manifolds for an L31 swap from 350? Thanks for the word of caution Captain, Ill look into it. __________________ Progress thread for my 66 http://67-72chevytrucks.com/vboard/s...d.php?t=623848

12-22-2019, 10:14 AM	#9
b454rat Senior Member Join Date: May 2004 Location: Binghamton, NY Posts: 3,453	Re: Exhaust manifolds for an L31 swap from 350? Iv'e read somewhere that the Vortec heads have a different shaped exhaust port, almost like a D shape.

12-22-2019, 10:48 AM	#10
msg Registered User Join Date: Feb 2013 Location: GA Posts: 1,313	Re: Exhaust manifolds for an L31 swap from 350? That link Rocknrod listed is saying the bolt holes arent centered on the exhaust ports causing a mismatch. I have to believe that is correct info, but when I put the pics from summits site of the engine I bought and that exhaust port they look centered to me. Pics arent always right, and Im probably looking at it wrong though. Attached Images __________________ Progress thread for my 66 http://67-72chevytrucks.com/vboard/s...d.php?t=623848

12-22-2019, 04:50 PM	#11
The Rocknrod Moderator Join Date: Aug 2011 Location: China Spring, TX Posts: 7,280	Re: Exhaust manifolds for an L31 swap from 350? The bolt holes "look" lower to me in that pic. What's the link? __________________ Master Chief, US Navy, Retired 1964 C10 Step-side Short Bed - In Progress 2009 2500HD Duramax LTZ 1948 GMC Panel 1956 Big Window Stepside 1953 5 Window Chevy Stepside 1932 Coupe New Seat Foam for Bench Seats?

12-22-2019, 05:13 PM	#12
msg Registered User Join Date: Feb 2013 Location: GA Posts: 1,313	Re: Exhaust manifolds for an L31 swap from 350? Heres the engine I bought https://www.summitracing.com/parts/NAL-12681432 and the manifold I used in that comparison pic https://www.summitracing.com/parts/sum-g9200s/overview/ __________________ Progress thread for my 66 http://67-72chevytrucks.com/vboard/s...d.php?t=623848

01-15-2020, 06:52 PM	#13
bhap Senior Member Join Date: Mar 2006 Location: Pittsburgh, PA Posts: 240	Re: Exhaust manifolds for an L31 swap from 350? Have you had a chance to match the Vortec heads to the Rams Horn manifolds? I'm thinking of doing a similar setup so would like to hear how yours is going. Thanks

01-16-2020, 08:34 AM	#14
gulfcoast66 64-66 CHEVY JUNKIE Join Date: Apr 2007 Location: Cypress ,Texas Posts: 1,516	Re: Exhaust manifolds for an L31 swap from 350? D-Ports on the Vortecl31 Heads and Square Ports on the Ram Horns... __________________ 1966 C-10 Fleetside LWB, 350 Lt1 4l60-E 2008 Silverado Crew Cab, 4.8 4l60-E 1998 GMC Yukon 4x4 L-31 Vortec, 4l60-E 2017 GMC Serra 4x4 5.3 Vortec, 4l60-E Do It In A Chevrolet

01-17-2020, 06:40 PM	#15
msg Registered User Join Date: Feb 2013 Location: GA Posts: 1,313	Re: Exhaust manifolds for an L31 swap from 350? I wish I was at the point of install on the engine, still getting the brake lines worked out first. But hopefully it wont be long now. The gasket on the engine looks like this Attached Images __________________ Progress thread for my 66 http://67-72chevytrucks.com/vboard/s...d.php?t=623848

01-17-2020, 06:42 PM	#16
msg Registered User Join Date: Feb 2013 Location: GA Posts: 1,313	Re: Exhaust manifolds for an L31 swap from 350? The same gasket on the manifold looks like this. I am no expert but I think this would work. Attached Images __________________ Progress thread for my 66 http://67-72chevytrucks.com/vboard/s...d.php?t=623848

01-17-2020, 10:50 PM	#17
Captainfab 60-66 Nut Join Date: Mar 2007 Location: Coeur d'Alene, Idaho Posts: 23,246	Re: Exhaust manifolds for an L31 swap from 350? I don't see why that won't work. Exhaust manifold ports are seldom a perfect match to the head ports. __________________ Power Steering Box Adapter Plates For Sale HERE Power Brake Booster Adapter Brackets For Sale '63-'66 HERE and '67-'72 HERE and '60-'62 HERE and "60-'62 with clutch HERE Rear Disc Brake Brackets For Sale. Impala SS calipers HERE Camaro Calipers HERE D52 Calipers HERE 6 Lug HERE Hydroboost Mounting Plates HERE



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01-18-2020, 01:23 PM	#18
The Rocknrod Moderator Join Date: Aug 2011 Location: China Spring, TX Posts: 7,280	Re: Exhaust manifolds for an L31 swap from 350? That's a great pic MSD (both of them). Thanks for that. __________________ Master Chief, US Navy, Retired 1964 C10 Step-side Short Bed - In Progress 2009 2500HD Duramax LTZ 1948 GMC Panel 1956 Big Window Stepside 1953 5 Window Chevy Stepside 1932 Coupe New Seat Foam for Bench Seats?

01-22-2020, 01:27 PM	#19
52 gimmy Registered User Join Date: Dec 2018 Location: Myrtle Beach South Carolina Posts: 4	Re: Exhaust manifolds for an L31 swap from 350? They will work. I have used them before on the centerbolt heads. No issues

01-23-2020, 10:29 AM	#20
MikeN Senior Member Join Date: Oct 2007 Location: Marietta, GA Posts: 776	Re: Exhaust manifolds for an L31 swap from 350? I didn't clarify in my first post above - my Impala has a 355 SBC with EngineQuest (EQ) heads, which are new castings that are basically exact copies of the GM Vortec castings. I have the inexpensive Dorman (Chinese) reproduction 2.5" rams horn manifolds on it. They look great and work great with the Vortec-style heads. Off-topic, but anyone building a performance engine should research the EQ heads. They are really nice heads, and a great value.

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