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.

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/

Re: Exhaust manifolds for an L31 swap from 350?
 

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

Re: Exhaust manifolds for an L31 swap from 350?
 

Very nice.

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.

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.

Re: Exhaust manifolds for an L31 swap from 350?
 

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

Re: Exhaust manifolds for an L31 swap from 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

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.

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.

Re: Exhaust manifolds for an L31 swap from 350?
 

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

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/

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

Re: Exhaust manifolds for an L31 swap from 350?
 

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

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

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.

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.

Re: Exhaust manifolds for an L31 swap from 350?
 

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

Re: Exhaust manifolds for an L31 swap from 350?
 

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

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.