Vortec heads vs 350 exhaust.

[DavidinNC]

I’ve been looking but can’t get a confirming or disconfirming answer. Will stock exhaust manifolds for a 1987 350 fit on Vortec heads? Thanks for good answers!

 

[SquareRoot]

Maybe. Why would you run vortecs and choke them with factory manifolds?

 

[DavidinNC]

I’m just wanting to know. I prefer to use manifolds rather than headers. I’ve seen a lot of complaints about keeping headers sealed. Do they really cause that much HP loss?

 

[Frankenchevy]

They’ll bolt up. The port may not match perfectly. Having the manifold port slightly longer on the bottom side than the head is supposed to increase scavenging. In other words, there should be a step down into the manifold.

 

[Rusty Nail]

Do they really cause that much HP loss?

Yes.

Voted bad port match. You'd kill even more power than if the ports actually matched. (Cathedral)
Think vortex manifolds or buy vortex headers if they got those? dont know.. All part of the fun!

GoooOoOooo Vortex!

 

[DavidinNC]

Ok then thanks for the input! It will help me decide which engine to use. I’m trying to decide on either an ATK HP31 or go to ATK HP32 or HP74.

 

[Vbb199]

Im running a 350, stock manifolds, vortec heads, cam, stock intake.

Lots o power.

Also Op, where you at in NC??

 

[DavidinNC]

Im running a 350, stock manifolds, vortec heads, cam, stock intake.

Lots o power.

Also Op, where you at in NC??

mom in Reidsville. My 87 TBI 305 is near end of life. I started out thinking I’d just put a matching stock engine in to replace. But after looking and seeing the power advantages I want to improve things. Just want to make sure I have all I need before I start so I’m not having any more delays than needed.

 

[Vbb199]

mom in Reidsville. My 87 TBI 305 is near end of life. I started out thinking I’d just put a matching stock engine in to replace. But after looking and seeing the power advantages I want to improve things. Just want to make sure I have all I need before I start so I’m not having any more delays than needed.

Im in salisbury, nc.

If you got the doll-hairs, a 383 or 350HO would change things up.

With either change you will need bigger injectors(350 cid), or a larger bore 650cfm tbi (383 stroker), and a PROM chip burn.

 

[77 K20]

I had ramhorn manifolds on my old 400 and when that engine died I put them on a vortec headed 383.

I didn't want to mess with headers either- these cast iron manifolds haven't leaked.

Although I'd stay away from the 2.5" center dump- had to have the motor mount clamshell modified for clearance on the driver side. I think they made a truck version with a 2" outlet.

You must be registered for see images attach

You must be registered for see images attach

 

[Salty Crusty]

You're leaving a good bit of power on the table by not using headers.
Use Stage 8 locking fasteners and a good gasket and you'll be fine.
I'd encourage you to get coated, particularly if you're in a wet/humid area. Coating protects them from rust and can lower underhood temps a good bit.

 

[68post]

I'd make sure to use a dual exhaust with headers and H-pipe crossover too, you'll get your money back with increased gas mileage. Works even with a TBI or regular 2bbl.

 

[Catbox]

With headers, you want to make sure you get a set that have 3/8" flanges on them.
You should not have any problems with them leaking.
Install them and drive them for a couple hundred miles and then retighten them.
They should stay tight.

Here is a set that I pulled from the junkyard last year.
They have the thick flanges on them and are a direct fit for my stock manifolds on my 1995 Suburban.

You must be registered for see images attach

You must be registered for see images attach

 

[Vbb199]

With headers, you want to make sure you get a set that have 3/8" flanges on them.
You should not have any problems with them leaking.
Install them and drive them for a couple hundred miles and then retighten them.
They should stay tight.

Here is a set that I pulled from the junkyard last year.
They have the thick flanges on them and are a direct fit for my stock manifolds on my 1995 Suburban.

You must be registered for see images attach

You must be registered for see images attach

Do you have a part number on those?

 

[77 K20]

I had spent a lot of time researching manifolds vs headers when I made my decision. Found some articles that included dyno runs. For the most part the 2.5" ramhorn manifolds were within 5-6 ft/lbs up to about 4,600 RPM. Then some great gains above that RPM.

With my 400 or the 383 I have now (redlines at 5,000) that is a non-issue to me.

Speedway still has the manifolds for $59/each. They used to be a bit cheaper.

I've enjoyed zero leaks even after filling the engine bay up with snow while offroading.