trevor s

Since my 73 Cutlass 350 will be mild / stock, would I get much out of a set of headers? I hear lots of install and fitment nightmares, If it's worth doing who makes the best fitting header for a 73 350? I was looking at Thorton's manifolds and leaning towards that. I am sure this has been done to death, sorry if it's redunts.
Thanks
Trevor

oldcutlass

Headers are good for about a 5% increase in power with a good flowing exhaust system. Yes, there are some fitment issues at times depending on brand. The Thorntons are 1 step over stock manifolds.

cutlassefi

Ok, so on a 200hp application they're worth 10hp and on a 500hp one they're only worth 25?
Sorry but that's simply not true.

olds 307 and 403

A shorty set like the Sanderson headers should be worth 20 hp/tq. The full length cheap headers should be worth 25 hp/tq. The Thornton manifolds might be worth 10 as is, just a guess. I go off an article in Mopar Muscle with a 300 hp 318. Started with awful 318 manifolds, then 360 manifolds, Hi Po 340 manifolds, shorty headers, then full length, stepped headers. 11hp/tq, 13 hp/tq, 21 hp/tq and 28 hp/tq. I had a pair of the truck/van 318 manifolds, just as awful as the SBO ones. Remember, not all mufflers are created equal. The Dynomax Super Turbo are quite and supposedly flow well. I think the Hooker Compettion headers with 1 5/8" primary tubes would go nicely with a stock 350.

oldcutlass

I agree, however what I stated was for his anemic 350, it was good for about 5%.

DoubleV

IMO, headers aren't worth the hassle on a mild/stock 350. Now if you build the engine a certain way, then headers could make a big difference. On a stocker, not so much.

About header tube diameter; In theory a small tube header would work best on a mild/stock 350ish engine. The problem I see is port mismatch though. If you put a small tube ( 1 5/8" ) header on a SBO, there's a big port mismatch due to the huge exhaust port in the head feeding into the much smaller header. That can't be good for flow. As a result, your kinda stuck using a bigger 1 3/4" header which seems a little big for a 'stock' 350.

If you had tons of money to have a set of custom built headers that were designed to work the best with your mild combo then I'm sure you could see decent gains, but I don't think any over-the-counter header is really going to be worth more than a couple of tenths at the track over manifolds. Just my opinion.

cutlassefi

I understood your post but I promise you they'll make more than a 10hp difference, even on a bone stock 350.

oldcutlass

How much gain do you think he will realize with just adding headers.

my71olds

So its worth getting a set of headers on a bone stock 350? If so any brands you recommend? Hooker?

Thanks

JPMDaddy

have long tube headers on my chevy - PIA

Putting these on my Cutlass 350

DSC_3806_zps636d9c47.jpg

QS442

I have a new set of Hooker 3107 that fit excellent for the late 60s/early 70s 350. I purchased for my Omega and they are wrong application.

1970-W30

Another point to consider is the fact that the header power gains, 10hp on up, are not across the entire rpm range. Would there be any noticable gains at all in the 1500-3000 rpm range over a freeflowing dual exhaust in a stock 350?

Raydermiike

First of all if it floats your boat go ahead and do it. Since you are asking if it is worth it I would say no. With fitment issues, notorious for exhaust leaks and cost of a set that wont look like trash in a short time for a stock 1973 350 I wouldn't do it. If you are looking for a noticeable performance gain you can smile about on a street car 220 hp from 200 hp isn't going to do it.

Raydermiike

I would throw in one caveat. If you or a buddy have the ability and resources available and this is just an afternoon of fun, what the heck go for it.
If you are taking the car in to have it done the cost of removing the old manifolds, bolting on the headers, mating the the exhaust to the new headers and any fitment problems, which could be none or could be steering in the way, starters in the way, engines needed to be jacked up etc will be considerable. That to the cost of the headers IMO is just not worth the little gain on that engine. Remember, there are a lot of talented guys here, what is a DIY job to them isn't always, at least to guys like me.

captjim

Well stated, IMO. I went the Sanderson shorty route several times because the engine was already out and I decided they were a reasonable compromise for the money. I would do that before the Thorntons. Also keep in mind that the scavenging effect is minimized with the open center divider. Personally, I would not spend $500 on decent headers for a stock, low comp 350. IMHO

trevor s

I admit my skill level is low and Iwant something that won't be a constant issue

Raydermiike

"I admit my skill level is low and I want something that won't be a constant issue"

I figured that was likely the case as it is with me as well. Other than simple or basic I don't do a lot of wrenching. I do have an idea of what I would do in certain situations though. The cost of the headers and having them installed will net you nearly no bang for your buck on that engine as it sits.