After long consideration i purchased the thornton stainless short tube headers for my 455 .I hope they flow a little better than the w/z manifolds since they are 150 dollars more.but still far less than the hookers(and i dont like the way one tube wraps around the frame and limits steering)of corse the american racing headers would be the way to go and keep everything inside the frame rails on my 80 cutlass, but i simply didnt have the money for them.Thorton states no fitment issues with plenty of clearance.sort of true but, the drivers side had to come up from the bottom because it wouldn't get by the steering shaft. had to remove the starter as well to slide it up in and remove the oil dipstick tube.with that said it bolted in nicely and has a nice 1/2 thick flange on it .the passenger side went right in from the top with a little struggle tightening the rearmost bolt.I used stainless 3/8 x1 hex head bolts and suspect regular header bolts may have given more room to work .I seriously thought about the ebay 150 dollar specials and just beat the hell out of them to make them fit ,but decided against it.i bought the standard pypes a-body downpipes for it and two cherry bombs that with just dump out in front of the rear wheels and call it done! Ill add to this thread when its all together to let everyone know the final result

 

Please let us know more when your done.
I have a set also I'm planning on using but mine is still a project.
As with you,I don't want long tube headers for a few reasons,I don't expect these to compare to the flow of LTH's but I am not building a race engine.
I'm hoping they will end up flowing slightly better then stock manifolds and with these I get a non stock look that I'm after.
I love the thick flanges on these shorties.
Did you notice a dent in one of the tubes? It's supposed to be there to aid in bolt installation.

 

there were no dents in these .and i will give you an update

 

It is the new bigger SBO headers with the flattened tube. I would like to see them use an expander on that tube, there is an open space behind the pipe where it could take up space and have more cross section. For the added cost, they should.

 

What kind of HP gain can be expected from these headers? 10 to 20 HP?, also how much nosier are they compared to stock manifolds? I really like the look and what appears to be great quality.

 

I personally don't think you would see any gains in horse power the tubes are too short.If you want horse power don't be cheep spend the money and get good headers period.

 

I’ve been running these Thornton’s for a couple years now and really like the quality . I wish I knew the actual hp numbers in comparison to factory manifolds .it would be hard for me to evaluate the sound because mine have pypes downpipes going into cherry bombs and dump out in front of the rear tires so it’s pretty loud , but that’s the way I wanted it .my unprofessional opinion would be better than stock but not as good as full length headers . Well worth the headache and cost of a full length header in an a/ g body.

 

When I dyno tested my one of my cars (not Olds) it gained 2hp at the wheels (above 4500rpm) when we switched from manifolds to shorty headers. IMO not worth the money.

 

Not a question of money at all, just want to see what the gain is if any. I am perfectly happy with my stock manifolds but looking for some "breading room". I am not going to modify my "Garner exhaust" for full headers. Shouldn't one want to know what they are getting for $500.00?????????????? Hello, is there anybody home?

 

In my case I started with nothing so going 150 dollars more for the Thornton shorties over the wz wasn’t huge . However 8 or 9 hundred more for the arh was another story I don’t have money to burn . Until someone actually does a test and has documents to prove the results it’s all just opinions . Maybe Mark will do this on his 350 Dyno mule and put a rest to this ongoing debate 😬in any case they look good and I’m perfectly happy with mine

 

deadeyejedi, that makes perfect sense. Starting from nothing i would do the same thing you did because the extra $150.00 sure covers the looks and rust free tubing. Thornton should be the one dyno testing to incentivize purchases.

 

I have full length headers on my engine and I don't think there is any increase in sound compared to the manifolds. It's the rest of the exhaust that makes the difference, the mufflers specifically and exhaust pipes all the way to the rear of the vehicle.

 

I installed a set of the Thornton stainless short tubes on my '69 442 about a year ago. I detailed that in another thread. My 400G is slightly modified (aftermarket crank, H-beam rods, aftermarket cam, aluminum heads and intake) and I ran the stock W/Z manifolds for a couple of years prior to switching. I have a good aftermarket 2.5" exhaust system on the car and didn't want to go the route of a set of full length ARH.
Quality, fit and installation of the Thornton's are top notch. No issues whatsoever.
Performance? None, really. I suspect any improvements in breathing are so minor that the butt dyno can't register them.
Sound? My wife says the car sounds like a cigarette boat when it's idling in the garage. In my opinion, the Thornton's actually quieted the tailpipe noise down a slight amount.
Bottom line - good quality parts and an affordable alternative to W/Z manifolds. However, if you're expecting a performance gain, look somewhere else.

 

I am hoping Cutlassefi can test the brand new Sanderson shorties I sent him to test on the dyno. They were sent right to him and they looked like crap. There have been some issues on the Thornton headers as well. I say about 1/2 the power as full length but more than Thornton JR manifolds which aren't as good as the W/Z BBO manifolds due to space and the 2 1/2" vs 2 1/8" outlet size difference.

 

Question is, did Thornton even ever intented these to be performance-headers? Do they state it anywhere? I quess it was invented here by some guys that they should be performance-items.
They state as following, right on their web-site "Thornton design; a direct replacement for an exhaust manifold."

No mention of increased performance anywhere. Now its up to the buyer, do they want the cast manifolds, or nice and shiny tubular ones, with the addition of both fitting stock exhausts, making the install easy, and opening market opportunities for Thornton? They are in business, and making money to keep the company rolling and get paid themselves is surely one of the priorities. And yes, their products are good quality, seen more than few. And everyone here seems to also write it down, performance or not, that the quality has been there on most part.

 

You pretty much told it as it is. Thank you.

 

Seriously??? So what exactly is the purpose if not performance? To answer the question no one asked? Or are you just admitting that they're targeted at posers? Sorry, but not buying it (figuratively and literally)

 

Glass packs? That's some hillbilly shjt, right there.

 

Damn straight! 😂

 

I see what you did there! Touche'!!

 

No problem, couldnt care less

 

Isn't there one dyno test on a hotter 350? They did gain over manifolds on a dyno test, a noticeable amount, talking the larger primary tubes and 2.5" outlet version. What is 2 WHP off the motor? Pretty sure it was more than that. The stock 350 manifolds are a big compromise and due to less space than a BBO, so are Thornton JR, again due to less space. The JR manifolds seem to be cast much better now and have 2 1/8" outlets, with 2.25" being the max the castings will take. This is info and pictures from a recent buyer. These shorty headers are a compromise, no **** but they are a gain even over Thornton JR manifolds or any SBO manifolds. They are very similar to the Sanderson but have larger primary tubes, one is flattened pretty good, are stainless steel but a smaller outlet. Of course they don't look like they were welded by small children in third world countries😉.

 

I bought the used set that was in the classifieds. They came with the down pipes and after pricing just the down pipes I decided to purchase them. I’m not expecting the same gains as full length headers but i am hoping they are lighter. I will try and weigh them today.

 

I bet they are close to half the weight of manifolds, another bonus. My Sanderson headers weighed almost exactly 1/2 the weight. My 403 manifolds weighed around 20 pounds each and I believe the Sanderson were 11 pounds each, I believe, they may have even been 10 pounds. Someone weigh and compare.

 

this is another point of note if your trying to shave weight . You are correct the Thornton’s weigh half the weight of original manifold .

 

Or, move the battery to the trunk and save the money.

 

Take the spare out of the trunk and the weight is lost in proportion. The bottom line is a lack of transparency from the manufacture.

 

I'm not going to put the 'bombs on any muscle car I own, but my old man's Vette is rocking some vintage cherry bombs that are probably straight pipes by now.

I do have a 73 Econoline with a 302 that I might dual exhaust with glass packs just to be Peak 70s.....unless I went for the full out Thrush sidepipes.

 

When i bought my 68 442 111 years ago it had "Cherry Bombs" on it but i quickly replaced the entire exhaust with a "Gardner exhaust system" which i truly love the Cherry bombs were way too loud for me.

 

Man you’re old.

 

Typo mistake 11 years ago but yes i am older than the automobile itself.