Macadoo

Hey guys,
Sorry for all the posts but I'm trying to get the last of my parts together.
Has anyone tried these Flowtech headers on a 455 in 70-72 Supreme with auto trans?
A couple fellas on Facebook Olds page say they have used them and they fit. Might need a massage around the steering column.

https://www.summitracing.com/parts/big-11154flt/reviews

Other suggestions? I don't want to spend weeks next summer getting this motor in so I'll go with manifolds if I have to.

Oldsmaniac

Any header that fits a 442 will fit a Supreme and conv. however I do not recommend flowtechs. Put them on a 72 vert and had to bang the crap out of a tube or two on the driver's side. This was an auto trans car. I always recommend Hooker headers.

Macadoo

Well sir, that's what I needed to know about the Flowtechs. Although odd that a dude with a '71 Supreme said he didn't have to dent his.

I'm seriously considering the repro manifolds but I really want the sound and extra power of the headers.

https://www.opgi.com/cutlass/C240268...8aAs7jEALw_wcB

Troys Toy 70

Mac,

If you decide to go the Flotech jeaders let me know. I have a set I only used for my Dyno day.

Troy

olds 307 and 403

Don't forgot they rust badly. Mine rusted through ceramic coating within a year, pin holes everywhere. Others have also had this issue. Also thin flanges. Did you have headers on the 350? Either Hedman or Hooker for reasonable priced full length headers.

Macadoo

Well hmmm, if the price was right I might not mind taking a big hammer to them. PM me?

Thin flanges sound kinda bad. Not sure I like that. The rusting may not be an issue since I like to glop on the black stove paint. It's easy to touch up with a small brush and really doesn't look bad since on our cars, they can't really be seen all that well.

The tree fitty has Hedman shorty headers. I wish I could just swap those to the 455. There's just not enough room. And would they even bolt up?

coppercutlass

For what its worth the rust bad if you don't maintain them. I have had the same set of blackjack headers for over 9 years. When ever I pull the engine the get a coat of hih heat vht ceramic paint. Don't loose sleep over the thin flanges if you don't over tighten them with a good gasket like remflex you are golden.

Don't buy those crappy repro tube manifolds if that's what you are talking about lol. at that point just get regular manifolds .

Imo get the flowtechs if you gotta hammer em hammer em . Its been proven it don't hurt squat . This way you will see how the headers will work for you and you didn't plop a crap ton of cash into a set.

I got my blackjacks for free they are older like late 70's but Still working great although I smashed a few primaries bottoming the car out over the summer. made for cool sparks lol.

Macadoo

So I found these and was told by many that they are crap.

https://www.ebay.com/itm/OLDS-CUTLAS...19.m1438.l2649

Copper, the manifolds I'm talking about are the OPGI units.

https://www.opgi.com/cutlass/C240268...8aAs7jEALw_wcB

Long tube headers are a bucket list kind of thing. And as much as people say they hang low, they can't hang any lower than the shorties I have on my small block. They dump straight down, close to the bottom of the pan AND THEN you have to make the turn. My down pipes are now flat on the bottom, lol.
Copper dude, are the remflex the graphite things? They worked awesome for me.
Also, I love the VHT paints. Not always the best color but holds up well.

coppercutlass

Those top ones are glorified manifolds. Those things have none of the features that make headers work.

Those manifolds look nice but headers work better. My front end also sits really low which is why I smacked the railroad tracks. . When my front end sat at stock height I never had issues at all. How your car sits with headers you will be fine.

Macadoo

Right? They dump straight down into the main pipe; because we all know that air naturally want to make a 90* turn for no reason. The welds look pretty sketchy as well.

I have time to figure this out but I really want long tube headers. What is the usual process for installing? Lay them in the bay while the engine is lowered down? Mark where they need "massaging", raise the engine, remove the headers, hammer the crap out of them, and repeat as necessary?

Will I need to relocate the brake lines and valve?

olds 307 and 403

Mac, I have Sanderson shorties on my 70S. I only reason I have road rash on them was when the system was on my G body. I would have to Dukes of Hazard to get road rash with 2.5" pipes on my 70S. Remember the 455 will sit lower, even less road clearance. If you cross the pipes by the oil pan and go under the passenger side, the driver's pipe will have clearance. Is the passenger side hitting as well? They may fit, try your shorties. I may be interested if they don't. Want to trade for a Hughes deep 2004R pan? If your car is that low, get the Thornton Big Block manifolds with the larger outlets.

Macadoo

I think I'll pass on the trade, 307, but thanks. I know those pans are pricey. These shorties have been in service for what? three years? I'll probable ask $200 locally and see what happens (but that won't be for a while).

Yes, I scrape both sides. The shop just couldn't make the bend I needed. Which is why I don't think long tubes will be any worse, lol.

Are these Thornton's better than the OPGI's then?
http://thorntonmusclecars.com/produc...aust-manifolds

Does anyone know exactly how much wider the BB will be and where? I'm assuming right there at the heads.

Macadoo

These. The W/Z's.

http://thorntonmusclecars.com/produc...aust-manifolds

These look like they would flow pretty well for a manifold.

oldcutlass

Hedman street series or Hooker competion series would work great on your car. They are a bit less expensive than the manifolds your looking at. Follow the manufacturers direction for removing the coating and applying paint.

olds 307 and 403

Thornton are ones getting them manufactured. The W/Z are the ones you want. Unfortunately they still give up 30 hp/tq over good full length headers but a definite improvement over regular manifolds. Let me know if you can't move those shorties locally, I will need a set, determined to get my 403 to the machine shop.

Macadoo

Eric, I looked up both. The Hedman's still sound like a PIA to install but I don't want to lose 30 HP after going to all the work and expense of building this motor.
How does one actually massage a header anyway? Heat with a propane torch and whack with a hammer? I actually have a couple body hammers and some dollys ("dollies" looks funny).

I like the look of the W/Z's but don't want to lose that much HP. Still looking into my options.
And of course, I'll let you know. But like I said, it will be a while. Most likely next summer. I need to make sure this BB I'm building doesn't, you know, explode on first start. Lol.

oldcutlass

Yup, thats pretty much it. Sometimes you get lucky and they bolt right in...

Troys Toy 70

Mac,

From my dyno run 30 hp/tq increase is correct when running open headers vs Manifolds with 2 1/4 pipe that was about the same length as the headers. However keep in mind that if you are running full exhaust at 2" to 2 1/2" you are
choking that flow down on the headers. I watched a video not long ago, and they did a really good comparison of open headers and full exhaust and I think the full exhaust lost about 15 hpr vs open headers. This is one test I haven't seen on an Olds, but it makes sense.

My my suggestion is build it to your taste and and normal driving conditions. If you are rarely ever going to take it to the track, then you may not miss those extra 15 to 30 hrs/trq. Then again maybe you will. My thoughts are once you get 450/500 hpr/trq. It will be a fun car.