I need stock exhaust manifolds for the 425 in my 66 Starfire. I believe the ports in the manifolds are larger than the ports in the manifolds from a Delta 88 425. Also, I'd like to know if the manifolds from an early 455 would be correct for my Starfire. I'm most concerned about: port size, rear dump (exit downward), and configured so my dipstick will clear between the head and the manifold. Can anybody help me out??

 

I don't know much about the differences in manifolds but if it is the same I have a VERY nice passenger side manifold from a 66 olds 98.

 

I think the Olds 98 had center dump manifolds dude. Can you take a quick look at yours, its amazing how often I don't know what I'm talking about!

 

All factory BB exhaust manifolds had the same size ports. There was no special size for the Sfire. The 65 thru 70 full size Oldsmobiles with BB had the center dump manifold on the driver's side for single exhaust. Dual exhaust cars used the S manifold on that side. These are available repro. The passenger side manifold was the same for dual or single exhaust. For duals the center opening was capped on that side.

 

Thanks for the feedback Oldsmaniac. I was aware of the repro manifolds, but they're pretty spendy and I wanted to see what else was available. BTW I thought the HP difference between the Delta 88 425 and the Starfire/Toronado 425 was partly because of better breathing/larger exhaust porting in the higher HP versions. Not true??

 

i too am also checking for manifolds,pass side on mine is cracked(see pics) and want to go duals so thorton seems to be the way to go.www.thortonmusclecars.com.

 

$240 plus cost of a pretty RH unit and blockoff is not all that spendy.
Done, like that.

There are no special SF manifolds of the 65-70 era exc. the "S" dual exhaust LH unit. Surely the DE vs single exhaust makes a good power difference.

 

Higher HP came from yes better breathing as in dual exhaust and slightly higher comp pistons in the Toro and different camshafts and 4bbl carbs and larger intake valves on some engines but not on the starfire. Also remember that factory HP ratings were a numbers game of sorts.

 

Good information you guys, and thanks for the feedback again Oldsmaniac. I may have to bite the bullet and go with the Thornton repros.

 

Hey Jensen, What do you want for the pass side manifold and can you send me a picture? Thanks.

 

Here's a hint:

If there was a lower-cost option available, the repros wouldn't be priced as high as they are.

The 1965-1970 full size cars have a unique rear-steer linkage configuration, making the manifolds unique to those applications.

 

I had forgot till i looked at it. It has 3 bolts broke off in it. $25 + shipping

 

just got my thorton manifolds,350.00 for both.

 

Kick butt! When I checked Thornton's site a couple of weeks ago their pic of the 425 Starfire manifold said they only sold the driver's side...... Do your manifolds have the divided large center port?

 

hi,no they didn't have the divider but no matter as this will do me good for now..also have edel. intake with a 30yr old holley 600 from my olden days..if that doesn't work,i'll go fuel injection..will pull the engine to install manifolds and clean up things.

 

a few pics..

 

Thanks! I just got off the phone with Thornton and made the same purchase you did. They were easy people to work with and I don't care about the configuration of the center port either. Good luck with the fuel delivery; I always like Holley carbs.

 

I think your Holley is gonna need a kit.......... (grin).

 

hi,moose2 did you get your manifolds??.i'm thinking of getting mine coated as i got mine for my gn.

 

Hi, I got the manifolds and plan to have 'em powdercoated. At first I thought I'd have them done black, but the guy showed me a couple of manifolds he just finished that looked chromed and I thought that was pretty cool...... I don't like leaving them unfinished because they always rust up and look like crap, and the hi-temp engine paints don't really hold up on exhaust manifolds over time. Do you think you'll go with black or what? If you don't have much powder coating done, my experience has been that you have to find a facility that you know turns out a nice product.

 

hi,do not powercoat your manifolds!!.that will not last,others might chime in here but i'm pretty sure this will not work.too hot for powdercoating,jet coating that they use on jet turbines is the only thing to use that lasts and looks good.black or silver.IMHO.

 

There are special high temperature powder coats that are good for 1000 deg F. These work fine on manifolds, though I do prefer the ceramic coatings like Jet Hot and Ceramacoat.

http://www.caswellplating.com/powder...lications.html

 

hi,thanks joe for clarifing,if so,wouldn't it be nice to have red manifolds,or blue,or white,or you get my point,wouldn't vht high heat paint work for these manifols as they are not headers and don't warm up as much??...as an aside,joe can i pm you?..thanks paul.