[Lifetime Goat]

So now that I am running around town with my lifetime project I am constantly revisiting the issue of headers vs. the Ram Air III exhaust manifolds. I just put another set of header gaskets and have them snug and quiet for now but that little bolt behind the #5 drove me crazy. So much so that I considered putting on the cast iron pieces that I have from Ram Air Restorations. Question is how much of a power loss will I have to accept to be a little quieter and have less maintenance? I know that this must have been debated and was wondering what were some of the thoughts on this.


455
#64 Heads
231/239 Ultradyne
HO Intake system

[mkpontiac]

SD Performance has a write up about that topic in the tech info section of their website. - www.sdperformance.com/techTips.php
From reading the write up the headers make the biggest difference when using cams with a lot of valve overlap. Typically tighter lobe separation and longer duration cams increase the overlap and thus benefit more from headers then wider lobe separation shorter duration cams. They describe a couple of examples in the write up.

[TCSGTO]

My case may be unusual but I have found that the RA manifiolds were louder than long tube headers. The manifolds always increased resonance and noise for me over headers, at least when the header flange gaskets seal. I've had best luck with Fel Pro header gaskets.

[67 Lamnas]

Originally Posted by Lifetime Goat

....... I just put another set of header gaskets and have them snug and quiet for now.....

Why are you continually putting header gaskets on? If you run a decent set of headers, decent quality gaskets and make sure to tighten them a couple times after the first few heat/cool cycles after putting in the gaskets, you won't have any gasket blowing problems.....

[Murf'sDad]

Originally Posted by 67 Lamnas

Why are you continually putting header gaskets on? If you run a decent set of headers, decent quality gaskets and make sure to tighten them a couple times after the first few heat/cool cycles after putting in the gaskets, you won't have any gasket blowing problems.....

Famous Last Words!

Stewart

[Lifetime Goat]

My headers were not level where the bead weld had to mate with the heads. So over time I blew a gap in the gaskets. I removed the header and use a dremel and straight edge to fix problem. I then install two percy carbon gaskets. As usual when it came time to tightening that hidden bolt on #5 cylinder I started wondering if I had to do something like this again should I just put on the RAIII's.

The cam I have is a 231/239 at .050 with a LSA of 110. After reading the SD webpage can it be that the difference between 110 and 114 LSA is that significant in the power output of headers vs manifolds?

[Half-Inch Stud]

Is my opinion that the Exhaust system (primarily the manifold header/collector scheme.) determines the fella's LSa needs-case.

Cam-Overlap needs the Exhaust systems to sustain a vacuum pull during overlap. Yet the exhaust backfills the vacuous primary pipe/chamber/Intake tract/Plenum with exhaust gas when the driver really wants to fill the CYL with Air&gasoline.

A fella should ponder the Hi-Vacuum & WOT Plenum cases to figure on how good the sustained Exhaust scavenge need be.

A fella's Vacumm gauge reading is an indicator of the "dynamic gas-operation" during Overlap.

[Don 79 TA]

you can get ARP bolts that will bolt in and have a 5/16" head on them
makes using headers a dream
may want to think about using that
also, and this is debateable, but i have had sucess, is to cut the flanges so the headers seal up better
just some options that may help

[Half-Inch Stud]

Your combo is pretty good for Manifold vs Header influences, since you have the HO Dual Plane. A single-Plane will AMPLIFY the effects of exhaust leaks & backflows into the Cam overlap events.

Gaskets: use the metal-clad haeder gaskets of that "Briggs&Stratton head gasket technology"

[vertbird]

I went from headers to RAIII manifolds on my 69FB and it was the right decision for me. I was tired of dragging the ground with the headers everytime I went through a dip in the road. Gaskets leaked....evenutally, and they were just louder than I wanted for a street car. For street use the RAIII are hard to beat IMHO.

[Murf'sDad]

Originally Posted by vertbird

I went from headers to RAIII manifolds on my 69FB and it was the right decision for me. I was tired of dragging the ground with the headers everytime I went through a dip in the road. Gaskets leaked....evenutally, and they were just louder than I wanted for a street car. For street use the RAIII are hard to beat IMHO.

That is the exact reason I'm going with a set of RARE's OS manifolds on my motor. I'm willing to give up some horses for less maintenance and hassle and more ground clearance (I live in a rural area).

Stewart

[mchell]

the manifolds were louder on my engine...the performance gain (track tested) going from manifolds to headers on my engine was marginal...

[Lifetime Goat]

Mchell I see that your setup is very similar to mine. Did I read correct that you felt that the RA manifolds were louder than the headers? I tightened them up again and will see how long they last this time.
By the way I did cut the header flanges as was mentioned and believe that this is part of my problem. With the full flange there is more force to keep the center tubes on the head. With cut flanges that hidden bolt is all by itself.

[Half-Inch Stud]

MY 12.9 Et signature ran "THE SAME" going from custom 3-tube to basic 4-tube to Long BRanch Manifolds. However my cam was waaaay wrong, so performance sensitivity (60foots) was masked by cam. Furthr however is the MPH stay "THE SAME" cnad that would point to the Exhaust being pretty darn OKAY for the non-varied MPH.

[mchell]

Originally Posted by Lifetime Goat

Mchell I see that your setup is very similar to mine. Did I read correct that you felt that the RA manifolds were louder than the headers? I tightened them up again and will see how long they last this time.
By the way I did cut the header flanges as was mentioned and believe that this is part of my problem. With the full flange there is more force to keep the center tubes on the head. With cut flanges that hidden bolt is all by itself.

Yes......on my current 445 combo they were definately louder than with the Dougs I am running now.....ran the manifolds and headers thru a 2 1/2 x system.....the manifolds had a high raspy pitch to them ......the headers have a lower pitch..

[lust4speed]

The Percy carbon gaskets will blow out - seemed like such a good idea, but the reality is the opposite. It's hard to beat the Doug's gaskets - I even reuse them without problems.

Regardless of the bolts or technique, installing headers on a Pontiac is a trying experience. When replacing gaskets, I take the new gasket and cut slots for all the bolt holes so I can simply slip the gasket in place with having all the bolts loosened about a quarter inch. Still a pain, but much easier than removing all the bolts and aligning the holes.

[440GP69]

Another tid bit FWIW Two Machined Surfaces IE Manifold - ex side of head Don't need a Gasket Just Have to be Flat

[Lifetime Goat]

I was concerned that if I cut slots in the gasket that there would not be enough material between the bolts and the seal area on the center ports. Maybe worth a try the next time around. I also agree that the Percy gaskets blow out contrary to what their advertisement states.

[Half-Inch Stud]

Cast Manifolds with metal-clad Header gaskets is ideal (for me) to keep Manifold heat from conducting back to the head.

[old66tiger]

Anyone here have problems with the HO manifolds not fitting properly to the heads? Mis match in port dimensions? I used the metal shims and noticed when the manifolds came off this last time that there was carbon deposits on the gaskets...kind of like the gasket shifted up 1/4" from where it should have been.