# 455 engine rebuild



## vera_jr (Aug 17, 2012)

I'm gonna be dropping off my 455 to the engine shop soon. I am getting the engine torn down to bare block. Since I've had the car, I have not torn deep into the engine. This will be the first time. Once it is open, I plan on replacing the cam (the one in it has a flat lobe which is making me go ahead and tear the whole thing down), new lifters because of the new cam, have the heads machined (6X D Port heads), put a new HEI distributor and get rid of the points, put a new timing chain and pulley, and hopefully keep the other internal components if the set up allows. 
My main question is on Headers. They range from $150 (which I can afford) - $1500 (which is way out of budget), is there a big difference in all of them? I am not a mechanic, nor do I know as much as many people on here. I like the black headers, but does going with ceramic make that much of a difference? 
I want to order the new headers and have them when I put the engine back in. I'll also look to putting a new exhaust system as well, probably sticking with Magnaflow on that part. Is there a specific diameter on the header I would need? How do I pick a good header?
I feel like I can pay for the good stuff inside the engine, but save on the external stuff that can be changed easier as budget allows. 

Thanks in advance for the help.


----------



## PontiacJim (Dec 29, 2012)

Not a lot of info on your engine build. About the only thing you will keep internally is the crank. The cost to rebuild/resize the cast iron rods is not worth the chance of failure when compared to a few extra dollars spent on forged I-beam rods. Most likely you will find the engine needing to be bored oversized, so pistons will be in the works as well. With new rods/pistons, the engine assembly will need to be balanced. 

With regards to headers, the cheaper priced ones are that - cheap. They are usually thinner steel, and their fit can be problematic requiring some denting or modifications to fit. Mounting flanges can be thinner leading to exhaust leaks or gaskets blowing out. Higher priced headers typically use heavier steel and can fit better - but no guarantee. Painted headers typically burn the paint off and rust over time. Ceramic coatings typically don't rust out unless you bruise/scrape them while installing - so they last way longer. They keep heat within the tubes so your engine bay runs a little cooler. Here is an article on ceramic coating: https://axleaddict.com/auto-repair/...mic-Coat-your-Exhaust-Headers-and-Turbo-Parts

You will also find the oil filter a bit tight with headers and many complain about all the oil that will cover the headers when removing the old filter. Ground clearance can be a problem as they typically hang lower than stock pipes. 

For the high costs and grief of installation, or rusting out if selecting inexpensive headers, it would be worth the investment to simply go with the Ram Air cast iron exhaust manifolds as many recommend. You are not going to lose a lot of HP over headers with a matching exhaust system.

Header tube diameter depends on HP & engine RPM's. You could go anywhere from 1 5/8" to 2" depending on your engine. Here is a calculator that will get you the size you should be going with: Primary Header Tube Length and Diameter Calculator


----------



## vera_jr (Aug 17, 2012)

Great info there. I am not going to make it a track car. Just a street car. Being in South Texas, rust is always an issue to have to recognize. I would probably go with the ceramic coated just to keep them from rusting longer. I am not wanting to cheap out, but not seeing a need for something that costs as much as the engine itself. I currently have Hedman headers. I might just go ahead and stick with Hedman, but go ceramic. The Hedman Black Maxx headers are what I'm looking at. As far as diameter, I'm going to have to get the machine shop to calculate the specs.


----------



## bigD (Jul 21, 2016)

"...it would be worth the investment to simply go with the Ram Air cast iron exhaust manifolds..."

X2

https://www.summitracing.com/parts/...RZQxvEbUsmKKH36YR--U1lJhnjnIwl0BoCEJMQAvD_BwE

Pontiac Ram Air Manifolds


"...I plan on replacing the cam, new lifters..., have the heads machined (6X D Port heads)..."

No reason to go any smaller than an 068 cam. These were used in the 455HO engines. But, most consider them too small for a 455. A Summit 2801 is sort of a higher lift version of an 068 cam, and is cheaper than an 068 clone. 

The Summit 2802 is the same price as the 2801, but most consider it a decent 455 cam. 

https://www.summitracing.com/parts/...-RzGGxietZQw_KF_FlLQq1jbmLPSeP7RoCJdgQAvD_BwE

For idle to 5000rpm, a Voodoo 262 would also be a good cam. But they cost more than the Summit cams. 

http://www.lunatipower.com/Product.aspx?id=1775

There are plenty of bigger cams out there that will make power past 5000rpm. But, if you're not going to race, and will seldom if ever rev past 5000, then one of the smaller cams will provide a smoother idle, more vac, and plenty of low rpm torque. Most guys are much happier with a cam that is a bit too small, rather than one that is too big. Bigger cams can provide less vac, a ruff idle, can waste gas, and some have bad street manners, below 3000rpm, where most street engines run, MOST of the time.

As with cams, opinions differ when it comes to lifter choice. Paul Spotts says the Delphi lifters are best. He sells 'em for $59 shipped, from his Ebay store.

https://www.ebay.com/itm/New-Hydrau...ash=item3f8e18ef4e:g:JDoAAOSww9xZODlz&vxp=mtr

Many consider the Hylift Johnson "R" lifters the best. You can either buy 'em direct or thru a dealer. A PY member, Paul Knippen sells 'em, for $105 shipped.

http://hylift-johnson.com/wp-content/uploads/2014/09/HyLift-Johnson-Lifter-Catalog_2014.pdf

http://forums.maxperformanceinc.com/forums/showpost.php?p=5822027&postcount=19

https://www.facebook.com/PaulKnippensMuscleMotors/

Then there are the Crower Cam Saver lifters, which splash extra oil on the cam lobes. Haven't read any bad reviews of these. Some guys on the PY forum are running them. 

https://www.summitracing.com/parts/...Q5fYSGadeUgqmhxbjEASIGfUuhz-uA-BoCI_kQAvD_BwE

As the cam gets above .450 lift, you need stronger springs. The cheapest I know of are from Paul Spotts.

If you go with a 2801, you can get by with his $77 springs.

https://www.ebay.com/itm/Pontiac-V8...ash=item3f8628b00d:g:LYAAAOSwmrlU0mJ9&vxp=mtr

But, for the bigger cams I mentioned, his $99 springs are probably better.

https://www.ebay.com/itm/VSH3-Ponti...ash=item41d56c9779:g:hvgAAOSwB4NW0LgK&vxp=mtr

For the short valves, which have an installed spring height of around 1.6", some recommend the Crower 68404-16 springs. They are a few bucks higher. 

https://www.summitracing.com/parts/...76xK1EIMto7Nkh1MveCYJwQez4g3FrDxoCJRkQAvD_BwE

Most recommend one piece stainless valves, since the stock 2-piece valves can come apart, causing major damage. These are aprox $150 per set. Well hey, these are just a few ideas. And, as we all know, ideas and opinions differ, depending on who you ask. 

Disclaimer: I'll confess that I'm not an expert, like many on these forums are. But, I've owned & raced Pontiacs for a long time. And I try to keep up with the latest Pontiac info, on some of the Pontiac forums. Some have criticized me for posting links, especially to parts/services I have not used. So, anyone reading this should take this into consideration when reading what I post. Info posted are my personal opinions, which are not shared by some in the Pontiac community.

Anyhow, good luck with your build !


----------



## vera_jr (Aug 17, 2012)

I like the look of the Ram Air Exhaust Manifolds, but is there a significant difference between those and using headers in Performance? Again, I'm not racing, just a street car with mild performance.


----------



## dd68gto (Nov 14, 2012)

vera_jr said:


> I like the look of the Ram Air Exhaust Manifolds, but is there a significant difference between those and using headers in Performance? Again, I'm not racing, just a street car with mild performance.


Here is some good information on headers vs manifold. In your case a nice street car go with a good set of ram air mainifolds and wuality down pipe . Best luck Doug http://www.hotrod.com/articles/hppp-0312-headers-vs-manifolds/


----------



## vera_jr (Aug 17, 2012)

The Ram Air Restoration Enterprise Ram Air Exhaust Manifold really didnt perform much lower than the long pipes, so that will definitely be the way I go. I will give a cleaner look to the engine, and its a little cheaper, only $349. Thanks for the article.


----------



## PontiacJim (Dec 29, 2012)

vera_jr said:


> The Ram Air Restoration Enterprise Ram Air Exhaust Manifold really didnt perform much lower than the long pipes, so that will definitely be the way I go. I will give a cleaner look to the engine, and its a little cheaper, only $349. Thanks for the article.


Yep, I think that is the best way to go and the power loss based on the test is nothing. Keep in mind that you will also have to purchase the matching flanges to bolt up the pipes.


----------



## Pinion head (Jan 3, 2015)

It's not just the manifolds & matching flanges that need to be ordered, even a really friendly local muffler shop guy is going to put you into his common compression bent head pipes. The number one obstruction, hindrance to exhaust flow, isn't the design of Pontiac exhaust manifold from a log type manifold to a Ram Air style manifold. Instead it's the tight necked down bend that begins the head pipe. Personally, for a 455 with 6X heads, I would strongly suggest skipping the base priced 2.25" outlet repro manifolds & go straight to the larger outlet versions. Desiring budget header performance without the hassle & maintainance issues, buy the 2.45" outlet repro Ram Air exhaust manifolds from either PYPEs or from R.A.R.E, then back them up with a minimum of the 2.5" mandrel bent drops, that you can buy from R.A.R.E. 

SSP-6* Pair of Short Mandrel "Splice Pipes" - Pipes & X-over Kits - Pontiac

Since the mid 90's, have personally been assembling high flowing exhaust systems with original cast iron Ram Air manifolds as well as using reproduction oversize outlet R.A.R.E manifolds. The first bend coming out of the exhaust manifold is critical. As the head pipes moves further backward the small slight factory bends are not near as restrictive. Under an A-body with 2 1/2" exhaust, it's very hard to beat a large case Dynomax muffler for best flow. Desiring loud & obnoxious with less flow through the muffler, its not that hard to find a shop that will throw on some flowmasters. 

Earlier RA manifold exhaust discussion.
http://www.gtoforum.com/f12/repro-ho-ra-exhaust-manifolds-119161/


----------



## cij911 (Oct 25, 2017)

Interesting that the headers didn't make more of a difference on the 389, but they appear significantly better (20hp) for the 455. Since your car (OP) is a 455, I would probably go the Doug's header route.....Just my $0.02

I have a 400 and I am struggling with a similar decision, but leaning towards the Doug headers with the hopes of extracting every free pony and with the thought that I may someday jump to a 455 or 461....The piece that is holding me back is I don't want to have issues changing the oil and I don't want to get a smaller starter....Happy shopping


----------



## Pinion head (Jan 3, 2015)

cij911 said:


> Interesting that the headers didn't make more of a difference on the 389, but they appear significantly better (20hp) for the 455. Since your car (OP) is a 455, I would probably go the Doug's header route.....Just my $0.02
> 
> I have a 400 and I am struggling with a similar decision, but leaning towards the Doug headers with the hopes of extracting every free pony and with the thought that I may someday jump to a 455 or 461....The piece that is holding me back is I don't want to have issues changing the oil and I don't want to get a smaller starter....Happy shopping


My .02, as have had my hands on building quite a few performance 428 & 455 Pontiacs for both A-body's & '67-80 F-body's. Once you install a truly free flowing headpipe/muffler/tailpipe combination under either body style of car, the actual "need" for headers doesn't come until the engine is putting out high 400 HP & well over 500 ft lbs of torque. For sake of argument, the car is an NHRA stock class racer & has a max attention to detail 455HO or 455SD engine, then, a pair of as near equal length primary headers are going to be part of the build. Have just such a pair of 45 year old JR roundport headers. They have their share of banged up primary tubes. The passenger side header will not fit on my other 455 HO cars, as all 3 have factory AC. Needless to say, as headers, they are a wall hanger. If they were Dport design I'd try them in our '72 LeMans.

- Pontiac V8 engines are designed to put out strong torque numbers. That was the case from the early 60's till the last turbo 301 rolled out of Pontiac engine engine plant dyno cell. Same deal for decades in a Pontiac V8 performance street to street/occasional strip performance engine build. The numbers to look at in a 455 build are the Torque numbers from about 2800 rpm, to the torque peak to the hp peak. the broader the big torque numbers, the better with a street engine. 

-of note- The entire engine dyno runs in the above test were not printed, but with the above 455 engine, the torque peak was at 4300 rpm. Only 9 ft lbs of torque was the noted difference between the 4 tube header test & those wirh the RARE 2.45" outlet manifolds & 2.5" mandrel bent head pipes. thats typically about the same amt of ft lbs of torque measured at the flywheel that one would drop going from the freeest flowing Dynomax long case 2.5" mufflers to shorter case name brand supposed performance mufflers. 

Another few things about the HPP headers vs manifolds test, the intake manifold chosen was a single plane street dominator, a choice which is odd but fits with Taylor's single duration cam choice. the Dyno engine carb (a Holley) was jetted 80 square. *no effort was made to maximize the tuning Holley 4bbl when the engine was equipped with with RA exhaust manifolds*. Last, since the test used '67-69 Firebird headers, if all one was only concerned about is peak HP comparisons, the test would have been much closer, if a pair of long branch factory manifolds or 2.45" outlet RARE long branch (1st Gen Bird) manifolds had been used.


----------

