Will late model Chevy Truck Thorley Headers fit on my 1984 Elandan?

[Peter_Crowl]

I just came across a very good deal on a pair of Thorley headers for the 454. Seriously - Never mounted -  ceramic - $175.

Thing is they aren't the part number Thorley specifies for the 1984 P30 chassis Class A MH. They're built for a later model Dually Pickup - with Oxygen Sensor port - which can easily be plugged - or used should this one get an injected engine at some point.

They're not local to me so I can't hold them up and see if they're a fit.

Anybody know if the 454 Thorley Headers are that model specific that these wouldn't work?
It seems that I have a ton of space down there.

Peter
Exhausted
in Denver

[fgutie35]

With headers, the most important thing to know, is if you are going to improve or restrict the performance of the engine with the change. Keep in mind that headers, come in many sizes, materials and configurations; each has its purpose and application. Our 454W's are not tune the same as a corvette 454 or a pick-up with a 454 in it. We have a "heavy emissions" configuration, which could mean that the parts used and the tuning used on our specific engine, is for heavy duty application. There is another member on this forum that could give us more details on the matter. RV mechanic, if you read this post, please enlighten us!

[RV Mech Tech]

There are several other members as well that can answer questions about headers so here is my 2 cents worth- as far as fitting this specific chassis, the original application is for a Chev pickup  which indicates that although they would have a common BB Chev flange at the cylinder head - they would probably  tuck in closer to the engine block  since the p-up would not have the same amount of room between the engine and the frame rails-  this probably would not be a problem since there is more room in the MH but  that also indicates  that the header collector that the exhaust pipe is attached to may be closer to the powertrain and there may be some misalignment between the original MH exhaust and the collector on the header- in most cases this can be fixed with a little fabrication but I have seen it cause big problems with clearance in two applications- this is basically a judgment call and I would have the headers in front of me and take measurements and double check on the MH first before buying them - if you purchase them and then remove the stock exhaust and find they do not fit then you are out that much $  - as far as emissions go does Peters E have an AIR system on it? and do the headers have the mounts for the tubes for this system? - not likely  because the Thorley headers have O2 (oxygen sensors)  on them and by the time they started using the computer system the AIR system was obsolete and you do not see  the mounting  holes for the AIR system on late model headers (you still see a few around on heavy duty applications but not very much anymore)  - so there is one problem if Peters RV has the AIR system - the O2 sensor holes can be plugged - as far as the benefits go  the engine running  temperature  will be decreased slightly as the cast exhaust manifolds are large heat sinks and the headers dissipate the heat  much faster- the noise level will increase slightly but may not be noticeable in a MH - as far as tuning is concerned the purpose of headers is to scavenge the exhaust better and may require re-jetting the carb (in some cases) - I have had to do this on some applications in cars and trucks but the jetting in those early carbs is usually very generous - I would keep an eye on the spark plugs after installing any headers for indications of leaner running and make any changes necessary - -it's later model computer controlled engines that you really have to watch when making modifications - also this information may not apply in some cases (such as the AIR system) if the State emission laws do not require these systems to be connected which has been the case with other members so again this is a judgement call for specific applications and I would make sure that these headers would fit first - if that's not possible then pass up the deal.    Hm?

[Peter_Crowl]

Hmmm the AIR system.....didn't consider that. I'll check that.

Probably best to let them go since I can't physically check fit. Thanks for your generous help!

Peter

[Oz]

As an afterthought, you may want to read the existing topics on whether or not headers are worth the investment and other considerations if they are installed.  Very good reads!

[Peter_Crowl]

Actually I have read the existing threads on headers both here and elsewhere - that's what brought me to the Thorley products. Highly regarded, thought to be a cure for manifold warping, performance and MPG enhancing.

OTOH - they're about $900 pair which makes the issue moot. Unless a killer deal such as the one I descrbed can be found.

[bluebird]

They're a couple areas for concern. 1st do you have to have your coach inspected to pass emissions and get a sticker? Some countys require a visual, to make sure your emission equipment is in fact working and present. If your exhaust manifolds are cracked now, it'd probably be cheaper to go the header route. Don't just do it for increased fuel economy, as you probably won't notice any difference. That is a very good price for a ceramic coated set of headers.

[RV Mech Tech]

Peter - one other thing comes to mind - since you just purchased this MH I would do whatever is required to get it on the road and see what it's like the way it is- if you do not know this you may not recognize any benefits any modifications may offer - start with square one, drive the coach around and then if you feel something is not o.k. or you would like to improve on anything mechanical or otherwise then find out what is involved in making improvements - that way you will have a common/base knowledge of this RV and you will get to know its benefits and weakness - one thing I learned when we modified cars and powertrains in the 60's and 70's is that you make one change at a time and see what the difference is  - you also have a great knowledge base with not only the resource center on CWVRV, but also first hand experience of many members who have gone through the repairing and modifying there vintage Winnies and other makes and 'on hands knowledge' is very valuable  to not only make the correct choice for you but also to avoid wasting money doing the wrong modification or change to your MH - everyone looks forward to pics any members can provide as this is not only interesting but may serve as a guide  for other members.