What Headers for my '91 V3500?

[ehjorten]

So I am thinking about re-doing my exhaust system on my truck.  It currently has Tri-Y Headers on it now of an unknown origin (Updated: I think they are probably Doug Thorley 304Y's) with dual 3" exhaust, but the system is starting to show it's age and the previous owner didn't do a very clean install.

My first issue I find is that it seems very confusing out in the internet land on what headers fit on this truck.  If I look up 1991 Chevrolet I generally do not find V3500 listed (like so many other sites).  If I go back to 1987 I can sometimes find like V30 or whatever.  I am assuming that I can generally use any 3rd generation Chevrolet Pickup that is a 4WD and maybe 3/4-ton or 1-ton.  Would that be a correct assumption?

Lastly...any practical/real-world experience with various headers for these trucks?  I'm looking for full-length headers.

Thanks!

-Erik

[ehjorten]

I've got Hedman Elite Headers on my '77 and with the exception of the Ball and Socket collector flange they fit and function really nice.

Did some searching on the Hedman website and came up with several numbers:
69827, 69386 & 62826

However, they seem to be all over the map as far as application goes.  The 62826s are stainless steel and the catalog lists them for 67-91 3/4-ton Suburbans.  The 69386s are standard-duty HTC coated and listed for 1-ton 4WD pickups. And, the 69827s are Elite, coated and listed for 1/2-3/4-tons 82-87 pickups.

It seems that any one of these would fit, but why are they all over the map on applications?!  I am not familiar with other header manufacturers to know what they offer.  I haven't been really impressed with Hooker.  Hedman and Hooker are my only personal experiences.

If I go to Summit they list 3 different headers (all Hedmans) for my crew and they are all different numbers than what Hedman lists!!!  WTH???

[Captkaos]

Generally speaking 67-91 trucks engine bay would be the same, hence the long range of applications. Some that list specific years could be fitted headers.  For a 91 I would be looking for 81-87 in the 1 Ton applications.  I would also call the manufacturer and ask.  I would also be very picky about a 4x4 as some tend to hit in the most inconvenient spots.

[ehjorten]

A little more searching today and I found Flowtech 31350FLT which I think will fit my application, but just not sure.

As Capt'n said...there are various issues with fitment on these headers and I am hoping someone has real-world experience with them so that it can cut down on the trial-fit/return routine!

[Edahall]

Doug Thorley makes highly regarded headers.  Any reason for not replacing with the same?

[slammed79]

Are the headers you're looking at have the air tubes? I'd assume you'll still need them for emissions/inspection reasons.

Any reason not to just clean up the headers you have and replace the rest of it?

[ehjorten]

My truck is a 1-ton so as such was exempt in it's day from having CATs!!!!!   No air tubes for me or air pump or any of that stuff!

The headers are pretty crusty looking.  I could probably clean them up.  Just weighing my options.  Not opposed to the Doug Thorley Tri-Y design, but not sold on it either.  I know the theory behind the double reflection waves created by the subdividing of the cylinder banks and looking at the headers on my truck the wrong cylinders are paired, probably for packaging simplicity, but it negates the scavenging effect that the design inherently has.

That is the pickle I get myself into being an automotive engineer! LOL