exhaust manifold question

[bill76]

Ipicked up a very clean 76 K5 a month ago and am trying to put stock single exhaust on it (headers were shot)I have stock manifolds part numbers are--LH334763 RH--346222. I shot blasted and coated them then put them on but the Y pipe does not come out in the right place for the extention pipe.
Some one said the LH manifold did not look like correct so I bought a new one from lmc and it's the same as the one I have except made in china.
I rechecked with my napa man again and he said all the pipes are what the book calls for.Does anyone know the manifold numbers or what the heck I'am doing wrong? I have been working on cars for 40 years and never has anything blown my mind this much...Help me please...
e-mail me at [email protected]
p.s. it has a 350 engine with a 4 speed tranny

 

[496truck]

So, the y-pipe lines up with the manifolds, right? What's up with the end of the y-pipe? too short? hitting frame? hitting x-member?

Too short and my first guess is no cat? If you're not using a cat, and I have no idea what exact year they started using them on these trucks, then I would say have an exhaust shop make up a short connector pipe.

Either way, I'm sure an exhaust shop could modify the y-pipe to fit correctly. Probably a cheap fix too.

 

[76zimmer]

I think cats started in 77 for trucks, If no-one gets any results I can see if it is in the Chevrolet numbers book I have at home...

 

[bill76]

Thanks Brian that what I think I will have to do---truck never had a cat and the y pipe comes out allmost hitting the frame it also is much lower on the right side and then slopes up on the left side where it crosses over,it's allmost level if I don't have the heat riser on the right side--I think your right it may be time for the muffler shop and I can take $300 of pipes back to napa---------------thanks again Bill

 

[diesel4me]

I had a hell of a time getting a Y-pipe for a K5 I had,a 1975 2wd that I yanked a straight six from and replaced with a small block--a friend who just installed headers on his '79 Jimmy gave me his pristine stock manifolds,and I ordered a Y-pipe for a '75 Blazer 2wd with a 305 or 350 ,they were the same part number--my friends truck had a 305 in it...when the pipe came in,I noticed one side was set up for a dognut gasket,the other was flared....bummer,because both of the manifolds were the type tht needed donut gaskets!..I knew the passenger side may have had an EFE or heat riser valve ,but I had both styles,the one with a vacuum can and one with a thermostatic spring and neither was the correct length to fill the gap on the right side between the pipe and manifold--plus the heat riser uses a flat gasket at the manifold,so the donut gasket would still not fit or work ..

I ordered 3 more Y-pipes from other years,I tried the year the manifolds came from,it was for a 4wd,wouldn't fit past the crossmember under the engine..NEXT!..

I finally found one we had right in stock haning in the back room of the parts store just by gawking at all the ones we had,and found one from a 78 2wd pickup with a 305 or a 350 had the Y-pipe ends at the manifold that used 2 donut gaskets...my boss was pissed ,because I had to now send back 3 pipes we special ordered and would have to pay a 25% restocking fee..which I ate,to prevent me from having to listen to him whine till the day I left that job....

So ya,been there !...I think I'd just make dual exhaust in your case,like I was about too with my truck...I have made many complete exhausts over the years for my GM trucks,and not to brag,I dont use store bought parts--I like using things like EMT conduit or galvanized chain link fence pipe--one system on my wagon lasted the 8 years I owned it and it still was silver when I sold it!..stuff just dont rot like regular exhaust pipes..