after much searching i have these questions.
I just got my new hedmen headers in the mail! (3 days after ordering) wow and i dont think my pipes are 3 inches like I originally thought.. but since i bought the y-pipe, can i install 3 inch headers with y-pipe into a smaller exaust pipe? it doesnt look much smaller ui'd say 2 and 3/4 pipes into a magnaflow muffler. I dont have the money to buy a cat back either yet so i might go with current setup. the y-pipe they sent me doesnt look like the same as the stock one. i assume it isnt going to go in the same spot as the old setup.
also the site said these pipes were 02 accesable.. i have thes small adapters that look like a pipe with a funnel type end. am i susposed to drill a hole for the o2 sensor? i have 2 of the cone things. but only 1 o2 sensor..
finally if anyone know where i may find install directions for heamen or a link i could go to of a prevous post that would be aazing... if not i'll just go at it blind like i do all my other projects haha to bad school gets in the way!
thanx for any help guys!
BIll


88 trans am TBI lo3 305

 

Headers don'thave 3'' pipes, yours have 1 5/8 dimensions.

 

Mark, he's talking about the y-pipe and plumbing rearward being 3", not the primaries.

You bought new Hedman headers, and they don't have any instructions with them? That's a little surprising. I suggest you get a hold of them and get a set sent out to you.

Which parts did you get exactly? Hedman offers several variants, each having their own peculiarities. I would assume you have a 3" slip-fit connection at the y-pipe. If that is the case, I would suggest you get a cat for '86-'90 TPI single-cat application (I know that's not what you have, just hear me out), and adapt your current cat-back to that new cat. Then, when you've got the funds, get a cat-back for the same application. That will offer the best flow potential for you. Until then, your current cat-back will be okay (just not ideal).

 

sounds good yeah i was talking about the collector was 3 inch... i got 1 and 5/8 primaries
i got instructions but there are kinda weak
mentions liftuing the engine and refears to the engine as right and left side..
is that facing the nose or in sitting in the drivers seat.
headers,y-pipe, 4 adapter type pipes, 1 looks like a small pipe into a larger cat application,
2 are identical and i'm not sure how or which pipe they hook onto.
they look like 3 inches longand open up twards one end.
the last one attaches at the end of one opening in the y-pipe.
directions have no indication of what these do.
i'm hoping they are header extenctions for the 02 sensor but if they are i would have to drill a hole for it so this lead sme to think theyare not what i hope they are.
thanx for the advise
BIll

 

sorry that confused me

 

I just installed headmans and a y-pipe yesterday in the IROC
OK, this is going off of memory so bear with me. the headers that angle straght down go on the driver's side, while the ones that sort of angle back go on the passenger side.
a few things to remember
plugs and wires need to be removed.
your starter needs to be removed.
yes the engine mounts need to be removed and the engine needs to be lifted.
your plug wires might need to be replaced.where they connect to the plugs if the end is straight and not bent then you will need new pugs (more on that later)
your oil dip stick needs to be removed
your oil filter needs to be removed.

first thing we did was take off the cat and old stock y-pipe.
where the cat and pipe where conected we had to heat it up,even though the new cat has only been on there 5-6 weeks.
the old y-pipe looks nothing like the new one because the exaust manifolds are shorter than headers.

the driver side manifold was not that hard to take off.
we sliped the driver side header through the bottom, thats why we needed to take off the oil filter. but we needed to raise the engine to make it fit right. ***check the brake lines insure they do not touch the headers***
about the o2 sensor, I don't know what you got but this is what I did. We had a "bung" that I got through summit for like $6. we blew a hole through the collector and weilded the bung into that and then screwed in the o2 sensor. ***check the o2 sensor wires too that they don't hit the header***

the passenger side was a pain in the butt.
the started needed to be taken off, some of the smog stuff on top needed to be taken off. and the bolts are just more of a pain to get too.
same thing the engine needed to be lifted to get the headers to fit in right.
after the headers were on and the starter and engine were back in place, the y-pipe was put on.
once you get under the car you'll see how the pipe fits right.

the problem with the plug wires was solved like this. I bought plug wires for a 79" z-28 350. they should come all with bent ends. the only problems I had with them was the ends that fit into the coil did not fit. so we took the ends off of the old ones and sliped them right on the new ones. also the new wires are going to be longer than standard wires so you will need to use some zip ties to clean it up. ***keep the wires off of the headers too***

after everything was put into place the car was started up. my car started to run like doo doo. the reason was where the y-pipe was conected to the drivers side the pipe was in two peices (it came that way) we spot weilded it there to seal it. after that that the car started up great, no check engine light, nothing. car sounds alot meaner. couldn't take it out for a spin because of the rain.

all in all it took 2 people about 7 hours to do it. this is in a garage with a lift, a blow torch, a welder, and all the tools in the world.
car went up and down about a dozen times......
the guy I was with is a master mechanic and runs his own shop, and I know squat about working on a car, and I was also going 24 hours with out sleep.

 

that sounds like the part that goes into the end of the y-pipe that goes into the cat.

 

I hate this I am on probation so I can't edit my own posts

I also used copper gaskets on the headers and collectors too.
also needed new bolts where the header connected to the engine. my collector gaskets came with bolts where the y-pipe and headers met.
also right after you run your car, insure you check your header bolts and insure they are still tight.
biker

 

thank you for that great post! i will use it greatfully! Looks likei'll have to rbing some stuff home to dad so he can weld it! but i dont have a lift ro any of that garage stuff so it looks like i'll be at it a couple of days! it looks like i'll also have to do that welding job for the 02 sensor thanx forthe help again

BIll