I have an 85 firebird v6, I swapped in a 350 from a 75 blazer. So since it is not a 3rd gen 350 will 3rd gen headers and y-pipe fit? Or will I need to swap something on the engine to fit?

 

a small block is a small block, except really early ones lack accessory bolt holes in the heads.

you will be fine, it will all bolt up, should clear the oil, unless its something crazy

 

Well I have a set of stock manifolds and y-pipe from and 89 trans am and on the passenger side manifold the last bolt doesn't line up but the rest do, and the passenger side of the y-pipe doesn't line up to the manifold. It is a couple inches too short and the angle is off. So I don't if its my engine or if the junk yard gave me the wrong parts.

 

manfolds warp, probably why the bolt doesnt line up. Can you start all the bolts loosely, then tighten them all to pull things back to shape is it if off a whole lot?

sounds like you have a mismatched y-manifold setup. Maybe look into a aftermarket header and y-pipe setup.

 

actually an easy way to confirm this is visit summit racing... I think from 87-92 there was a difference in small blocks... don't remember exactly if it applies to the exhaust, but I think it does...

 

Late small block heads (at least by the late 70's) have two holes at the end of the head for the exhaust. Early manifolds will bolt up to late heads, but the late manifolds use that hole that doesn't exist on early heads. Note in this pic how the spacing of the holes at the rear of the passengers side manifold is wider then the end spacing on the rest?



The reason the Y pipe on the passenger's side doesn't line up right is because either A) you don't have the exhaust flapper or the spacer that takes it's place... Or B) you've got an HO/non-HO match up.

Notice how in this pic the HO manifold at the bottom dumps at a different angle then the low output manifold right above it.



Usually when running an early SBC in a thirdgen, headers are the only option since the drivers side manifold dumps right where the dipstick on early Chevy's is located, and the bolt spacing is different.

 

I have the low output manifolds, and they don't have a spacer or a flapper. The rear bolt doesn't even touch the heads, the hole is completely past the rear of the engine. So do you guys think that these will fit?

http://www.summitracing.com/parts/SUM-G9005/
http://www.summitracing.com/parts/BIG-11102YFLT/

I know that they aren't nice headers but I do not have the money to get nice ones now, and really need to be able to drive my car asap.

 

Most aftermarket headers are designed to use the old style, closer together, exhaust bolts, so they'll fit both early and late heads.

If you really need to drive the car, you can leave the bolt out, you'll just more then likely have an exhaust leak. As long as you know it'll probably cause a problem if left that way, and fix it before too long, it might tide you over until you can afford a set of better headers.

The low output manifolds date back to the carbed days when GM used a flapper in the exhaust to speed up the process of getting the engine up to temp on cold days. Later cars have the casting without the flapper to fill the gap between the manifold and Y pipe.

Adapter..


It's not uncommon for the adapter to fall out while pulling the Y pipe and get lost. Sometimes you can get away with using an exhaust donut that's flat on one side and a flare on the other. It's a little thinner then the cast iron adapter, but it'll work in a pinch. If you can only find an adapter with the flapper, you can cut out the flapper and it's virtually the same thing.

 

Thanks for all the help, one last thing, what headers would you recommend I save up for?

 

oh so then it's the heads that changed, duh ...

to op verify the p/n of the options in manifolds/headers you have by searching google and making sure they work with your heads, you may want to take one of the covers off and check the casting to make sure you know which head you have exactly and go from there... you might also end up having to spend on custom tubing to hook up the headers to the y pipe ..

 

So if I switch to stock 3rd gen heads then I shouldn't have any problem with headers fitting. Will those heads fit my engine? And would I have to swap any other parts?

 

You should be ok with either early or late heads if you're using headers.

Take a look at your engine... If it's from a 1975 it's probably got a driver's side dipstick. If so you'll need headers to clear the dipstick, and it won't matter which heads you have.

If you have a passenger's side dipstick block, you can use late heads and stock manifolds.

 

Ok, thanks for all the help.

 

I don't know at which point the bolt pattern changed, but you may want to look into that as well...

not sure if this applies to your situation, but like I said I am just throwing stuff out there... kinda' like what' ifs...

 

Ok, so I ended up just getting a set of cheap headers so everything would fit right and I would be able to use the dipstick. Put them in everything bolts up and fits except the starter. Its a stock starter for the 75 blazer. I have a third gen starter but it has the inline bolts, where my 350 has the staggered pattern. Any idea's on what to do?

 

Are you saying your block doesn't have provisions for both starter bolt patterns?

The starter has to match the flywheel. If the starter you have won't fit and the stock starter will, the usual fix is to find a 153 tooth flywheel that matches your engine (1 piece or 2 piece rear main seal). Then after you've changed the flywheel you can use the stock starter.

But if your block isn't drilled and tapped for both starters, you might want to look into aftermarket mini-starters to gain the clearance you need.

 

I have same problem. 68 block and heads. Did the headers match up good, and what kind of problems will come about with last bolt left out. I just got the car few mothes back so I have no clue how long the bolt has not been in there. Would the hooker 2055s match right up and bolt in with stock exaust?

 

I went with these headers because I didn't need the o2 sensor hole. http://www.summitracing.com/parts/HED-68470/
They fit the engine and all bolts lined up, but they hit the starter, so I bought a mini starter which hit the a-arm mounts, so I ground them down a little and it all fit together. Now the only problem is the recommended y-pipe for those headers hits the mini starter. If I was to do an engine swap again I would just get a 3rd gen 350, would have saved me a ton of money and time.

 

Yeah I hear you there. I have a 68 327 in mine. I may just change the heads, from what I have read in the threads the hooker 2055s bolt in well. Curious if they would bolt to 68 heads though

 

If you call summit I am sure they will be able to tell you, they usually have pretty good tech support.