- This topic has 9 replies, 5 voices, and was last updated 11 years, 10 months ago by
.
-
Posts
-
I almost posted this in the Chevy/Ford forum, but this is a weird one. I’m rebuilding my head, make that cylinder head, on my BCW with a 1.6L Chevette engine. When I went to reinstall the exhaust manifold, the forward four holes did not line up with the head (off about a quarter inch). The rear four holes are fine. I immediately called Rick Drake and this one even had him scratching his head. He recommended I heat the manifold in the oven at 200 degrees and try again. I haven’t done that yet and am wondering if anyone has a suggestion.
Years ago they sold a “spreader” for the Chevy small block exhaust manifold for just such a problem.
Don’t know if it would work on 4 cyl but an Internet search might turn one up.Bill Ascheman
Fiberfab Ford
Modified 5.0, 5sp., 4:11
Autocross & Hillclimb
"Drive Happy"The exhaust manifold is now a quarter inch smaller?
Dudes, I bolted up my share of Chebby small block exhausts and don’t remember ever getting one that was off by that much.
But, generally with everything on those cars (chassis, body panels, suspension bits, etc. etc.), I always had better luck starting the end bolts first, just a couple threads, then working it in. Sometimes even had to use too-long bolts to start and then switch them out.
Is this an iron manifold?
If the exhaust manifold is too short, get the block as cold as possible (open to outside overnight for example) and the exhaust manifold as warm as possible (baked slowly in an oven or barbecue grill) and then see if it fits better. Just don’t heat the exhaust manifold unevenly because cast iron can be brittle. Don’t forget to use oven mitts. If it’s the other way around, put the exhaust manifold in the freezer overnight and heat the block somehow. Re-torque the bolts after the assembly gets to a stable temperature, like on the next day.
Obviously, that didn’t work. I was trying to upload photos of the problem and of the spreader I made using a socket and a bolt.
Wow,, this is a good one. first, is the gasket wright ? did you try it with out the gasket , I did the head on mine this fall I put it all back together off the block , that made it a lot easier to do the intake . if you used the same manifold , i don’t see why it would not just bolt up!.. Dan R
Nothing worked! I heated the head in the oven and used spreaders. Nada! Zilch! So I solved that problem by getting another exhaust manifold from Rick Drake. And that led to problem number two. See new post on head bolt threads.DickH2012-12-22 18:36:18
At this point Sherlock would have said Aha! Your two problems could be related. Real likely that someone broke a bolt in that hole and drilled it out off center. Then repaired that with a helicoil, again somewhat off-center. Then forced the bolt in and screwed everything up. If that is true, then I would drill an oversized hole in the manifold and use a grade 8 washer under the bolt head.
If it is a helicoil, I would not try and drill it out since it is harder than the cast iron around it. A Helicoil is just a spring with sharp edges in the shape of threads. You should be able to see the start of the coil if you look real close, maybe with a magnifying glass. Try using a dental pick to get the coil way from the grooves. Then use needle point pliers to unscrew the coil.Ooops, sorry. I didn’t explain it very well. The exhaust manifold is on the right side of the head, with no problem with the bolts that hold it on. There are eight bolts, two per exhaust port. I can line up the four rear bolt holes on the manifold with the proper bolt holes on the head, but then the four front holes on the manifold will not align with their holes on the head, and vice-versa. Somehow, the exhaust manifold warped after I removed it, and I cannot get it back in shape. I heated it in the oven and used spreaders. No joy. So I contacted Rock Drake and bought a replacement manifold.
My other problem is with damaged head bolt threads in the engine block. The two are not related. It looks like the threads in the engine block had been repaired earlier, I’m not sure, but suspect with Heli-coil. Oh, boy.
- You must be logged in to reply to this topic.