Wow, just, wow! - Impala Tech
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post #1 of 17 (permalink) Old 08-05-2009, 02:47 AM Thread Starter
 
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Wow, just, wow!

So, the past couple of nights after work I have been tearing into the Biscayne. Mainly cleaning things up, painting up the engine bay and overall trying to make it look better under there. While doing this, I knew I had an exhaust leak issue to address so off comes the y-pipe and the manifolds. I sprayed down the y-pipe to manifold bolts with some PB and WD40 before I left for work because it was VERY rusty under there. What do I find when I get home? I didn't even need it! The bolts were finger tight on the y-pipe, AND the manifolds!! I found 3 bolts (both sides combined) that I actually had to use a ratchet on. Not only were the manifolds on finger tight, there were NO gaskets between the head and manifold!! The y-pipe had the gaskets on the passenger side and a shredded donut gasket on the drivers side. No wonder I had a leak. Hope I don't have a burnt exhaust valve in there somewhere (the motor runs good so I doubt it). Another thing I found, when I pulled out the 2 rear driver intake manifold bolts (they were holding a spark plug wire loom holder), they smelt HORRIBLE!!!! Like REALLY nasty. I can't figure out what the smell is honestly. I don't seem to have any fuel leaks/intake leaks anywhere. The engine runs/idles fine, so I'm kinda curious. I also found that my exhaust heat riser on the passenger side has 2 small cracks in it (right above the hole for the butterfly shaft to pass through) and seems warped. Any ideas for this one without replacing it? Don't want to slap it back together and have another exhaust leak. I should probably just buy a new one but would hate to spend the money on something that will just be coming off soon. Just thought I'd rant a little bit. I can't believe how loose everything was, now it makes me worry about other stuff.
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post #2 of 17 (permalink) Old 08-05-2009, 04:36 AM Thread Starter
 
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Think I could just cut the y-pipe and extend the passenger mounting flange up a few inches to make up for the heat riser (I know the y-pipe side uses a donut gasket and the top of the riser has a 3 hole collector type gasket, haven't looked to see if the donut gasket would fit in the manifold)? Or could a small piece of pipe sandwiched between the y-pipe with donut gasket pushed against the 3-hole gasket on the manifold? (yes this sounds ghetto but just an idea. The delete plates and new riser's are like $50 and I could use that $50 for alot better things lol)
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post #3 of 17 (permalink) Old 08-05-2009, 07:52 AM
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I have replaced the snorkel type air cleaner with open one (including breather for the valve cover and air filter) for something like $25 from local PepBoys store (cheaper from Summit but you pay shipping). It looks way better and really cleans up the engine bay. All the extra stuff like the heat riser, vacuum lines to butterfly valve are gone now and car still drives :-)
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post #4 of 17 (permalink) Old 08-05-2009, 08:39 AM
BA.
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pretty shocking stuff there Dallas.

just the other day I also noticed that my rear-most intake manifold bolt had a HORRIBLE smell to it. Like way way old, burnt, nasty oil. Just wanted to let yo know you weren't alone there. I'm ignoring mine,...it's not detrimental.

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #5 of 17 (permalink) Old 08-05-2009, 09:26 AM
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Dave,
67 small block did not have exhaust mnifold gasket from the factory. It was just metal to metal. I'm not sure what year your engine is though.
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post #6 of 17 (permalink) Old 08-05-2009, 11:49 AM
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No SBC left the factory with an exhaust gasket. That is a replacement item. When the car shipped the heads and the manifolds were machined flat; no gasket needed since there is no pressure worth noting (exhaust back pressure is under 5 psi).

The reason the bolts are loose now, and will loosed again is because of heat cycling. As the metal expands the tension on the bolts relaxes because cast iron expands ay a miniscule amount less than the steel of the bolt. Over thousands of heat cycles the bolts loose their torque and eventually will fall out all together. The problem is so bad with aluminum heads that you have to use special bolts or safety wire them to keep them in place over time (constantly retorquing the bolts metal fatigues the threads in the head). If you run headers your constant blown header gaskets can be attributed to heat cycling and not poor quality headers. I recommend Stage 8 bolts with headers or safety wire with cast iron manifolds. Exhaust manifold gaskets are used on old exhaust manifolds because the lack of bolt pressure to hold them flat allows them to warp with time. So a used manifold often (but not always) requires an exhaust gasket.

As noted there are heat riser spacers (used on 3/4 ton and larger trucks with a single exhaust) that you can find in bone yards if you are lucky. You might try some JB weld on the crack as it is far enough away from the exhaust valve where the heat isn't as intense.

Big Dave
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post #7 of 17 (permalink) Old 08-05-2009, 03:27 PM Thread Starter
 
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I know about heat cycling but the engine's been replaced at one point so I know someone put the manifolds back on. Shoot, with 160K miles on my 98' GMC, the bolts weren't even loose. I'm all to familiar with header bolts, headers are a pain in the butt so I avoid them unless I NEED them for a particular build. The only set I had that didn't need constant attention was gibson stainless headers for my 98'. The aftermarket y-pipe bolts came loose once but that wasn't a big deal just crawled under the truck, and zapped em' tight. Thanks for the info on the gaskets not originally being there, I knew they did that but thought it stopped early 60's or something. The shortblock is a 69-73 "020" 307 but the heads, intake, carb are 67' 283. As far as the air ceaner, I'm running a dual snorkel unit instead of the factory single snorkel with polished lid.
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post #8 of 17 (permalink) Old 08-05-2009, 03:40 PM
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You know a they had a dual snorkel on the L-79 (325 horse 327) that is one of the rarest of parts to find. It is a chrome plated dual snorkel top with the inlets 180 degrees apart. Last time I looked they were selling for $900 to $1,200 on e-bay, but that was before the non-great non-depression we are in the middle of finding an end to one of these days.

Big Dave
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post #9 of 17 (permalink) Old 08-05-2009, 04:04 PM Thread Starter
 
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lol ya I wish it was one of those, it's actually a ford part (don't shoot me). I got one of the 79-85 Ford 302 H.O. air cleaners like this:



Except my lid is from an earlier version with a polished lid (with black ring around it). Similar to this:




Got it for $15 so can't complain, and they flow REALLY well.
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post #10 of 17 (permalink) Old 08-05-2009, 07:43 PM
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Blasphemy!!! You should be exiled! Ford parts on a Chevy aaaahhhhhh!
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post #11 of 17 (permalink) Old 08-06-2009, 12:57 AM Thread Starter
 
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lol tell that to guys running a Ford 9in It doesn't say ford on it and look good under there. If I didn't tell you what it was from, some guys would never know.
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post #12 of 17 (permalink) Old 08-06-2009, 01:59 AM
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Quote:
Originally Posted by Big Dave View Post
You know a they had a dual snorkel on the L-79 (325 horse 327) that is one of the rarest of parts to find. It is a chrome plated dual snorkel top with the inlets 180 degrees apart. Last time I looked they were selling for $900 to $1,200 on e-bay, but that was before the non-great non-depression we are in the middle of finding an end to one of these days.

Big Dave
Look like Yearone sells one for the L79 for just uner 500 bucks.

Ape Out.

Make: Chevrolet
Model: Impala Custom
Year: 1969
Doors: 2
Engine: 327 V8
Trans: Powerglide
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post #13 of 17 (permalink) Old 08-06-2009, 02:59 AM Thread Starter
 
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Here are some pics of what I have been working on, tell me what you think so far:

Before:


As of now: (still have to put the fan/shroud/radiator/alternator back on and I have a chrome breather coming for the oil fill tube and chrome thermostat housing)








sorry for the quality, I couldn't find my camera.
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post #14 of 17 (permalink) Old 08-06-2009, 08:10 AM
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Looks nice man. One question though, with such a nice engine, valve covers, etc, why didn't you put chrome open air cleaner? It would look so much better. I did that to mine and difference is like a day and night.
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post #15 of 17 (permalink) Old 08-06-2009, 07:36 PM Thread Starter
 
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The air cleaner top is polished (just dirty in the pic). I personally don't want an open element on it. I've ran them alot in the past but wanted to keep the engine looking somewhat "traditional" but upgraded and I like the dual snorkel setup. That and I would want a black air cleaner to match the valve covers. There isn't much chrome on the engine.
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post #16 of 17 (permalink) Old 08-08-2009, 07:49 AM
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I just bought my 65' Impala about 4 weeks ago. 283 , 2 BL.

For the most part it was all original AND it had this exhaust leak. It leaked at the heads ,( the manifolds ) , the heat riser and so on. I modified the heat riser spacer ( removed the butterfly and shaft , plugged the holes ) machined the collector gasket side flat , restored the chamfer for the doughnut side and used it all for a few days before I just decided the hell with it and put a set of Hedman headers on it. You would not believe what I went through to remove the exhaust manifolds since 4 bolts broke off in the heads , but I have the tools and experience for dealing with these issues so I got them out. I also added a Edelbrock dual plane and 600 Holley , open element Chrome air filter , degreased the entire engine bay and now it looks acceptable and runs better too. Next step will be to get rid of the points ignition and replace with an MSD box and distrib.

Eventually ( and very soon ) the Powerglide is coming out and in its place a nice 350 turbo . I believe these cars had pretty steep gearing so the ring and pinion may also get changed.
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post #17 of 17 (permalink) Old 08-20-2009, 03:14 AM Thread Starter
 
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Here are some pics of the "finished" product (might add a chrome air cleaner lid instead of the polished one, and will end up with a cog drive with A/C down the road)







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