by SpyderByte » Fri Jul 22, 2011 9:35 pm
I just have gone through the exhaust options for my '80 Spyder 350. I do not like exhaust headers because they put too much heat in the engine compartment. Dorman makes a very long list of factory style cast iron manifolds for many differnet applications and after sorting through the list I have found two different styles of manifolds that will work for 2+2 Monzas AND will clear the steering shaft. Vegas, I'm not so sure about. My 350 is out of a '90 truck so it has the passenger side dipstick which limited my options on the passenger side manifolds, but most should work. I chose Dorman # 674-202 for the passenger side, this is basically the stock type manifold that was originally installed on the small block V8's and it also let me use the passenger side dipstick. This unit has the 3 bolt flange just like the original. The only difference is that you can find these manifolds on Ebay for $40, with shipping instead of paying twice that or more for a used original. They do all have the AIR holes unfortunately, but 1/4" plugs solve that. You can also use the 67-72 Chevy truck style which drops down in the middle instead of at the aft portion of the engine, these will also fit, both sides. Driver's side # is 674-201 and also costs $40, with shipping, brand new. Can't beat that. This unit is VERY close to the steering shaft, but it will work, and it points out underneat the oil filter. Again, 3 bolt flange with AIR holes. I used this manifold because of the 3 bolt flange to match the passenger side and because of the price, since your only other option is an IROC driver's side manifold 87-92 Camaro, which has the AIR holes and has an oxygen senser bung and 2 bolt flange. This is part number 674-518 and costs $66 brand new with shipping. I almost went with this manifold but I wanted the exhaust flanges to match on both sides. The IROC is as close to a driver's side factory correct Monza manifold that you're going to get from new production. They are all made in Chino California unfortunately, but that's why I have a grinder, to grind off the CHINA on anything I have. Hope this helps, it took me about a week to find the right manifolds. Again, these manifolds will work for the Monza type applications, not so sure about whether these will fit a Vega, I don't know what the differences in the engine bay are as far as that goes.