I've searched a whole bunch and cannot seem to find the info that would help me. I need help with picking a suitible head and cam(ie no getting ripped off!!). Here's where my motor stands right now (to the best of my knowledge) :

Rebuilt 350 (L98) 35,000miles ago, supposedly rebuilt 10k before I bought the car 25k miles ago (181k on car now, 156k when I bought it). It smokes on start up, typical sbc. The heads are some swirlport truck heads, checked the casting numbers a couple years ago, flow worse than l98s. It seems to have a vibration at higher rpms, say, above 4000rpm (is this normal or not?). Power numbers in sig, I'm thinking the heads are mostly to blame. Milage sucks, never more than 21mpg all highway, most of the time high teens all highway, cruise set at 70-75mph (3.27 axle) I really don't want to know what I get in the city. Leaky injectors maybe??

I'm not going for a power monster here, I'd just like to get a bit above stock power #s and better milage. These are my thoughts so far:

I've seen all sorts of heads on ebay, but I'm unsure what I really need. As best as I can make out I should be looking for something with 180-195cc intake runner volume, 64cc chambers, I'd like to go aluminum for the weight savings, but they seem to cost a lot more. On the other hand vortecs seem to be cheaper, but I'd then need to get the new base.

As for the cam, I figure I'd call comp cams once I get the heads figured out.

I'd love to get headders, but I think that doing the heads will cost enough with all the nickle and dime stuff added in there. All this needs to be done by mid June so it has some miles on it before I take it on a 600+ mile (one way) roadtrip.

Sorry for the length, I thought I'd err on the side of detail rather than saying "what head is best for me? but first guess what motor I have".

 

I'd recommend finding out whats wrong with it in its current configuration first. I would think you should be making 25 more rwhp and getting 23-24 mpg on the highway.
I know I was getting 25 mpg in an 87 IROC with a motor just like yours and a 3.27 rear end.

 

Any ideas on where to start looking? I vowed that I would never pull the runners off that thing again (I kinda messed up the allen head bolts, oops) w/o making it really worthwhile. Thats why I've been waiting to do something fairly major. If the whole thing was out of the car, it probably wouldn't be too bad, or not as bad anyway.

The reason I had the runners off the first time, was to replace the injectors. I should have gotten them flow checked and cleaned first, but I went cheap and just threw them on. Bottom line they didn't change anything. It has had a new O2 sensor since I bought it, the original PCM had a bad circuit for the O2 and was messing things up royally, so that was replaced with a known good one with my chip in it. I'm pretty sure I've gotten all the vaccum leaks (dried out hoses), The next thing is to fix the exhaust leak on the pass side manifold (recently developed), though that wouldn't affect the o2 reading, so I doubt that is hurting me. The cat is gone, as it broke apart and was rattling around, thusly the AIR line that went down to it has since been tossed.

It has always had a miss at idle that I cannot fix (new plugs, wires, cap and rotor didn't cure it). I cleaned out the IAC passages and as much of the plenum and runners as I could reach while they were off.

If you have any suggestions, please tell me.


EDIT: I know that it definatly runs rich. I have had 2 ppl who have followed me mention it.