Finally...First TRUE Impressions on engine mods.

Subscribe
Mar 21, 2007 | 09:34 PM
  #1  
I say finally, because the car has been together a week, and I have been fighting a gremlin since then. Today, finally traced it down to a bad connection on #7 fuel injector. What a PITA figuring it out.

Car is a 1985 Corvette L98 TPI with 4+3 manual transmission and 307 gears.

The new mods:


Summit 170 heads
Crane 1.6 roller rockers
Hedman Elite coated 1-5/8" longtube headers
Mid America 2-1/2" front Y pipe (w/custom welded collectors)
Mid America AIR pump delete kit
Self Ported & Siamesed stock plenum
Self Ported and Siamesed SLP runners
Self ported Edelbrock base intake
TPiS adjustable fuel pressure regulator

The heads (made by TFS) are very nice IMO, well worth the $950. Very pleased with decision to buy these as part of my plan.

Rockers are also nice and were bought used from a Corvette forum member

Headers are very nice, fit great, allow easy oil filter access, and do not have to be removed to replace big factory starter. I really like the fact that these do not require collector gaskets. They use a ball and socket type connection which works very well. Really am baffled as to why anyone would badmouth these.

Y pipe is also nice, but welds near rear flange were rather crappy. When cut to proper length, it lined up near perfectly with the longtubes.

AIR pump eliminator setup was easy to install and looks purty.

SLP runners are rather crappy out of the box, IMHO, but I had no intention of waiting forever for AS&M, or of using them stock anyway. They aren't all that much bigger than stock, internally. The biggest issue I had with them is they are way too close to injector #7 and injector #2, which caused me a LOT OF GRIEF finding my miss and stumble in my new setup.

I did all the portwork on intake pieces myself, and aside from me maybe going a little too big on runner entrances, fitment of all 3 sections was pretty good for being from three different manufacturers. (GM, Edelbrock, SLP) I had a little trouble with vacuum leaks at runner to plenum connections...easily remedied with a slight bit of Ultra Black RTV smeared onto gasket mating surfaces.

As for the MEAT & POTATOES...

Though the car literally has NO TUNING, it runs very well. It pulls MUCH harder than stock from any rpm. I purposely retained the stock camshaft and may experiment with cam timing in the future. Intake/runner mods seemed to help push powerband higher up into the rpm range. It used to barely rev to 5000, and was pretty much done at 4500 or so, but now revs (and pulls) easily to 5300-5500 and at that point seems to just run out of breath, which is fine and was expected. First gear is all but useless now as it simply obliterates the tires from any rpm. Second gear which used to just have the TPI torque sensation, now tries (and did once or twice) break the tires loose from a roll...

At this point, I am glad I chose the game plan that I did, and so far am very happy with the results. I haven't even tried playing with timing or fuel pressure yet. Base timing is stock 6 degrees, and base fuel pressure is stock 38psi.

Reply 0
Subscribe