After a year since I started this project, my engine is now running. First, my goal was to build a street engine, stock appearance, no ruff idle, that would run with my 3,07 gear and unleaded gas (no octane booster). I like to do long trip too, so no big Holley carb that sucks gas like pig (sorry Holley lovers, I really like my Q-jet :D ).

I study in mechanic but I don't pratice anymore so building an engine was a challenge. I was so affraid when I turned the key (did I forget something??? what's that package overthere, d'oh!! piston ring????). Anyway I collected info on the forum ,chevy high performance and other publication plus speed shop.

The block came from a GMC express or savana 1996. It's the vortec option. I kept the crank and rod (they are the powdermetal ones). The rotating assembly was balance.

Cam, torque and hp. So you need low speed engine torque for the street and 3,07 gears. The engine had provision for roller cam so I chose the XR-270 that has 218 intake dur. and 224 exhaust dur. @ 0.050''. Since it's a rollercam, the lift was still 0,495" in and 0.500'' ex. I didn't go the 1.6 roller rocker arm to avoid extra machinig on my vortec head. So dyno 2000 predicted 400 lbs of torque at 2000 rpm (a little optimistic but a lot of torque anyway) and 434 lbs at 4000 rpm. The max hp is of 385 at 5600 rpm.

Compression. To run with 91 octane gas, I had to stay under 10:1 of compression. At 9.8 to 1 with a 0.040'' quench, the engine run extrêmly well with 34 degrees of advance. I had the block decked and bought some flat top forged piston 4 valves reliefs from TRW.

The vortec head were machined for stock valve cover, screw in stud, 3 angles valve and were mildy ported.

I rejetted my Q-jet and the ignition has a curve that give full advance at 2800 rpm. The vacuum advance give a total advance of 52 degrees at cruise speed (3000 rpm).

Driving impression. First in neutral, the engine is rev happy with the full roller setting. It don't vibrate in any Rpm anymore (the separated engine rubber support probably didn't help). On the road, it's so fun. I can lite the tire with just the throtle (it grip fairly quick though) and smoke those 17" :eek: with a little help from the brake. The engine has a lot of torque off the line and when it gets to 3000 rpm, it pulls harder until around 5600 rpm. I'm amaze that I still have the 3,07 gear (3,36 or 3.55 with 5 speeds is in my future).

Now, I'll take those stock manifold and put some headers with real dual exhaust to get all the hp and torque it's suppose to give. After that, I'll go to the track for some times.

Thanks for reading my long post, I had to take it out (after a year :D)

Stephan

 

Looks great :thumbs:

 

Sounds like a sweet combination to me :thumbs: With your bottom end power, I suspect that with the low 1st gear of a 5spd you won't see a need for lower rear gears.


[Modified by Vetterodder, 8:24 PM 5/11/2003]

 

:iagree:

 

Thanks!!! :cheers:

Vetterodder:

Yeah, maybe I could go with a richmond 5 speeds with my current gear(3.07). It would retain it's economy and boost the 1st ratio. This transmission have an ideal spread between each gear. I have a 2.72 too that I could try. But It's not in my near future. I have to get the $$ before.

Stephan


[Modified by American Boy, 7:35 AM 5/12/2003]

 

Stealthy... I like it.

 

Stephan, with a 3.27 1st geared Richmond, or Tremec, your final drive in first with your 3.07's would be about the same as a 2.52 1st gear and a 3.98 rear gear or a 2.20 1st gear and 4.46 rear gears. While the Tremec 5 spd has an overdrive 5th, as you said, the Richmond has much closer gear spacing.

 

Looks like a winning combo. Nice work. :thumbs:

 

:cool: :cool: :cool:

:cheers:

 

:withstupid:

As installed you would have no idea....until you started it.

Very nice. :steering:

 

:yesnod: :yesnod:

:smash: & :steering:

 

Zwede and SAC:

The Edelbrock performer allowed me to install the stock air filter and the XR-270 have a idle that is really close to stock. A little suprise when you depress the pedal though. :eek: :D