This car has a 353 cube SBC. The 400 block is bored 4.155” with a lightened 3.25” stroke 327 large journal steel crank (pendulum cut, knife-edged, and drilled = removed 7 lbs), 6” Eagle H-beams, SRP flattops, and a wicked 256/262-540/506-105 lc (99 degree intake) solid tappet cam. The final combo is 11:13 compression (to keep up with the cam) with Canfield heads, Professional Products intake (we have compared this to a Vic Jr. and dyno numbers don’t lie), Crane wiz-bang fully adjustable distributor, a Barry Grant Race Demon Road Race 750cfm carb, Comp Cams belt drive, Probe shaft mount rockers, Milodon kick-out full length pan, Isky EDM lifters (these are a god-send for Chevies), Manley pushrods, and BHJ stock car balancer.
The dyno numbers are below.
I flowed the heads and the numbers are fantastic. I will work on posting those soon, but put it this way - stock location intake port, 197cc head CNC'd out to flowing 168cfm on the intake at .250" lift and 296cfm at .550" lift! Originally I was around 287cfm at .550" lift (thought trust me, I claim to be no expert head porter!), but Jay at Pacific is really impressive, given his age, for his ability to get good flow (yes, there is bad flow!). The current CNC pattern on this head is based on his port now, not mine. Exhaust flows right at 71-72% of the intake (I found 74% by back-cutting the valve, but chose not to do so and keep a fatter exhaust seat and better match the split-duration cam). The heads have a lot of work in them currently such as angle-milling 1/2-degree for 56cc chambers and the intake surface has been fly-cut 1/2-degree to match. Running double-thick intake gaskets puts the manifold at perfect height.
All engine parts are sourced through Troy Bowen, a very good friend of mine and owner of Pacific Performance Products. Check this guy out, he really knows his stuff whether Ford or Chevy. He is the only person I have ever met that is a walking encyclopedia for FE Fords for instance. He is an invaluable friend... a friendship I feel like I almost abuse every Friday for the past 9 months when I head over to Anaheim and takeover his machine shop. I have burned more tool bits and broken plenty-o-stuff figuring out half the things on this car :o)
Dyno sheet shows 525HP at 7100rpm and torque of 438 lb-ft at 5000rpm
The overall dyno work took two days (three weeks apart as well). Day one at the dyno was completely painful - the Comp Cams belt drive wanted to chew the belt up, so I had to pull that off and machine a custom spacer for the lower pulley. Then the valve covers had some baffles I thought I machined enough off, but under running conditions they just nicked them, so off they came for rework. Finally, after all of that, I was able to break her in for 20 minutes. Of course, this is really why I dyno - to find any problems before I put it in the car. We changed the oil and opened up the filter and it was virtually spotless and the oil was clean - minus the obvious mix-in of assembly lube and so forth. John Beck at Pro Machine (in the same building as DYNOmotive) was an immense help to me as well - you may recognize that name from some of the Engine Master's Challenges.
Then, I had to pull the springs off to shim them to correct pressure - this was a conscious decision since Chevies frankly suck and like to flatten cams, so it is best to break them in at low pressure. Two hours later at 8:15pm (!) we set the timing to 32o and made the first test pull to 5000rpm. Eric (the owner of DYNOmotive in Yorba Linda) had been there since 5am getting the engine on the stand, I was there are 10am, so it was a long day for both. So, at 8:45pm we had managed to work our way up in 500rpm increments to 7000rpm and I saw what you see here. Oh yeah, all on 91 octane from the Mobil down the street and not a sign of detonation - long rods and big bore - no problem. So, that was it - no time to tune it, but I knew it had more, so I scheduled the next open time - a Saturday 3 weeks later...
In the interim time, I pulled the cam belt off and replaced it with a new one. In only three minutes of running, it had sanded the 1" belt down to .700"! I also put the cam timing back to zero - I had initially retarded it 4 degrees. After reviewing day one with Troy at Pacific, he thought I was bleeding too much cylinder pressure by retarding. He was right...
Day 2, the engine fired right up and we warmed it up, made a couple test passes, and then the third pass was to 7000rpm to match day 1. The only change was advancing the cam back to zero - and I saw 507HP at 7000. That is 29HP that I lost retarding the cam 4 degrees!!! I had always said I thought the motor should make 530HP, so off to tuning I went. So, I removed the 1" spacer since Troy had a similarly cammed 383 with the same manifold lose 10HP to the spacer. I had absolutely no change - the spacer did nothing but supply a vacuum reference. Then, we added a couple degrees of overall timing to 34o. Added more power, but looked like we should add a little more fuel so I went to 78 jets (from 75s) and only lost 2HP, but the fuel curve said it used every drop. Added 2 more degrees timing to 36o, put the spacer back in for a vacuum reference, and then started to see a little detonation at 7100-7300rpm, but HP was up over 520. Finally, switched the fuel over to 110 octane, ran the 91 out of it and went to 7500rpm. The 353 kicked out the highest HP at 525 at 7100rpm and was at the highest torque of 438 at 5000rpm. The whole day, not an ounce of smoke from the breathers or anything - it ran absolutely perfectly. I was just happy to see it get near the 530HP I thought it would make! Not a bad day 2 - it was worth 50HP and 20 lb-ft.
So, for street driving on 91 octane, I can set the timing at 34o and have around 510HP, or go to the track on race fuel and 36o to have the 525HP on tap.
All in all, the BG carb was pretty much perfect out of the box. I gave them the engine specs and cam, and they hit it near perfectly, so at least I didn't have to mess with that too much.