I would not suggest a Thumpr on a stock SBC (like the OP suggested he has) I have a Roller Big Mutha Thumpr for my SBC. What Comp suggested to me were 2 key points. #1 Maximum compression. These cams love compression as much of it bleeds off. 10.5 is not out of line. Easily 2 full points over the average stock SBC. #2 Maximum timing. These cams rely on a significant amount of ignition timing. Advance the distributor until it "pings" then back it off 2 degrees. Comp's words, not mine. I will say, I have always had good luck with Comp and believe I get the no bullshit answer when I call. FWIW.
Sounds great, but it also sounds like it is about ready to die unless you keep revving it. I had a RV cam in a .30 over 305, with a Edelbrock 4 barrel & intake, and block hugger headers. I also used a stock torque Converter. I used MEGS exhaust tips, on a dual exhaust set-up, and got a nice little rumble from the exhaust, good idle, and good gas mileage. It had a 3.08 geared rearend. I was very pleased with the sound and performance.
That really depends on which Thumor is installed. The lower level I posted specs for is a very good cam to put in a stock 350.
That's why I was asking about the vacuum advance. If you hook it up to a full-time port, you will pull max advance at idle which will smooth it out a little. He would need to use a special vacuum advance can though - one that pulls with a weak signal. On my small cap delco, I use a B-28 can. It's what they used on 65-66 fuelie vettes. The throttle response will be snappier. Here's a good read http://www.corvette-restoration.com/resources/technical_papers/Vac_Adv_Spec.pdf
The 12-600-4 Thumpr has a very advanced (102) intake, but it is a 279 intake, the intake closes at 63 (.006). That means an iron headed 350 will want to be in the 9.5 -9.9 static range. Also because of the high (77 degrees ) overlap the carburetion and advance curves will be critical to have acceptable part throttle. You will definitely want a Vacuum advance and a have the mechanical in early. The B-28 canister can be found as: NAPA/Echlin VC-1810 Niehoff DR-305 Borg-Warner V329 BWD V329 Standard Motor Products VC-177 Standard Motor Products Hygrade VC177
Neat car! For some reason that sounds odd to me, Maybe it's just recording quality. Hard to describe sound and analogies suck But it's like out of rhythm when its your favorite song and the drummer is 1/2 a count off.
Sorry, been away from the computer for a couple days. It was running a vacuum advance at the time of the video. I have since changed, and it runs like a champ. The video was taken the day after its initial run. It took some tuning, but it runs great now. Its a little cold for a new video update right now though. hahaha!
I've searched, but the only place that still sells the B-28 is Autozone. The p/n you want is DV1810. It's around $14 ea Don't buy the V329 on ebay for $50 http://www.autozone.com/autozone/parts/_/N-93xnh?itemIdentifier=118067_0_0_
All of the part numbers above get you a B28 Can. Here is a pic of the SMP VC-177 See the B28? From the Corvette Forums http://www.amazon.com/Airtex-Distrib.../dp/B000C1ES7I Alternate Part Numbers: NAPA/Echlin VC-1810 Niehoff DR-305 Borg-Warner V329 BWD V329 Standard Motor Products VC-177 Standard Motor Products Hygrade VC177 AC/Delco part number D1312C GM part number is 88924985 Wells DV1810
Have you actually tried to buy one? Go ahead & order the GM or Delco http://www.gmpartsdirect.com/results.cfm?partnumber=88924985 & here's the 177 summit sells... http://www.summitracing.com/parts/smp-vc177
The SMP-VC177 at Summitt has B28 stamped on it. I havn't tried the AC or GM numbers, they are interchange numbers. The SMP looks available. The Airtex/Wells is available many places.
Using vacumn advance does work for sure, it sure helped the idle, still these cams will drive u fugly crazy trying to tune them for perfect drivability , I wouldn't put another one in any engine period , strictly a parking lot , rumpty rump pos cam . I would recommend anything but a thumper cam !
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