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 ******** 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 ****ogies **** 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 va***n 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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