snomobeelr Posted May 17, 2016 Share Posted May 17, 2016 What can a BBC Rev up to safely, if there is such a thing ??? Ive been driving the Monte and started getting a feel for her and beating on her. The old engine build would Tach out at 5800 thats where it started to float , nothing past 5800. So with the new build It snaps right to 6 g's. I am rolling in 1st gear and hammer on her she breaks loose and snaps right to 6 g's. I was messing around driving and she snapped up to 7000 before I shifted. That happened twice and I almost had a heart attach and I just took it easy after that. Worried I would blow it up. I am pretty sure my stock tachometer is off and just ordered an Auto-meter tach. I realize it all depends on what is in the motor but I don't want to launch anything being stupid. Also attached Cam Card 468 BB 10 to 1 Steel crank 2 bolt mains Forged Pistons .095 Dome Don't know what connecting Rods Brodix Aluminum Race Rite Oval port Heads Roller Cam - Roller Rockers EDL-Air Gap Intake Pro Series 850 Carb MSD-PRO-BILLET HEI Distributor 2500 Stall 3.73 rear end Quote Link to comment Share on other sites More sharing options...
Jason72 Posted May 17, 2016 Share Posted May 17, 2016 First it all depends on too many things, valve train parts and geometry, was the bottom end balanced, head flow, ... That being said, that cam is smaller than what I have in my 427 sbc and I only pull to 6200 rpm. you have more cubic inch so I would say less than that. my advise is to get it on a dyno or a drag strip and see where the power curve is at. A tired 305 will turn 7k with no load(spinning tires). sounds to me like you need some suspension and tire mods to get it to not spin so easy. I also assume it is a hydraulic roller lifter so just with that I wouldn't go too much over 6k even if the rest of the engine is capable. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted May 17, 2016 Share Posted May 17, 2016 The rods is what I would be concerned with If the are stock rods with 3/8" bolts, 6000 max, if they have had some ARP rod bolts installed maybe 6500, now this is for the bottom end That cam should be good to at least 6500 but the hydraulic lifters may limit that depending on whos/what lifters they are Quote Link to comment Share on other sites More sharing options...
waupachino Posted May 18, 2016 Share Posted May 18, 2016 I would say with your set up 7K is not a big deal. My 496 is set to shift at 6750, and has seen over that before. Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted May 19, 2016 Share Posted May 19, 2016 Like Sam my big concern would be rods and rod bolts. It would be nice to know what you have. I have Molnar rods with ARP2000 bolts in my 565 shift at 7200 Quote Link to comment Share on other sites More sharing options...
Its Just Me Posted May 20, 2016 Share Posted May 20, 2016 Ditto Sam & Mike...they know. Rods & rod bolts are the main concern. Not knowing what you have, leads me to think they are stock, or you would know because you would have a receipt (bragging rights) of some sort. If the assembly has not been balanced, and if you don't know about rods or rod bolts, I would not spin over 6000 max. Sure, it will hit 7000+, and it's really cool to do it, but to do that on a regular basis is asking for trouble without the right parts. Good luck. I'm afraid you have already crossed over to the dark side of 7000 as being OK (because it did it once). Lighten up the foot and let the big block do it's thing-torque. Scott Quote Link to comment Share on other sites More sharing options...
snomobeelr Posted May 25, 2016 Author Share Posted May 25, 2016 I finally got another tach installed in the car. I bought an Auto-meter, Z-Series, 0-8,000 rpm, 2 1/16 in. Just finished and took out the car. At Idle the Auto-meter is 2 to 300 RPM lower than my Factory Dash gauge. At 45 MPH the Tach's are 500 RPM different. The Auto-meter was at 2000 RPM and the Dash Tach was at 2500. Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted May 25, 2016 Share Posted May 25, 2016 The factory tach are know for this Quote Link to comment Share on other sites More sharing options...
72-CLASSIC_RIDE Posted May 25, 2016 Share Posted May 25, 2016 Yep! My factory tach shows 2000 RPM but when checked with calibration instruments, the actual was really 1800 RPM. So at 1800 calibrated RPM, my Factory Tach displays 2000 RPM, so is 200 RPM higher than actual. Doug Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted May 26, 2016 Share Posted May 26, 2016 and the higher the RPM's, the more it will be off Quote Link to comment Share on other sites More sharing options...
snomobeelr Posted May 27, 2016 Author Share Posted May 27, 2016 Then the good news is I didn't hit 7 G's. The bad news is I didn't hit 7 G's. I had debated about putting a tach in that would mount on the Column or dash so it was easy to see. I ended up getting a smaller one that mounted on the pillar. Here's a picture. Quote Link to comment Share on other sites More sharing options...
snomobeelr Posted May 27, 2016 Author Share Posted May 27, 2016 Opps, here it is Quote Link to comment Share on other sites More sharing options...
John S Posted May 27, 2016 Share Posted May 27, 2016 and the higher the RPM's, the more it will be off A while back I got the math formula from you to determine rpm at a certain speed and I also saw the same formula in Hemmings Muscle Car. I tend to believe the formula is accurate would you agree? John S Quote Link to comment Share on other sites More sharing options...
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