13.1 ~106 MPH shifting at ~6000 RPM
12.67 ~109.xx MPH (1.87 60') shifting at ~6800 RPM.

Also, this car was an automatic with 4.10 gears (which help a lot with staying in the powerband). The lower the gear (numerically), the more drastic of a change you will see from not shifting high enough. With 2.73 gears (like some people do) and a 306 cam, you will probably run stock times. Choosing a cam depends on a LOT of factors.

 

Yeah Im dealing with that. Im only running 3.23 gears with my T56. When I did the conversion I had a ford 9" I was planning on putting in the car with some 4.10s. But everyone I talked to said I would loose alot of power going to the 9". So with me not having alot of power to give up with a cam only car. So I just toughed it out with the 10 bolt. So far Ive managed a 12.74@111.9mph with a 2.00 60'. I cant get the 60s down at all. Ive launched the car EVERYWHERE with every possible kindof tire and nothing helps. So if I just drive the car out of the hole instead of trying to dump the clutch it runs better. But it still boggs and the car is recovering till about the 330' mark. Im in the planning stages of an 8.8 swap with some 4.10s. Hopefully that will get me down in the 12.0-12.2 range where my car should be. I also need more tuning I belive.

Jeremy

 

It's the 3.23s, trust me. You should switch to 4.10s asap.

 

I belive you 100%. I just dont want to throw away money by installing 4.10s in the 10bolt. Ive already blown 2 yolks apart and broken an axel. Im still on my stock gears and diff though. Im working on the 8.8. So hopefully it will be in befor the end of the summer. I would LOVE to hit an 11.9 with only a cam. But its hard telling if my motor is strong enough to do it. Its got 140k HARD miles and 83k of them being put on by the Indiana state police. So we will just have to see.

Jeremy

 

Ever do a run where it shifted at like 6300-6400 RPM's? I would bet my life on it that it is within a 10th or so of the the 6800RPM run. Thats totally overrevving on stock heads. They dont flow enough for that. You might be bale to tune PCM's well, but a few of the very reputable builders on here, have said, several times that your not making any real power past 6K and spinning it any more than a couple hundred RPMs past the peak power is a waste of time.

And if you read my post, youd see I didnt tell him to shift at his opeak power. I said to shift at around 6300-6400 on it. A few hundred past his peak power. And I stick with my origional post. No stock headed car with any cam, even a GM847, should be shifted that high. Its overrevving and will be hurting it as bad as short shifting would hurt the times.

 

My car runs the best shifting at 6600-6700rpm period. I have well over 100 passes on it and Ive tried shifting it at every rpm imaginable. Hell look at TPI engines they stop making real HP at around 4500-4600rpm but they still run the best shifting at 5400-5500rpm. I have had many TPI engines as well and I do know what Im talking about there. Short shift a TPI engine and you will be getting passed by a 318 dodge ram.

Jeremy

 

Daniel's car is set to shift at 6300-6400 (unless the tranny slips a little or the converter is too loose). The stock tach is off and shows 200-300 RPM. On my car, 6400 to 6800 made a 1.4 MPH difference. I just don't set the customers' cars to shift as high as 6800 unless explicitly asked so, because it's their bottom end - not mine.

Those cams should be reved that high. On stock bottom end, it might not be a good idea, but if you do go with one and don't shift where you should, you will not get the times the 11 second boys got out of them. That's one reason I always recommend the cc503 for those who don't plan to shift that high and still want good times.

 

Put a 12 bolt in it then with 31 spline axles. I have always run a 9" so no personal comparison.
A 9" will NOT take THAT much power as ya will see a big difference in the 60'.A 12 bolt is suppose to take less though.Both can take the beating up to say 8/900+ FWHP .Get some MT's and drop the hammer on it.
A tenth on this end = two on the other end.
Then ya gonna need a drive shaft,then a clutch and then a T56/A4 gonna let go on ya--- Always something.

If ya got traction ya ain't making enough HP.

 

I think a 9" or 12 bolt is over kill at the moment. Like you said Im not making enough power. So why lose some by going to a 12bolt or 9"?? Im going to stick the 8.8 in it and see what happens. Im turning 112mph with no spinning at all. BUT its because I have NO first gear at all. I barely have more total 1st gear ratio than a 2.73 auto car. I can dump it at 4K or milk it and drive out of the hole. Either way I dont spin at all. The car just falls on its face. Then it has to recover the first 330' of the track. My car is only a bolt-on car with a CC306 cam. Shoot I dont even have all the bolt-ons done yet. My clutch is in need of a replacement. My SPEC4 has about 50k on it and its starting to slip some times. My trans was just built by RPM transmissions last summer so its good to do. I think with a rear and some 4.10s I might even gain a MPH or 2 sence Ill actually be useing all the track so accelerat instead of everything after the 330'. Who knows? It might just be doomed to be a slow turd..... Thanks for the info though. Once my 396LT1 is done then I be in need of a 12 bolt

Jeremy

 

Ya are breaking s*** now but it's your choice.
BTW a 4.10 in a 10 bolt don't last long if ya "hook" it good.

Stock axles ain't safe either.

 

No no, Im not putting the 4.10s in the 10bolt. No way will I spend a dime on that pile O shiz. The 4.10s are going in the 8.8 ford rear on building. Ive seen WAY to many 10 bolts spit r&p teeth out. Im not taking any part in that mess.

Jeremy

 

Make SURE ya get "C" clip eliminator axles and 5 lug 31 spline and an Eaton posy.

 

Im getting Moser axels for it. Ill have to look into the C-clip elim. kit. I didnt know they made them for 8.8s. Like I said in the earlier post Im still in the planning stages. Im still trying to make a good design for the t-arm mount. I should have it finished up in a month or 2.....hopefully.

Jeremy

 

 

Thanks for the advise. Do you think it would be a good idea to build the negative pinion angle into the t-arm mount? Or will the pinion angle not effect anything in the rear adveresly? I dont really know how much preload a negative pinion angle would put on the springs, but it might be worth bring up.

Jeremy