My New TSP Sleeper 482 Stroker Motor

Hi Jim
I like the early rockers on my 67 400 would like to fit them on a 71 455 with a mild cam ,not real sure about the hybrid adjustable pushrods though,better to buy a new stamped steel set ?
Thanks ,Ron

 

Ron - I run 67 rockers and adjustable pushrods on my 71 motor, and they work out fine. You can measure and purchase solid pushrods from a vendor, but I find the adjustables hold together just fine, i frequently run mine up through 5700 rpm. The hybrid tips are a good idea, but not strictly necessary for short term use.

 

I would run the stamped steel rockers on that, you won't have any issues with a mild cam with those.

JW

 

This will be a good news/bad news/good news post. I ran the car 5 times in BG at the Nats. Aside from the video Larry posted where it went 12.91 with traction issues at the launch, the other 4 passes were all between 12.49 and 12.60 at 107-108 MPH. Here's the best pass with just a 1.81 short time (I didn't push it at the launch).


Now, the bad news................after my last qualifying pass and idling back in the pits it broke both rockers in cylinder #5. Upon removing the valve cover we found all 8 rockers had serious wear on the steel pads. Fortunately, we found a pair of used '69 430 full assemblies in the swap meet and had it fixed by Saturday morning. Thanks to Jim Weise for showing up and doing the repair for me.

So, I decided not to race it any further and wait until getting home to analyze the problem further. So, why did the rockers break? That's been discussed at length in Facebook, texts, and emails with many knowledgeable Buick engine builders/racers weighing in. Several maintain that the motor experienced detonation when fuel pressure dropped to near zero as viewed on my windshield mounted pressure gauge at the top of 2nd and 3rd gear. Since I was running a mix of 50/50 93 octane & 110 leaded race gas, the counter to that is that the motor didn't detonate. There are several that suggest that the combination of the stock 430 rockers working with the .590/.565 lift cam and 350 lb open spring pressure was the cause of the damage. I'm not mentioning names as I don't want to start a "he said, she said" thing on this forum but if anyone wants to weigh in here, I'm happy to hear your thoughts.

The last piece of the "bad news" chapter is that about two weeks ago while just returning from the muffler shop I had just turned into my subdivision when cyl. #2 rocker broke. (as discovered when the valve cover was removed. I had only put about 300 miles on the motor since returning from BG and all of it while being sure to keep revs below 5000 and watching the fuel pressure gauge like a hawk. So, why did #2 break? Jim W. suggesgts that the passenger side rockers were probably damaged when the two broke on the driver's side. The rocker tips were damaged pretty much like the driver's side were in BG. I also examined the driver's side that was repaired in BG and they still look good. Here's what the damage looked like.


I'll post the "Good News" chapter and the avenue to a solution in the next post.

 

I myself wouldn't want that much spring on those rockers,...the thick steel clamps would be better imo also with those rockers,...I assume that's a stock shaft also and not the HD version

 

I ran that particular setup for years on my pops car but also deburred the rockers at the casting lines,..eventually broke one then went roller

 

The shaft is the HD version.

 

Was the Guage liquid filled?

 

If there was no fuel PSI it would have fell on its face

 

Geez looks to this guy the valve tip is not oriented properly to the rocker arm. Maybe a valve height issue causing an odd geometry. Looks like the valve tip is riding off the rocker at max lift.

I'd get away from the detonation theory as well. Any time detonation would occur both the valves would have to be closed and the load would be on the valve seats not the rockers.

If you want to speculate the excessive pressure from detonation, as Larry suggests, then only the exhaust valves would see it as they would be opening after the detonation. It would be business as usual for the intake valves.

 

Yes. Liquid filled Summit gauge

 

Car never nose dived or stopped accelerating. All passes were between 107 & 108.

 

That's what those guages do,....you never lost PSI more than likely the liquid filled will LIE to you,...if it was pulling you had fuel PSI

Unfortunately I would start planning on roller rockers to much lift and PSI imo on those rockers unless you wanna try deburring a set and habe them vibratory polished with the HD clamps,...but even then I think 350lbs is JUST past their limitations

 

In the heat we had at BG with your weight and the power you made ,....108 is on the low end,..but in the range of where it should be,...112 to 114 is where I would expect and with more seat time and better conditions it should hit 112

 

I agree. 110-112 was my estimate. The hot weather and the possible lean condition might have held it back. Jim says the lean condition (whether it detonated or not) held down both the 1/8 and 1/4 MPH. When I get the fuel system upgraded, I'll do some more testing.

 

OK, the solution plan.............................I've sent the rockers back to Jim W. He has ordered and received new steel tips from TA and is having them cryogenically hardened. As soon as I get them back on the motor I'll drop the tank and replace the pickup with the RobbMC 1/2 in. pickup with no sock. Also their large billet filter will go in place of the rubber line under the driver's door. I also have a new '70 fuel tank vent filter and a vented gas cap. It's also been suggested that I run no less than 1/2 tank of gas for 1/4 mile work. To begin with, I'm also gonna back up the total timing a bit from 36 (where it produced the most HP) to 33 or 34 until I build up some confidence that the new setup is OK. And perhaps a gallon or two of 110 race fuel with each fill-up. I'll pop a valve cover off every few hundred miles and take a look at the rockers.

AND, as a backup plan I'm ordering a set of the TA roller rockers and new pushrods. If I don't need them I'll pass them onto someone on the forum that's building a motor. As always, your comments are welcome.

 

I eould suggest using a holley "hydromat" off the pickup,..it solves a few issues with the stock tank,..but if not absolutely run a minimum of half tank fuel slosh is a huge problem in a stock tank,...some aftermarket are baffled,..the spectra premium were for the 71/72,...use a dry Guage or if budget permits an electric in cabin,..pricey but worth it

And honestly I would just run the TA rockers once they arrive,....you will simply be eliminating the future chance of a failure,...I too have faith in the 400/430 rockers but if budget allows,..there's no real reason to use them,..you'll pick up a little bit of power and gain peace of mind

 

I can send a picture to the instructors for Advanced Failure Analysis training at work. If they're interested and you'd be willing to part with the rocker, they might be able to help determine why it failed.

The fatigue which led to the fracture started on the pushrod side of the bore, but I do not know if that was the initial point of failure or if the pad wear & material removal came first.

 

You sure your getting enough oil up to the push rods on that side?