1970 Pontiac LeMans "The Bomb" Build Thread

[Way2qwk4u]

Ok gaskets and studs are on the parts list. Also getting a push rod length tool. Also did find that Tanks offers the Hellcat pump. Might get it on the way as well. Guess when I get a few other projects done in the morning may get started on the tear down to check for damage and pull the lifters. Sent a message to a few vendors to get a lifter suggestion. Looking at johnson lifters drop in ls race lifters. Or just go ahead and get tie bar lifters and be done.

[Way2qwk4u]

Ok got the top end off the motor. And found that the #7 exhaust lifter was collapsed. Inspected the cam lobe and it looks the same as all the others. So looks like I dodged that bullet. The roller looks good and is not loose. Do not see any other damage. Heads and cylinder walls look good. Did find an issue with an oil leak. So I will fix that while I am in there.

[ryeguy2006a]

Glad you caught it when you did, our you wouldn't be so lucky. I've heard good things about the Johnson lifters. Be careful if you go with the short travel lifters because they have a smaller margin of error for lifter pre-load.

Also, while the Supercharger is off, my suggestion would be to pop off that stock pulley for a ZPE hub and griptech pulley. If you didn't want to run the higher boost levels right away, go with the 2.75" unit that is just slightly smaller than stock (2.95"). Then when you are ready, just swap out the upper pulley, rather than pulling off the whole supercharger unit.

[Way2qwk4u]

That was my thoughts exactly. I was looking at a pulley change as well. If I am looking at this right I can get the pulley/hub and as long as I stay with same brand, I can just swap pulleys at will.

I got a pushrod tool as well and will be double checking the pre load on the lifters.

[ryeguy2006a]

Yes, that's exactly right, just stick with the same brand and they are interchangeable. I personally went with a ZPE hub with Griptech pulley. They use 10 5mm bolts that hold the pulley on. Pretty much all the CTSV and ZL1 guys run either the ZPE or Lingenfelter hubs/pulley's.

[Way2qwk4u]

Rodger that. I will get to looking at having one of those sent out as well. Will probably get the measurements on the push rods and have my math checked as well. Nothing has been decked on the motor. But not sure on what change the head gaskets will be.

[Way2qwk4u]

Ok got the drivers head back on and am checking PR length. Put cam on base circle and inserted the comp tool. Adjusted for zero lash. Counted the turns on the tool. And then verified the exhaust valve for that cylinder as well. Someone check my math on this.

Comp tool base length 6.800
Number of turns 2 zero 14.75
Each turn is .050

So then 14.75 x .050 = 0.7375

6.800 + 0.737 = 7.537

Preload is .030

7.537 + .030 = 7.567

Looking for a 7.56 push rod

Does my math work? Going to check the whole engine to make sure its the same.

Thanks

[ryeguy2006a]

I'd say that the math works, but remind us what you did to the engine again? What cam is in the car? What length pushrods came out of it? Stock length is 7.400 for most common LS motors and unless the cam has a much smaller base circle, those calculations are quite a bit different. My cam for example took a slightly longer 7.425" but mostly because BTR recommends a slightly higher .100" preload vs the stock which is recommended to be around .060".

I'm not saying that what you have isn't right, but seems quite a bit higher than what I usually see. Good idea to double check on a few different cylinders around the motor.

[Way2qwk4u]

Summit 8711 cam. Short travel lifters. 7.400 was in the car. I checked each corner ex and int. Verified for any difference on each corner. I think the math is good as well. I know that the new lifter cups were visually lower/shorter than the stock lifters. Thanks for the input.

[Way2qwk4u]

Ok new lifters and new pushrods are in. Re verified the pre load with turn method just to see. Got the new valley cover on. And got everything but the drivers header hooked up. Also serviced the blower and swapped to a ZPE modular pulley setup as well. Got to get a shorter belt and finish the exhaust connections and we should be good to start her back up.

[ryeguy2006a]

You work quickly! What pulley diameter did you go with?

[Way2qwk4u]

I try. It does not always happen that way. But when I get my mind to it and time to do it then it usually gets done. That was the worst part of the build. Bull headed me just "HAD" to the the trans in the car. Laid on my back and wrestled the full 4l80e in by my self alone. It got done but there were quite a few words and I was glad the boy was in the house. :-). Now I did empty a 4l80e case to use for fitment and clearance first. I went with the 2.45. So I will have to see what the new boost level is. Had to work late tonight so I will have to get the exhaust finished up later and get the newer belt on. With new pulley I was able to get a gates HD green that will be in the length that will work. Waiting on the Hellcat pump to get here and want to get the car out and drive some of the fuel out of the tank before I do the pump.

[ryeguy2006a]

Nice! You should see a pretty huge gain with that smaller pulley. Just be careful going WOT right away because boost should come on sooner now and at a higher PSI. May want to check in with Andrew first.

[Way2qwk4u]

Yup well as soon as I can get it running I will for sure get with him on the tune to double check. I do not think that I will over run the boost scale but with what I was seeing on the dyno I do not want to be lean. I have actually been thinking of adding some sort of custom table to do timing pull on fuel pressure drop. Also got a spare block striped down. Going to send to the machine shop in the beginning of the new year. Planning on a forged stroked engine for the next phase of the power train.

[Way2qwk4u]

Well got all the parts in and got it started up. No noise from the valve train. I think the lifters have been an issue for while. I hear no valve train noise anymore. Only noise I can pick up is a little noise from the charger snout. Also picked up a little manifold vacuum. I wonder if the old lifter and pushrod setup was loose the whole time. Will have to get it out of the garage tomorrow and drive it up the road to verify a few things.

At the dyno



First clean pull before adding timing.


Collapsed lifter causing the tick noise.


Cylinders looking good.


Back together with a new green belt and pulley.



Thank again for all the information and help.

[ryeguy2006a]

So what did it make after you added timing?

I think you may have an issue with the pulley hub. The hub needs to sit flush with the end of the shaft, and in your picture it looks like it needs to be pressed on a little more. I noticed it because with the engine accessories at the truck spacing, the 6 rib belt runs in the center of the 8 rib supercharger pulley. I know it's a lot of work to get the snout back off, but if you don't address it now, you may have issues down the road.

[Way2qwk4u]

You are correct on the spacing of the hub. I saw where they are supposed to be flush. I am not sure if there is a tolerance stacking issue. I measured the rib location on the old pulley and matched them to the new. I plan on moving it back even more. I noticed that the bearings are noisy in the snout. So I guess I am going to get the snout rebuilt. Might have been my fault. Did drive it out to mom and dads for Thanksgiving. Drove great and id say engine was smoother as well. Also noticed that the oil dip stick o ring is leaking. Added a catch can setup as well. And so far there is not any oil in the can either.

As far as after adding timing I don't have a clean graph on that I will scan and post it as well. But it was pretty much +45 WHP and same torque. Maybe even closer to 50 in the meat of the curve. It was a dramatic change I thought for only 2 degrees.

I logged the drive to my parents and was planning on looking it over tonight and getting it over to Andrew. Still waiting on the pump so I never pushed it and was watching the fuel pressure the whole drive.

[Way2qwk4u]

Very small update. Warmed up enough to get out and do some stuff in the garage. Un winterized the car and added the catch can to the system. Started the car and warmed it up. Installed new tune and verified all fluids. Getting ready for the warmer weather.

[Way2qwk4u]

New Snout is in and on. Amazing the difference in the openings. Got the pulley set back to where it needs to be. Have not had a lot of time to drive it. Been busy with work and with the new baby on the way have had other things to do. Did order new tail light lenses from OPGI. Ordered a hellcat fuel pump. And got a new fast ratio steering box for the car. The old box is leaking pretty bad and is the original unit.


Well cant get pics to load

[Way2qwk4u]

Did something change or am I just Dumb? Don't answer that part :-). But I every way I save these Files they are not loading.