Impulsive 3.8 swap.

[WarWagon]

I bumped the engine over watching the pistons and I stopped just after TDC on #6 the piston just began to fall in the pic. The even bank has the head gaskets off but the odd bank has both stacked still.

https://photos.app.goo.gl/iBT75s2FpWbH8gmf6

Odd bank:

https://photos.app.goo.gl/BhGjfirxrzhN6FeN7

I finished up cutting guides with the last head and ran a wire brush over the chamber real quick.

https://photos.app.goo.gl/YkrariTLcdChfZHQ8

https://photos.app.goo.gl/DurH6wNL1JBJdJmn6

https://photos.app.goo.gl/URhn88fL3xaLuCxN6

 

[WarWagon]

Just eyeball measurement, the piston crown is almost at the deck but the piston fell so it's probably closer to 0 deck. I have new gaskets to redo the it the way it was" helps with piston/valve clearance too".
I have the old KB lifters I can make one a solid like you did to check piston to valve.

 

[WarWagon]

OnBusy week/end for me but back on this project. Finished two lifters up to be solid for checking put them in #1 cylinder position bosses. Heads are clean I put the new exhaust valve in with the stock intake and got the head on the odd bank over the doh on#1 piston with 6 bolts then installed two push rods adjusted to stock length followed by the rocker assembly. Spun the engine over by hand slowly two full camshaft revolutions nothing bad happened and all looked good so off came the head and all the rest I mentioned above. The clearance is quite a lot now that I have a good look at it, both valves just barely made contact with the doh enough to transfer the oil on the face of valve and chamber.
Now that's out of the way this will get done much faster now that all I have to do is finish the heads and assemble. I can delete the copper shim head gaskets with the clearance available and only run the composite gaskets. There's a good chance I smacked the valves on the pistons by the two push rods I made lomger to get the play out before I pulled the heads originally, only 2 are bent.

https://photos.app.goo.gl/N7GQeB5vMXhdUQwZ6

 

[ek02]

Looking good. Glad you don’t have to fly cut the pistons. You may have had some lifters that had not pumped up yet causing the play. It takes a while sometimes.

 

[WarWagon]

Done! I finished up last nite and drove it to work today. So the push rods are all 3/8 and I set them up to stock length, I just have the single 8723 felpro NA headgasket on and I put in my new NGK ur45 spark plugs.
Runs good almost the same as the 1XB cam, this one is slightly choppy on idle.
I'll try and get a video of it. Pic after I got to work:

https://photos.app.goo.gl/fWC99pGUGcP9P45w8

 

[ek02]

Great. Glad it worked out finally. Lots of extra work, but its right now. It should have a little more top end power.

 

[WarWagon]

Indeed it does pull harder and further now I have 60+ miles on it. I was early this morning and didn't get on it but leaving work I tried it out on the highway. Almost 2k more rpm to use now, it pulls up to 7k rpm. The KB 1XB cam was dead a little after 5k I still ran it out to 5.5k though. I didn't mind the extra work to make it right, it was a bonus to learn what the rest of the parts in this combo were.
Thanks Ed! Your camshaft gift and trouble shooting comments made this possible

 

[WarWagon]

The local-ist track is having one last TNT this Saturday. I'm wanted to take the Buick powered Isuzu out for the last passes of 2020.
The engine maintenance and cam swap are the only changes since I had it at the track in 2019.
At the time last year I found dragging park brakes and only on 2bbl mode with the carb.
I fixed the brakes and have the secondaries working now. The old Borg T50 trans is my speed limiting factor for shifting.
I'm going to try and get it in the 16's or better at over 85mph.

 

[WarWagon]

Rained out and the end of 2020 season. I'll take everything to the track in 2021 if the future happens.

 

[WarWagon]

Muffler broke off the Impulse so I brought it to work to repair today. Dropped the H/Y pipe off for that and to get a picture of the collector of the headers. Never seen this before home made merge style:

https://photos.app.goo.gl/aAfjN4NUAKLroMxf6

Pipe before muffler goes back on:

https://photos.app.goo.gl/VPS2R3xe9CwK5ddy9

 

[ek02]

That merge is interesting. Do you have a photo of the outside of the collector? I use what's called a goulet at the merge. It's just a three sided or four sided point welded to where the pipes join instead of a flat piece of metal like yours has. It had to be hard to weld inside of the collector. The collector may be hand built from larger diameter tubing and then welded to the flange.

 

[WarWagon]

The 4l60E went out in my Avalanche so I'm still driving the Isuzu temporarily.
I got a picture of the collector flange and pipes today.

https://photos.app.goo.gl/LvG1L8JAgBTeoy2D6

 

[ek02]

Unusual collector, but it works. When I was a Bellsouth/AT&T Fleet Manager we had an all GM fleet. We replaced 4L60E's all the time even though we serviced them every 24,000 miles or 24 months. We used rebuilt units from GM called Certa's, certified rebuilt. Hope you can get it fixed soon.

 

[jdpolzin]

I may need to get some of those cam specs from you guys. I'm building a 4.1 3.625 crank carbed motor. Has GN1 heads, 10 to 1 comp.

 

[WarWagon]

There's going to be a few of these 4.1 builds this year, and they are similar I like seeing that.
I'm going to get my hands on a copy of the KB mk 2R cam (EK02) sent me the cam card for the roller version he had Comp make.
Schneider has a few hydraulic and several solid shelf grinds I'm interested in trying out as well as two more hydraulic versions from Lunati.

 

[ek02]

Here's a copy of the Comp roller I had made that is close to a KB MKIIR. The lift is .523 with 1.65 rockers. The LSA is close at 108 and it idles at 800-900 RPM in gear with a 2800 stall converter. The mid range is strong with the tight LSA. It will idle better in a 4.1 with a stroker. In a 3.8 it's a little too rough with an automatic, very low vacuum.

View attachment

 

[jdpolzin]

Do you know if there are any cores available to get our cams custom ground?