79' GMC C15 - Spruce Caboose

[folkenheath]

Bore is 3.78 and stroke on some cranks ive looked at are 4.000 stoke , stock stroke is 3.68 I beleive , so thatd be around 360 Cu i from 330 stock? Id be happy with a bit of stroke , new bearings and rings and a healthy bottom end to build off for the future. Ill window shop it all and find out some actual costs, and although my rare tax return is almost all going to paying things off, an extra engine goodie would be nice. Regardless of how much power the truck has, its such a leap from my smog 350, that i dont think it can ever feel slow, ... unless it woopsies a window in the side of it.

....

As comfortable as I am getting exploring uncharted waters... Any suggestions or things to watch out for when it comes to swapping an aftermarket crank in would be greatly appreciated. Cause I’ve read a few places that state stroking an LS too much is bad due to the bottom of the piston hanging out of the bore ,ect... and I’m sure there are things I’m not going to account for…

I've stroked LS engines to both 4.00" stroke and 4.100" stroke. But they were all 6.0, 6.2. My uncle has stroked several LS7 blocks to 4.100 as well.

I think if you are going to spend the money I would start with a larger bore, it's hard to fit enough air through the smaller valves of the 5.3 bore to feed the 4" stroke, especially as the RPM climbs. But it will give you more torque and power for sure either way.

We did not have any issues with the modern components and did check the protrusion at the bottom. The piston is so short on some of these setups it's not nearly as bad as you think. You may have to clearance the block for the rods, has to be checked.

Keep in mind you will have to balance the crank unless you buy a complete balanced rotating assembly for your bore and stroke and target wheel pattern, etc.

 

[centexk5]

I’m not super LS savvy but I’ve read enough complaints and comments on the boards that the 408 strokers have a much shorter life due to piston protrusion at the bottom of the stroke. Never built one so just relaying what I’ve read.

 

[bix]

I've stroked LS engines to both 4.00" stroke and 4.100" stroke. But they were all 6.0, 6.2. My uncle has stroked several LS7 blocks to 4.100 as well.

I think if you are going to spend the money I would start with a larger bore, it's hard to fit enough air through the smaller valves of the 5.3 bore to feed the 4" stroke, especially as the RPM climbs. But it will give you more torque and power for sure either way.

We did not have any issues with the modern components and did check the protrusion at the bottom. The piston is so short on some of these setups it's not nearly as bad as you think. You may have to clearance the block for the rods, has to be checked.

Keep in mind you will have to balance the crank unless you buy a complete balanced rotating assembly for your bore and stroke and target wheel pattern, etc.

This advice comes at a time where its sort of the final smack into reality As I’ve been veering away from the situation gradually..Sometimes i try and think about doing things in the manner that involves the most ideal situation ie: throwing a crank in now while i have it out. But after starting to realize its can snowball so quickly ive decided to continue my research in stroking these things and what my end goal is going to be. I zig zag alot in life and i think this is something that shout be tackled head on when i dont have other moving parts happening as well. Its also just another thing that could keep the truck off the road this summer, and its probably best to tackle reconfiguring the engine over next winter when i dont have a transmission to finish and a trailer to try and pull.

I will pull the engine still because im right here anyway and i do remember thinking i should check the cam bearings, so id like to check those and also maybe pull a few main caps and see what the main bearings are looking like. If all is well it will get buttoned up as is. Not sure if a new set of rings would be worth the hassle of disassembly ,or just wait until i want to bore it out some .20-.30 over. Either way i should finish the current tasks before getting distracted by a squirel and ending up lost in the woods.

I’m not super LS savvy but I’ve read enough complaints and comments on the boards that the 408 strokers have a much shorter life due to piston protrusion at the bottom of the stroke. Never built one so just relaying what I’ve read.

Ive seen in videos lots of people deburring the engine and also taking a cartridge wheel to the bottom edges of the cylinders so the pistons dont scrape on their way out and back into the cylinder bore.

 

[bix]

Going back to work with a 1 month old son sure kicks your ass, but it makes you realize how precious free time is. I managed to trip and find some of that today and got the rear stator bushing removed and the new one installed. I also replaced the one input shaft teflon ring that got roughed up with the past pump install. I bought the resizer tool which was nice. Its tapered at the bottom so it compresses the ring into place. Took some finessing but seemed to work better than nothing.. I re clocked it all and put the assembly in the case. I got the pump in and torqued the pump bolts down to 18 ft.lb. It turns nice and smoothly this time..


I have yet to check endplay on the input shaft which i beleive is .15-.30, but the book does mention there is a .150/3.8mm gap to verify as well.

The rear stator bushing rides at the very bottom of the input shaft. the pictures show the dia. of shaft and the I.D of the wrong bushing i put in. The new Sonnax bushing was bang on and also a little wider as well.














































Now to clean it all up and check endplay, then hopefully install the harness, drill the seperator plate to Sonnax spec, and re assemble valve body...

 

[Chevy305]

Honestly I wouldn't even touch your engine. It's been working and running without issue for however many years and miles. If your compression is good and oil pressure is good, don't let the magic out. The more you mess with it, the more can go wrong. And like you said, things can quickly snowball.
Oil in the intake is totally normal for these engines as the PCV system isn't the best. But put it in perspective, how many of these engines are running 300k miles completely stock untouched with oil filled intakes? I think people make it out to be a much bigger problem than it is.

As David Frieburger says, "it doesn't have to be right, it just has to be running"

 

[tRustyK5]

"Perfect is the enemy of good" is another Frieburger gem...

 

[bix]

Honestly I wouldn't even touch your engine. It's been working and running without issue for however many years and miles. If your compression is good and oil pressure is good, don't let the magic out. The more you mess with it, the more can go wrong. And like you said, things can quickly snowball.
Oil in the intake is totally normal for these engines as the PCV system isn't the best. But put it in perspective, how many of these engines are running 300k miles completely stock untouched with oil filled intakes? I think people make it out to be a much bigger problem than it is.

As David Frieburger says, "it doesn't have to be right, it just has to be running"

don’t let the magic out… I like it. Freiburger has a camera van to get parts, a Finnegan, and no family members with him when the thing nukes on the highway though Haha.


I’m kicking myself in the ass for not checking the cam bearings when I had the chance , because some did look like they were a little beat and it seems like a common failure point on these engines but you’re right , I don’t think I’ll touch the bottom end until I’m ready to commit to the full process. I’ll check pushrod length / lash again on all cylinders but mainly 6-8 since it’s always sounded extra sewing machiney back there, maybe bump them up from the factory length to 7.400” for a tighter valve train.
I’m focusing on the trans for now since I’m on the home stretch, then I’ll figure out what to do with the motor if I find anything that seems suspect. If I pulled the cam out enough to look at the main lobes , I should know right away if the cam bearings need attention or not? Hoping to find some 5/16 dowels so I can lock out the lifters, and pull the cam without the heads off… that would be ideal. Anyway back to tranny land I go. Once I’m off diaper duty I should be able to check the end play and move forward. I wonder what the proper torque spec is on a diaper….

 

[imiceman44]

don’t let the magic out… I like it. Freiburger has a camera van to get parts, a Finnegan, and no family members with him when the thing nukes on the highway though Haha.


I’m kicking myself in the ass for not checking the cam bearings when I had the chance , because some did look like they were a little beat and it seems like a common failure point on these engines but you’re right , I don’t think I’ll touch the bottom end until I’m ready to commit to the full process. I’ll check pushrod length / lash again on all cylinders but mainly 6-8 since it’s always sounded extra sewing machiney back there, maybe bump them up from the factory length to 7.400” for a tighter valve train.
I’m focusing on the trans for now since I’m on the home stretch, then I’ll figure out what to do with the motor if I find anything that seems suspect. If I pulled the cam out enough to look at the main lobes , I should know right away if the cam bearings need attention or not? Hoping to find some 5/16 dowels so I can lock out the lifters, and pull the cam without the heads off… that would be ideal. Anyway back to tranny land I go. Once I’m off diaper duty I should be able to check the end play and move forward. I wonder what the proper torque spec is on a diaper….

Torque spec is snug.
No uga duga

 

[tRustyK5]

If you need to add pushrod length to some your cam is focked. As for cam bearings, maybe I'm a hack but I wouldn't even look at them unless it was getting a full rebuild. Probably the last bearings that will leave you on the side of the road. Got oil pressure? Your bearings are fine.

For LS I would say the best reliability upgrade is get rid of the Stupid lifters GM used for cylinder de-activation. That is your biggest LS failure point bar none. If you already have, just run it. They're way tougher than you think.

 

[bix]

If you need to add pushrod length to some your cam is focked. As for cam bearings, maybe I'm a hack but I wouldn't even look at them unless it was getting a full rebuild. Probably the last bearings that will leave you on the side of the road. Got oil pressure? Your bearings are fine.

For LS I would say the best reliability upgrade is get rid of the Stupid lifters GM used for cylinder de-activation. That is your biggest LS failure point bar none. If you already have, just run it. They're way tougher than you think.

i should have been clearer, I would swap all the pushrods out and not just the two. When I did my cam swap it said to check pushrod length as a slightly longer ones may reduce valve train noise. I believe stock is 7.375 length and they suggest going up on .025 increments If you want to try and get it tighter.. I’m more concearned with assuring lash it right on that noisy section, and check the ball and seat for wear. Stock pushrods besides the 2 I changed out from wear along with the rocker arm…and the problem is I can’t remember what I checked or who even built this thing …

I had to ditch the gm lifters when swapping out the cam. The lobes on the AFM cam are meant to match those donkey dick lifters gm put in there. So it has all new lifters and trays

 

[bix]

 

[bix]

I still seem to have an endplay issue although it turns nice n smooth now, not too tight or hard to spin, and feels secure.
Ive read with new bushings ect it could be hard to get the endplay easily, but im getting around .005".
I Also have the .150" gap between the sun shell and the reverse drum that the book assures is normal. Photos are hard to see because my camera wont focus but i measured with my feeler gauges at .147 and it was good. You cant get head on square with the gap, even with bent feeler tips, or atleast i couldnt.

The input drum thrust bearing that the stator would sit on at the bottom of the shaft has a numbered washer under it, and this is where the input shaft endplay is adjusted from ( if all was properly aligned of course ). The Manual says to use a different washer from the chart if you need to adjust... i just want to ensure i dont need to because of a mistake, which doesnt get solved by less washer and ruins it anyway. So ive been thinking..

The input drum has 4 clutches inside at the bottom which clock into position to the planetary gears in the case, have verified fitment prior to installation.
I have clocked all the clutches in the reverse drum onto the input drum housing and verified fitment and smooth movement on the thrust washer that sits ontop of that selective washer, and do this before setting the input drum into the case to clock the 4 clutches below.

When installing input drum assembly, i have verified with straight edge that after clocking it all into position, the back of the drum is below the pump flange mounting surface in the case. And the directional thrust bearing that sits ontop of the washer is installed properly..

Im wondering if potentially the beefier sonnax reaction shell and roller race have eaten up a few thou throughtout installation, the reverse drum i had to purchase was GM/Acdelco so it should be the same spec. Maybe the swap from 4wd to 2wd would change something, or maybe that bushing in the rear stator need to be recessed a certain bit more..

i found a place that sold a thrust washer kit with 4 selective washers.. none of the kits i found labelled the numbers to identify the washers, but its worth a shot for the 30 bucks for the kit. Mine is stamped with a 71 which according to the chart is .100 - .104" thick.

Im not going to open it until i get those washers most likely and do one final sweep, and i will start to re clean and assemble the valve body in the mean time.

 

[bix]

 

[Truckman4life]

My wife's 6.2L in her yukon xl has 262K miles. It goes through a fair amount of oil between the stuff it burns and the stuff it leaks all over and I just keep adding oil to it and driving the shit out of it. It's had lifters stick a couple times and I just changed the oil and ran some atf through it and it went back to being all good. Oil pressure on the gauge has got to be like 10 psi at idle when hot. It's low but doesn't set off any codes and it's still going so it must have some oil pressure.

 

[bix]

 

[bix]

Its going to feel real nice cleaning up this firewall and wiring

 

[bix]

Found this hiding In a friend of friends rafters,, and finally convinced him to part with it.

 

[mrk5]

I don't think I've seen one with the embossed logo, that is cool!

 

[bix]

I don't think I've seen one with the embossed logo, that is cool!

I’ve never seen one either but im real jazzed about finding it. I have some cab trim as well but not sure if I will install it or not, but this is definitely going on the truck. I even have an orange gmc emblem to match for the front grille. Also got some orange marker lights from him for the front turn signals.

 

[bix]

As for the transmission, I received the washer kit from cyclone transmissions ( eBay ) and I ensured the thrust washer orientation, made sure the input drum was fully seated. You can verify this by the clunk noise and seating when you have clocked all the clutches into place as well as the planetaries. End play on the output shaft is around .030, and with a new selective washer installed I ended up with .018-.020 end play on the input shaft. I have no mention on output shaft endplay pin the book but im going to look up some specs on that. I did stumble across a neat way to check endplay without installing it all first but It required me having to make a jig, and I figured it’s easier to just install the pieces and see at this point.