84 GMC C2500, V12 powered

[cayoterun]

Originally Posted by 1985-GMC

Best of luck my friend, I hope it's something minor!

I like your "fingers, truck" sayin'!

Each time I read it, I smile.
Cayoterun

[1985-GMC]

Originally Posted by cayoterun

I like your "fingers, truck" sayin'!

Each time I read it, I smile.
Cayoterun

Haha a long time ago I saw that on a car at a local classic car "dealer"(for the lack of a better word), I thought it would make a good sig. Right now I couldn't care less if someone touches the paint on my trucks but eventually they will be painted nice and I might have to make a sticker for my back window saying that.

I'm glad you found the source of the knock and it just was a minor problem.

[cayoterun]

Hit paydirt!!
I found a new .30 piston in a neighbors shop. Now, if I can get the rings off the old one on the new one without breaking one, I'll feel like I killed a bear bare handed.

Cayoterun

[locomotive breath]

Glad you found it and the crank was ok. I've seen that before and it was caused by the ring end gaps being too tight. They get hot, butt together, and bind up in the bore, the ring grooves become the weak link.

[cayoterun]

Wow! Thanks a million, LB. Learn something new everyday, regardless of age.

Should I file a bigger gap in these old rings before putting them on the new piston? If so, would a small file be the best way? I'd be afraid to use anything that might create heat so it wouldn't take any temper out.
I hope my service manual might give the recommended gap.

Based on carbon accumulation, I think the motor had been run more than a shop run-in, but still all looked good. Some hone marks still showing in cylinders.
Memories fade on details after 10-15 yrs.

Cayoterun

[locomotive breath]

I used a small fine tooth file for years before I bought a fancy special tool made for the job. Just make sure to file inward and keep the ends square. Also make sure the rings are square in the bore when you check the gaps.

Here is some more info. I copied from the Hastings website concerning end gaps just in case you can't find it in the manual.




Ring gaps are often a confusing and misunderstood part of a rering job. There re MINIMUM and MAXIMUM ring gap specifications which must be observed for the best performance of a new ring set.

Minimum gap tolerances must be observed in order to prevent the ring ends from butting together as the ring expands when the engine approaches operating temperature. Hastings recommends a MINIMUM of .0035 gap per inch of cylinder diameter. Example: 4" (bore) x .0035 = .0 14 minimum gap.

Maximum ring gap is an important part of ring performance in that too much gap results in lost compression, power loss and ultimately poor oil control. The following chart indicates the specifications for compression ring gap as outlined by the SAE (Society of Automotive Engineers) as standards for the automotive piston ring manufacturers.

SAE RECOMMENDED
AUTOMOTIVE COMPRESSION
RING GAP CLEARANCE

Ring Diameter


End Clearance
Inspection Limit
1.0000 2.3624 .006 .014
2.3625 2.9524 .008 .016
2.9525 3.5424 .010 .020
3.5425 4.3299 .012 .022
4.3300 5.1174 .014 .026
5.1175 5.9049 .016 .030
5.9050 6.8899 .020 .035
6.8900 8.9999 .024 .041
9.0000 10.9999 .029 .047

An important fact to remember is that the manufacturers rigidly adhere to these tolerances and that the ring gaps are inspected in gauges accurate to .0001" at the cylinder diameter the ring is manufactured for. Any increase in the diameter of the cylinder is being used in, over the designated size, results in an increase of approximately .003" in ring gap for each .001" increase in cylinder diameter.

In order to check ring gap, the rings should be placed at the lowest possible part of the cylinder (below ring travel area) as this is the portion of the cylinder which is unworn and which the ring is sized for. Checking ring gap in the worn portion of the cylinder will show a gap increase in direct relation to the amount of cylinder wear present. The illustration on the following page shows the effect of cylinder wear on ring gap.

This graphically illustrates the effect on ring gap that cylinder wear has. You will notice that the tapered cylinder has .012 wear at the top portion of ring travel which increases the ring gap .036. Therefore, it is entirely possible for the ring to have .061 end gap in that portion of the cylinder and be within recommended manufacturing tolerance.

For this reason, Hastings recommends a MAXIMUM of .003" wear per inch of cylinder diameter, not to exceed .012" in any case for successful reringing. If a cylinder is worn in excess of this it should be rebored and the proper oversize ring installed. Checking ring gaps can give an approximation of cylinder wear as well as keep you from installing wrong sized rings for the application being rerung.

[cayoterun]

Crazy, sneeky cracks in piston. When I was taking the rings off the broken piston, when I pulled the 3rd ring from the piston, another piece of the piston fell out. Sure left a sad looking hole. Several have agreed, I was lucky neither one had scored the cylinder wall.

I got it back together, and sounds like it should, with the typical clunky sounds. There's a noisy lifter, so will adjust them, but for now I'm a happy camper.

LMB, thanks for the gap clearance chart. I'll sure print and put it in my service manual.
Cayoterun

[cayoterun]

Saturday afternoon play time with Haystack, my son, and "Thumper's truck".
This is the hardest it will ever be kicked around, as long as I own it. The motor still rattles and clunks, but starts, runs and 700-R4 all runs great. We didn't hold it @2400rpm very long, so neither of us looked at the GPS, but supposed to be 73mph, top speed.
What a high, and a great Christmas present!!

gmc v-12 702 cid 'Thumper' walk around - YouTube

Going for a ride in 'Thumper' GMC v-12 702 cid -...

coming back in Thumper gmc v12 702cid - YouTube

A big THANK YOU to Rap-em-Pappy, Locomotive Breath, and all the others for helping me bring her this far.
Merry Christmas to all,

Cayoterun

[1985-GMC]

Awesome job!

Do you have any plans for a speedo?

[cayoterun]

Originally Posted by 1985-GMC

Awesome job!

Do you have any plans for a speedo?

Maybe sometime in the future. Having driven road-rigs years ago, we depended more on our tachs, than speedos, as you soon learn speeds from what gear, and rpm.

I do have a nice dash insert that I can swap in with a speedo, and add tach. For now, plan to work any bugs out which I'm sure will show up with some use.

I'm ready to enjoy it for awhile and add a few miles on it. I've run it about 120mi. so far, within 10miles from the house. Sure sucks up the little propane tank in a hurry, so a larger one will probably be swapped in before long.

Cayoterun

[6066gmcguy]

Nice Job on tht truck Marvin.

[Telecasterjoey]

too cool! sounds nuts, Good job, Looks awesome.

[cayoterun]

Originally Posted by 6066gmcguy

Nice Job on tht truck Marvin.

Welcome aboard over here, Jolly. Now you can help me keep the V-12 running. I'll probably be bugging you for pointers and advice pretty often. You've offered a wealth of knowledge since I've been working on both trucks.

Long live the GMC V-6/V-12s. and You've been a great help to us to do that!

Thanks,
Cayoterun

[cayoterun]

Probably only ol' Geezers will remember when this model pickup beds looked like this, except those who lived in farming areas where they grew grain crops in the '40s and '50s. They'd haul 60-70 bushels. They'd load them up, the wife, and kids would head for the grain elevator. 65 bushels @ 60# per bushel, meant these old flivvers had 3900# on their backs.

I've run the pickup about 400mi. around here locally, and it's doing good. Still have to keep my eye on the temp gauge, tho.

[cayoterun]

Temperary 80gal fuel reserve tank added. I'm looking for a 30-40gal propane tank to replace the 16gal tank in front. With 2-3mpg, 16gal don't last long. Old truck doing ok for my purposes.

[Rubble]

Just read thru your build thread,that truck is awesome!!! Not something you see everyday. I am glad you went with that body too,it really suits it.It's really something to be proud of,great job man!!!!
Posted via Mobile Device

[cayoterun]

Originally Posted by Rubble

Just read thru your build thread,that truck is awesome!!! Not something you see everyday. I am glad you went with that body too,it really suits it.It's really something to be proud of,great job man!!!!
Posted via Mobile Device

Thanks for your comment.
This truck probably should be in alternate tinkerings, but still really don't fit anywhere.
I've always enjoyed watching the old car/truck hobbiests preferences and how they change over the years. This is what we were tinkering with 50 yrs. ago during the "Jalopy" days, when bits and pieces were put together from the salvage yards. No one had any money, so learned to make do with scraps.
Would be interesting to look in a crystal ball and see what they'll be building 50 yrs from now.
It's really all about a great hobby, self-expression, personal preference, and enjoyment anyway, so room for all, imo.


I've hauled lots of watermelons, coffee beans, and all kinds of produce to Sask., Man. and Ont. back in the early 60s. You Canadians always treated us great, and welcomed us while we were in there. Eight day turn-around from Ark.-Gulf coast/southern Florida-Regina/Winnepeg-back to Ark. $.04 cents a mile. Big bucks back then.
(Two drivers, and run 24/7, except for fuel, food, and showers)
Thanks for your hospitality.

[Vernski]

We think it belongs here just fine Cayoterun...Vernski

[Rubble]

Originally Posted by cayoterun

Thanks for your comment.


I've hauled lots of watermelons, coffee beans, and all kinds of produce to Sask., Man. and Ont. back in the early 60s. You Canadians always treated us great, and welcomed us while we were in there. Eight day turn-around from Ark.-Gulf coast/southern Florida-Regina/Winnepeg-back to Ark. $.04 cents a mile. Big bucks back then.
(Two drivers, and run 24/7, except for fuel, food, and showers)
Thanks for your hospitality.

That was before my time eh!! lol!! I ran stateside flat deck/ step deck from 93-00 ,was thru your neck of the woods on 287 going from Colo to Tx. Your hospitality was always good too....thanx.
Posted via Mobile Device

[cayoterun]

Originally Posted by Rubble

That was before my time eh!! lol!! I ran stateside flat deck/ step deck from 93-00 ,was thru your neck of the woods on 287 going from Colo to Tx. Your hospitality was always good too....thanx.
Posted via Mobile Device

Good Grief, You ran by the museum we volunteer at, and where the other V12 GMC 1Ton is that I donated at Boise City, Ok. Last year, they built a new by-pass around Boise City on 287. The traffic was about to shake their old County court house down as you guys went around it on the town square.

Also, Thanks, Vernski. I plan to hang around until my junk is banned. This is a great place for us ol" Geezers to hang out, spin yarns, and tell lies.
"I used to have an old '51 Ford that would-----Oh well, you wouldn't believe me anyway". (grin)

[Rubble]

[QUOTE=cayoterun;6081459]Good Grief, You ran by the museum we volunteer at, and where the other V12 GMC 1Ton is that I donated at Boise City, Ok. Last year, they built a new by-pass around Boise City on 287. The traffic was about to shake their old County court house down as you guys went around it on the town square.
Ya,I have not been thru there since 2000, but been around the court house lots before that.Too bad I didn't know about the V12 in the museum...
Posted via Mobile Device
Posted via Mobile Device

[ol'blazer]

I've never seen anything like this build! This is awesome!
Posted via Mobile Device

[cayoterun]

Originally Posted by ol'blazer

I've never seen anything like this build! This is awesome!
Posted via Mobile Device

In your quote, "16 and little money".
If that means your 16yo, and money is tight. Keep plugging, just think of all the stuff your learning on your truck. Money management, personal priorities, patience, determination to reach a goal, independant thinking, and hard work.

Some stuff can't be learned from books, but what your learning in the "school of hard knocks" lasts a life time.
Enjoy your journey with the ol' Blazer.

[ol'blazer]

Originally Posted by cayoterun

In your quote, "16 and little money".
If that means your 16yo, and money is tight. Keep plugging, just think of all the stuff your learning on your truck. Money management, personal priorities, patience, determination to reach a goal, independant thinking, and hard work.

Some stuff can't be learned from books, but what your learning in the "school of hard knocks" lasts a life time.
Enjoy your journey with the ol' Blazer.

Thanks! my truck has taught me a ton, not just about mechanics, but staying determined to get the end result i want, and managing my money. but most of all this has helped me choose my career path, i have been working at a shop apprenticing as a mechanic for the past 8 months. im planning to have my first year hours before i graduate high school.

[cayoterun]

Originally Posted by ol'blazer

Thanks! my truck has taught me a ton, not just about mechanics, but staying determined to get the end result i want, and managing my money. but most of all this has helped me choose my career path, i have been working at a shop apprenticing as a mechanic for the past 8 months. im planning to have my first year hours before i graduate high school.

Good for you!! With a balanced education between the books and hands on you'll do well. Do your best, keep you eye on your goals. You'll be proud of the effort you made someday.
The best to you,