Home » Public Forums » GMCnet » [GMCnet] My Engine builder, and the case of the hard-to-find pistons
| [GMCnet] My Engine builder, and the case of the hard-to-find pistons [message #362279] |
Sun, 07 February 2021 17:38  |
 |
fitzmorrispr
Messages: 137
Registered: February 2013
Location: Los Angeles
Karma: 0
|
Senior Member |
|
|
I don't recall if I posted previously on it here, or not, so, my tale of
woe, or at least of worry (to skip, Ctrl-F for "which leads me to wonder"):
As some may recall, my '73 has had a bit of an engine knock, on cylinder
#8. I'd hoped it wasn't the bearings, but had no good way to check. The
fact that pulling the plug wire cured it during testing, multiple times
made me suspect that, even though it only knocked in time with valvetrain
and ignition, it must still be the bottom end.
So back in August of 2020, I drove it to a storage yard that said I could
work on it in their yard, borrowed a gantry from Grant Schaffer (who has
been extremely generous about it) and pulled the motor. Then I sought out a
builder, since as a returning college student, I didn't have much time to
learn by doing, and didn't want my learner motor to be one that's quite so
hard to pull.
Well,
I found a guy who used to run a performance rebuild shop out in Yucca
Valley, and he sure sounded like he knew what he was talking about, and so
I ultimately ended up going to him.
To keep the price down, I agreed to have him swap my unique parts over to a
motor he had previously built for another customer (who had sold it back
because his car got burnt in the wildfires up in central CA before he could
install it) and take some of the performance parts out in favor of those
more suited to the motorhome.
Or so the story goes. I think it's probably mostly true, though most of my
friends doubt him.
He came out and picked it up on September 21st, and was ballparking a six
week turnaround, as he's semi-retired, and he hadn't fetched back the fresh
motor yet. Like a dummy, I paid him up front, in cash, and didn't get a
receipt.
About a week later, I got a picture of my old motor (which had '75
passenger car stickers on the valve cover, so probably not original) with
intake hanging in the air above it. He noted it had an aftermarket style
gasket, and no bathtub gasket, and that the crossover had been left open.
About a week after that, he called to discuss ordering a new timing cover
and intake manifold (my timing cover was bent at one of the holes where a
nut was supposed to be welded on, with a large machine screw poked through
from the back to clamp the wp gasket there, and he says my factory intake
was cracked).
He talked me into that one vintage square bore one, think it's an o4mc,
telling me I could get a deep dish air cleaner and put on TBI parts, which
is something I wanted to do, but not just yet. The intake was due to arrive
10/16. we texted back and forth about other pieces I would need for the
project, and prep work I would need to do. on 10/22 he told me the manifold
had arrived, and that he'd figure out what bolts he needed as soon as the
box was open. Then he went radio silent. I was pretty busy with college
courses, so I didn't really notice
I tried to reach him on 11/16, and on 12/6, I asked what the chances were
of me seeing a motor before christmas. He said they were "Getting pretty
good." and that "it's a long story you probably don't need to hear."
I expressed some understanding, and told him I would really like to see it
in about a week, when I would have time to really buckle down and get the
job done. I tried a couple times to get further response, finally
succeeding when on 1/2/21 he replied to my 12/31/20 message where I asked
what the deal was, when he said:
"One complete set of L2390F-40 or L2390F-60 and I can finally finish this
project. The -40 is preferred. I have searched every where and cannot find
any from vendors, and the factory just keeps moving the promised delivery
date up. There is nothing I can do without the part. It is not me delaying
the project. Lots of parts are turning out to just be unavailable during
this Covid nonsense.
I do understand your frustration. I am in the same situation with two other
projects."
Frustrated is a mild word. I've almost moved into the Sixth Stage of Grief
here. It's been 19 weeks, and I've been almost wholly out of the loop. not
that I necessarily want to know what personal tragedy has contributed to
the delay, but at least tell me what's going on once a fortnight.
Anyway, I haven't heard from him since. My own searching does agree, nobody
seems to stock those low compression forged pistons. (it also seems that
Sealed Power no longer has the part number in their systems, only L2323F
turns up anything on their catalog:
https://www.drivcat.com/overlays/part-detail.aspx?pNum=L-2323F&partType=POWERFORGED%20Piston&brandId=SD
)
so the story seems to check out.
I don't think he's scamming me, as some have suggested. He hasn't charged
me any additional amount, despite ostensibly ordering parts, and he has
continued to communicate, if sporadically. If I was a mark, I'd have
expected him to try to get more money out of me, or to have decided there
wasn't any more to get, and so cut off contact.
Which leads me to wonder, since I think the motor legitimately needs
pistons, what, aside from the dish depth, (apparently, 0.142 on the 23, and
.306 on the 90) is the difference between an L2323F and an L2390F? could
one be machined to match the other? Has anybody got a set laying around?
How important is it to go with forged pistons, would it really be so bad to
go with cast ones?
My last message to him, earlier today, was to ask if maybe that piston
machine work could be done, and to say that if he can't come up with a
solution soon, i'll need my cash & core back, so I can take my FWD parts
off and use them to stuff some used motor out of a 442 or something in
there. I want this thing back on the road.
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
The Greatfruit: 1973, 26', Canyon Lands or Painted Desert, in Pineapple Yellow
|
|
|
|
| Re: [GMCnet] My Engine builder, and the case of the hard-to-find pistons [message #362284 is a reply to message #362279] |
Sun, 07 February 2021 20:34  |
 |
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
|
Senior Member |
|
|
Patrick,
Has your builder confirmed what the issue was? I would be worried if he has not done a full inspection.
I am sorry to hear your tale, but I am also not surprised. I case you don't remember me, I am several kinds of engineer that has been doing engine stuff a very long time. When you start real young, long time comes sooner. I had to do an overhaul on my engine in '18. The lube oil consumption increased dramatically, but there were no strange noises. #7 piston had shed it rings for a 120°. Suffice it to say that required attention, but not like knocking does.
Unfortunately, of all the people that do this that I worked with over so many years are not in the business anymore. One of the reasons I would never go to a performance shop for a coach engine is that most performance people are stuck in that groove. They know whose parts they want to use and they are hard to push of the stump. Those are nice pistons, but GMCs don't need forged pistons. They do need the right size and the right dish.
I needed pistons. Surprised? As it turned out, I really only needed one. I had three choices of suppliers that I knew and it turned out that one had bought another, but that still left two and so I made inquires as to availability of specific and delivery. I found a set and got them coming. I also had trouble getting the bearings for my undersize crank and a few other issues. This is just what happens in engine building.
Well, I wish you luck.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
|
|
|
|
| Re: [GMCnet] My Engine builder, and the case of the hard-to-find pistons [message #362296 is a reply to message #362284] |
Mon, 08 February 2021 18:37 |
uprooted
Messages: 72
Registered: December 2019
Location: Hilliard, OH
Karma: 0
|
Member |
|
|
Matt/Others,
As I am pricing out my DIY rebuild as well (anticipating the inevitable) , I was starting to come to the realization that forged pistons might be difficult to find. So you have piqued my interest with your statement that cast pistons are fine. Are the factory pistons cast or forged? Also how many cc's does the dish need to be?
Corey P /
Hilliard, OH /
1974 Glacier 26' /
3.70 FD /
ION Wheels
|
|
|
|
| Re: [GMCnet] My Engine builder, and the case of the hard-to-find pistons [message #362297 is a reply to message #362296] |
Mon, 08 February 2021 18:51 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
|
Senior Member |
|
|
Factory pistons are cast. EXCEPT FOR HIGH OUTPUT 455'S like in the 442's
and Hurst Oldsmobiles. There were a very few C.O.P.O. cars made for early
"funny car" examples that had some very different stuff inside, like solid
lifter camshafts, double row roller timing chains, two piece cam chain
covers, special intake manifolds and Carburetors, cast iron headers, etc.
I have seen a couple of examples of these Central Office Purchase Order
cars back in my drag racing days, including one example of a hemi-headed
455 with dual 4 barrel Quadrajet intake manifolds. All factory stuff. But I
don't think any of that stuff found it's way into motorhomes.
Jim Hupy
Salem, Oregon
On Mon, Feb 8, 2021, 4:38 PM Corey via Gmclist
wrote:
> Matt/Others,
>
> As I am pricing out my DIY rebuild as well (anticipating the inevitable) ,
> I was starting to come to the realization that forged pistons might be
> difficult to find. So you have piqued my interest with your statement that
> cast pistons are fine. Are the factory pistons cast or forged? Also how
> many cc's does the dish need to be?
> --
> Corey P /
>
> Hilliard, OH /
> 1974 Glacier 26' /
> 3.70 FD /
> ION Wheels
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
|
|
|
|
| Re: [GMCnet] My Engine builder, and the case of the hard-to-find pistons [message #362299 is a reply to message #362296] |
Mon, 08 February 2021 19:56 |
|
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
|
Senior Member |
|
|
uprooted wrote on Mon, 08 February 2021 19:37Matt/Others,
As I am pricing out my DIY rebuild as well (anticipating the inevitable) , I was starting to come to the realization that forged pistons might be difficult to find. So you have piqued my interest with your statement that cast pistons are fine. Are the factory pistons cast or forged? Also how many cc's does the dish need to be?
Cory,
JimH answered the forged question adequately. I have torn down three 455s, and none had forged pistons, but mine and another that was not a coach engine both had noodle (Nodular) iron cranks. No matter what else happens, identify the crank in your engine before it leaves your hands. If it is steel and it goes to a rebuild shop, they might "loose" your crank.
I can measure my souvenir piston here if I can find on the desk top but I know the OE were deeper than they can be because Olds always lied about their compression ratio. What ever happens, don't let the shop bore the block without measuring all the bores. My engine had over 80k since the last overhaul and it had 30 over pistons in it. That meant that if I had to bore it again to clean up a damaged hole, at the very least the pistons would have to be special order. (No manufacturer stocks 455 pistons for greater than 30over.) And possibly, if damage was bad enough, the block was toast.
As it happens, I was able to get a god fit with pistons sized for 4.155 (30 over) and that was even after the de-glaze.
Also, if you get to this, call me. I may make this sound simple, but this was not my first rodeo. I also may have some tools to lend.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
|
|
|
|
Goto Forum:
Current Time: Wed Oct 02 19:28:13 CDT 2024
Total time taken to generate the page: 0.02494 seconds
|
GMCforum
Search
Help
Register
Login
Home
