this has gone on way too long to follow along. and no, you don’t want help …Christ man, you think the world should stop for this years long project where you absolutely refused to listen from the start?

you are as stubborn as they come.

you should have done a compression test the day it was first fired up….I said that multiple times.

it’s first very first thing you should do when diagnosing the problem you are having..

 

My assumption is it's cut and squared. The machine shop that took it upon themselves to do explained it as "this shaves the block to allow the piston to get as close to the top as possible". This was from machine shop 1, who pretty much did what they wanted (including reconditioning and balancing pistons that wouldn't fit and rods that had been bent)

 

 

I have to post just to be able to follow along, or get stuck on page 10...Stupid, I don't get it.

 

I think you need to be pretty stubborn to complete an Olds project. Things don't always come as easily as they do in the Chebby world.

 

Ha! and I thought Malaise era Mopars were a challenge.

If I don't get to testing this weekend, I'm off Thurs/Fri next week and will definitely work on getting that done. In speaking with the assembly shop, they're pretty well refusing to touch it to make things correct. He did admit to not degreeing the camshaft upon instillation, contrary to the cam installation instructions provided..so with that I feel like he needs to make things right, but then again he also sent it to me with the distributor 180 out.

 

Cut your losses there. You don't want him touching your car again.

 

Agreed, and thats the only reason I'm not pushing him harder about fixing it. Sure, it may cost me quite a bit more to take it elsewhere..but peace of mind is worth more than anything.

 

Cut and squared to what ?

So, if the pistons are only getting close to the top, how are the spark plugs getting closed up ?

 

Squared up as in getting rid of any potential warpage, but milled to the point where the pistons are flush to the top of the block. Again, it was literally over the phone as "the block has been bored, 2 cylinders sleeved, and I went ahead and zero decked it" with absolutely no information in regards to how much was taken off. I understand that even with the plug being inset the head/chamber, as well as the fact that there's a gasket between the two-there should be no reason the plug should have made contact. The only thing that changed was going to a shorter plug, and they were no longer getting closed up. Again, I share the same consensus as everyone else-it shouldn't happen.

 

7" rods in a 400G block. Do you have specs on those pistons to verify the compression height?

 

Yeah.. gimme a few there somewhere amongst either my notebook in the garage or in my PMs. I had countless conversations with cutlassefi over this via PMs, phone calls, etc.

The piston is an Icon KB846 (pretty sure that's the part number). I had to call and get back stock of the standard bore piston (3.910) as they only sell the oversized now.

 

Detonation will close the plug gap

 

Correct, but why has it stopped with the shorter plug...unless it's just further from the explosion/detonation. I'll be honest, I have a very small exposure to detonation conversations..and thats simply due to either poor fuel quality, too lean mix, or too advanced timing.

 

There is no dome on that piston, it's a flat top with valve cutouts. Perhaps the heads were cut so much that the S plugs protrude into the flat top of the piston and the non-S plugs don't. Or as someone speculated they closed due to detonation. Perhaps we can decipher that if you can tell us, did all the S plugs close up right after the start up (which would indicate a mechanical problem)? Did only some close up immediately after start up? This still could be mechanical and just the ones that were indexed in a way that cause some to close and others not close. But if they didn't close up immediately and only closed after a few days, or after a few hard runs, then it would be more likely that it happened because of detonation.

 

I dont remember if it was immediate or after a short time. Detonation makes sense, however I'd think I would still be experiencing it.

I'm antsy to see what the compression test shows. I've had the suggestion of rockers too tight, but being non-adjustable I'm not sure how that'd happen. I'd also think the weak spot would be the pushrod rather than pushing the valves open, but I've been wrong.

 

Detonation severe enough to bend electrodes would be, like, really audible.

 

I hadn't given any thought to it until discussing it, however at higher ROM before it shifts (normal cruising) it does clatter every once in a while. I just hadn't ever really thought about it as the only time I'd ever experienced ping was under hard acceleration

 

I've been following along since you bought that car and appreciate your diligence but I gotta tell you, in my opinion, one (or more) things were done incorrectly in the machining and building of that engine. These things are pretty straightorward and simple. When they're built correctly, it takes very little to tune them and have them run reliably. These are the kind of experiences that drive people to conclude Olds engines suck and the only path to glory is an LS swap.
I hope you get it sorted but, if it were me, that engine would be out of the car and apart so I could measure and check everything from the crank up. I suspect if you eventually do this you're going to find more than a few things you don't like. Best of luck to you.

 

I have definitely come to agree with that. As has been previously mentioned..it should have been taken back when it was discovered it was 180 out, however I'll be the first to admit I'm guilty of assuming that's the worst and with it being months past due, figured I could get it squared away. While this isn't my first engine I've ever messed with, this is the first one I've ever had these kind of issues with (though the last one had a strange issue as well until we got it squared away). I'm going to do the compression test and see what it shows, but in terms of needing to tear into it-it'll probably go in to a different shop come fall/winter. Especially if it exceeds my limitations.

 

This is a very long thread, so forgive me if this has been asked and answered before. What octane fuel are you using? Perhaps low octane is leading to detonation which was closing the plug gap.

 

It was broken in on the dyno at 87 (which I still don't understand) but I run Premium from the pump (91 or 93, can't remember off the top of my head)

 

You need to remember. There's a difference. And who's the goof who ran it in on 87?

 

The assembly shop dyno'd it on 87.

I'm 95% sure the Premium is 91 Octane..but I won't swear to it.

 

If he just ran it on the dyno with no load just to break in the cam, you can run kerosene in it if you want to. It’s not an issue.
And I’ve never seen detonation close the gap on a plug without damaging the porcelain as well.
Brian, you need to get someone reputable to dig further into that engine. All this dancing around is just going to cost you more time and money. Sad but true.

 

It would be called the push rods are too long.
You said the deck was milled, and maybe the heads were milled, and that means the factory length push rods are likely no longer the correct length. Unless someone actually measured to determine the necessary push rod length, then ordered the correct length push rods so they work properly with a non-adjustable rocker system, this may be (at least part) of your problem. If so, it is easily corrected.

 

I'd have to check, but I don't believe the heads were cut. The only thing done to the heads aside from ensuring they were able to be used was a valve job. I'd given thought to pushrod length, but figured they'd bend well before a lifter would collapse or it'd hang valves open.

@cutlassefi I am in agreeance as previously mentioned. I've had multiple conversations with the other shop during my many years tinkering with Mopars and they've always seemed to be helpful in the past. The reason they weren't considered off the rip is because it was my understanding the shop I went to specialized in GM and the shop I was familiar with specialized in Mopars. Didn't even think to ask where they fit in with Oldsmobiles.

I'll share the compression test results here, as well as pass them along to the shop I plan on having work done with. They are the shop that I'd planned on taking the car to be dyno tuned on the chassis dyno anyway...its just a matter of when that happens and what all needs adjusted/replaced/repaired before then. Still pretty irritating that almost 10k sunk into this thing and it needs MORE work, but it doesnt change anything.

 

This is what I was referring to.

 

right, I just figured they'd bend first. Though the longer I think on it..I suppose it is a possibility. The last engine I built, I had everything mathed out right. During assembly, the guys at the shop we were using talked Dad into using the head gaskets that came in the rebuild kit (.054 versus the .028 that I bought) and for some reason it kept breaking rocker bolts. After changing to the smaller gaskets, the problem went away. A difference that should have been made up via the hydraulic lifters was evidently enough to cause the heads of the bolts to break off.

So with that, I suppose the opposite could be in effect.

 

Alright, not much of an update..but just to get things back up to speed.

Thursday Im off work and aside from a dr. appt I have nothing planned other than a compression test.

Friday while at work, I made a few more phone calls and after speaking with everyone, it seems as if the culprit is improper valve timing due to the cam not being degreed. The assembly shop offered to "look at it" in the next couple of weeks, and if I got the 9 keyway timing gear he'd install/degree the cam appropriately. My concern is, even though I've barely even let it run since determining it may be an internal issue (which I agree a compression test would have alerted that much sooner) I'm now extremely concerned about the condition of the valves/pistons.

Best case, everything is just out of time and no damage has been done. But I'm not holding my breath.

 

What cam and compression does this motor have again?

 

If the valves were hitting the pistons, A you would’ve had to have a huge cam in it, and B they would’ve been bent enough by now to let all compression out.
Do the compression test before you make or field any other assumptions.

 

Cam is an Erson TQ50H. Compression after it was all said and done, not sure...

Test will be done Thursday after my Dr. Appt. Nothing is being scheduled/purchased until then.

 

From what was posted, zero deck block, light plane on heads, and Icon KB846 pistons with 4.7cc dish.

 

Well, hopefully lots of compression. I looked up the Erson TQ50H -- that's quite a bit of cam for a poor old G-block.

 

I’m pretty sure it’s a TQ40, not a TQ50. Even at that, his compression and converter should be fine with it.

 

Paperwork said 50, but thatd make more sense as to why I can't find it online..ha


I would assume the CR would be better than stock, but then again when it comes to this engine, my assumptions not always been the best.

 

That cam in a 400 would need a minimum 10:1 , better with 10.5+

It has a ton of adv duration. I would put that in 6 deg adv in a 400 for an int centreline of 102

I would like to see 175 psi min.

should have adjustable rockers to get correct lifter preload

 

Per the assembly shop (and yes, that is a measured statement based on the current situation) the preload is .050. That's what he sets preload on every engine he assembles, and with that preload in the lifters that's how he verified pushrod length. (Something to that extent anyway)

In regards to intake centerline, why 102 when the cam card states 106? Not questioning the reason, just looking for a better understanding as the most I'd ever paid attention to was LSA for sound, and lift for springs as the stuff I worked on previous was notorious for weak springs

 

Most don’t know this, but those adv duration numbers are at .000, not .006. Erson never changed them from years ago. Take about 12* off of both.
I used the same lobe family but a 222/228@.050 on the same 108lsa in at 105 on a 9.5:1 350. I had 14-15” of vacuum and it ran great. That cam isn’t too big for a moderate 400 build.