1972 351C runs crap

[barnett468]

Yes that was my question. I did heat the small end of the rod when i installed the piston, the only problem was i couldnt get the rod exactly centered in the piston if i were to use wrist pins (altough extremely close).

But i suspected they wasnt neccesary.

no it is not necessary to get the pin exactly centered but the closer to center the better . one problem with heating is if you get them too hot, it can damage the metal . they use a special machine to heat them to the proper temp.

 

[Odmark]

Yes i know, i was very cautious and used a LPG heater with a wide nozzle so i would not risk overheating.

On the first two pistons i was too cautious with the heating though because the rod cooled almost instantly so the pin just barely got trough the rod and a couple og millimeters in the piston on the other side.

Can i press this trough or do i have to press it out and reheat?

 

[barnett468]

you should not press it cold because it can damage the piston . you might get lucky and you might not . this is why i said you should have a shop do it.

 

[Odmark]

Left the rods and pistons at the machine shop and he sorted them out for me.

Block is finished tomorrow or friday so im starting assembly this weekend.

 

[barnett468]

Left the rods and pistons at the machine shop and he sorted them out for me.

Block is finished tomorrow or friday so im starting assembly this weekend.

well unfortunately he had to cold press them too so the pistons still may have gotten damaged but you just cant see it.

 

[Odmark]

Maybe that is the case, he said he has done it many times with no issues and that it wouldnt be a problem.

I guess i have to trust him on this because i can not afford new pistons right now even from the states.

Im guessing there is no way to test the pistons for damage?

I remember i had to replace a rod on another oldsmobile v8 i had in my youth, the only time i separated a piston and a rod before.

That time i was even more clueless and just cold forced the pin in with a medium sledgehammer against a vise when assembling. That engine still runs after 7+ years.

Youre probably going to think im mad but win or lose, im putting it together and trusting the machine shop guy, at least he has 40 years of experience.

And if the engine turns out to be crap i will either haul it and go big block or haul the car as it is...

Best parts is that you can sell a junk 2V cleveland for pretty big money in sweden, and i got the car so cheap i can still sell it with profit with a shot engine.

There is no sin except stupidity - Oscar Wilde

And yes i know its probably stupid to install these pistons as well.

At least i learned my lesson...

 

[barnett468]

It's really hard to say . They can be tested for micro cracking with a sonoflux but the pistons are fairly hard, and unless something obvious is wrong I wouldn't loose any sleep over it, but as you say, you leaned something new.

 

[basstrix]

If the inner surface of the wrist pin boss on the piston is parallel to the edge of the rod, the chances of centering the pin w/o damage is good. Not all pistons make this surface parallel.

From my experience, the telltale sign of damage is that the pin/rod does not rotate freely in the piston. I've seen a shop press apart a sticky pin and hone the bores slightly...in my opinion, this is not the right way to do it but it's dependent on how much material is removed...you might be able to detect this by comparing the finish inside the bore of each piston to look for any that might have been touched up by the shop.

 

[Odmark]

Each pin rotates freely in the pistons, no signs of honing on any of them as far as i can tell.

No signs of damage whatsoever.

Another thing, i got stiffer valve springs for the new cam, but i need new retainers and possibly new keepers.

Are there any retainers for dual springs that the stock keepers fit in?

 

[basstrix]

That's good news on the pistons/rods.

In short, yes, you should be able to find a set of retainers for your stock keepers compatible with dual coils. Is the inner coil a flat wound (damper) or is it an actual coil spring? If the former, you shouldn't need different retainers, but that's not a guarantee. Also, if you do have dual coils, are the spring seats on the heads cut down to accommodate the smaller inside diameter of the dual coils?

 

[barnett468]

comp cams will have them

 

[Odmark]

They are true dual springs with a damper, so 3 "pieces" total.

No the spring seat has not been cut down, how do i do this? I test assembled earlier and found no issues except for the retainer.

Also a thing that just hit me now is that i need other valve seals.

Could anybody be very kind and find me some part numbers? most comp cams stuff can be found in a dealership in sweden.

Also if someone could be even more kind and contact elgin for me since i did not get any cam card or break in instructions for the cam. And i cant get hold of them...

 

[barnett468]

if the inner spring is much larger than the valve guide base, you should buy inner spring seats to keep it from moving around.

the outer one should be the same size as the step in the head s it doesn't move around.

 

[Odmark]

Hello again. As for springs, i decided ill be going for a head swap asap and then put the money on new seats etc. Ill be using stiffer single springs atm.

Okay so this happened... i let my cousin, keen to learn, help me install the pistons in the block.

Pistons 1 and 2 were okay, but on no 3 i had to go to the gentlemens room and leave him to keep installing, well apparently on no 3 the bottom ring had popped out of the compressor and he just kept on smashing with the wooden handle of a hammer.

Wich resulted in first, a snapped piston ring. Oh well i thought, have to get some new rings.

Proceeded to put a new one on when i realised the piston was cracked between the bottom and top ring grooves.

So instead of waiting another month for a new piston, cause they dont sell them seperatly here.

I found a cleveland guy in sweden that sold me brand new forged pistons for a steal.

And yes i know they are not ideal for my setup, but for the price.... yeah well.

Left the pistons and rods at my builder and he assembled them properly this time.

Except for the last piston that is the f*cking wrong way. Oh help me god, this never ends..

So im stuck with 7 complete properly assembled pistons/rods in the block and the last one is mirrored...

 

[c9zx]

I hope your luck changes for the better very soon.

 

[Odmark]

Me to... this is rubbish.

But these flat tops, does it really matter if they are installed backwards? I mean the valve grooves are just identical and mirrored. Or is it because of how the material expands?

Edit, just noted that the wrist pins are offset...

 

[barnett468]

If you had your engine balanced, the new pistons will change the balance factor a little.

 

[Odmark]

It is not balanced.

Machine shop sorted the wrong turn piston out, so thats good.

Question... when i had the engine dissassembled for the first time, and all of the rods/pistons out. I was going to put them in numerical order.

But someone probably swapped some rods out before because i had like three rods numbered 4, and two numbered 2. Or sometging like that. So i have absoluteley no clue wich one came out of what hole.

My shop guy said it does not matter when the crank is machined, it would have been worse if not. As long as i had them facing the right way when installing.

But a frend of mine insisted today that it is extremely important to get this right.

Please enlighten me on this...

 

[Don C]

It's pretty common to find them like that. I agree with your mechanic, not important. Being the way I am, though, I would check the weights on them, just to make sure none are too far out from the others, but it sounds like we're way to late for that. I believe that when they're found like yours someone was trying to match rods, though, so I believe yours should be fine.

 

[barnett468]

ok, with the non original rods, it is likely your engine had a vibration before but just not one that was big enough to be annoying, therefore, it "shouldn't" be much worse now, but if it is, you will know it is the engine because it was not balanced.