i cant get the pistons back in the bores

[jtybt]

Re: i cant get the pistons back in the bores

Watching the video reminded me...do you have the crank positioned so the rod bolts aren't hitting it.. It don't take much to screw up the rod journals.

 

[dr_bowtie]

Re: i cant get the pistons back in the bores

I tried this type ring compressor last time. It helped by keeping the band square to the block and not letting the band get between the piston and bore.

http://www.amazon.com/gp/product/B0009OR93I

this is the same one I have been using for the last 20+ years...awesome tool...

we are too much alike here....

 

[jtybt]

Re: i cant get the pistons back in the bores

 

[fishingman220]

Re: i cant get the pistons back in the bores

i think i have found the problem, i hope, i was looking through competition products mag and i was looking at rings, well under 4.000 rings for sealed power they offer regular rings and a 4.000 chevy with .165 shallow oil groove, part number e377x. well i went out and measured the oil groove in the piston and it was .165, i measured the new rings i am trying to use and they are .150, and the little piece of the expander ring that the ring is on is .030, so that would make it .180, .015 to big if i am correct. what do you think? i need the other ring set??

 

[dr_bowtie]

Re: i cant get the pistons back in the bores

if .165 is the depth of the oil ring slot then the .150 is fine...

if you are talking total width then the oil scrap assembly wouldnt fit in the groove..not at all..if you can put it all together and it moves freely it is fine..

 

[fishingman220]

Re: i cant get the pistons back in the bores

right but wouldnt mine be the shallow grove rings? the oil ring is my problem, that is the only thing i could imangine could be different

 

[dr_bowtie]

Re: i cant get the pistons back in the bores

measure your new ones against the old ones....

the depth of the grooves is all the same for all pistons...the spec you are talking about is the gap thickness....

like the top and 2nd groove rings are 5/32in rings....this is 0.15625 that is the thickness of the ring not the depth...

same thing on the oil rings....

 

[fishingman220]

Re: i cant get the pistons back in the bores

i will go measure real quick, but if you look up the part number e377x it is for a different oil groove, the depth not the gap.

 

[fishingman220]

Re: i cant get the pistons back in the bores

i will get some pictures

 

[fishingman220]

Re: i cant get the pistons back in the bores

see how the oil ring is shallow comparied to the rest

 

[jtybt]

Re: i cant get the pistons back in the bores

I don't know if this is an optical illusion but the oil groove looks to have a 'step' in it...and, the oil groove doesn't look to have support in the pin area.

What and where did you get these pistons?

You should be able to easily compress the scrapper ring with your fingers and it should compress to the piston size.

I never had trouble with scrapper rings until I kinked one and tried to use a new one from a different mfg with the other oil ring set. They were made differently and wouldn't come close to compressing but it was very evident.

 

[dr_bowtie]

Re: i cant get the pistons back in the bores

let me check some pistons I have in stock...I have both for regular and low tension...

I dont think the grooves are as deep on teh oil rings as they are on the regular rings...and I think both regular and low tension are the same depth...

what year is that engine...???

 

[jtybt]

Re: i cant get the pistons back in the bores

Found a stock 5.7 flat top piston. Top groove was .212 and oil was .200

Came out of a volvo engine.

 

[Apollo75]

Re: i cant get the pistons back in the bores

Not as simple as more lube and push

Yeah, it sounded like you were doing everything right --- with all this good experienced advice you should be moving across the lake by now.

I would investigate the possibility of the "wrong rings" for those pistons --- Let us know what you figure out.

Best of luck

OFM

 

[fishingman220]

Re: i cant get the pistons back in the bores

yes there is alitlle cut area on each side of the piston, but once the expander is in you cant push the scrapper in these cracks. the motor is a 96 mercruiser 5.7 L with a 2bbl out of a proline cuddyfish, you said the oil groove was .200 well on mine it is .165 you can see how much of a step there is in between the oil ring and the middle

 

[dr_bowtie]

Re: i cant get the pistons back in the bores

you need "low-Tension" oil rings....

mine are the same is his.....200/.210

low-tension oil rings are smaller...you got the wrong ones...

 

[fishingman220]

Re: i cant get the pistons back in the bores

so your positive it wouldnt be the .165 rings?

 

[wca_tim]

Re: i cant get the pistons back in the bores

you need "low-Tension" oil rings....

mine are the same is his.....200/.210

low-tension oil rings are smaller...you got the wrong ones...

digging it up for him on a holiday - that's service!

 

[dr_bowtie]

Re: i cant get the pistons back in the bores

eh yea...I had to go to the shop anyways...cousin needed to borrow some space to fix the exhaust on his newly acquired hoopty...fun watching mechanically challenged people work on cars...

you dont want to know how many times I said today...no I said 6-point...thats a 12...lol

yes...you need the smaller oil ring set...these are called Low-Tension...like I said match them up with your old ones...they should be different...they shouldnt be...they should be the same...

 

[fishingman220]

Re: i cant get the pistons back in the bores

just curious but what exactly is the difference in the reg rings and the low tension?