slow40sx

So I just had my bottom end on my SR rebuilt a few months ago by a really good well known shop in my area, wiseco 9:1 pistons .020 over, ACL bearings, hot tanked, decked and all that, put it in the car about a month ago, car has run great since I first started it, haven't been giving it WOT obviously since its a fresh bottom end, but I have been giving it half throttle to 3/4 throttle into boost up to 6 grand and letting it engine break back down again here and there to help bed the rings, put about 70 miles on it so far.

Now on to the issue, drove it one day and at random it started spitting and bogging, wouldn't respond when I gave it gas then it would for 200 rpm then bog down again almost like a rev limiter but worse, and then it cleared up, drove the car for another 30 minutes no problems. A couple days later I drove it around for an hour 0 issues, then a couple days after that it happened again for a few minutes then ran fine again, went to drive it yesterday and I took it down the street ran fine, made a left, great through 1st, into Second gave it gas and it coughed and started bucking and spitting and sputtering, idled fine but under load just sounded like a machine gun Bap Bap Bap Bap, fucking terrible.

I pulled my plugs all are black due to the car running rich but plug number 2 was completely soaked in oil from the top of the threads down, no oil in the plug tube only on the cylinder side, I cleaned all the plugs put them back in took it down the street ran great 1st gear good into boost into second bog spit sputter garbage all over again, pulled the plugs cylinder 2 plug had a tiny tiny bit of oil on the tip, stuck an extension into the cylinder and pulled it back out, had a tiny bit of oil on the tip of it.

My question is wtf? And how the fuck? Could this be bad valve seals or Are my rings fucked? **car sounds great, pulls properly, feels solid when sputtering bs isn't going on**

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Mikester

If you added octane booster, that is why it sputters under load & runs rich now- NEVER use it. If you did... change the plugs- They are spent.

However, I don't this is the problem... The problem is that you need to seat the rings throughout your entire RPM range under load. Not sure why you kept it at 1/2 - 3/4 throtlle... It needs to be fully loaded... This isn't an old Dodge where everything physically 'wears' into each other... The machining is very precise so that is not necessary- There is no reason to baby it.

If I were you, I'd take it back to whoever built it; have it compression checked & looked over. If they are as good as you say they are- they will stand behind their work.

For something like this, you are bound to get better advice from others who may chime in. In the meantime; Google how to break in an SR.

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KoukiMonsta

Yea good info from mike there.

Can you do a leak down test? That always provides useful info. Especially on that cylinder 2.

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@UpshiftEngineering

hobbs

Are you sure that it is oil? Make sure that it is not a fuel/carbon mixture. A leakdown will tell you if your rings are done.

Also had a similar issue - it sounds like, this was the result of a failing walbro:

Broken G - YouTube

slow40sx

No octane booster, I was always told to never beat on a brand new motor that's was also what I gathered from driftworks and a few other places i found from google so I had no idea I could just let it rip on a new motor, its definitely oil on the plug golden brown, clean Mobil 1 15w50, I guess I'll do a leak down and go from there

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KoukiMonsta

Yea get back to us with the leakdown.

Break in procedure is a hotly debated Internet topic. I have a recently built first start motor myself so done plenty of reading lately..personally with machining tolerances today and materials ..etc I'm not exactly gonna baby the thing.

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@UpshiftEngineering

Mikester

Yessir^^

It's important to load the rings ASAP... Something to the tune of the first 20hrs of engine life will dictate how it performs for the rest of its time.

Plenty of threads and writeups on this by reputable builders/companies. Really surprised Driftworks gave this info- unless he was referring to forum posts...

Google is a powerful tool for things like this=)

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ShadowMan

If you have oil in your cylinder on the piston and are 100% sure it's not coming from the rubber gromets between the head and valve cover, then there are only 3 culprits that come to mind, headgasket, rings or valve seals. Headgasket not being the likeliest, as it usually is accompanied with coolant in the oil, but not always. Rings could likely your culprit, either being they were incorrectly clocked in the ring lands of the piston or you washed the cylinder out by running it too rich and over wore the rings on that piston. Or your valve stem seals being the third. You said it was a fresh bottom end build but did not mention any attention paid to the head. New valve seals would have been a good idea while it was apart, but oh well. It will just be a slightly bigger pain in the ass to change with the motor together. I'm really just spit balling ideas. Who knows,you could have a giant hole in one of your brand new pistons. Do the compression and leak down test and get back here with the results.

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in any situation....thou shalt blaze

slow40sx

Gonna do a leak down this weekend and see what I come up with, thanks for all the help guys I appreciate it

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