Should I rebuild bottom end??

[BLK3DGT]

I'm the original owner of a 1991 Mustang Gt with 125,000 miles. I replaced the headgaskets and had a valve job done on the stock heads at 100,000 mi.The car has been maintained regulary and does not smoke.
I just purchased Trick Flow's Street Heat top end kit complete with their twisted wedge heads. I was debating on pulling the motor and installing a 306 stroker kit from either DSS or Coast high performance.
I would rather spend the money on upgrading my AOD.
But, I don't want to install the new top end kit and have the bottom end crap out on me.I know that there are a lot of high mileage 5.0's out there that are still going strong. How long should I expect the bottm end to hold up with this kind of mileage? I would appreciate any recommendations.Thanks in advance.
Current upgrades 3:73 rear end, BBk equal length shorty headers,Bassani stainless X pipes with cats, Borla stainless cat back exhaust, Kenny Brown Level 1 suspension kit, 155 lph fuel pump, 73mm C&L MAF, Accufab 70mm throttle body w/spacer.

 

[FastDriver]

If the motor has been well-maintained it won't crap out. Slap on the new stuff and enjoy.

Chris

 

[JBeezy53]

As long as you took care of it like you said it should be fine. Just put that extra money in the AOD. How much longer it last depends on how well you take care of it.

 

[Realmongo]

The 306 is not a stroker, it is a .030" overbore. If you are looking to build in more power a bottom end rebuild is good insurance after the 100K mark.

 

[Topdowncruise]

If you rebuilt the bottom end now you could relax and not worry about it.It would be a waste of labor to build the top end then have to tear it down not long after to rebuild.But who knows,you could go another 5 years or longer without any bottom end problems.

 

[87'GTstang]

If the motor has been well-maintained it won't crap out. Slap on the new stuff and enjoy.

Chris

 

[criticman]

Don't toss money at something that works just fine unless you want to. I would trust your bottom end for now and go ahead with the top end install.

I say this because I am doing the same thing (blower instead of top end) and hoping the bottom end lasts. If not, I do want to do a mild stroker setup anyway, so a crapped out bottom end would be a good excuse to buy a short-block from RNH or CHP.

 

[llwood]

well you might start by giving the the engine a compression test that will give you a good idea of how the bottom end is doing.

 

[DW5.0L]

I got 197,240 miles on my stock 5.0 before the bearings gave out. It wasn't too bad, but you could see signs of wear when it was disassembled prior to rebuilding it.

Are you burining oil and losing compression? If not, just put your new parts on and enjoy it until you can afford having it rebuilt.

 

[Tonys96Cobra]

If you are just doing the h/c/i swap, then you should be jus fine with your stock bottom end. If your gonna throw on a supercharger later, Id rebuild now, and upgrade the critical peices.

 

[Topdowncruise]

I would at least do a compression test and leakdown test first.

 

[gcwh02]

I would do up your AOD first, get the 306 in, put on the TF top end, and be done with it. Whats the point of taking that whole top end off again and throwing it on a new motor, a waste of time or money. No need to tear it all back up again. And then if your even want a power adder, pop it on.

 

[BadAndy]

they always seem to last way past 200.000, you are just geting broke in

 

[Topdowncruise]

they always seem to last way past 200.000, you are just geting broke in

That seems to be true in a lot of cases.I think though that when we read about disappointing dyno results after someone has done just the top end upgrades,it is perhaps sometimes due to a tired bottom end.

 

[NKau]

I would at least do a compression test and leakdown test first.

Agreed. Also, what does your oil pressure look like? Hook up a mechanical oil guage (factory units don't tell you much) and take a look. You should be running 15+ psi at a warm idle, and 40-50 psi when the engine is warm and under load ideally. If your oil pressure looks good, as do the compression and leakdown checks, you should be golden. Don't just guess, take your time and check it out; it will pay off in the end.

 

[BLK3DGT]

I did a compression check this afternoon and all cylinders were at 125 lbs. I was planning on replacing the oil pump. I should be able to get to it without pulling the motor right?

 

[NKau]

I did a compression check this afternoon and all cylinders were at 125 lbs. I was planning on replacing the oil pump. I should be able to get to it without pulling the motor right?

Don't bother until you verify what your oil pressure actually is. No sense putting a new oil pump on an engine with worn bearings. Getting at the pump with the engine in the car is a pain. You have the option of dropping the k-member (bad option) or loosening your motor mounts, and lifting up the engine to get the oil pan off and out. Again, your going to feel stupid if you do this, and you have poor oil pressure anyway due to worn bearings.

 

[Sicarius428]

I had 135k on my stock bottom end when I did my H/I/C.
I did a compression test to make sure everything was within spec. If it's working fine now, just run it. There is some piece of mind knowing that the bottom end has less chance to fail but the stock bottom end should be more than strong enough for an H/I/C with 125k on it. No use replaceing things that are in working order.
Kevin

 

[BadAndy]

I had 135k on my stock bottom end when I did my H/I/C.
I did a compression test to make sure everything was within spec. If it's working fine now, just run it. There is some piece of mind knowing that the bottom end has less chance to fail but the stock bottom end should be more than strong enough for an H/I/C with 125k on it. No use replaceing things that are in working order.
Kevin

very true!!!! if it is-not broken ,dont fix it

 

[BLK3DGT]

Thanks Bad Andy, I received more plus messages to go ahead and installed the h/i/c than not too. The compression readings were 125-130-lbs. some say this is low others say not bad for a motor with high mileage. anyway i'll be putting it together soon.
Thanks