motor has 120,XXX, need opinions on rebuild!

[greenstang1313]

The motor is getting pretty old, and this spring I want to completely go over it, and do it the right way. I'm working with a budget, so anything crazy is out of the question for now.

Basically I want to know what I should do so my motor will run like a fresh new engine and I wont have to worry about it crapping the bed for at least another few years. I'm thinking about going the 306ci route but im also thinking about maybe just doing a 302 rebuild kit with a whole new H/C/I setup. A mechanic told me that with 120,000 i shouldnt put anymore than 5 or 6# of boost through my motor and id like to supercharge in the next year and I'd like to do at least 8# so I want my motor to be strong.

Is it worth going to 306? If I plan on doing an S-trim or Kenne Bell should I think about forged internals? Ive never had any serious engine work done to my car so I want to get as many opinions as possible.

***oh and just to throw a figure out there, Im looking to spend somewhere in the vacinity of $3k or maybe a little more

Thanks guys,
-craig

 

[trav_19]

H/C/I is where a lot of your money will go....if you plan on putting boost on it i wouldn't skimp on the internals but you will want a better h/c/i so is you can get quality internals cheap and a good hci i would probley go that route...other wise go 306 and then when you can afford do hci and blower ...when you do a trim you will have to upgrade your fuel pump and injectors so you will be pulling parts off anyways might as well throw on the intake then

 

[earleys94gt]

With that mileage if you plan on going with a supercharger at some point, forged internals would be a very good idea. You don't want to blow the thing up and have to go back and build it again, when you could have done forged from the beginning.
I also say this because a friend of mine's 95 Cobra just grenaded itself. It was mostly stock when he bought it, but the guy he bought it off of had a supercharger on it and he took it off before he sold it...we are talking a catostrophic failre in his case(harmonic balancer exploded and went thru radiator)
So if you are going to rebuild AND plan on doing boost, forged internals.

 

[greenstang1313]

Do you guys think I could do a basic 302 rebuild with forged internals, and a new heads/cam combo for $3000 give or take a couple hundred bucks? (i can keep the street heat intake for a while, a new intake can wait) Id have a shop do the work.

 

[Therian]

my opinion.

120k miles is still a decently young 5.0. Are you burning oil or getting blowby? Without these symptoms I wouldn't touch the bottom end at all. Throw an H/C/I on there and be happy.

If however you are getting blowby, or are extremely paranoid...I'd suggest a simple re-ring kit from summit. Don't do a 306 unless you need to, or it is a purposeful build (hi rpm beast). Save your money for a 347 down the road.

I would also recommend a compression check and a leak down test for you.

 

[chaos254]

i agree with therian.... as long as its not burning oil or blowby, leave it alone. As for going with forged internals, IMO i think this is a waste of money because on our stock short blocks the block will go before the rotating assembly does. Take your $3000 and spend it on the supercharger and have fun. 120k is fine for boost and many guys on here have done it all the way up to 200k without any problems. You'll be much happier then spending 3k on a rebuild and having it blow up just as quickly as the completely stock one would have.

 

[trav_19]

i have 17x,xxx miles and mine runs great still these motors are beasts...i need a rear main seal but thats not bad atleast its not burning.....but to your question....

a h/c/i is around 2 grand....give or take a few hundred...and depending on what internals you want...and having it all installed i think you will blow past 3k easily....unless you know people


take care of the problems if you have any...if you just want a build because you think it has high milage...well these motors can go a very long time w/ proper maintence.... i would use 3k on a poweradder.

 

[trav_19]

i would probley do a H/C/I and NOS if it were my 3k and the motor was not burning oil that is

 

[greenstang1313]

My motor is not burning oil and it runs great but I'm just sick of having high mileage cars, I want to have something that I beat on and not worry about it crapping the bed.

The heads that I want are around $1200 and the cam is no more than $180, and I said I wouldnt mind keeping my street heat intake for a while, so thats $1600 left over to figure out internals and what sort of rebuild i want to do (if any).

my friend has been telling me that at 120,000 there is no point in rebuilding it unless im gonna bore it and hone it at the same time, is that true?

 

[trav_19]

if its not burning oil i wouldn't bore in unless i was throwing in a 347 stroker....if its not burning then your shortblock should be fine....with heads and a cam i think will really freshen that car up....with the remander...(i forgot to look at your mods already) so i would suguest getting a nice flowing exhaust system.....rear gear ...nos!

 

[greenstang1313]

if its not burning oil i wouldn't bore in unless i was throwing in a 347 stroker....if its not burning then your shortblock should be fine....with heads and a cam i think will really freshen that car up....with the remander...(i forgot to look at your mods already) so i would suguest getting a nice flowing exhaust system.....rear gear ...nos!

Ya i already have an o/r H and flowmasters right now, and I'm dropping the car off in the morning to have longtubes and a new o/r H installed. But my buddy was saying like the cylinder walls get crap on them over time and that is why I should have the motor bored and honed, and he actually sorta knows a lot about motors so Im trying to figure out what I should do.

 

[fast4cheap]

all the stock short blocks I have been into with those miles has very little wear, as long as there is no ring grove new rings would be fine. To save money you could scource out a set of good forged pistons from a 87-90 5.0 motor, these were forged TRW and can handle about anything you throw at them, recondition the rods with new rod bolts and have you crank checked, this is as good as new and tough as nails, plus you got more money to spend else where.

 

[greenstang1313]

all the stock short blocks I have been into with those miles has very little wear, as long as there is no ring grove new rings would be fine. To save money you could scource out a set of good forged pistons from a 87-90 5.0 motor, these were forged TRW and can handle about anything you throw at them, recondition the rods with new rod bolts and have you crank checked, this is as good as new and tough as nails, plus you got more money to spend else where.

thats what I wanted to hear, thanks for the opinion! ...But yeah, basically I want my engine to be tough as nails like you said, and that sounds like a great way to do it. How do I find out if I have ring grove?

 

[Therian]

I'm still missing the point on the forged internals. As was stated above, the block is probably going to let go before the rods and pistons. a typical H/C/I or power adder is not going to put you in the territory of hurting your internals.

New pistons is going to require your block to be balanced. I assume you don't want to pay for that (it's more of a time hassle than anything).

Do a leak down test and a compression test. Go from there.

 

[greenstang1313]

well all the talk of peoples internals blowing up at high horsepower is what worries me about not going forged, when I clearly have plans of going 375+rwhp. The block is supposedly good to 500+.

 

[urban96]

if anything get the block honed and just do new rings/bearings

 

[trav_19]

you can tell if the walls are scraped when you pull the heads off...your getting new heads so you will be able to look in at the cylinders i wouldn't imagine much anything to be wrong maybe just a little dirty....it will give you an idea on how well the previous owners took care of it though.....with the H/C/I and long tubes with o/r h and flows your set on intake and exhaust....you already got gears....your to the point now where its more cubes or poweradder....im still a fan of the gas.....you can run up to a 125 shot safely in these engine...i will be spraying a 100 just so im below the safe level...but im putting it on without tearing the shortblock apart and with almost 180,000 miles...lets just say a little fun and encouragement to get that new engine i want lol good luck and let us know what you find

 

[Therian]

well all the talk of peoples internals blowing up at high horsepower is what worries me about not going forged, when I clearly have plans of going 375+rwhp. The block is supposedly good to 500+.

I have rarely seen anyone destroy their internals, and I've been around here for 4+ years. I remember when Chris (eades) destroyed his crank....but I believe he was much over 400RWHP at that time.

I wouldn't put the block over 475RWHP.

If you want to run a high rpm application, or a stroker, then you should definitely change out the internals (obviously required for a stroker)...otherwise, it's just a waste of money.

 

[Bens95cobra8594]

It seems like we are missing basic information here:

Is there a compression issue?
Is the engine burning oil (blow-by, as mentioned by several members above)?
Is one cylinder (or more) worn to the point of crap? (see above questions)

I would REALLY think that unless there is a specific problem, rebuilding just because of high miles is sort of a waste of money.

IF this is a modular platform on which you want to add additional power adders or juice the thing way over stock, then maybe a rebuild is worth investing in, but otherwise, it sounds like a waste of money at this point.

Bank the cash you would use for the rebuild (if it is indeed necessary) and let it accrue for a few months and you will get even more money to spend on toys for the car.

Lets make an educated decision about what is REALLY going on in the engine before spending money on something that may not need to be done.

Heresay and speculation will only get us so far.

Keep us posted! ! ! ! !

 

[greenstang1313]

Ben, theres no compression problem and I'm not burning oil, its not that I have a problem right now, but basically I just want to get in there and just make this thing strong so I can forcefeed it and beat on it without having the constant worry that I'm running boost through a motor that has been operating for 13 years.

My whole idea is that I want my motor to be tough as nails so I can beat the crap out of it and then throw 10 pounds of boost at it, and beat the crap out of it some more, and still not have to worry about it blowing up.