Used forged 306 shortblock vs. re-ringing the stocker

dstang01

Member
Sep 22, 2005
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Vancouver, BC
My 5.0 is burning oil and its most likely a ring issue. Its not too bad, about a quart every 900 kms, but Im going to want to remedy it sooner or later because it bothers me (Im also uncomfortable modding a motor like this). I could probably simply re-ring my current motor and call it a day, its got only 110,000 kilometers on it, but for the effort of taking it out and having it torn down I think its only logical to improve a bit :nice:

Someone at a local mustang club is willing to part with his forged 306 bottom end for the right price. Here are the basics about it...

86-93 5.0 block, bored out .30
Notched, Forged Power pistons for 2.02 valves
H beam rods
All ARP bolts "but a couple are missing."
and the cam has .544 duration (apparently similar to the ford racing X cam)

Would it be a bad idea to pick this up, build up the top end myself, then eventually drop it in and sell off my stock longblock? What are your opinions and how much would you offer (ballpark) for his shortblock?
 
To me forged parts in a stock block is a waste of $$. The block is the weak point not the internals. If you crack the block there is a good chance of damaging or even ruining those expensive forged parts.
 
How much does the person want? Used parts like that is a gamble to start with. Personally I would keep running it, just because it burns alittle oil doesnt mean its broke. If you knew how much oil my car burned you might faint.
 
To me forged parts in a stock block is a waste of $$. The block is the weak point not the internals. If you crack the block there is a good chance of damaging or even ruining those expensive forged parts.

+1

Stock pistons and rods are already forged pieces. Unless you are getting a good deal on the set, really at the most all you need is new pistons with a bigger bore.
 
What would it cost to have a shop rebuild my bottom end/ hone to a 306? Ill essentially have just what I started with except it wont burn oil. The reason I'm looking at the forged bottom is because it will give me the ability to run a blower down the road if I like (I dont want to start the "you can boost stock internals fine with a tune" debate, Id just feel safer with the forged slugs. Ive also got hypers because I'm a 94). Because my car is a semi-daily driver the supercharger or big shot of nitrous route is a nice option to have.

Thanks for your input guys, any ideas on what I should offer the guy if I do decide on that route?
 
I still think you're better off just re-ringing your stocker. A 306 is essentially just an overbored 302. There's nothing really special about it. The slight bump in displacement isn't really going to do anything for you.

The stock bottom end will handle moderate boost or nitrous with little issue. Unless you can afford to do it all at once, I would just freshen up the stock bottom end and start putting asside for a better build later on down the road.

A rebuild with "a couple of missing bolts" would make me nervous enough to take a pass.
 
I dunno...i don't have the experience building engines that some guys in here have, but just going by what i've seen, i would prefer aftermarket internals to stock pieces. Yeah, they're gonna handle more power than the block will, but i've seen some ~500hp engines where the block held up fine, but the stock rods either bent or snapped. If you can get it cheap, i don't see why not, it's just added security. Then again I know there's guys using shot peened stock rods with good results (i think Thumper may chime in on this one).
 
Since you have a Hyper motor, and, if I were in your shoes I would tear the original block your car has down and spend your money in it. Get it overboard and buy a set of forged internals. Might be a a little more in the long runs but you will have more options and you will know that it hold up under boost, etc.
 
What would it cost to have a shop rebuild my bottom end/ hone to a 306? Ill essentially have just what I started with except it wont burn oil. The reason I'm looking at the forged bottom is because it will give me the ability to run a blower down the road if I like (I dont want to start the "you can boost stock internals fine with a tune" debate, Id just feel safer with the forged slugs. Ive also got hypers because I'm a 94). Because my car is a semi-daily driver the supercharger or big shot of nitrous route is a nice option to have.

Thanks for your input guys, any ideas on what I should offer the guy if I do decide on that route?

Its official, I'm retarded. I didn't pay attention to the fact that your car was a '94 when I made the comment about the stock pieces being forged. You're right, the pistons are hypereutectic, and really not great for boost or spray. Some people will argue that with a good tune though, you can make them work.