Short block vs Junkyard engine?
05-26-2010, 11:06 PM
#1
2nd Gear Member
Thread Starter
Join Date: Apr 2009
Location: Massachusetts
Posts: 435
Short block vs Junkyard engine?
sorry if this question has been asked before but just wanted to get your opinions on which is more budget friendly. i have a 72 351 i bought awhile back to swap in place of my 5.0 but i am still saving for the swap. there are some short blocks out there for $1000 and up. now is it worth me getting new pistons having the block machined and keeping the crank and rods? or am i better of with a short block to start? i do not plan in the near future to have tons of horsepower but as you guys know instead of me throwing money into my high milage 302 better off starting with a fresh 351. oh and the new articles in the msutang mags on a budget 351 build inspired me. thanks mike
05-26-2010, 11:38 PM
#2
4th Gear Member
Join Date: Mar 2009
Location: CA
Posts: 1,291
This type of question has come up for myself several times. It ends up coming down to machining costs. If you can find a nice short block that only needs a quick hone, then buying pistons is definitely budget friendly. However, if you end up with a block that needs boring, honing, decking, freeze plugs, main bore aligning and cam bearings- than it may be worth getting a new shortblock- especially if it's .30 or more over bore.
Something else to consider is the condition of the crank and rods. Usually, most factory iron cranks won't need straigthening, but they may need grinding and polishing depending on how the journals are (and are usually reliable up to 450 tq). In my experience, rods usually do need reconditioning. The factory tolerances for weights and finishing back in 1972 isn't near what they are in 2010. Plus, I would also throw on a set of ARP rod bolts. So, the cost of resizing, weighing and installing new bolts can almost equal an inexpensive set of aftermarket ones.
To summarize my long post, it can be a bit of a gamble if you don't get the right engine from the yard, but you can save some money- just as long as you don't spend it with additional machining costs. Be careful what you buy. Knowing where the engine came from is a must. If you can find an engine that was supposedly running before being removed- you're ahead of the game.
Something else to consider is the condition of the crank and rods. Usually, most factory iron cranks won't need straigthening, but they may need grinding and polishing depending on how the journals are (and are usually reliable up to 450 tq). In my experience, rods usually do need reconditioning. The factory tolerances for weights and finishing back in 1972 isn't near what they are in 2010. Plus, I would also throw on a set of ARP rod bolts. So, the cost of resizing, weighing and installing new bolts can almost equal an inexpensive set of aftermarket ones.
To summarize my long post, it can be a bit of a gamble if you don't get the right engine from the yard, but you can save some money- just as long as you don't spend it with additional machining costs. Be careful what you buy. Knowing where the engine came from is a must. If you can find an engine that was supposedly running before being removed- you're ahead of the game.
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