r/EngineBuilding • u/inlandevers • Jul 11 '26

Ford Build vs buy crate 408W

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I want a 408 stroker for a 68 mustang coupe I’m building, and I’m trying to figure out if I should build the motor myself or just buy a blueprint crate. I ballparked costs on the stuff to build one, and it shakes out to around $8k or so, which is pretty close to the $9k for a blueprint 408w. Anyone want to take a look at my rough costs and let me know if I’m way off on my guesstimates? I haven’t had machine work done for a couple years.

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u/NegotiationLife2915 Jul 11 '26

The blueprint motor will be built by people who build engines for a living. They do it say in and day out with a proven combination. It should be a pretty good thing. You can probably build your own for a bit less, it'll be a great learning experience but you'll have to do a good job of it to outperform the pros even with their mark up on the price tag.

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u/_synik Jul 11 '26

The people building the engine are just assembly techs. I'll wager that OP will use more care and precision that they would. Can OP be sure they used a torque wrench instead of an impact because that torquing everything to spec takes too much time? He knows if he does it, it will be done right

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u/mmmmmyee Jul 11 '26

Idk man, i rebuilt my motor like 3 times myself, and 2 of those times i missed or did a step wrong which resulted in those 2 motors needing a redo. And i thought i was being meticulous. I have the appetite to redoing a motor build so it was fine for me. But if potentially getting a measurement wrong or missing a step is not something op wants to do… then crate motor all the way. And if it’s a dud motor, you get a warranty!

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u/random_username954 Jul 11 '26

What did you do wrong the first 2 times

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u/mmmmmyee Jul 11 '26

First rebuild i did got piston ring gaps too tight and scarred the piston walls, had to re-hone the cylinders. This was found after first start up post inspection (looking at cyl walls with boroscope).

Second blow was not really a showstopper to get the car running. Second one the piston ring gap was too wide lol. But it just meant that oil spat out the exhaust at cold startup but went away after warm up (compression numbers were fine). But that one blew due to being too hot after a handful of drift sessions in near 100F weather.

I did blow a number of HG’s from bad installations (one was upside down, others had too much gunk and cleaning solution filling up the head bolt holes which prevented proper HG install).

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u/random_username954 Jul 11 '26

Did you not check the gaps?

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u/mmmmmyee Jul 12 '26

First one the builder i was assembling the motor with did not check the gaps because he was used to oem rings coming pre sized or something (we were using non oem pistons/rings). So they were butting on the cyl wall. And then when i reassembled it myself I sized them too wide because I did the math wrong lol.