so i want to build a 351 for my 94 f150 the truck in my sig. i wanna keep the efi. so far i found a 79 short block the guy said he thinks its got 69 rods in it which put the piston father in the hole. cast pistons bored 60 over. ive also found a set of 69-74 dooe-c heads. this will be my frist engine build. i have a couple of ?s will this block bolt up to my e40d, can i use the headers and the intake off my 94 motor any and all input is apperciated thanks

 

It will bolt to your trans. I have the D0oe heads and stock manifolds, so the headers should bolt up. Those heads dont have hardened seats so you'll have yo run some kind of lead additive or have seats installed and the exhaust ports need to be opened up. They also take an oddball spark plug with (I think) 18mm threads. I am pretty sure your intake will work

 

Pistons down the hole are a bad thing.. it lowers compression, so you'll want to address that and either get different rods or other pistons.. there's nothing wrong with running 9.5:1 CR on an EFI motor.

 

The 1969 con rods are the same length as all other 351W con rods. One awful practise that piston manufacturers used to do was lower the compression height on oversize pistons, typically .020" on a .030" oversize piston. I don't know if they did even more on a .060" piston, but if they did this ill-considered modification to the former pistons, hey, why wouldn't they do it even worse for the big oversize?

The reason they did this was to keep the compression ratio the same as original. Overboring the cylinders increases the swept volume slightly, thus increasing the compression ratio. So the slightly lower pistons increase the combustion chamber volume, therefore correcting back to the original ratio or thereabouts. This was common on replacement cast pistons (in the 1980's catalogues I looked at they pointed out this feature) but I don't know if it is still done. I am pretty sure the more expensive pistons nowadays don't, most even list the compression height so the customer can double check.

The real problem with this practise is that it makes the "squish" or quench distance too large which apparently leads to increased octane requirement to avoid detonation.

You are already at the maximum overbore, I think, so you will not be able to overbore anymore unless you can find pistons larger than .060" oversize.

 

sounds like doing too much im still looking for a newer setup but id only pay about 300 for the short block and stripped heads

 

A roller block like you have would be a better choice, there is a greater cam selection and you don't have to but the roller assembly.