360,390 or 427

[vette64ac]

I just acquired an aftermarket AC Cobra, I was told the engine is a 390 with two fours, the casting is either C3AE or C8AE with four number below the C8AE that appear to be 6016, the main caps or crossed drilled, were 360's or 390's ever crossed drilled

[FLASH 1]

only ones I know of that where cross drilled where 406"s, BUT They did offer a kit to do it on the Fe's back then

[Twisted_Steel]

The 427 SOHC had cross drilled main caps since it was a high revving big block (7,500 RPM and 620 HP or 660 HP depending on single or dual quads)
Not sure if the standard 427 or what other engines had cross drilled mains.
Thanks to Flash, I learned the 406's also were.
You might have found a rather desirable combination of car/engine.
Keep us posted on what you find!

[FLASH 1]

the 427 SOCH Where cross drilled,, ALL True 427's where cross drilled and 1968 427's where hyd. lifters, our 1968 here is serial # 568 Many people will tell you at the shows OH its a 427 or put 427 valve covers on it but when you look at by the oil pan and don't see those extra bolts then its a lie and one other look closely and see if you see the high oil pressure relief valve also..

[My427stang]

So all 427s (other than some oddball industrials) were cross bolted

The casting number matters, so if you can figure it out, that helps

However, cross bolting 390s and 428s is doable and done, but expensive and looks different. If you can lay under it and take a picture of the three things below, we can easily tell if its a converted pass car FE, a center oiler 427, or a side oiler 427

1 - Pan rail, cross bolts and at least one freeze plug pass side
2 - Pan rail, cross bolts and at least one freeze plug drivers side
3 - Front of block towards bottom drivers side, where power steering would go, picture staring directly the front pulley but offset to the drivers side

FYI, there are supposedly some cross bolted 406s, but rare as hens teeth, and I build a lot of FEs. Unlikely, but would look like a 427 center oiler.

[FLASH 1]

See back years ago Ford had a Kit for cross bolting, especially on the 406's and reason behind was NASCAR outlawed the 427's due to all crybaby's with Chevy's etc. could not run with them so they where doing the 406' s true way to tell . LOOK and see if the relief valve is there on Drivers side by bell housing , that will tell the real story

[My427stang]

Let me help here, easier to walk out in the shop and show you what you are looking for, you don't have to pull the engine, and plenty of signs if it is a side oiler, you have plenty of options to see the oil galley and threaded freeze plugs.

The 427 side oiler will have a galley that runs down the side (I know, Capt Obvious commercial) however, you can see it from the front at the timing cover



You can see the passage and the three oil galley plugs above the cross bolts. Also note the thread in freeze plugs.



You can also see from the back, if the engine is out



If it is a center oiler, first if it has a hydraulic cam, none of the things above, and cross bolts, it is likely something else converted to cross bolts. 63/64 427s were solid lifter only, although in theory could be drilled, it isn't a common occurrence. In that case, yes, looking for the relief valve on the pass rear will tell you. You will see a pipe plug in the bellhousing much like the one in the side oiler picture.

I also believe my own 64 427 has an HP where the 352 is on most blocks, but the car is currently bagged up in storage.

Finally, if asking 360 vs 390 vs 410/428, and you don't have the pan off, easiest way is to measure stroke with a dowel through a plug

3.50 inch stroke - 352 or 360
3.78 inch stroke - 390 or 406 (assuming no crossbolts, if you have crossbolts, I am in the "probably 427 camp" and if you have a side oil galley, definitely
3.98 inch stroke - 410 or 428

Easy to check quick, because each is approx 1/4 inch from each other making easy measuring.