Say you are doing an engine out restoration for your dad. He wants it all stock. Stock in my book is looks stock. You have a built mildly cammed 327 rotting in the corner. Swap it and make it look stock and tune around the motor? Or leave stock 305 in place... The only way any perfectionist would know is by the pad by the head.

Not a 350/327/305 thread.

Would you do it and tune it to work with the ECU or not?

85 sport coupe, EM4C, 700R4.

 

There's nothing different about a 327, from any other SBC. Think of it as a 350 except with less stroke; sort of like, you can improve a 350 by adding ¼" of stroke and turning it into a 383, or, by removing ¼" of stroke, you can turn it into a 327 and .... have some other effect on it.

That said, it'll have to have heads with accessory bolt holes in them, to bolt into one of these cars without a major ordeal of some kind with the alternator, power steering, etc. Once you get past that, bolting in and looking stock is a non-issue. Most 327s came with heads that WILL NOT work; and while anybody can bolt any SBC heads to any size SBC, most often, the only people who build 327s are either doing a numbers-matching thing to some degree, or are simply stuck in the past, and so they tend to bolt on some one of the old double-hump head castings without the bolt holes such as 461. Those WILL NOT work with the more modern accessories, or with modern fuel either, or at least not very well or for very long.

Then there's the matter of the cam... depending on how the motor was "built" (whatever that means) and what cam was used, could be quite easy, or could be nearly impossible, to get to work with the stock control system. And would be quite cheap to make EXACTLY whatever it needs to be, instead of whatever happens to be there now, for whatever use is intended. A cam, being both one of the CHEEEEEPEST parts of an engine and also one of those with the most profound impact on how it runs, should always be chosen to be THE EXACT ONE for the situation at hand, and should NEVER be compromised.

What the best path to take is, would depend on how much the car is used, what it's used for, what tuning skills you have, the condition of the stock stuff especially the carb and wiring, and so on. There's no "one right" answer. What I would do, is probably not the same as what you would do. However, I'll give you a major clue: NO WAY would I leave a stock 85 LG4 in a car I intended to actually drive. Which is not the same as saying, I would put THAT SPECIFIC 327 in it. However, no matter what motor I put in it, I would at least make a serious attempt to renew and re-use the stock carb system and to select a cam that's reasonably friendly toward that goal, because the feedback carb setup is not usually the performance-limiting component of one of these cars. It will support ALOT LOT more HP than any LG4 will ever make.

Then of course, there's the matter of THE CAR, beyond the engine; it will have super crappy gears in it, an exhaust that's BEYOND merely crappy, and so on. Part of the decision process would be, how far are you willing to go to upgrade all of those crippling parts.

The devil is in the details.

 

"Rotting"? Figuratively, or literally?

The 305 heads are bound to be better than factory 327 heads (depending upon what was done to the 327). But, as sofa explained, keeping it "looking" stock requires heads that have the accessory bolt holes. Swap the 305 heads onto the 327 shortblock (after having the heads gone through, new valve springs installed, some port clean-up would be beneficial, 1.94"/1.60" valves would help a better cam to work).

Also as sofa said, cams are cheap. The likelihood of the one in the 327 being better than what you can get now is pretty slim, if the 327 has been in the corner for any length of time.

BTW, what's "stock" mean in your dad's book?

 

The engine is figuratively rotting. It's a mutt 327. 4 bolt 350 pass dipstick block, 307 large journal crank, for the 3.25" stroke, uses 5.7" rods, and 327 pistons. It's been sitting for 10 years since the rebuild/parts combo assembled. I don't want it to rust up. The cam is a retrofit comp roller, 224 intake duration, spec'd to run fuel injection. It's a custom grind I had made for my Caprice before I junked the car. I'd be using the 305 heads. Oh, it has 3.08 gears. If I do it, I may use a 4.3 torque converter or an aftermarket one if I can find it used and lighten the governor weights in the trans to raise the top shift rpm to 6,000 to 6,200.

He likes things BONE stock, but as long as it idles nice, looks bone stock, and gets as good if not better mileage, he won't even know. It would have the air pump and all emissions, and stock exhaust. It'd still be a way better engine than the lowly LG4.