I am considering swapping my 305 LG4 piece of crap engine for a 67 Chevy 283 engine out of my old truck. The 283 ran like a monster and was built up a bit and only has around 15,000 miles on it since rebuild. The truck has been parked for about 3 years now. The engine in my Trans Am is taking a major crap, and i dont have the money at the moment for an engine. So I want to use the 283 engine which is right around 300hp, and would be nice upgrade from that crappy LG4.

Anyway, I need to know a few things:

#1 will the motor mounts match up? Or will I have to fabricate the mounts?

#2 anyone know of a place I can buy accessory brackets for the old style 283 engines that dont have accessory bolt holes in the heads? Can I just drill and tap the holes myself?

#3 will the flywheel from my LG4 fit the 283 crank

#4 will the 283 bolt up to my 5 speed manual trans?

#5 can I use the HEI distributor from my LG4 on the 283? The distributor is aftermarket 65K volt, adjustable advance, and only has about 500 miles on it so I'd really like to use it in place of the crappy points distributor thats on the 283 right now.

 

1. The 283 has the same motor mount holes as every other SBC.

2. Don't bother with the 283 heads, use your LG4 heads.

3. Yes

4. Yes

5. Yes

 

Why would I want to use the LG4 heads?

The LG4 heads are in terrible shape, the valves are junk, guides worn out, seals shot, it would have to be completely rebuilt to be used.

The 283 heads were rebuilt with new valves, 3 angle valve job, bowls ported, new rockers/hardened valve seats, performance springs, and has basically same size valves as the LG4 heads, and were pre-smog heads and should flow better than the LG4's.

the only forseeable benefit of using the LG4 heads, would be the accessory holes in front of heads.
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thats what I thought too, but at the parts store they said the mounts were different, which is why I asked here, cause I dont really trust parts store people since they are usually idiots anymore.

 

The LG4 heads aren't smoggers, they're a relatively decent stock head. Having the accessory bolt holes is enough of an advantage to make them worthwhile.

 

You have to ask the right question. You don't ask for mounts for a 283, you ask for mounts for the car it's going into.

Of course, there is one exception: If the 283 is a 1957 model year casting, it won't have the provisions for side mounts cast into it. I know you said the engine came out of a '67 truck, but IIRC, trucks didn't use the side mounts back then (could be bad memory cells, though). That would mean someone would have put a '57 engine in a '67 truck, but hey, anything's possible, right?

There wasn't a 283 head made that has as much performance potential as LG4 heads. Period. If extensively and expertly worked over, it may be that the 283 heads currently run better than the LG4 heads, but with less work to the LG4 heads, they'll be the better head.

 

My 67 with 283 used side mounts but it used an older style with the rubber mount bolted to the engine and a solid lower. That's why they said they are different.

You can take all of your good parts out of your 283 heads and put them in your 305 heads to save money. Then, you just need a valve grind on the head castings to get them ready. That's not much money and much easier than adapting brackets or making new holes.

Good luck!

 

Yes, the motor mounts are different for the two applications, but the mounting holes on the block aren't. You'll just bolt your LG4 mounts to the 283.

 

not sure what IIRC means, but I think I am understanding you, and your saying that the 67 Chevy C10 didnt come with a 283 with side engine mounts. Is that right? Yes the motor is infact a 67 model year engine, and it does infact have the side engine mounts like other Small block chevy engines.

I have considered using the 305 heads on the 283, I have a set of LG4 and a set of L03 heads, so I have a choice. Either would need major rebuilding. My main issue is cost. Like I was saying I dont have much cash to work with right now so rebuilding a set of heads just isnt doable at this time. And before I absorbed the cost of that, I would get a 350 engine.

How would the compression ratios differ with the LG4 heads. I dont want a huge increase in cr. I wouldnt want it any higher than 9.75:1.

There are so many variables in this that I'm afraid if I started mixing parts then I hit a snag that I cant afford. Head gaskets arent cheap and if I swap heads thats a cost I could only afford once.

However you do have me curious about how the LG4 or L03 heads would match up with the 283 block. Would the chambers overlap and create hot spots or areas for carbon build up.

 

Are you 100% of the compatibility of the parts? I hope so. That is a great idea, and I can grind my own valve seats, so I could throw a 5 angle grind on it and work the bowls and port the heads a bit. Being able to use the valves, springs, and all that stuff would make it worth it. Only snag would be the guides. Anyone know their cost? I have access to the equipment for head repair and rebuilding, so the labor is all on me. Just the cost of parts that hurts. Wish I had the equipment for drilling the accessory holes.

 

How sure are you that the guides are even worn?

 

232,000 miles, a wiped out cam, burnt valves, burns oil like crazy(about 4 quarts per tank of gas=200 miles) at startup and at high load or rpm, leaking front and rear mains, intake valley fully of crud over an inch thick for lack of maintenance, and crud coated valve stems....hmmmm, to tell you the truth, I'm not sure where I came to that conclusion....lol.....jk, yeah man, I'm pretty certain nothing in the engine is in good condition. If only you could have seen inside this engine when I replaced two lifters, I think you would agree. I'm stunned this thing even runs at all. If it were anything but a low output 305 this thing would have croked long ago. the engine is so bad I couldnt even replace valve seals because the valves wouldnt seal good enough to hold up the valve. Its pretty bad.

 

Considering the tendancy of the valve seals to leak, the valve stems actually tend to be overlubricated, so it's possible they're not worn too badly.

 

You, and everybody else that's had a set of old heads without those holes, that they've wanted to put into a car whose accessories require them, over the last 35-40 years.... You'd think, as popular of a "situation" as this is, that if there was a way, it would have been found, eh?

There's several good reasons why it hasn't; chief among which is, there's NOTHING there to drill. If you look at a head with bolt holes, you'll see a nice little bolt boss all cast into there, for the bolt to screw into. If you look at the same spot in a no-hole head, you'll see the thin layer that makes up the outside of the water jacket; and the water jacket is only about ¼" wide; and that's all. Game over. If you try to drill there, you'll go through about 1/8" of metal, and then you'll hit the water jacket. So there is no "equipment" that can make it possible. That's why you can buy the old double-hump heads WITHOUT the bolt holes for so cheap; nobody can use them in any car any more. Not without spending gigabucks on $$$ aftermarket accessory brackets$$$ that mount elsewhere. You could in theory drill a larger hole, and weld in a nut, and put sealer on the bolt threads; but is that REALLY a good idea? Probably not.

Apeiron is exactly right: the 283 block will however accomodate EVERY SINGLE PIECE, with only 2 exceptions, that you need in order to install it in your car. One piece is totally trivial, the oil dipstick; that can be overcome by using headers. The other is it's missing one starter bolt hole for the 12.8" flywheel or flex plate. There IS metal to drill that hole into, so it's only barely less trivial than the oil dipstick... IF you do it BEFORE the motor is in the chassis.

The heads will bolt up, the bell housing is the same, the accessory bolt holes on the front of the block are there (since those were actually the original front motor mounts starting in 55, and just got re-purposed later on), the side mounts are there if it's a 58-up 283, distributor is identical, even the knock sensor will go in if you want it, because it goes into the coolant drain hole that's been there since 1955.

The 305 heads are DEFINITELY the way to go. If you can do a valve job yourself, then go ahead and do that. The way to fix the guides, if they need it, is with K-Line bronze inserts. No doubt some machine shop in your area can install those for you, it's a very common procedure. Should cost maybe $7.50 a valve or so, or roughly $125. But who knows, a new set of functioning positive seals might be all it takes to get them working right.

 

I got the 283 pulled out of my old truck today and was surprised to find that I hadnt put as many miles on it as I thought, only has about 21K miles since rebuild so its a perfect candidate for what I'm doing. I was thinking that with the 305 having a smaller bore, wouldnt the chambers be smaller. I know its not much with the 305 at 3.736 and the 283 at 3.875, but would this allow the 305 heads to have larger valves installed? How big could I go. I got ahold of a machine shop and they will put new guides in the LG4 heads for only $95 so I figure at that price I'd rather have them do it, than to do it myself. But I'm thinking about going ahead and completely rebuilding the LG4 heads. I'm working on the cost right now to see what I'd be looking at before I decide for sure what I wanna do.

What size chambers does the 283 have stock and will the 305 heads raise or lower it. I know the 305 heads are 58cc, but dont know about the 283 heads. In stock form the 67' 283 had 175hp and 275tq with 8:1 compression ratio and 2 barrel carb with 1 1/4 inch choker exhaust, so it would be nice to bump up the compression a bit and with the 30 over bore, aftermarket cam and 1.6 rockers, 4 barrel q-jet balanced 780cfm, adjustable vacuum advance non-cc HEI distributor, aftermarket intake, 2 1/2 exhuast, and some bigger valves, I'd like to see 350 hp and at least 350tq. If I have to stay with the 8:1 compression ratio I'll be looking to run a turbo in the near future.

 

The size of the bore doesn't have anything to do with the size of the chambers of the heads. They put some pretty large chambers on small bore engines. Get the casting #'s off of the 283 heads, that will tell more than anything else (unless, of course, the chambers have been modified).

You can easily put 1.94"/1.60" valves in LG4 heads.

 

Yeah thats what I thought, but I thought there was a limit due to cylinder bore clearances with a big cam. I am going to be running a fairly large cam, and want the biggest valve possible that will still allow the .500+ valve travel. Would the .15 inch bigger 283 bore allow a 2.02 intake and 1.60 exhaust valve to be used and still clear the cylinder bore?