Hi All, New to the thread and building a 71 Skylark. Its currently running a buick 350 and a th350 with a 10bolt open in the rear. I've already picked up a 12bolt that I'm going to put 3.55s in and a 200-4R thats been well built by Automatics Only in London Ontario. I've currently got 2 engines I'm looking at: a 72 455 with an offenhauser intake. Looks clean and no leaks. And a 70 455 that appears to be stock but in good shape. I just want to get a general Idea of what you pros think i should go with... is the extra compression in the 70 worth it? Are all 70 455s the same? (Skylark compared to riviera etc) Or is the 72 a better choice with the aluminum intake and lower miles? My car is a street car and I have the GS hood and Intake. Any help or suggestions are appreciated! Jonathan
Depends if your just dropping it in and running it (go with the '70) Or if you want a candidate for a rebuild, which either one would be good.
Thanks. Just wondering though, Is most of the smog stuff on the intake? Or Is some of it internal? If its all on the intake thats been replaced with the offy.
Most likely just dropping it in for now. But id like to upgrade it as the funds become available. I'd like to run headers and Fitech from the get-go though
Depends on condition and how treated. I'd take a 72 any day over a 70 that was run on regular gas. Offenhauser intake isn't that great and may mean it was run harder. If you can hear both I'd listen carefully to bottom end for noises. I once looked at a 70 Riv for the 455 and asked the guy if I could change his oil filter...he looked confused and said sure. I put a dry filter on to see if it made any knocking before pressure came up. No noise and bought it....that was 30 yrs ago and it still runs great.
I generally lean towards the 71+ up engines, solely on the fact they have the larger oil pickup tube and galley, there is no real smog equipment to speak , only difference is compression which isn't a huge factor imo, I put a stone stock 72 455 in a 70 Lark couple years ago and it would flat get down to be a stock engine. My opinion, if budget allows, buy both throw the 70 in there and build the 72 And a properly built matched Qjet will run like fuel injection, just sayin
Thanks guys. Really appreciating all the feedback so far. Interesting bit about a 70 run on reg fuel. The 72 add says he freshened it up to put in his Riv but sold the car. It looks clean. I think im leaning towards the 72. So the offy intake isn't very good eh? I thought it was supposes to be good, discription says it distributes fuel 360 degrees like a single plain but sits lower like a duel plain, sounded good to me at the time. Maybe an edelbrock performer would be better?
I like the offy, sits lower fits nice under the hood. I ran low 12s on one with a at 70 bottom end, some port work on small valves and the lunatI version of the hem killer cam, eddy 750 carb, 4.1 gears, 2800 rpm stall. Very consistent combo. Pull 1.53 60 time on a foot brake 2000 rpm launch, shift 6k,6k. I won way more money with that set than anything since. Still have the intake and carb it's painted red now on my brothers 68 gs 400, looks stk. Saves a lot a weight
Last time my good 464 needed work I ran a totally stk from junkyard 430, pulled my heads, sp1, carb,from one to the other. Put in a small 500 lift custom cower cam, used same converter as my 464. 430 ran 11.30s 464 was running 11.0s and 10.90s in good days. Beat that motor more than a full season, till it stretched a rod and pinched a bearing. Tried to do a cheap bearing swap and go, 15 passes later put a rod through the block. For the grand total of 500 bucks I had a lot of fun with it. It wasn't balanced and we run 6k shifts and sometines more. Even after the rod snapped the pistons still look good, I still have them
Bottom end is more the crank and rods, main and rod bearings. A good bottom end is a quiet bottom end, and good oil pressure. You don't want a knocking bottom end, whether its main or rod bearings. The stock pistons are fine for performance, it just all depends how far you want to push the performance envelope, nitrous, turbos, supercharger, NO
Make sure you get the tv cable brackets on the carb setup correctly. Have these automatics only fellow(s) assembled a 2004r that lasts before? I'm not familiar with them. A 2004r isn't one you want assembled by the local "racing" trans builder Not sure why you would need a 12 bolt unless you just have to have the 3.55. I would go to a 3.70 or 3.73 in your stock 8.5 ten bolt and sell that twelve bolt to a chevelle guy and probably come out ahead. While you are in there upgrading the gears and adding a positrac move up to some 30spline axles.
