High Reving Big Blocks

[Elwenil]

Ok, here's my question: How high can the average big block rev? I've had several that would only go about 6500 or 7000, regardless of cam and intake/carb size, but we have one oddball in our shop. We don't know a lot about this engine, but it looks pretty stock to me. Compression is in the neighborhood of 11 to 1, God only knows what cam, stock 906 heads, and a normal 383 block. We bought this engine used, 12 or 13 years after it was put together. We found the guy who built it, but after that amount of time, who could remember what went in an engine? He did remember the engine, being a Chevy man, he couldn't understand why this engine ran so well. He swears to this day that he has never seen another one like it, regardless of brand. The valvetrain is mostly stock with the exception of adjustable pushrods and something the engine builder called "anti-pump-up" lifters. Whatever that is. I have never heard of such a thing, but he said they were popular when the engine was new. The block is stock except for the Hemi sized oil pickup. The bottom end is balanced ans appears to have been a thorough job judging by the amount of metal drilled out of the forged pistons. When we got it, it already had a reputation, but it was after all, 12 years old. My friend put a dual plane Edelbrock on it and a 650 Holley and ran it. It ran really well, but we knew it could do better. I put my Edelbrock Tarantula single plane on it and my 750 Holley Double-Pumper, and it really woke up. This engine revs to 8000+ and pulls well all the way through. I can't figure it out. We set the rev limiter at 8000 and shifted the 727 right at the limit, and the car would tear up some stuff on the street. I'm talking about cars running 7.40's in the 1/8th that we would take by two car lengths in the 1/4 running the same gears and 3 speed autos. Has anyone else had a Mopar big block wind this tight when it was mostly stock? Just as a side note, we tore this engine down to refresh it and check it over before putting it in our 71 Road Runner and the only thing wrong was some dirt in the cam bearings. Strange...
~Elwenil~ ~.\|/.~

[340king]

We had similar experience with a 383 in high school. We were working on a '68 RoadRunner 383, 4spd car. What I'm about to tell you, I would never even imagine working now. Here's what we had.

'68 383, dished 2bbl pistons, 906 heads(stock springs), Crane SSH320NC cam(320° adv dur.), Offy 360° equal flow intake, 1-7/8" headers. We also had the close ratio 4 speed, 11" clutch, 4.11:1 ratio dana 60 and a Holley 780 vac. sec. carb.

This thing was a real pig to get rolling when cruising. First gear was like overdrive. The big cam and low compression made for very poor idle caracteristics, but light it up and watch it fly. This enigne liked 6000+. My friend Tyler (see my post on Street Warrior Forum) launched it at 6200 and shifted at 7200. With the close ratio trans, it didn't take long between shifts. Tyler usually left about 2' for the gap between tire marks from one gear to the next.

Everything was wrong with the engine combo by todays standards, but it really ran up top.

The "anti-pump up lifters" were common when racers were using hydraulic cams instead of mechanical flat tappets. The idea was to limit the oil pressure in the lifter itself, so that it would not pump up at high rpm - high oil pressure. I have a set in my D350 on a stock 340 cam. It rattles every time I start it cold, as it takes some time to fill the compressed lifter

[Christopher]

We have a lot of experience with the 383.I really like this engine.The first one is the engine currently in the Road Runner(We call it "the Bird" and I will refer to it as such from now on)Actually the engine is on a storage crate as the car is undergoing restoration.Anyway...This engine was pulled out of the car in 1976 just to give it a look at and a freshening.All we actually did was replace the bearings and the rings with Speed Pro moly's.It has 906 heads cut.030,a old street hemi grind cam from 1972,Hemi valve springs,and a 750 Holley'pumper and a ancient Edelbrock tarantula intake,3800 Turbo Action converter,4.88 Dana.We blew up the 8 3/4 when it was a 4-speed car.This engine would rev to 7500 with no problem although we shifted at 6500 and it would trap at 6500.We talked to Herb McCandless about another engine we were building with a solid lifter cam and talked about this 383.he said that engine shouldn't run that high,the cam should have given out at 6 grand.We told him the car ran solid 12.20's all day long.He didn't belive it until we went to a race in Rockingham N.C. and then he saw us and the car.It was running 12.15 at The Rock.Our other engine is in my Demon and it has the same things except for TRW 11.5 pistons and a 284/484 Mopar cam and the Demon has 5.13 gears.It runs 11.50's.It also wants to rev past 7000 easily,although this too is a 65-6800 shift point motor.

[DartGT66]

The 383 has a very short stroke, almost the same as in the small block. Therefore it should be able to rew alot. Many engines will turn 8000 rpm, but I doubpt that they make good power there, if your 383 makes good power up there, or is even able to rew that high with a moderate valvetrain, there must be something wrong. The valves should float a lot before that etc etc.

[Elwenil]

We never had any trouble with valve float. I forgot to mention that it had double springs. We did have a bit of fun trying to keep the valves in adjustment. I think the adjusting nuts on our pushrods were on their last legs. As of now we are trying to figure out the specs. on the cam. The cam journals got a little scratched and I am reluctant to try and polish them out and use it. I'll let ya'll know when I get more info on it.
~Elwenil~ ~.\|/.~

[PRO]

I had a 383 that spun a honest 7200rpms,it had a mechanical tach and tach drive dist,I later sold it to "Dart" so he can attest to it. To make a long story short I bought it already machined and assembled for $200 from a guy in a pinch,so I disassembled it and balanced it and decked the block and milled the heads. I put a hemi grind cam from P.A.W., which was .480/292*, I never degreed this cam but I'm sure it was retarded some.It was a 4spd w/3.91s and would pull from 3000-7200rpms. For every 1* you retard you gain something like 100 rpms which makes sense as this cam should of only spun 6000rpms or so.It ran a best of 12.98 thru the mufflers w3.55s, best damn 383 I ever owned.When "Dart" took it apart 3 yrs later all the rods were stretched!!! ....PRO...

[Dart]

I will attest to this nasty 383 of PRO’s. I am to blame for the stretched rods. The return spring on the secondaries (Holley 850) got loose while I was banging gears, needless to say it stayed at Wide Open Throttle for about 5 full seconds and buried the tach. The tach read 8,000 rpm for about 3-4 full seconds. I freaked, as this was the first fast car I had ever owned. I managed to shut it down, but I thought I had cooked the motor. I reattached the secondary spring and started her up, still had good oil pressure and it ran fine. That motor still ran like a banshee, until I decided to take it apart and put it into another car. I learned my lesson there. Thought I had to have an automatic, what a stupid thought. Never ran the same after putting an automatic behind it. That car was really fun to bang gears in. PRO and I used to put it in first and cruise real slow, around 3500 rpm. Push in the clutch, floor it and bang second. That car (’68 Sat) would spin, hook and go. Best ET was 12.9/107mph in Idaho. Not too shabby for a 383 B-bo