I have researched this so much that I am making myself sick with so many options. A little background. Bought a 383 engine and was guaranteed 420 HP. Well, the numbers were not even close. Ended up being 243 HP on the dyno at the flywheel. The tuner did all he could and that was the max. Needless to say I am BEYOND frustrated. The car drives very well, it is just not too quick. The specs are as follows:

383 Stroker 95 roller block

10:1 Compression

CCA-08-600-8 Thumpr Cam

Knockoff Heads 64CC, 2.02 and 1.92 valves with 200 Runners

1.5 roller rockers

Air Gap Intake

Holley Sniper EFI System

Vehicle:

62 Nova convertible

TKX Transmission

342 gears

I can’t do anything about the engine being that it sat on my engine stand for two years before I installed it. Honestly, I can bite the bullet and take the loss on that one. That is not my concern. My concern now is whether or not I do something like go with a set of AFR heads on the 383 and ditch this cam for something better or go with a 2002 LS6 that I have on my engine stand. The only thing I am lacking for the LS6 is a camshaft. I already have the Terminator and all the other things that go along with it. I bought it a while back for another project and just never used it. This SBC vs LS thing seems to just go around and around on every post I see on this site or any other one. That is obviously expected due to so many variations as well as so many opinions. I love the sound of this slow *** 383. It also dynoed 335 Ft-lb of torque @ 3000 rpm’s. Again, I want more power but I really like the low end grunt of the SBC.

My expectations are as follows, and maybe they cannot be met but that is why I am here. I am looking for expert opinions.



The car is just a toy for the weekends. The wife and I do take it out on cruises from time to time and run around town a bit and it is pretty snappy as I watch older folks past me up in their wheelchairs. Typically we are cruising at very low RPM’s. Never even sees 2000RPM’s between 1-4 while cruising which is why the LS concerns me only from what I read. No real world experience. I am looking to maintain torque down low. The car will NEVER see the track and won’t be spinning up past 5000 rpm’s. Just getting on it from time to time while getting the groceries. Money aside, what is the better option to meet this goal. LS or an AFR head change? Trying to get 450 HP or somewhere in that area. Of course I do want to keep the nasty muscle car tone, like most do so that is a factor as well. Any advice would help.

 

Roller cam 383 SHOULD be shredding '62 Nova tires in first 3 gears.
" You have the wrong camshaft, and your Tuner is an idiot "

 

Sounds to me like getting that 383 running correctly would be the best bet.
LS is great but for what you want I don't think there is any reason to go through the effort of swapping based on your use case.

 

Can’t argue with you there, but what is my approach now? AFR heads is what am looking at. 195 eliminators, 65 CC’s. Cam recommendations?

 

thanks for the advice. So when you say “running right” is it just because I have a poo *** combo? Again it runs fine, no hesitation, stumbling or anything like that. Just lacking power. It is torquey but not as I would expect. I want more.

 

Look at timing tables, adjust as necessary. Are you pretty sure camshaft indexed correctly ?
I don't know what " THUMPR " specs are, but you might find a camshaft with specs more suited to " street cruising " with wife aboard, and a lot of operation under 2000 rpm

I like 212/218 duration sticks in my heavy vehicles.

 

Sihtcan that "383 stoker", sell it with full discloser on what it is, and how it runs. Lick your wounds on the thing, I'd probably sell that LS6 too. Then get a 6.0L take out, get it swapped in. Do as much as you can afford on the upgrade side now. Cam, lifters, headers. Your still wont be at "450 HP", but that 6.0 will get you there a lot sooner than that SBC ever will.

(There's always gonna' be someone that buys into the "383" school, and will just have to have your old one.)

 

When my single cab silverado was NA it made 400 rwhp and went 13's all day long so i don't see why a 6.0 couldn't get 450?

 

My .02.
Start with the basics.
Check compression. I know it's a new engine.
Check ignition voltage in run.
Check base engine timing.
Check total engine timing.
Check spark plugs wires.
Vacuum leak some where?
Check fuel delivery. I'm not a carb guy but I believe most carbs like 5-6 psi?
I assume no clutch slip?
As said above that 383 even with knock off heads should smoke the tires.

 

Thumpr's are **** cams - designed for driving in and out of Dairy Queens.

These will work far better:

https://www.summitracing.com/search/...ller-oe-roller

Cheapest/easiest route to fix your machinist's error.

 

Agreed, the Thumpr cams make noise, they don't make power. They are for kids, not adults.
As mentioned, do both a compression and leakdown test. With 10:1 compression you should see 160+ psi on compression.
The Summit racing SUM-8807 would be a reasonable choice with 232/232 duration and designed for 1.5 rockers. With a quick cam calculator, it has 2 degrees of overlap which will give a nice sound yet be easy to tune and perfectly streetable.
Assuming the engine is good mechanically, with that cam and a proper tune, you should get 400 Ft/lbs torque and 400+ HP. You can ask Summit if they have a dyno run from that cam; they have many others.

I love the LS engine I have swapped, but especially with a 60's car I would stick with a SBC. Swaps always cost so much more than expected.

 

Something not adding up at all on the 383 SBC and even with that cam 227/241 @ .050 and 107 LSA .513/.498 lift roller.

Cam not installed right ?
Not 10:1 comp ?
Not that CCA-08-600-8 cam ?
Not a 383 ?
Those heads are REALLY crappy ?

I would pull the motor and do an inspection AFTER verifying that #1 piston is at TDC and the pointer is at 0 on the dampener.

 

I’ll second all this. Something doesn’t add up.

 

Good call on the confirming the crank dampener is correct. Determine TDC on #1 cylinder and it matches the dampener.