Building a S̶t̶r̶o̶n̶g̶ ̶3̶5̶0̶ 383 for Frank the Tank…

Allright.
Grumpy did not pick this cam.
So I do not have to worry about hurt feelings.
No screwing around after baseline.
Going right for an Isky Cam. Safe Zone.
 
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66 Chev Impala 3800lbs+ not including me…
Mainly a cruiser, but like the odd skid and fast acceleration… ;)
Drag racing 4-5 times a year – best ET 13.4

'68 010 4 bolt mains block, 4.040 bore (now has a crack.. needing to be replaced)
385 stroker
Scat external balance cast rotating assembly - 5.6" rods, hyperutectic pistons (flat top with approx 5cc relief)
Promaxx 185cc, (had) 72cc chamber heads – potentially/probably machined for CR when built… unfortunately unsure at this stage to what.. will clarify during rebuild..
1.5 roller rockers
Cam – see below..
Larger volume oil pan
Holley 4bbl 725cfm vac sec carb
Performer RPM intake
1 5/8 Hedman headers – removable plates after collector for racing/sounding cool..
running 98RON fuel...which I think is equivalent to US94?
26” tires – ET streets
12 bolt posi diff - 3.31:1 rear gear
TH350 auto 1st 2.52, 2nd 1.52, 3rd 1.00
Hughes GM25 2500 stall convertor
Non-power brakes

Where if anywhere do you guys see some room for low cost improvement..? I felt like there was still some tuning room, but what do you think?
 
I am unable to complete a baseline engine simulation without the Actual Paper printed Cam card Jimmy from Crow Cams.
 
Ok I picked my own 280 Mega Hydraulic Isky Cam. Found the IVO, IVC, EVO, EVC events @.050.
Ran a simulation & results are very good.

Played around & found 503 HP @ 6500 RPM with a single plane intake & 1085 cfm 4150 Holley. Still has very strong low end torque. Bumped compression to 12.5 :1.

Post results as is with Jimmies Combo. Assume static compression is 10.5:1 because we do not know for sure because he did not final assemble the 383 sbc years back now.
It wants a Single plane intake to get max HP.
 
So the Pro Max 1 heads are Ok yet.
Sure there are better heads out there.
To me its still the same without True Big Tube Racing Headers at least 2.000" primary & 3-1/2" inch collectors used your wasting your time and money trying to get more out of a SBC 383 -400 ci on pump gas 91 -93 octane and daily driver 100 % reliability.
 
I can tell you in the real world all these 383 - 400 SBC guys on pump gas claiming 500 -550 HP are full of it.
They have 350 -400 Hp Max.

Jimmie actually had more than 99 % of them.
 
Awesome stuff Brian!! tracking info down like a detective.. Thanks mate. I'm trying to take it in.. I'm not experienced with dyno simulators.. I'll ask questions as I look over it... :) Seems like my current build comes pretty close to what I was aiming for though yeah...?
 
Ok.. I'm embarrassed to say Brian's (and others') original advice back a few pages now was a new block (I'm a bit slow to see the writing on the wall with these things.. :oops: all I could see was $$$ leaking out my wallet..) and my local engine builder is not keen on another used block rebuild if I want to keep drag racing and plan to keep the car for a long time... Both I do.. :cool:

So, with a nod from the head of the house... I'm almost (pretty much) convinced to seal the leak in my block if I can and save up my $$ for a new block and rebuild.. Which means I may not get to the strip next summer... But, it decreases the risk of throwing more $$ away on the same problem in future..

My engine builder has ballpark quoted approx NZD$7k for a rebuild using a Dart SHP (NZD$3K) with 4.125 bore + new pistons/rings and other wearing parts (seals and gaskets etc) machining and boring the block and balancing.... that doesn't include a new cam or porting the heads...

Brian you've been awesome so far and other guys I'm open to your thoughts... With budget still being important and at this stage only changing the engine components not the rest of the drive train setup.. what can I achieve with the Dart SHP 4.125...? There's still a couple of unknowns with the chamber size on the heads etc.. which can be nutted out when it comes apart.. But, I can dictate compression ratios etc and what machining gets done based on your (and the builder's) recommendations..

Can you guys dyno simulate me a build with my current cam (am I right that it will be well off optimal.?) and a purpose chosen cam for the 4.125 block?

In order of importance, I'm after... durability ( I can't afford to do this again soon and don't want to be worried I'll break something..), 1/4 mile performance, bearable/acceptable street manners (I don't cruise very far very often and don't mind a bit of a rough idle...).. Thoughts..?
 
The Dart SHP block is rated to 650 Hp.
No more. So with your present cam it's reached the power limit with a 175 Hp -225 Hp Shot of nitrous oxide.

The Dart Little M block for a SBC.
Rated for 1000 Hp Racing.
Cost to buy it is $ 3000 + USD $.
 
I can not Dyno simulation your Crow Cam Jimmy.
No Cam card with IVO, IVC, EVO, & EVC Valve events listed at .050" valve lifts.

Isky 280 Mega Hydraulic cam flat tappet I used in the DD2000 Simulation.
232 @.050 on a 108 lobe centerline LCA.
It's a Good One from Isky Cams.
 
Your Fighting Repair costs now and parts replacement along with machine work.

A good way to look at things is how much does each additional Horsepower cost ?

What does it cost for 20 -50 Hp more?
What does it cost for 100-250 Hp more ?

I know what it costs SBC.

Want Real Power you need A Pontiac V8 or a Big Block Chevy.
 
Maniacmechanic1 said:
The Dart SHP block is rated to 650 Hp.
No more. So with your present cam it's reached the power limit with a 175 Hp -225 Hp Shot of nitrous oxide.

The Dart Little M block for a SBC.
Rated for 1000 Hp Racing.
Cost to buy it is $ 3000 + USD $.
Click to expand...
I hear you Brian.. But, the little M block is almost double at NZD$5300.... :( I'd be pushing shit up hill to get a $10k rebuild past the boss of the house.... ha!

I figured for the extra $$ for the shp block, I guard against the risk of cracking an old used block and can add a few cubes at the same time.

The SHP block can build a safe NA 500hp or 550hp though yes? I'll not likely ever use nitrous or other power adders in this car (hopefully one day in a purpose built race car..), because the transmission and driveshaft won't cope...and it'll will blow out $$ from there if I start replacing those..

What cam would you recommend for a durable and fast 400sbc (it would be a 400 with shp 4.125 bores yes?) The isky cam you suggested? another?

Or, do you think I could reuse my current cam in a 400 and safely add nitrous later? I don't know much about nitrous engines..
 
JimmyDuncan said:
I hear you Brian.. But, the little M block is almost double at NZD$5300.... :( I'd be pushing shit up hill to get a $10k rebuild past the boss of the house.... ha!

I figured for the extra $$ for the shp block, I guard against the risk of cracking an old used block and can add a few cubes at the same time.

The SHP block can build a safe NA 500hp or 550hp though yes? I'll not likely ever use nitrous or other power adders in this car (hopefully one day in a purpose built race car..), because the transmission and driveshaft won't cope...and it'll will blow out $$ from there if I start replacing those..

What cam would you recommend for a durable and fast 400sbc (it would be a 400 with shp 4.125 bores yes?) The isky cam you suggested? another?

Or, do you think I could reuse my current cam in a 400 and safely add nitrous later? I don't know much about nitrous engines..
Click to expand...
The easiest and most cost effective way to get to 500-550 Hp with your combo is to use a small shot of nitrous oxide.
The Isky 280 Mega with its 108 lobe centerline will work.

Still be Ok with a Dart SHP block.
Just can not exceed 650 Hp recommended.
 
550 Hp can be done Normal aspirated with a Sbc on pump gas.
Need true 400-450 cfm @28 inches of water intake flow.
Need Big Tube headers like a BIG CHEVY AND PONTIAC HAS RIGHT OFF THE SUMMIT WEBSITE AVAILABLE.

Other way is to use 13.5 -15.0 :1 static compression.
Race gas uncut.
Not practical on Street daily driving.
 
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