[388chevelle]

Hey guys I'm in the middle of finishing my 383 but I'm wondering what kinda of #'s ill be getting I'm shooting for 450+hp and I wanna know what all you think thx

350 2 bolt main
Bored 4.030 stroke 3.75 rod 5.7
10.5.1 statistic compression ratio
Dart shp heads 64cc 200 intake runners
6qt kicked out oil pan h.v oil pump
Msd 6al ignition box with pro billet dist.
1.6 full roller rockers Holley single plane intake
Holley 750 dp mechanical sec. No choke
Solid flat tappet cam xe cam from comp cams
Cam specs:
282 int./290 exh.
520int./540exh. Lift @ 0.50
Lobe Separation (degrees): 110
Th350 3000 stall converter n 4.11 grs 10blt rearend

 

[RB69SS396Conv]

Well-tuned, that's probably a realistic goal.

 

[Calculated Risk]

450 at the flywheel or tires?

 

[388chevelle]

To the flywheel

 

[CNC BLOCKS N/E]

Hey guys I'm in the middle of finishing my 383 but I'm wondering what kinda of #'s ill be getting I'm shooting for 450+hp and I wanna know what all you think thx

350 2 bolt main
Bored 4.030 stroke 3.75 rod 5.7
10.5.1 statistic compression ratio
Dart shp heads 64cc 200 intake runners
6qt kicked out oil pan h.v oil pump
Msd 6al ignition box with pro billet dist.
1.6 full roller rockers Holley single plane intake
Holley 750 dp mechanical sec. No choke
Solid flat tappet cam xe cam from comp cams
Cam specs:
282 int./290 exh.
520int./540exh. Lift @ 0.50
Lobe Separation (degrees): 110
Th350 3000 stall converter n 4.11 grs 10blt rearend

450 horse and added stroke will surly make those 2 bolt caps walk.

 

[PA Camaro Guy]

Easily 450. But what kind of crank is in it... big cam is gonna want RPMs further assume that's what the ign box is meant to work with.

 

[Hiline51]

I'd be a little nervous with a 2 bolt block. Don't plan on much highway cruising with 4.10s and a TH 350, you'll be over 3000 rpm. Your motor is very similar to mine (except the 2 bolt mains). I got 475hp on the engine dyno. Mine will turn up to 6300, that's the chip limit. With that block you might want to chip it a lot lower. I'm with Carl and Brian, 383s like this need RPMs to get the HP and a strong bottom end.

 

[cv67]

244 and [email protected] used that flat tappet before decent street cam
Youll like the way it runs with the parts you got
if it were me Id just use a regular ol HEI. Heard they have modules with rev limiters built in these days.
4 bolt a plus but if its already together just drive it

 

[Iforgot]

Build isn't far off from what I'm throwing together as a "spare" until I finish a 555/565.

Only difference is I'll have IK200 heads, a slightly bigger cam @ 050, and 13:1 or so instead of 10.5:1.

I have a friend with a '62 Chevy II all steel bracket car, weighs 3100 with him in it, he's got nearly the exact build as you except slightly more compression (11.5:1) and is ran a 6.77 weekend before last in the 1/8th mile. It's a nice, easy, relatively cheap combo:thumbsup:

 

[Cam]

Just a thought, a 2-bolt block is ideal for adding splayed outboard bolts & caps to. The splayed bolts are supposedly stronger than the factory 4-bolt caps because the outboard bolts are splayed, spreading the stress over a larger area of the main webs and on a different plane.

Down the street from me a neighbor has run many sbc 383s with about the same specs as you have. They were good for about 450 horsepower (and they sounded sweet).

 

[PA Camaro Guy]

I'd work back from what kind of crank is in it. If it's a machined factory crank, I wouldn't spin it so fast. If it's a cast SCAT crank or other reputable supplier of good cast cranks, it is said that you can flirt with 6000 now and then and be ok. But that folk lore implies a 4 bolt situation. That is no frequent operating guideline. Forged is a whole other ball game but I don't see someone spending on a forged crank only to hold it with 2 bolt main caps.

The 2 bolt caps will reduce your safe RPM figure further from cast limitations. I'm really not sure what the right rev limit is. If this were my engine I think I'd probably have to say that the cam isn't well sized to the RPM level the rotating assembly is constraining you. I might set the rev limit at no more than 5000. 5000 is going to cut off some of your HP curve. But we're talking some high speeds here anyway... are you really going to drive it like that? If you are never going to be on a track then don't worry about it. You'll still have a mountain of low end torque coming in probably right at converter stall speed to go have fun with on the streets. I can tell you with my 383... getting up past 4 grand if I'm not on a highway equals a trip to jail.

New splayed caps and other products can help- but it's expensive and means tearing it down, precision drilling, etc. I think you have a wicked fun engine to go play with, nothing else to do to it as long as you know where it's weak and obey the laws of physics.

 

[Hollow65]

2 bolt caps are a downer, th350 might hold up, 10 bolt won't take too much abuse. I have a 871 BDS blown 383ci 4 bolt with scat crank. Red line is 6800, I shift at 6000 daily on the street. I push 741hp at the crank. You might want to get another block as a spare. Your parts are nice but the block is a bummer. Best of luck to ya!

 

[bowtie0069]

If you don't care if it explodes, it will live forever!! I have a 2 bolt 350 I got for free--cast 4 eyebrow pistons, stock rods, stock cast crank; it's a cheapie rebuild job (I have the original owners receipts) 216° at .050" hydraulic cam. I had about $100 invested in valve springs and gaskets so I didn't care what happened to it--Threw my AFR 210's on top, hit it with a 200 shot and ran 6.60's at 101. Made about a dozen passes and it still seems pretty happy. Ran 7.60's without the bottle.

 

[cv67]

Bowtie those are the funnest types of motors

Guy locally has a super clean 70 Chevelle

Runs stocker type shorblocks, lots of cam decent head solid flat tappets and tons of nitrous
Beats the hell out of it til they break they last longer than youd think
Runs 10s all day and can cruise it anywhere. Long as the heads dont get beat up he doesnt cry if the bottom end goes. Picks up another and away he goes.

 

[CNC BLOCKS N/E]

If you don't care if it explodes, it will live forever!! I have a 2 bolt 350 I got for free--cast 4 eyebrow pistons, stock rods, stock cast crank; it's a cheapie rebuild job (I have the original owners receipts) 216° at .050" hydraulic cam. I had about $100 invested in valve springs and gaskets so I didn't care what happened to it--Threw my AFR 210's on top, hit it with a 200 shot and ran 6.60's at 101. Made about a dozen passes and it still seems pretty happy. Ran 7.60's without the bottle.

Just looked over a street rod build that had a 871 and you can just about turn the caps around in the registers they are so loose. The owner wants splayed caps installed if the rest of the block checks out fine.

 

[bowtie0069]

Carl,
I have a later 1 piece seal, roller block that is going to get a 51lb. 3.75" stroke crank; lightweight 6" rods, and 343g pistons. Do you think it will survive if kept under 6500?

 

[CNC BLOCKS N/E]

Carl,
I have a later 1 piece seal, roller block that is going to get a 51lb. 3.75" stroke crank; lightweight 6" rods, and 343g pistons. Do you think it will survive if kept under 6500?

Its the added stroke that will push the caps around along HP and torque. After all the year of building engines and I have seen it all I would not put a 3.750 crank in 2 bolt block.

There again if I was basing all my info on just one engine it might be different.

Like I said the added stroke will side load the caps more then a 3.480 stroke crank will.

Its always a gamble.