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Looking at 2 engine mods. Whats your opinion?

READ THIS if you haven't!
NOW I have a better understanding of how my best friend's 70 Air Grabber Roadrunner 4 speed 8&3/4 3.90 geared car was such a consistent street champion!
I have to say that I also have longed for an article on building up a 383! Lots of important, deep seeded nostalgia there for me!
 
READ THIS if you haven't!
NOW I have a better understanding of how my best friend's 70 Air Grabber Roadrunner 4 speed 8&3/4 3.90 geared car was such a consistent street champion!
I have to say that I also have longed for an article on building up a 383! Lots of important, deep seeded nostalgia there for me!
Will do thanks
 
I have a numbers matching 383 71 road Runner. Have had it for 30 years. 10 years ago I rebuilt it. It is not used much still runs good. It is 40 over, block was zero decked, I put on Stealth heads they are supposed to be 80 CC. Compression ratio is 9.38 Static. Cylinder compression is between 150 to 160. Pistons are hypereutectic 5cc valve reliefs. Factory intake and a holly 3310 750cfm dual feed vacuum secondaries. Comp cam is hydraulic .475 lift duration at 50 is 233 and 240. (Nostalia Plus Cam). 1 7/8 headers. 3.55 rear. 10 inch turbo action converter I think it is a 3800 stall. Looking back I think the stall is to big. Street car.

Thinking of trying to get more compression if it would help? I would like a snappier throttle response and more low end and hp. I think the low vacuum 12 is causing poor velocity.

I understand the heads can be milled up to 060 safely. Not sure about piston to valve clearance if milled? Not sure where my compression would end up? I also have a edlebrook rpm sitting on the shelf that will replace the factory intake. Does it make sense to mill the heads will I notice a difference or do I just put on the new intake. The intake will have to be milled to fit regardless.(Block Decked.)

Thanks for any input.

Make sure it is tuned good, before throwing money at different parts.
Has the ignition been re-curved to run more initial timing? like limiting the mechanical advance to about 18-degrees?
 
Make sure it is tuned good, before throwing money at different parts.
Has the ignition been re-curved to run more initial timing? like limiting the mechanical advance to about 18-degrees?
Yes it has thank you
 
I believe I used the felpro gasket .039 compressed thickness for quench. I like what you said about compression. Have you milled a set of Stealths before? No one I spoke to could tell me how much I needed to take off. I have heard 25 to 60 thousands. My block is zero decked.

I haven’t milled my stealths, but a buddy of mine did on his low compression 440. He did the math, lots of calculators out there, and that’s what he and the machine shop came up with. And your engine, 383, will be slightly different, but you should be in the ballpark.

440 source may know exactly how many cc’s are removed for every .010” you mill off. Give them a call maybe?

I actually have the opposite problem, which is zero deck flat tops on a 470..will yield ~11.0:1 with the stealth’s. I need 5-10 more cc's to drop the compression to a more pump gas friendly number. The machine shop is talking about polishing the chamber and relieving the chamber around the intake valve closer to the head gasket which should increase flow around the valve and increase the chamber ccs.
 
You have the intake. It needs to be cut. I'd cut it far enough to fit with milled heads. Add paper intake gaskets as necessary to make up the gap. Then if you want to mill the heads later it's no big deal.
Doug
 
Last time I heard stealth doesn't recommend going more then .050? From the engines I've done B engines are harder to get shaved parts 2 fit then a rb(extra deck height is more forgiving). I am not a opponent of getting some more compression shaving heads but usually pistons are a better choice.

We've shaved heads on several builds, b and rb, open chamber and closed chamber. Getting stuff to fit can be a challenge sitting on a engine stand....doing a shaved head swap in the car?? Eeek. That does not sound like much fun. It's not just the intake manifold fit but fitting valley tray as well, getting intake bolted, and preventing valley oil leaks are all tasks at hand. It may not be 2 bad, all depends on how much machining we are talking. Engine builders that machine in house have a advantage over a do-it-yourselfer, if something needs a little more shaved off they can do it right there. If your lucky, the shop will get it real close to fitting. But, it can be pretty frustrating when it's so close...but only one intake bolt will thread, or the valley is leaking oil. Sometimes it's just involves making some intake bolt holes oblong, other times....back to the machine shop multiple times, and a day spent making a custom valley tray.
If it were my car...I would look at ANY other areas before getting shaved heads to fit while in the car! I would only tackle it on a engine stand.
 
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That article that I've emphasized that another member posted shows TREMENDOUS power output improvements from BASIC BOLT ONS! Stuff that is commonplace and intuitive!
Here's the bottom line (I am SO impressed by this, and like I said, really happy to see how much performance value was added)
Dyno Results
TORQUE
RPM STK HDRS CARB INTKE CAM
3000 382.7 406.3 427.1 405.5 394.2
3200 388.1 406.6 422.6 410.9 400.0
3400 388.3 412.6 431.9 421.2 414.7
3600 394.6 411.2 433.7 426.1 431.5
3800 392.4 408.3 430.8 430.0 435.5
4000 387.2 401.3 424.6 433.0 446.5
4200 377.8 396.2 416.4 430.1 451.5
4400 371.4 390.2 409.7 430.1 451.8
4600 367.8 384.6 402.0 427.8 454.2
4800 361.6 379.5 398.5 424.3 456.6
5000 355.1 373.4 385.6 421.3 450.3
5200 337.2 357.8 368.1 407.7 449.1
5400 322.8 348.5 351.4 395.1 435.8
5600. 417.0
5800. 407.6
6000 398.2
HORSEPOWER
RPM STK HDRS CARB INTKE CAM
3000 218.6 232.1 244.0 231.6 225.2
3200 236.5 247.7 257.5 250.3 243.7
3400 251.4 267.1 279.6 272.7 268.5
3600 270.5 281.9 297.3 292.1 295.8
3800 283.9 295.4 311.7 311.1 315.1
4000 294.9 305.6 323.4 329.8 340.0
4200 302.1 316.8 333.0 343.9 361.1
4400 311.1 326.9 343.2 360.4 378.5
4600 322.2 336.8 352.1 374.7 397.8
4800 330.5 346.8 364.2 387.8 417.3
5000 338.0 355.5 367.1 401.1 428.7
5200 333.9 354.2 364.5 403.7 444.6
5400 331.9 358.3 361.3 406.3 448.1
5600 444.6
5800. 450.1
6000 454.9
FOUR HUNDRED FIFTY-FIVE HORSEPOWER and 456 ft lbs torque
from headers, carb, intake, and a cam!!
 
Last time I heard stealth doesn't recommend going more then .050? From the engines I've done B engines are harder to get shaved parts 2 fit then a rb(extra deck height is more forgiving). I am not a opponent of getting some more compression shaving heads but usually pistons are a better choice.

We've shaved heads on several builds, b and rb, open chamber and closed chamber. Getting stuff to fit can be a challenge sitting on a engine stand....doing a shaved head swap in the car?? Eeek. That does not sound like much fun. It's not just the intake manifold fit but fitting valley tray as well, getting intake bolted, and preventing valley oil leaks are all tasks at hand. It may not be 2 bad, all depends on how much machining we are talking. Engine builders that machine in house have a advantage over a do-it-yourselfer, if something needs a little more shaved off they can do it right there. If your lucky, the shop will get it real close to fitting. But, it can be pretty frustrating when it's so close...but only one intake bolt will thread, or the valley is leaking oil. Sometimes it's just involves making some intake bolt holes oblong, other times....back to the machine shop multiple times, and a day spent making a custom valley tray.
If it were my car...I would look at ANY other areas before getting shaved heads to fit while in the car! I would only tackle it on a engine stand.
Yes that was and is a concern especially because my block was decked already. Had to cut the stock intake to make it fit. I really don't want to pull the motor now I am not sure what I will do. Maybe take 30 off and let it be. How much did you take off on your b body builds? Would it be better to take of the intake to fit or the intake side of the head? Not sure it would make a difference?
 
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Did .090 on the B, nothing off the deck, it was a pain, especially the valley pan, moved the same heads over to a 440....was not hard to fit at all. Metal removed off the intake on the head. None off the intake on that one.
Another one did .040 total head/block...but the edelbrock rpm was too wide, I don't think it would've fit good on a stock engine.....had 2 machine the rpm, and really needed more off yet, even after machined it was 2 tight.
If you had to shave your intake already I wouldn't be surprised if you have .040 off already.

10.5:1 is a great goal. When you start putting shaved parts on it really becomes custom. The first time getting parts 2 fit take some time, but after that taking it apart/ putting it together is cake. Until you want to swap parts...then back to square 1.

Are you running stamped steel rockers? If so, maybe consider intake swap and a higher ratio rocker ... if you don't want to switch cams. Rockers will probably not give you bottom end , the intake could. Cam swap could get you the bottom end your looking for and more hp. 3 cams dynoed in this article. Good read.
https://www.hotrod.com/articles/camshaft-comparison-testing/
 
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Running a similar combo in my 71 runner. .030 over with flat tops .010 down in the bore. 484 cam on 108 Eddy RPM heads 84 cc, .038 gaskets with a 4.380 bore. Eddy RPM intake, 1-3/4 Doug's headers. Street Demon 625 mixer. Set the initial at 18 and the top should be 38, mines at 40 for the moment. Too cold to play outside right now. tko 500 5 speed and 4.10s with 27 " diameter tires. Put the RPM on and get it aligned. For that duration cam 14-16 initial should be close, and dump the Holley and spend the 325 for the street demon. They mix better than any Holley or Edelbrock at the low end. I know, I tried all of them and for a driver, there is no touching that T Quad style triple booster small bore primarys for response and mileage. The 625 has made 650 hp on LS engines so it's plenty. A 750 SD will give you a slight hesitation on the secondary, been there. When I do the next build, I will bump the compression with a 0 deck and surface finish for .027 Cometic gaskets. If yours was done maybe check and see if the surface finish is smooth enough to use them. Anyway, very happy with it even being slightly soft on the bottom. It winds up so fast that you don't notice it, and will pull through 6500 in a flash. Idle vac is about 10-12 once it's warmed up gets 16 on the highway but Max cruise vacuum is somewhere above 100 mph,( still working on finding enough cop free highway to determine that). Very livable but the carb makes all the difference.
 
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Running a similar combo in my 71 runner. .030 over with flat tops .010 down in the bore. 484 cam on 108 Eddy RPM heads 84 cc, .038 gaskets with a 4.380 bore. Eddy RPM intake, 1-3/4 Doug's headers. Street Demon 625 mixer. Set the initial at 18 and the top should be 38, mines at 40 for the moment. Too cold to play outside right now. tko 500 5 speed and 4.10s with 27 " diameter tires. Put the RPM on and get it aligned. For that duration cam 14-16 initial should be close, and dump the Holley and spend the 325 for the street demon. They mix better than any Holley or Edelbrock at the low end. I know, I tried all of them and for a driver, there is no touching that T Quad style triple booster small bore primarys for response and mileage. The 625 has made 650 hp on LS engines so it's plenty. A 750 SD will give you a slight hesitation on the secondary, been there. When I do the next build, I will bump the compression with a 0 deck and surface finish for .027 Cometic gaskets. If yours was done maybe check and see if the surface finish is smooth enough to use them. Anyway, very happy with it even being slightly soft on the bottom. It winds up so fast that you don't notice it, and will pull through 6500 in a flash. Idle vac is about 10-12 once it's warmed up gets 16 on the highway but Max cruise vacuum is somewhere above 100 mph,( still working on finding enough cop free highway to determine that). Very livable but the carb makes all the difference.
I may try that carb down the line. Is a .027 cometic gasket small for quench with zero deck. I thought .40 is where you wanted to be?
 
Like the wise stated... there is more than one way to skin a cat....some are better than others...mine will probably in the others category!
I hear that the main thing you want is better throttle response. Start with the basics ( cheapest/easiest) first.
Verify your timing, check your ignition thoroughly, plugs/ wires ect. Second I would work on the carb, IMO with what you have that 750 may be an issue, play with jetting or if you have a 650 throw it on to test. I have a Street Demon on my wife's car and I love it.
I think your compression is fine for a street cruiser. My next step would to get rid of that low rise intake and put a RPM on. I would think this would help with the torque down low.
Sometimes I think we ( I've done too many times to count) throw the baby out with the bath water out of frustration and unreal expectations.
Best of luck and look forward to seeing more of your process!
 
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I may try that carb down the line. Is a .027 cometic gasket small for quench with zero deck. I thought .40 is where you wanted to be?
Your correct. That was figured if I could use them now with .010. down. Sorry about that.
 
I may try that carb down the line. Is a .027 cometic gasket small for quench with zero deck. I thought .40 is where you wanted to be?
Imo, going tighter on the quench isn't a bad thing. .030 shouldn't be a problem with a short steel rod unless your valve clearance is already on the tight side....but, like Mike mentioned, cheap and easy first and again imo, gears are one of the easiest ways to make a car perform better. Are the 3.55 gears something that you want to keep for some highway driving? If not, stick some 3.91's in it. It might be all it needs with the cam and converter you already have. Sounds to me with what you are talking about doing, you could throw some gears at it and if highway driving is important, maybe you could take some of the money away from engine mods and put an OD trans in it or even a GV unit.....?

And you might check out http://www.hughesperformance.com/tc-stall/ to see if your converter is actually producing 3800.....
 
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