Originally Posted by Sundrop (Post 6199326)

Im planning my 383 stroker build Im gonna be running a 750 Edelbrock carb,Performer Vortex Intake,flat top pistons and some Vortex heads with a compression ratio of 10.86:1 and I have no idea what cam to run in it...I want something with performance and nice hit to it...So guys I need yalls help :metal:

Originally Posted by Marv D (Post 6199766)

"Vortex" heads?? Are talking Gm 96-2000 Vortec iron casting, or is there someone out there making a head called "Vortex"

(Sorry, there is so many new-comers in the aftermarket throwing a name on some Chineese knock-off these days that I just want to make sure I 'm not making an incorrect assumption.

Step one, forget the Edelbroke carb. There nothing but a headache. But do as you will there. Just one opinion.


If this is stock Vortec heads, your limited to .43 lift without doing some work to them. An aftermarket head is typically tolerant of more lift. But again not knowing what you have will just get everyone in trouble.

Originally Posted by Sundrop (Post 6199872)

the Vortex heads are from Chevrolet and Ive never had any problems with Edelbrock carbs

Originally Posted by gofastnut (Post 6200062)

I think the Edelbrock/holley thing is a lot like Chevy/F***.
I think you're going to run into problems with those heads as far as the max lift you can run. I think detonation may be a problem at 10.86-1, unless you run a cam with enough overlap that it bleeds of some compression, but then it won't run as well.
Maybe look at some THICK head gaskets, or mill the dome off.
Keep us posted on what you do.

Originally Posted by Marv D (Post 6200162)

Yeah that would be VorteC, not VorteX. Produced in 1996 -2000 GM truck (L-31) applications. MAX lift is 0.43" as stated. The valve spring retainer hits the top of the valve guide if you try any more lift (destroying the seal and causing all sorts of valve train damage) The press-in studs are notorious for pulling out of the head on the Vortecs, and that is all assuming they are not cracked. The L-31 head was a great head,, 15 years ago. But they were a part of the GM 'less casting is better' (cheaper) being a lightweight thin casting and unfortunately the Vortec is akin to the ancient 'camel hump' heads of the 60's. Just NOT the ideal find they used to be. If you have / find a set, and having them totally rebuilt (assuming they are not hiding cracks between the exhaust seat the the coolant passage) Your going to spend as much on rebuilding them with new valves/ replacing and cutting the guides / springs / seals / milling.. the Aftermarket offers a much better head for less than you will spend 'fixing' a 15 year old used casting.

If your happy with your Edelbrock carb, then you should continue to use it.



I would have to disagree with a couple points gofast...

I've have ran Carter AFB's and Edelbrock 'performer' (simply a Weber produced clone of the AFB that Edelbrock puts their logo on) Yes there is a lot of brand loyality in carbs, but no one winning races is running a Edelbrock carb. They appeal to the "bolt it on and forget it' crowd like showcars and those that dont want to (or know how to) tune the things. I mean seriously,, how many people spend the $69 for the Edelbrock 'calibration kit' and it conveniently leaves BIG gaps in the provided jets and rods so you have to order additional metering rods to 'really' get it right. There pig fat out of the box, and most people are happy with that.

AND increasing gasket thickness to reduce compression on a detonation prone combination is really a BAD idea. He is calling out a 0.015 deck clearance, and a 0.039 gasket is already a 0.044 quench. Real close to the 0.045" quench ( 0.025 stock deck clearance and a 0.020" steel shim gasket). A large qench is a source of detonation to begin with.. Adding quench space by adding gasket thickness is really counter productive to solving the problem of a BAD combination of parts.

That said..
We absolutely agree he's going to have issues with this combination of parts. Too much compression, (just FYI contrary to common terms, Overlap doesn't bleed off compression and there is no pressure built during the intake stroke. It's the late intake valve closing that reduces cylinder pressure at the cost of low RPM torque, but I know what you mean) And trying to find a cam that offers enough duration to that end,,,, and not exceeding his lift limits on stock Vortec's,,, he has a tough ahead of him!!!

But BEFORE the build is the time to discuss things like this... How many have we heard that build with a combination of popular parts from the latest rage in the Chevy magazines,, hen come asking WHY is my motor such a gutless, detonating POS?

Originally Posted by Sundrop (Post 6200617)

Well Marv D nobody cant argue with that kind of compression cause that can bring serious power to the table I mean I cant argue with a almost 11:1 compression....I was actually hoping for a 10.5:1 ratio with the whole set up but Ill take what I posted above lol...Can you point me in the right direction of things Marv D? So when it comes down to it I'll make sure of no problems

Originally Posted by slowtruck (Post 6200737)

The problem with that compression on an iron head is you will not be able to just run pump 93 gas. You really need to stay at or just below 10.0:1 for 93 and iron heads, or you are going to need e85 or race gas to keep the motor out of detonation.
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Originally Posted by msgdsrf (Post 6201923)

I just went through all this on my new 383 which will be on the chasis dyno Tuesday (Woohoo!).

Typical cam specs for similar 383s will have about 280 adv/230 @ .050 and will then have lift about .45-.55.

If you want a good "hit", you want good torque. So I believe it's best to think in terms of air velocity instead volume of air at max RPMs. I'd rethink the carb size for certain and consider a well designed head with runners 180-190cc. You have some mismatching bits there with a 750cfm carb into 170cc head runners.

BTW, I'm at a calculated 11:1 running 91 pump gas w/ full timing and no predetonation. The rest of the numbers on Tuesday.

Originally Posted by slowtruck (Post 6209640)

How much power do you really think a 11.0:1 motor will make over a 10.0:1 motor on pump gas? Also I'm not trying to be rude but does it sound like Sundrop needs to be messing with that to get so little?

I have an 11.0:1 383 going into my 67 and it will be on e85 because its easy to get around my house and pump 93 I feel I would need to run a little rich and a little less timing to keep out of predetonation.
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Originally Posted by msgdsrf (Post 6212298)

Well, It was not a specific goal on my 383 to acheive 11:1, it's the way things came together. Compression itself doesn't add so much but it can make a build work better (i.e. cam).

We ended up spending too much time tracking a misfire (thanks to exhaust guy for breaking plugs) and haven't got everything out of it yet. Carb is dialed but I think the ignition curve could be better. Torque at the rear wheels was very flat, 305 ftlbs. at 3750 (275 from 3000). I have a few hundred miles on the engine, heat wave, traffic and even a load to the dump (That truck doesn't belong here...). No detonation (12.7 air to fuel, full timing, 91 octane pump gas), runs great.

Originally Posted by Marv D (Post 6200162)

...
I would have to disagree with a couple points gofast...

I've have ran Carter AFB's and Edelbrock 'performer' (simply a Weber produced clone of the AFB that Edelbrock puts their logo on) Yes there is a lot of brand loyality in carbs, but no one winning races is running a Edelbrock carb. They appeal to the "bolt it on and forget it' crowd like showcars and those that dont want to (or know how to) tune the things. I mean seriously,, how many people spend the $69 for the Edelbrock 'calibration kit' and it conveniently leaves BIG gaps in the provided jets and rods so you have to order additional metering rods to 'really' get it right. There pig fat out of the box, and most people are happy with that.

AND increasing gasket thickness to reduce compression on a detonation prone combination is really a BAD idea. He is calling out a 0.015 deck clearance, and a 0.039 gasket is already a 0.044 quench. Real close to the 0.045" quench ( 0.025 stock deck clearance and a 0.020" steel shim gasket). A large qench is a source of detonation to begin with.. Adding quench space by adding gasket thickness is really counter productive to solving the problem of a BAD combination of parts.

That said..
We absolutely agree he's going to have issues with this combination of parts. Too much compression, (just FYI contrary to common terms, Overlap doesn't bleed off compression and there is no pressure built during the intake stroke. It's the late intake valve closing that reduces cylinder pressure at the cost of low RPM torque, but I know what you mean) And trying to find a cam that offers enough duration to that end,,,, and not exceeding his lift limits on stock Vortec's,,, he has a tough ahead of him!!!

But BEFORE the build is the time to discuss things like this... How many have we heard that build with a combination of popular parts from the latest rage in the Chevy magazines,, hen come asking WHY is my motor such a gutless, detonating POS?

Originally Posted by Captainfab (Post 6213394)

If you don't mind, could we get some more info on your engine build that allows you to run the 11-1 static compression?

Originally Posted by msgdsrf (Post 6214104)

Nothing real special. I would say the cam intake closing at 67 ABDC keeps cylinder preasures where is runs well (and it really does). Does that take away low end, well not if you have the compression to begin with I'd say.

OEM Roller block .03 over, .015 deck (Yes, I would have perfered zero deck)
Cast 3.75 crank
Flat top Hyper w Moly comp ring
.039 gasket (x4.166 as spec'd by AFR)
AFR 180 street ported, 63cc
Compcams XR282HR-10
1.6 Rockers
Performer Air Gap
Speed Demon 650 Vacuum, Jets .07/.104, 6.5PV (@12.7AFR)

TH400 w/2600 stall, 3.73 gears and 29" tires

I have only limited experience with SBCs but have modified enough Thumpers and Twins to get a handle on four strokes. From the bike world I've always considered cylinder cranking pressure as the measure of how it might operate. Static Compression is only one factor towards what cylinder pressure will be and that is ultimately what will determine how easily compression contributes to detonation, IMHO. Then you have volumetric efficiency, cylinder heat, intake charge temps, and...