The Mahle powerpack is a real nice piston. Combine with 6" rods.
Small Block Advice Part II
Thread Starter
Racer
Joined: Sep 2008
Posts: 454
Likes: 7
From: SB County CA
Small Block Advice Part II
Since my last thread got CNX'd, I never got a chance to thank you all for the responses. I do have a few more questions. I'm about to order a short block and I've settled on a Dart SHP based 406 w/ forged assy (4.155x3.75). My new dilemma: 5.7" or 6.0" rods? 6.0" will provide a lighter assy and better ratio, but will place the pin into the oil ring land. The 5.7", although better than a factory 400, has a bit less ideal ratio, but gets the pin out of the ring pack. Of course street power is an important goal, but so is reliability and a bit of longevity. Any thoughts?
Thanks, Rob
Thanks, Rob
Drifting
Joined: Dec 2005
Posts: 1,360
Likes: 3
From: NORTHEAST
Since my last thread got CNX'd, I never got a chance to thank you all for the responses. I do have a few more questions. I'm about to order a short block and I've settled on a Dart SHP based 406 w/ forged assy (4.155x3.75). My new dilemma: 5.7" or 6.0" rods? 6.0" will provide a lighter assy and better ratio, but will place the pin into the oil ring land. The 5.7", although better than a factory 400, has a bit less ideal ratio, but gets the pin out of the ring pack. Of course street power is an important goal, but so is reliability and a bit of longevity. Any thoughts?
Thanks, Rob
Thanks, Rob
All the 383's we have built have been all with 6.00 rods and some of the pistons we use the oil righ does have a ring spacer and so far no concerns.
If you think its goin to be a problem go to the Mahle pistons as the use no spacer rings with their ring package, These piston I consider top of the line and have used quite a few sets of them with no problems.
A 6.000 rod crank will internally balance as well.
The Dart block is a very wise choice!!!
Good luck with your build
Carl
Thread Starter
Racer
Joined: Sep 2008
Posts: 454
Likes: 7
From: SB County CA
Three positives in a row helps a lot. The builder recommended 6.0" rods while he also discouraged a more expensive set-up, so I feel good about following his advice. Just wanted to put a feeler out there with you all for some 'piece of mind.' Thanks.
Pro
Joined: Jul 2005
Posts: 517
Likes: 7
From: Peoria IL
Look at Probe forged pistons. I just used them in my 409 SBC w/6" rods in my build a year ago. You'll be forced to use good quality rings (1/16, 1/16, 1/8" ring set, only made by total seal) if the .030 ones are like the .040 ones I was looking for, but you should use good rings anyway on an engine like that. With the thin rings and the modern piston design, the wrist pin is not quite into the ring pack.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Thread Starter
Racer
Joined: Sep 2008
Posts: 454
Likes: 7
From: SB County CA
All,
Thanks for the inputs. I ordered the short block from CNC Motorsports, but I ended up picking 5.7" rods. I asked the same question, and with some of the feedback, I ended up taking the conservative route over optimal performance. The builder mentioned slightly better low RPM cylinder filling as the only performance benefit, but he also said that it I would never half to worry about it slightly smoking on start-up. Thought that since I'll be running side pipes, it would be the safest way to go. So thanks anyway for the inputs. We'll see how it turn out.
I do have a new question. The pistons he recommended for my goals(Probe SRP) will yield about 9.7:1 static comp when decked. Does this assume a standard head gasket thickness, and if so how much can it reasonably be altered with different gaskets?
Also, I was originally planning on AFR 195 Eliminator Streets. I was reading their website and the AFR 180 Comps are getting just a tad under 500HP with a ton of low end torque on 383s. I would think the throttle response would be better than the 195s. What are your thoughts? AFR 180 Comps too small on a 406?
Thanks,
Rob
Thanks for the inputs. I ordered the short block from CNC Motorsports, but I ended up picking 5.7" rods. I asked the same question, and with some of the feedback, I ended up taking the conservative route over optimal performance. The builder mentioned slightly better low RPM cylinder filling as the only performance benefit, but he also said that it I would never half to worry about it slightly smoking on start-up. Thought that since I'll be running side pipes, it would be the safest way to go. So thanks anyway for the inputs. We'll see how it turn out.
I do have a new question. The pistons he recommended for my goals(Probe SRP) will yield about 9.7:1 static comp when decked. Does this assume a standard head gasket thickness, and if so how much can it reasonably be altered with different gaskets?
Also, I was originally planning on AFR 195 Eliminator Streets. I was reading their website and the AFR 180 Comps are getting just a tad under 500HP with a ton of low end torque on 383s. I would think the throttle response would be better than the 195s. What are your thoughts? AFR 180 Comps too small on a 406?
Thanks,
Rob
Pro
Joined: Jul 2005
Posts: 517
Likes: 7
From: Peoria IL
Your best bet is to call Probe and ask them. Have the gasket part numbers you're interested in ready and they should be able to help you figure out your options and final compression ratio.
I'd go straight for the 195cc Eliminators/
What intake manifold do you plan on using?
I'd go straight for the 195cc Eliminators/
What intake manifold do you plan on using?
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Why don't you just ask Carl at CNC? He'll answer your questions. That's why he's in business. You can also go to Probe's site and look up the tech specs on your piston choice.
I too would go with at least a 195 head. Unless you'll never turn the thing over 5k rpm, you'll run out of the 180s attrubutes well ahead of the engine's potential.
I too would go with at least a 195 head. Unless you'll never turn the thing over 5k rpm, you'll run out of the 180s attrubutes well ahead of the engine's potential.
Race Director
Joined: May 2005
Posts: 10,674
Likes: 122
From: Millington Illinois
St. Jude Donor '08-'09
With the Mahle pistons and 6" rods the pin is not into the lower ring groove. Pluses of this combo, lighter, better ratio, better cylinder filling. Negatives. None. Price, same. We tried to tell you.
Thread Starter
Racer
Joined: Sep 2008
Posts: 454
Likes: 7
From: SB County CA
dstaley,
manifold will be RPM air gap. set-up is this bottom end, AFR 195s, and probably a FAST or PJection I or III TBI. Haven't ruled out a 750 mech carb yet though. Exhaust is Hooker side exhaust. Haven't picked a cam yet. Car is a SRIII based 68 conv with 3.45 rear gear, and TKO 600 with .64 5th.
63mako,
I hear ya, and thanks for the advice. I feel good about the choice though. Its still a better ratio than factory, and I hope more durable than a more exotic combo. This is for a driver.
All, I agree on the 195 Eliminators. Just a sanity check. Is it true that the these heads should match well with the RPM air gap and 1205 gasket? Any blending needed? Next decsion is a cam.
Thanks,
Rob
manifold will be RPM air gap. set-up is this bottom end, AFR 195s, and probably a FAST or PJection I or III TBI. Haven't ruled out a 750 mech carb yet though. Exhaust is Hooker side exhaust. Haven't picked a cam yet. Car is a SRIII based 68 conv with 3.45 rear gear, and TKO 600 with .64 5th.
63mako,
I hear ya, and thanks for the advice. I feel good about the choice though. Its still a better ratio than factory, and I hope more durable than a more exotic combo. This is for a driver.
All, I agree on the 195 Eliminators. Just a sanity check. Is it true that the these heads should match well with the RPM air gap and 1205 gasket? Any blending needed? Next decsion is a cam.
Thanks,
Rob
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
dstaley,
manifold will be RPM air gap. set-up is this bottom end, AFR 195s, and probably a FAST or PJection I or III TBI. Haven't ruled out a 750 mech carb yet though. Exhaust is Hooker side exhaust. Haven't picked a cam yet. Car is a SRIII based 68 conv with 3.45 rear gear, and TKO 600 with .64 5th.
63mako,
I hear ya, and thanks for the advice. I feel good about the choice though. Its still a better ratio than factory, and I hope more durable than a more exotic combo. This is for a driver.
All, I agree on the 195 Eliminators. Just a sanity check. Is it true that the these heads should match well with the RPM air gap and 1205 gasket? Any blending needed? Next decsion is a cam.
Thanks,
Rob
manifold will be RPM air gap. set-up is this bottom end, AFR 195s, and probably a FAST or PJection I or III TBI. Haven't ruled out a 750 mech carb yet though. Exhaust is Hooker side exhaust. Haven't picked a cam yet. Car is a SRIII based 68 conv with 3.45 rear gear, and TKO 600 with .64 5th.
63mako,
I hear ya, and thanks for the advice. I feel good about the choice though. Its still a better ratio than factory, and I hope more durable than a more exotic combo. This is for a driver.
All, I agree on the 195 Eliminators. Just a sanity check. Is it true that the these heads should match well with the RPM air gap and 1205 gasket? Any blending needed? Next decsion is a cam.
Thanks,
Rob
