Hey guys,

I got all my machine work back from the shop about a week ago. I should finally be getting the rings and other stuff today. I'm trying to decide if I wanna gap the rings wide for Forced Induction (originally this motor was gonna be a NA 10.76:1 compression, but I didn't mill the heads down so that puts me at 9.5:1).

Here's the stats on my 383:

4 bolt main bock with ARP studs just about everywhere
4340 Forged Eagle Crank internally balanced
4340 Ultra LW Race I beams
TRW forged floater flat tops
210CC Race Ready AFR heads (76cc)
1.6 pro mag rockers with stud girdles
Solid roller cam (XE280R)

I think I'm gonna just finish the build up and slap the victor jr intake on it for now (all that stuff is already bought) and run it NA for awhile to break everything in. I switched out to a smaller head gasket so I could pull 10.1:1 for the cam. But I'm pondering about later on going to a roots blower at like 6 lbs or so and going back to a standard head gasket for my 9.5:1.

What do you guys think? Should I gap it wide for Forced and eventually upgrade or just go NA all the way? I pretty much built this motor to put off around 550 hp easy NA. I'm figuring for a blower the 177 is out of the question since I will about knocking on max flow as soon as I slap it on... I kind of want to keep serpentine since I already got all my underdrive pulleys on my stock 350 and a new stewart pump, so that means a 4-71 is probably out of the question.

 

I'll probably just research alittle bit on the 177 weiand. Just looking for something I could slap on reasonably cheap in price.

Ok with further research I decided theres no way a 144 will put out the kind of boost I want and a 177 doesn't have a super long nose type for a serpentine setup so I guess I'm thinking 4-71 or 6-71 now... For that low of boost I'm thinking a 4-71 or something along that line would work best since I only have 1 carb currently and I would loose a lot of pressure spinning the 6-71 that slow (6 lbs).

What's everyone else think?

 

if your stuck on a roots style blower, and dont want anything too custom (like rooster433, mrdude1, saturn5) then definately go with a 6-71. im no expert but from what i do know a 4-71 is out of the question aswell

 

You can get 15psi out of a 144 on a 305 don't know where that would be on a 383

I just ran the numbers on a 350/142 weiand combo at 15psi came out at 499 hp

 

My 383 with solid roller makes 577 hp on DD2000 NA.

That's with plugging in the custom flow chart from AFR and the cam lsa, intake centerline, durations, IVO, IVC, EVO, and EVC.

There's no way you can run 15 psi out of a 142 without some serious cooling... probably 7.5:1 and a superchiller with freon going through it. At 6 psi with 9.5:1 you're pretty much cracking on the edge of pinging cause roots aren't all that efficent at moving the air + there a pita to intercool.

Well I didn't really want to wrap a lot of money into a supercharger like a centifugal setup for a carb. I was thinking roots cause it would give me a lot more low end tq and I could pretty much slap new head gaskets on and throw it on since my AFPR is boost refrenced.

Well from what I read a 142 is done around 500 hp and a 177 is done around 600 hp. A 4-71 would be around a 258 cfm. Even that would be close to the edge like you said. Then going to a 6-71 I would need some carbs cause willing to bet another 750 Speed Demon DP would be out of the question. I would be looking at probably around 2500 bucks+ (ebay bargains). It probably wouldn't really be worth it.

I'll probably just pass on the idea. I don't feel like switching to a 6-71 and buying another carb. I probably just go NA.

 

I ran 15psi out of a B&M 144 (7.0:1) for two years almost 15k miles with no intercooler you just have to run good fuel all the time. I agree 9.5:1 is on high of static compression for 6 psi the effective compression on that is 13.4:1 but with good fuel thats still doable.
I think with 550 N/A you could spend alot less with a nitrous set up and get the same power advantage

 

Yeah I was wanting pump gas only like 92 or 93 octane. I've already spent all the money pretty much just looking for options down the road. I have the block and assembly all in my room it has all been machined. My piston rings, bearings, oil pan, gaskets and stuff are coming today. I forgot to order my oil pump stud and pickup so I gotta still order that stuff with my next purchase (need lifters, cam, few more gaskets... various other little stuff).

I was just thinking of gapping the rings wider incase I decide that the current 383 isn't enough power I would have an option to go forced or bottled down the road for an add'd jump.

I'll probably just gap them wide cause I'll be running 10.1:1 and the rings should expand a little bit. The solid roller cam is made for high RPMs as the heads are too since it's all internally balanced I should beable to turn 7000 to 7500 redline safey.

I might add a 100 or 150 hp shot on it eventually. I figured up the ring gaps for TRW pistons they say like .018 top with NA or .024 with Forced. I'll probably play around with it cause they list nitrous appls but I don't have the print out in front of me. I'm thinking .022 top with a .024 bottom or around there. That way I should be plenty safe for a 150 shot down the road right?

 

Speed-Pro top rings (ductile iron, 4" bore)
nitrous oxide - street .020 - .022 (.005 per inch of bore diameter)
nitrous oxide - drag .028 - .030 (.007 per inch of bore diameter)

Speed-Pro 2nd rings (cast iron, 4" bore)
nitrous oxide - street .024 - .026 (.006 per inch of bore diameter)
nitrous oxide - drag .028 - .030 (.007 per inch of bore diameter)

IMO I would do .024 top and .027 2nd just to be safe with the 150 (always want to leave room for "mo power")

 

I'm just wanting a nice mid 11 sec car. Hopefully this new motor will push me there NA.

 

If ya can hook up looks like there should be no problems

 

Nice car you got Flrtin1

 

Darnit! My motor still isn't done. This project is taking forever. And I can't remember if I did 22/24 or 24/26 ring gaps now.

Upon further thinking I believe I didn't see flrtin1's post until I had all the slugs in their holes.

So I guess the ring gaps were 0.022 and 0.024. That should be safe enough for a 100 or 150 shot if I dial back the timing by the regular rule of thumb (1 degree every 25 hp)?

 

I like doing the Gap around 30-32 on the top rings for a blown application. Those suckers love to expand when the heat is on. That is my pesonal preference.

 

mid 11's is easy with a 383 & a 6-71. Dont get a peon 144 or 177 blower, and good lord...not a 4-71 either. I put together a budget blown 383 w/a 6-71 in my 68 Camaro.. ran 7.30 in the 1/8 first time out without any adjustments. That was on 6# boost with a CompCAMS 282 (or 284..forget which #) Nitrous HP cam w/1.6 rockers. Heads were Dart Iron Eagle 215's, 7.8:1 CR, rods were 5.565" 400 rods and a SCAT steel crank. Have fun w/your blower, they are very fun.

 

Upon further review I highly doubt I'll go either way.

From what I can find the nearest refiller is about a 2 hour drive. The rest are 3 to 4 hours away.

Second, I'm only bringing in 100 bucks a week total before bills. So it's going to take me a really long time if I decide to get a procharger. As shown with this motor build... been a 4 year project so far.

Third, my motor isn't even done yet... so for all I know it could hand grenade on break in.

If I ever decide to get a procharger I'll just pull the motor back out for new bearings, rings, gaskets, and head gaskets (using shimmed ones now).

So, I'll just be happy when I get my 0.022/0.024 ring gap NA 10.1:1 motor done. Around in this area only a few motors are forced and making 500+ hp (in rural area). So I'll be on my way to having a really nice 3rd gen.

Thanks for listening to all my ranting and raving guys! Nice to have someone else to talk to besides the GF bitching about me spending 7k+ on a motor, before buying a ring.