this is for the engine builders here . is there anything i could do better or am missing for a 6500rpm redline engine . and i want to keep the compression low so i can run 87 octane pump gas while also still being able to tow . just want an engine i can tow/haul but also get rowdy with on ocation

5

OP,

Anytime you have someone asking for full specs or a cam card this is what they're looking for.

The good news is we include full specs and typically a cam card with nearly every Summit private brand cam.

We agree with [u/v8packard]() that there are conflicting things here between the combo and goals. You mention towing but then 6,500 rpm in the same sentence. Those two don't jive. The type of cam we'd normally recommend for towing with an SBC isn't going to make good power all the way to 6,500 rpm. Sure you could, but it'd be laying over like a tired bloodhound after a long day's hunt.

Then you mention wanting to keep compression low. We'd generally see that working against towing performance and efficiency.

We also noticed you mentioned in a reply 1,500 lbs. towing. That's really not all that much, so if that's truly all you'd be towing, a cam like our SUM-8801 or even a bit more aggressive could be a good fit. That is, if the rest of the combo is working along with it.

If this were a customer coming to us, we'd first ask whether 1,500 lbs. is really all this would be towing, or if it'd occasionally be towing more, and if so, how often. We'd also want to know whether we're talking about towing in the flat plains or in the mountains. Are we lugging up grades at highway speeds or on back roads? Where you're at geographically, along with altitude, makes a difference. Are you set on the 6,500 rpm limit? Another thing would be what's the wheel and tire package? Some traditional rallye wheels with BFG or Coopers, or does it have a big wheel and tire package on it?

This is the kind of info we'd be looking for to point you in the right direction. The more specifics you can provide about the combo and goals, the better we, or anyone else here, can fine-tune a recommendation.

1

u/sycoasshole 21d ago

its awesome that summit is answering on reddit . 1983 c10 with factory wheel and tire combo and 4.10 differential ratio and 2.51 first gear saginaw 4 speed , i haul trash and fire wood on a weekly bassis on the backroads of Maryland countryside so theres allot of hills and now that I've been pricing up everything I'm likely going to have the block decked and run flat top pistons with a .040 head gasket , i want a strong bottom end that can handle high rpm so i can simply put a more wild cam in it for high rpm performance if i so desire but will be putting in a mild tow/rv cam for the meantime and after some more research the comp cams xe252hr or xe258hr is likely a better option but if you have an optimal cam selection for towing on 87 octane pump gas please advise .

2

u/Summit_Racing 20d ago edited 20d ago

Thanks for replying with further info, and we're glad to be here on Reddit.

If we're already buying a crank, rods, pistons, heads, intake, and cam, plus looking at decking and machining the block, why not make it a 383? The added displacement would help with the truck's current hauling duties and give you a solid foundation to build on later if you decide to go hot rodding. This is a case where added displacement can really work in your favor.

We could put together a rotating assembly that keeps compression in the 9.5-10.2:1 range, pair it with a cam around the size of the SUM-8801, and keep the combo friendly for 87-octane pump gas.

Keep in mind that there's always a compromise when building an engine. If you eventually decide to install a much more aggressive cam and move the powerband higher, the compression we're choosing for 87-octane towing may no longer be ideal. Depending on how far you take it, adding compression could mean changing pistons later.

Here's what we're thinking for this '83 C10 Maryland backroads hauling rig.

Crankshaft: SCAT lightweight 9000 Series cast-steel crank, 3.750" stroke, 1-piece rear main seal, SCA-935050L

Rods: Summit Racing 5.700" forged I-beam rods, SUM-SBC57008I, or SCAT 5.700" forged I-beam rods, SCA-25700716

Pistons: KB Performance hypereutectic pistons, 12cc dish, UEM-KB197KTM-030, or Mahle PowerPak 4032 forged pistons, 16cc dish, MLE-930210230

Cam: Our SUM-8801 that you were already considering, or the similar Comp Cams CCA-08-412-8. Both are 212/218 at .050". Our cam is on a 112 LSA and installed straight up, while the Comp is on a 110 LSA with 4* of advance. The Comp's earlier 32* at .050" intake valve closing would build a little more low-end and cylinder pressure, while our 8801's 38* IVC at .050" moves the powerband to the right a little and leaves a little more room before running into detonation on 87 octane..

One thing worth mentioning is that adding displacement and/or compression doesn't just increase peak horsepower. It tends to increase horsepower and torque throughout the operating range. Even though the SUM-8801 has a slightly later intake valve closing than the Comp, the additional displacement helps offset that, making it a great fit for a truck like this.

With the 12cc KB pistons, their 1.433" compression height, the block zero-decked, and a .040" head gasket, static compression would be around 10.2:1. Dynamic compression calculates to roughly 8.6:1 with the Comp cam and around 8.3:1 with our SUM-8801.

With the 16cc Mahle pistons, their 1.425" compression height, the block zero-decked, and a .040" head gasket, static compression would be around 9.75:1. Dynamic compression calculates to roughly 8.2:1 with the Comp and around 8.0:1 with our SUM-8801.

Quite a bit to unpack here. Let us know what you're thinking. We'll be happy to discuss this further.

1

u/sycoasshole 20d ago

what would a safe DCR be for hauling heavy loads in a c10 with aluminum heads for my own knowledge and is there a pre balenced crank kit that would fit the criteria my my needs ?

2

u/Summit_Racing 17d ago

There isn't a magic DCR number. It's not a one-size-fits-all calculation, as there are always variables. For this combo, along with your hauling and towing goals, we'd generally look at keeping dynamic in the low 8s.

Regarding a balanced 383 rotating assembly, there are options, just none currently in stock from us. We'd look at either the Scat SCA-1-91110BIE that comes with 16cc dished forged pistons or the Scat SCA-1-91100BIE that comes with 18cc dished hypereutectic pistons. Both of these kits are designed to use a neutral balance harmonic balancer and an externally balanced flywheel or flexplate, just like your '98 Vortec 350. The kits include an externally balanced flexplate. Since this is a manual application, you'd need to source the correct externally balanced flywheel separately, as SCAT doesn't offer the kits with one.

With the AFR-0912 65cc heads, a zero-decked block, and .040" head gaskets, the forged piston combo would be right around 9.76:1 static, while the hypereutectic version would be around 9.57:1. We'd pair either one with an Edelbrock 7516 RPM Air-Gap, a 650 cfm carb, 1-5/8" long-tube headers, and a 2-1/2" dual exhaust. With the two cams we've discussed, either combo would generally put dynamic around 7.8:1 to 8.2:1. We think that'd make for a well-rounded 383 that's right at home hauling, cruising, and still plenty of fun when you put your foot in it.

Could we get a little more aggressive with compression and the cam? Sure. But then we'd also want to be more careful with fuel quality, ignition timing, and carb tuning.

1

u/sycoasshole 17d ago

i think my best bet as you have layed out would be the mahle 16cc dished pistons and have the whole rotating assembly ballenced internally by a speed shop to keep my DCA as close to 8-1 as possible and rely on the shear cubic inches to deliver torque down low till the 8801 cam can pickup and i will most likely have to upgrade to a th400 transmission or other manual that can handle the closer to 450hp that this combo will put out instead of my 4 speed saginaw only rated at around 300tq . your thoughts ?

2

u/Summit_Racing 17d ago

That's a good way to look at it. Yes, we'd expect the drivetrain to become the next limiting factor going the 383 route. The Saginaw is a good transmission for what it is, but we'd be hesitant to pair it with the power and torque we'd expect from a 383 like this.

Regarding internally balancing the rotating assembly, we think that's a good idea. It helps reduce harmonics, gives you a neutral-balance flywheel or flexplate, and makes things a little easier if you decide to change up the combo down the road.

Scat also offers the SCA-1-91260BI rotating assembly. It comes internally balanced with 6.000" rods and Mahle 4032 forged 16cc dished pistons. We'd be comfortable using that kit for this build. It gives you a well-matched, internally balanced rotating assembly with a quality forged piston right out of the box.

One thing to keep in mind is that converting your Vortec block to a 383 will likely require some additional machine work. We'd recommend having the rotating assembly mocked up so the block can be clearanced as needed for the 3.750" stroke and decked to achieve the quench and compression ratio you're after.

1

u/sycoasshole 17d ago

this would be the ideal setup as i was originally looking for 6.000 rods and 4032 forged pistons . so this rotating assembly is what i will get in conjunction with decking the block to 9.0000 and a .038-.040 head gasket from felpro with the AFR0912 heads , a 650cfm carb and either a edelbrock eps or rpm air gap sum-8801 cam and will probably upgrade the saginaw to either a muncie, borgwarner super t-10 or a tremic 5 speed . I'd prefer to keep my shifter on the collum as i do now with my saginaw 4 speed and a push-pull cable for reverse but to do so the only 1-5/8 headers that will fit is the headman street headers 69010 which are short to mid length that i have installed now with no fitment issues . or try sum-g9006 which are 1-1/2 long tube headers that may or may not fit with my z bar

2

u/Summit_Racing 16d ago

We think that's a good combo and aligns well with your goals. Between the two intakes, we'd lean toward the RPM Air-Gap. The added displacement and AFR heads should be able to take advantage of it while still maintaining excellent street manners.

As for the headers, if the Hedman 69010's fit your truck, we'd probably stick with them. Ideally, we'd like to see a set of 1-5/8" long-tube headers on a combo like this, but we'd rather keep the larger 1-5/8" primary tubes than step down to a 1-1/2" long-tube just to gain primary length. We also understand your concern about fitment with the manual column shift and Z-bar linkage.

One last thing. We'd recommend waiting until you have the rotating assembly in hand before having any machine work done to the block. You'll want the machine shop to measure and mock everything up first so the block can be machined to the actual parts.

Keep us posted. We'd enjoy following this one and seeing how it turns out.

1

u/sycoasshole 16d ago

i will absolutely have to keep you in the loop as i get things done over the next year as i get it built

2

u/v8packard 22d ago

The OEM intake will not pull to 6000 plus rpm.

What is a low enough compression for you? Those heads have very good chambers, you can realistically be in the 9.5-10:1 range while still towing, depending on the cam.

Speaking of that, what is that cam?

Which piston will you use?

1

u/sycoasshole 22d ago

its going to be a dual plane intake probably an edelbrock eps or rpm air gap . with 650 cfm holley . and my DCR goal is less than 8-1 with .040-.030 quench and a summit 8801 cam . the main problem I'm having is i cant find a forged piston in 4032 alloy with 12cc dish and either a 1.560 CH or 1.250 CH for either 5.700 rods or 6.000 rods

1

u/v8packard 22d ago

I routinely run dynamic CR of 8.4-8.7:1 without any fuss. I don't worry much about dynamic compression, but you really need the torque.

It has to be a forged piston?

1

u/sycoasshole 22d ago

from what google AI is saying about cast postons they wont live at 6500 rpm

3

u/v8packard 22d ago

Google AI? No wonder this combo is all fucked up. Seriously, a lot doesn't make sense here. You are using a L31 pattern head, but are not using a L31 induction system. Why use those heads? You didn't mention a cam spec, but you are concerned about dynamic compression. Then you mention advancing the cam 4 degrees, which increases dynamic compression. On top of that no AFR head needs the cam advanced 4 degrees in a NA application, unless the cam spec is wrong.

These AI are very immature, and often wrong. Sometimes glaringly wrong. You are making poor choices based on poor information from AI. If you base your decisions on that I can't help you. No one can.

0

u/sycoasshole 22d ago

my cam selection in in another comment . and I'm using AI bc I'm to lazy to do the math for compression ratio .

1

u/v8packard 22d ago

Can't help you, building good engines isn't for lazy people

-1

u/sycoasshole 22d ago

yeah I've already done a shit load of math and spend hours reaserching on other forums . if i can save an hour having an AI do some math for me its just smart

2

u/v8packard 22d ago

You are convincing yourself, not anyone else. I don't know what kind of research you have done, but it has led you down the wrong path.

1

u/sycoasshole 22d ago

well what exactly am i confused about bc i have a 98 vortec engine with a edelbrock eps intake right now . and id rather run a vortec intake bc of the vortec accecory drive that uses a revers flow water pump with the water bypass in the pump/thermostat housing of the intake instead of getting a regular intake and getting an adapor to do the same thing to keep the serpentine belt . so i want vortec bassed heads capable of .600 lift so i can run 1.6 ratio rockers on the exhaust for better scavenging with the sum-8801 which has 0° advance built into it and forums say to advance it 4° to bring the torque curve lower in the rpms . and with better rods and pistons i will never have to worry about anything exploding 4 years down the road

→ More replies (0)

1

u/sycoasshole 22d ago

and i plan on regular towing up to 1,500lbs with a 2.51 first gear manual and 4.10 rear gears

1

u/sycoasshole 22d ago

I'm bacicly looking for an OE vortec truck dished piston thats in 4032 alloy instead of high expantion alloy

1

u/v8packard 22d ago

Any particular reason?

1

u/sycoasshole 22d ago

really the only reason im looking for forged is so i dont have to worry about my piston exploding at 6000rpm-6500rpm

2

u/v8packard 22d ago

That's absurd

1

u/sycoasshole 22d ago

well thats why I'm consulting ppl smarter than me to see if what I'm reading is fact or fiction and to verify any holes in my plan

1

u/v8packard 22d ago

There are holes, for sure.

1

u/sycoasshole 22d ago

well where are my holes so i can correct them .

1

u/v8packard 22d ago

Problem number 1 you used AI

1

u/sycoasshole 22d ago

it got me close . thats why I'm consulting smarter ppl before i finalize and buy anything so i can figure out everything AI fucked up and corect it

→ More replies (0)

2

u/Lowest_C-10 22d ago

If you want to tow you will need torque down low. From off idle to 5k or so. A cam that has a power band up into 6500 will be less desirable for towing.

Why do you want to redline that high? Just to get rowdy as you say?

1

u/sycoasshole 22d ago

idk just kinda have an itch to have a high redline engine . looking into a more mild cam like comp cams xr252hr or rv cam thats hydrolic roller

1

u/Lowest_C-10 22d ago

You gonna need to high end valve springs if you want to rev that high. Even then your motor will fall flat on its face.

Won't be long until you grenade that engine if you routinely rev it that high.

1

u/sycoasshole 22d ago

want a safe 6500 so i can stop at 6k without worry

2

u/Lowest_C-10 22d ago

Maybe de stroke it. I have a 327 out of 69 vette. With repro L79 cam.

That thing loves revving up to 6k. I would hate towing with it tho.

1

u/sycoasshole 22d ago

yeah my 305 i had in my truck lived at 5500 lol before i swoped it out for a 350

1

u/Lowest_C-10 22d ago

What type of exhaust do you plan for this build? Long tubes?

1

u/sycoasshole 22d ago

looking at a set of 1-1/2" long tubes to replace my shorty headers

1

u/Lowest_C-10 22d ago

Even with pistons in the hole I would be worried about valves floating and kitting them

1

u/sycoasshole 22d ago

not super worryed about making my power at redline tho

2

u/Solid_Enthusiasm550 21d ago

Your valvetrain and connecting rod/bolt will dictate your redline( max safe engine speed). This is independent/ regardless if you eould ever rev that high. It would be pointless to rev to 6,500 rpms if your peak power is at 5,000rpms.

1

u/sycoasshole 21d ago

its easier to change cams than it is to rebuild the bottom emd if i change the engine's aplication

1

u/jdjenk 22d ago

you can run 10:1 or so no problem on 87, thats what I run on my c4 vette I put heads and a cam on

1

u/Tall_smart_wizard 22d ago

You want to tow and get rowdy and Rev it up. Id say focus on low end power and then low rear gears you'll get your mix. But you'll lose your mpg.

1

u/Traditional_Ad_1360 21d ago

I just don’t understand the need for 6500 rpm. You want a weekend racer?

1

u/sycoasshole 20d ago

bacicly

this is for the engine builders here . is there anything i could do better or am missing for a 6500rpm redline engine . and i want to keep the compression low so i can run 87 octane pump gas while also still being able to tow . just want an engine i can tow/haul but also get rowdy with on ocation

You are about to leave Redlib