OP,

Thanks for getting back to us with the piston. That is also +3.2cc so all the numbers work out. To help with the piston volume/compression see this tech article we have in our Help Center about piston head volume.

We have some cam options that would work for you. The first one we're thinking of is our Pro LS stage 4 truck cam SUM-8714R1. Specs on it are .550/.550, 226/230, 112+4 with 4* of overlap. This is the largest truck cam we offer meant for EFI. If this was more of a daily driver than a weekend toy this is what we'd lean towards. You'll have a nice lopey idle with this cam but being that it's carbed it will be easy to live with.

To give you an idea of the idle check out the video below.

You Tube

A 2nd option we're thinking of is our Pro LS Single plane stage 2 cam SUM-8704. This is basically a dedicated single plane intake and carb cam. Specs on it are .551/.551, 227/239, 108+0 with 17* of overlap. This cam will have that unsteady radical "racecar" idle. If this was an EFI application we'd steer you clear of it. Being that this is carbed it's a good fit. We'd lean toward this cam if this will be more of a weekend toy that goes to the track on occasion. Something to keep in mind is the exhaust system. The more overlap there is with a cam the more free-flowing the exhaust will need to be. This is needed to help reduce exhaust reversion which becomes more of a problem as the overlap goes up. With 17* of overlap, this cam is going to want headers and an exhaust system behind it with minimal restriction.

To give you an idea of the idle check out the video below.

You Tube

With either of these cams you're going to give up some low-end. However, with this not being a tow pig and wanting to take it to the track we think that's not a bad compromise. They're going to be strong come around 2,500 RPM. With your gears and planned converter, either of these will be a riot in the mid-range when the converter hits. Then with their .550 to .551 lift, you can run the budget-friendly LS6 style springs. They'll both be happy out to 6,700 plus with those springs. The upgrade option of the TFS-16918-16 (PAC-1218) beehives will add even better stability and extend the range out a bit.

We think either of these would be a joy with this combo. It comes down to how much rowdiness your friend is looking for. We'll keep up with the thread. Let us know if we can be of any further assistance.

 

Great. That's what im looking for. Do you think there will be clearance issues with the SUM-8704 cam and the pistons I'm using?

 

Holley dual plane intake manifold looks like the best torque producer, but tested on an LS3 by Motor Trend.

https://www.motortrend.com/how-to/ls...take-shootout/

 

OP,

Going with the 8704 the 12* EVC might be getting too close for comfort for PTV. It should be fine on the intake side with its 5* IVO. We'd recommend checking PTV before final assembly. We recommend .060" on the intake side and .090" on the exhaust side. That's with shims to simulate head gasket compressed thickness. We find it best to measure the intake 8* ATDC and the exhaust 8* BTDC.

 

I really appreciate your input and i think that cam is going to be awesome on this truck, but me not being a professional builder I understand that it is always better to check and doublecheck but I would like to avoid to have to fly cut the pistons just because I don't have any experience doing that and I don't have the cutter to do it either, and if I don't cut it and I need to I would have to go through the process of returning parts and that's not ideal for the vendor of myself either.

I would really like to learn how to do it (piston flycutting) definitely. I am always up for learning and doing stuff I haven't done before but when it's about someone else's expense I tend to think twice about it. You know what I mean?

On the other hand... If I order this cam from summit racing and I find out its not gonna work without flycutting the pistons I have is it returnable? may be a silly question huh?

As you can see im an amateur that likes to have fun.

 

OP,

It sounds like the 8714R1 would be the way to go for you to avoid the chance of needing to flycut. It's fully understandable that you don't want to try flycutting for the first time with someone else's motor. We wouldn't be able to accept a return for a camshaft that has been installed.

We like looking at cams in terms of the individual valve events.

8714 at .050 valve events
IVO: 5* BTDC
IVC: 41* ABDC
EVO: 51* BBDC
EVC: -1* ATDC

The 8714 has 4* of overlap @ .050 and 56* of overlap at .006 seat timing. Duration at .050 is 226/230 .006 duration is 278/282 so lobe intensity is 52/52.

8704 at .050 valve events
IVO: 5* BTDC
IVC: 42* ABDC
EVO: 47* BBDC
EVC: 12* ATDC

The 8704 has 17* of overlap at .050 and 81.5* of overlap at .006 seat timing. Duration at .050 is 227/239 and .006 duration is 290/305 so lobe intensity is 63/66. The higher the number the slower and less aggressive the lobes are so this is a pretty big downside to the 8704. It's going to be lazier down low and not match the 8714 up high because it's not going to match 8714's .200 numbers.


Timing Events Explained

IVO: Is basically idle quality. The earlier you open the intake, the more air you're taking in on the downstroke (at the expense of idle vacuum).

IVC: Is building compression and torque down low with closing the valve early. Or using inertial charge longer after BDC and closing the valve later to increase power higher in the rpm range.

EVO: Is blowdown. Most of the blowdown occurs even before BDC because of high residual cylinder pressure. Earlier = better evacuation and less pumping loss on the piston upstroke at high speed vs. slight loss of pressure on piston during last degrees of power stroke for low end.

EVC: Is in conjunction with overlap. Most useful with open headers, equal length headers, and primary lengths wave tuned to the intake runner and rpm. We don't place much emphasis on extending this event later as it produces reversion with street performance exhaust systems.

KEY:
IVC= Intake Valve Closing
IVO= Intake Valve Opening
EVO= Exhaust Valve Opening
EVC= Exhaust Valve Closing
BTDC= Before Top Dead Center
ATDC= After Top Dead Center
BBDC= Before Bottom Dead Center
ABDC= After Bottom Dead center