5.7 Carb'd Swap on a Reasonable Budget?

[Bighead440]

Kinda late getting into this mod Hemi thing, but when I bought my 300s 5.7L, and LOVED it, it got me thinking about a daily-driver swap into an older chassis. I have a complete (less wiring and belt-powered accessories) 2005 truck 5.7 (rear sump pan) from a mis-diagnosed truck at a nearby shop (needed a fuel pump, the shop condemned the motor and swapped it first!) that the owner swore was running mint. I have already repaired a 2005 Magnum R/T that dropped a valve seat, so I'm aware of that Achilles heel. My thoughts are what I've done in the past with good results: deglaze and re-ring with new bearings and fresh heads and cam/intake/exhaust upgrades. I see a dual plane carb'd intake is available (OCP?) and I already caught the HEMI6 MSD box and harness on sale at Summit. The truck Hemi manifolds suck but I see SRT shortys on Ebay occasionally and pass-car cast manifolds everywhere pretty cheap, so with my 400hp-ish flywheel HP goal, those might work. My questions are: at this level, would I be safe just installing upgraded-seat early heads or should I spring for Eagle heads? If I took the cheapest route here I could possibly justify a piston upgrade, and if so, what is the best choice for a little more compression and valve relief for a non-stroker? Being a traditional V-8 rodder, I want a tighter LSA cam for the sound and torque production with a 750ish CFM carb. I'm thinking a little less than 230*@.050" intake duration and 110*LSA or less. Thoughts?

 

[vegasanthony]

Pics

 

[Bighead440]

Pics

I'll shoot some when I get back to the shop. It's basically a complete, used 5.7 Hemi truck engine at this point. Just amassing parts and getting input/doing my research. I built that one 2005 R/T engine 100% stock after dropping a seat, and it ran great. This one I want to run a carb and a lopey cam in a retrofit swap.

 

[rumblefish360]

The only single carb intake I know of is the super super mighty crazy expensive MP intake.
Edelbrock makes a reasonable priced dual quad for a pair of Carters. IIRC....

 

[Bighead440]

Pics

 

[408 swinger]

You'll definitely need to swap pistons if you plan on a tighter LSA. You run outta room real fast with these. Putting Eagles on a stock early shortblock will give you a significany boost in compression. Like around 12-1. I forget the company (DSS Racing or DSX Racing?), they advertise on ebag. They have forged pistons for the gen 3 at a decent price. Starting at 600. The OCP intake should be a soild performer. Prefix(formerly Arrow Racing) makes a short runner single plane. I have this one. Works very well. Hood clearance is still a big issue.

 

[Bighead440]

You'll definitely need to swap pistons if you plan on a tighter LSA. You run outta room real fast with these. Putting Eagles on a stock early shortblock will give you a significany boost in compression. Like around 12-1. I forget the company (DSS Racing or DSX Racing?), they advertise on ebag. They have forged pistons for the gen 3 at a decent price. Starting at 600. The OCP intake should be a soild performer. Prefix(formerly Arrow Racing) makes a short runner single plane. I have this one. Works very well. Hood clearance is still a big issue.

Thanks for the info @Prefix! I have decided that 112 is maybe the LSA I want but the duration and lift will certainly cause issues. I like the DSS pistons, and I guess I'll go flat-top if I get small chamber heads. I was thinking a 4cc dome with big chamber heads and valve reliefs.

 

[Bighead440]

Well, I scored a OCP intake (dual plane, carbureted), and I have a 750 Street Demon (TQ style, phenolic center) carb, so ignition (MSD6) and induction are covered. Bought some PAC-upgraded 6.1 heads (smaller chambers/bigger ports & valves), so now I can go up to .600"plus on lift. Just trying to finalize a cam grind so I can finally select the amount of piston dome (compression). I think it's gonna be a drop-in DSS piston/ring set from Summit, just need to examine the bores good. My instincts are warning me to say conservative, with all the good Hemi flow available, so I was thinking a 219/227* .600/.575" 112*LSA cam from Howards. Then a 234/238* .585" 112*LSA shows up cheap, lightly used... Uggh

 

[rumblefish360]

Well, that’s all just power band the duration numbers. Question is, does it fit the plan?

 

[Bighead440]

Well, that’s all just power band the duration numbers. Question is, does it fit the plan?

It really doesn't, but I could alter the gear ratio some. I wanted to retain 3.55 gears with a 727 trans and maybe 2500 stall. I could always go 3.91s and/or a 3000 stall if needed. One of my problems is that I'm unfamiliar with the characteristics of a Gen 3 when you get up there in duration. My 5.7L 300s is crazy quick off the line, all stock, with a 2.62 rear gear and 20" wheels, etc. I know a stock one with short timing is a torque monster, and all the dyno tests I've seen on EFI engines (long manifold runners) with 260/268/273 etc. Comp cams show torque taking a pretty big hit with an increase in duration. I think I better err small, to avoid a 318 or 383-like loss in torque with the bigger cam listed. I know it will rev as high as I'll need with the small cam, just might limit peak numbers.

 

[dusted]

It really doesn't, but I could alter the gear ratio some. I wanted to retain 3.55 gears with a 727 trans and maybe 2500 stall. I could always go 3.91s and/or a 3000 stall if needed. One of my problems is that I'm unfamiliar with the characteristics of a Gen 3 when you get up there in duration. My 5.7L 300s is crazy quick off the line, all stock, with a 2.62 rear gear and 20" wheels, etc. I know a stock one with short timing is a torque monster, and all the dyno tests I've seen on EFI engines (long manifold runners) with 260/268/273 etc. Comp cams show torque taking a pretty big hit with an increase in duration. I think I better err small, to avoid a 318 or 383-like loss in torque with the bigger cam listed. I know it will rev as high as I'll need with the small cam, just might limit peak numbers.

You will want more converter than 2500. My swap has a 727 and 3.55 and I’m using a 2400-2600 B&M and it’s tight with the stock cam. Have a 28-3200 coming for it.