408 Build

[Lil Red Express]

Hey folks;
Just wondering on input for my 408 build, 360 block 30 over with a SCAT 4.00 stroke crank 6.123 rods and set of Promaxx 185 Shocker heads 65 cc. I am planning on running a solid Comp Cams 20-247-4 solid cam 236 @0.050 0.495 lift and 110 LSA, with 273 mech rockers. My question is piston selection to give me around 10-10.5to 1 CR, I was leaning towards ICON pistons. Any input would be great thanks. The application is mostly street driven in a heavy truck 6000lbs, but still capable to head to dragstrip if needed to lay down respectable numbers

 

[crackedback]

Pump swill... build it with a lower static compression

Cam - more lift

 

[gzig5]

The cam is very small for a stroker with those heads. You could easily run more than 245@.050 and at least .550 lift. Strokers eat up duration and those heads have good flow all the way past .550 -.600" lift.
There are compression calculators to figure out what a given piston will result in for a given chamber volume. You need a few numbers from the parts and need to know if the piston is at zero deck or in the hole. You didn't say what it's going into and how it will be used so any real parts recomendations are moot at this point. To get good information you need to provide vehicle weight, trans type, stall speed, rear end gearing and what you wan to do with it.

 

[Garrett Ellison]

With felpro 1008 .039 gaskets, JE/SRP SKU: 220156 https://www.jepistons.com/product/s...iston-kit-4-030-in-bore-1-460-in-ch-17-00-cc/
Get the block cut to put the pistons .004 above deck (.021 cut, give or take) and you'll be right at 10.3:, according to the Stan Weiss calculator. I'd go with this cam.
DODGE COMP Cams 20-631-5 COMP Cams Oval Track Camshafts | Summit Racing

 

[Lil Red Express]

It's going into a 78 lil red express 6000lbs 2500 stall converter 727 shift kit and 3.55's mostly street driven.

 

[Garrett Ellison]

Okay, this cam will be closer to the requirements of the 2500 stall, 3.55 gears, and three tons of fun vehicle weight.
DODGE COMP Cams 20-231-4 COMP Cams Xtreme Energy Camshafts | Summit Racing

 

[Earlie A]

I believe they rated that truck as a 6,000 lb truck to get around emissions regulations but actual weight is something like 3,900 lbs. Still heavy but only 2 tons, not 3.

Talk to Mike at B3 Racing about your rocker arm geometry on that head. I think the 273 rocker will be quite short without one of Mike's correction kits.

 

[Lil Red Express]

I believe they rated that truck as a 6,000 lb truck to get around emissions regulations but actual weight is something like 3,900 lbs. Still heavy but only 2 tons, not 3.

Talk to Mike at B3 Racing about your rocker arm geometry on that head. I think the 273 rocker will be quite short without one of Mike's correction kits.

Awesome, I was wondering because the truck rolls a lot easier than my Charger did for "that" weight should. Thank you I will check him out.

 

[NC Engine Builder]

Keep the compression moderate, in case you are forced to run garbage gasoline at some point. You will never feel the difference a 1/4 point of compression will make in a street situation

 

[Ottmundr]

Hey folks;
Just wondering on input for my 408 build, 360 block 30 over with a SCAT 4.00 stroke crank 6.123 rods and set of Promaxx 185 Shocker heads 65 cc. I am planning on running a solid Comp Cams 20-247-4 solid cam 236 @0.050 0.495 lift and 110 LSA, with 273 mech rockers. My question is piston selection to give me around 10-10.5to 1 CR, I was leaning towards ICON pistons. Any input would be great thanks. The application is mostly street driven in a heavy truck 6000lbs, but still capable to head to dragstrip if needed to lay down respectable numbers

Get this book.

 

[mbaird]

I believe they rated that truck as a 6,000 lb truck to get around emissions regulations but actual weight is something like 3,900 lbs. Still heavy but only 2 tons, not 3.

Talk to Mike at B3 Racing about your rocker arm geometry on that head. I think the 273 rocker will be quite short without one of Mike's correction kits.

Is 6000 the GVW or curb weight ?
What does the plate inside the door say ?

 

[mbaird]

6100# is the GVW…. Gross Combined Weight rating .
It’s the weight of the truck plus allowable passenger and cargo .
So the actual weight is probably around 4500#. I doubt they were rated for 2100# of payload . Base /6 models with an 833 and light rear axle may have been closer to 3900 curb weight .
This makes a big difference in your engine build .

 

[Earlie A]

Most references I've seen list the curb weight of the Lil Red at 3,850 lbs, give or take. The factory put extra heavy springs on them to get the GVW rating over 6,100# because in 1978 that would mean no catalytic converter. In 1979 the goverment raised the GVW rating so the Lil Red had cats in '79.

https://www.hemmings.com/stories/1978-79-dodge-lil-red-truck/

 

[jbc426]

Most references I've seen list the curb weight of the Lil Red at 3,850 lbs, give or take. The factory put extra heavy springs on them to get the GVW rating over 6,100# because in 1978 that would mean no catalytic converter. In 1979 the goverment raised the GVW rating so the Lil Red had cats in '79.

https://www.hemmings.com/stories/1978-79-dodge-lil-red-truck/

That's nothin', my '68 Barracuda convertible weighs 3750 lbs without me in it, and probably even more now that I added some items.

I believe a custom torque converter from Precision of New Hampton or other reputable place will make it perform even better than a 2500 rpm unit.

 

[MOPAROFFICIAL]

More cam lift ..like .530-.575
Build it to have an 8.1 dynamic
Replace the 273 rockers with something better.
750 carb
Use a step header 1.60-1.75

 

[fishmens67]

I'd kick the cam up a notch, something in the 245@.050 560 lift range.
What carb and intake are you planning on using? kind of a key piece you left out.

 

[Bewy]

I think the cam is a good choice. One word stood out in post #1. Heavy. So easy to over cam & turn into a turd....

That cam is a Variable Duration Cam that Comp released years ago. The seat duration can be changed +/- 10* by varying the lash. A great feature.

 

[SixPaksRule]

Good cam choice, everyone wants to over-cam the stoker as usual

HEAVY is the key word.

 

[furrystump]

If it is really at zero deck, the Icon dished piston of I think 22ish CC’s should get you close to 10 to 1.
DODGE ICON IC745KTD.030 ICON Premium Forged Piston and Ring Kits | Summit Racing

 

[mopowers]

I just finished putting together a 408 with Trickflow heads that measure 59.5 cc. When I asked here, the overwhelming consensus was to build for quench and let the compression ratio land where it lands w/ the parts I had. Mine ended up higher than I wanted at 10.4:1 SCR and 8.1:1 DCR. I'm hoping the tight .039" quench and aluminum heads will allow it to run on 91, but we'll see when I get it up and running.

With Icon 745 pistons and 65 cc heads, you're looking right at 9.9:1 at zero deck w/ a .039" gasket. No reason that shouldn't be a great pump gas combo.

As I recall, a potential alternative is to use Autotec pistons. They have a slightly shorter compression height and a larger 24.5 cc dish if I believe

 

[crackedback]

My f250 PS diesel weigh 6300 pounds... no way does that Lil Red weigh close to that!

People that assume or take incorrect info at face value and try to provide input are awesome. Well done.

More lift on the cam...

Invest in a GOOD converter. Not some off the shelf, factory high stall crap. JMO Single most important item in an auto trans build and the FIRST place people cheap out. Wrong spot to be cheap!

 

[autoxcuda]

I just finished putting together a 408 with Trickflow heads that measure 59.5 cc. When I asked here, the overwhelming consensus was to build for quench and let the compression ratio land where it lands w/ the parts I had. Mine ended up higher than I wanted at 10.4:1 SCR and 8.1:1 DCR. I'm hoping the tight .039" quench and aluminum heads will allow it to run on 91, but we'll see when I get it up and running.

With Icon 745 pistons and 65 cc heads, you're looking right at 9.9:1 at zero deck w/ a .039" gasket. No reason that shouldn't be a great pump gas combo.

As I recall, a potential alternative is to use Autotec pistons. They have a slightly shorter compression height and a larger 24.5 cc dish if I believe

I don't put faith in that quench recommendation... it's like quench will solve all your detonation issues.

I've got about that same quench with 9.7:1 and it's on the edge of pinging with 91 california pump gas.

 

[gzig5]

pinging with 91 california pump gas

That's more like apple cider than performance gasoline though, isn't it?

 

[Lil Red Express]

I'd kick the cam up a notch, something in the 245@.050 560 lift range.
What carb and intake are you planning on using? kind of a key piece you left out.

I’m using a M1 Dual plane with an 800cfm Edelbrock for street.

 

[Lil Red Express]

My f250 PS diesel weigh 6300 pounds... no way does that Lil Red weigh close to that!

People that assume or take incorrect info at face value and try to provide input are awesome. Well done.

More lift on the cam...

Invest in a GOOD converter. Not some off the shelf, factory high stall crap. JMO Single most important item in an auto trans build and the FIRST place people cheap out. Wrong spot to be cheap!

It’s hard to find good parts sources in Canada sometimes, I was thinking of getting a new hole shot or TCI converter, you thinking something built instead?