Help me pick a stroker 440 500" cam

Hello all, I need some help picking a cam for a stroker 440 =500". This will be going into a stock 68 Coronet R/T with POWER BRAKES. Car is original and strictly street driven and want to maintain drivability yet utilize parts I have laying around from my race car to keep her running during a restoration of original engine .


1968 HP Block +.030 over full race prep and fully studded
Mopar 4.15 crank
Scat rods with L19 Rod bolts
3 bolt Roller
JE Flat tops 10-1
Stage VI Mopar heads fully ported flowing 328+ cfm at 700 (small port not Max Wedge)
Stage Vi match ported single plane intake
Harland Sharp 1.5 roller rockers
2" TTI headers + 3" TTI Exhaust
F.A.S.T. EZ 2.0 fuel injection system with master fuel system

This is a motor I have laying around from my race car and want to throw in my 68 Coronet with power brakes while I am restoring original engine, I Don't really care about max power im worried about Vacuum, I need 9 to 10 for fuel injection to work and need some for power brakes also, best cam I can use for vacuum in a 500" stroker, Im sure somebody has used something im looking for. Thanks ahead of time.

I would contact these guys 931-815-3260 https://www.youtube.com/watch?v=KSGf8IjX4cY they built a fuel injected big block for a friend of mine, amazing motor, super nice guys, I got some good info off of them and bought a set of bbc heads from them, that I never got to run but they looked awesome...

My '69 Coronet has a 10.3:1 compression 505" EFI engine (0.030" over 440, 4.25" crank and 7.1" rods from 440 Source.)
Mild port Stealth heads (around 290 cfm.) Edelbrock XT EFI, but soon to have FAST XFI electronics.
I used the Comp XR286HR-10 Hydraulic roller cam 236/242 duration @ 0.050. It seems pretty mild in the 505" engine.
With the OD trans it has no trouble doing 50 MPH at 1,500 RPM. I have the rev limit set at 6,000 due to the lower pressure valve springs.
For a street engine it is OK, but I don't think the Hydraulic roller is worth all the extra expense.
I should have just gone with a slightly larger solid roller, and then I could use stiffer valve springs and raise the RPM limit.

Anyhow, it sounds pretty close in specs to the engine in the video above:
http://precisionraceengines.com/cra...troker-crate-engine-fast-ez-efi-500cid-540-hp

This is a pic of my engine when I was putting the XT EFI and Tru-Track on.

451Mopar said:

My '69 Coronet has a 10.3:1 compression 505" EFI engine (0.030" over 440, 4.25" crank and 7.1" rods from 440 Source.)
Mild port Stealth heads (around 290 cfm.) Edelbrock XT EFI, but soon to have FAST XFI electronics.
I used the Comp XR286HR-10 Hydraulic roller cam 236/242 duration @ 0.050. It seems pretty mild in the 505" engine.
With the OD trans it has no trouble doing 50 MPH at 1,500 RPM. I have the rev limit set at 6,000 due to the lower pressure valve springs.
For a street engine it is OK, but I don't think the Hydraulic roller is worth all the extra expense.
I should have just gone with a slightly larger solid roller, and then I could use stiffer valve springs and raise the RPM limit.

Anyhow, it sounds pretty close in specs to the engine in the video above:
http://precisionraceengines.com/cra...troker-crate-engine-fast-ez-efi-500cid-540-hp

This is a pic of my engine when I was putting the XT EFI and Tru-Track on.
View attachment 272031

Click to expand...

I actually have a 236/242 roller cam from hughes, any idea how much vacuum you were pulling at idle ?

- - - Updated - - -

Also what springs were you using on roller cam ?

Unless the pistons are in the hole and the stage vi's are over 78cc, it's more like 11.6 to 1 and it won't like pump gas with a small cam.

First my idle speed is around 950-1000 RPM, and I believe vacuum is 10-11", but that is at 6,000 ft altitude, so at lower altitude, it should be better.
I think when I switch the XT computer for the FAST XFI, I should be able to lower my idle speed. although not a big deal with a manual transmission.
The XT computer does not have any input/output for the A/C clutch so it does not have the idle compensation for the A/C, the computer also does not control the electric cooling fans which the FAST will do.

The cool thing with the EFI, it you can advance the ignition timing at idle/no load to get good idle and vacuum, then when off idle or under load, the timing can be retarded to where it normally would be.
I haven't done much tuning with the XT computer because I am changing it out.

For a fuel tank, I currently have a stock tank with a sump kit welded on and an external EFI pump. I don't like how it looks, so I am replacing it with a Spectra CR9CFI B-Body (coronet) fuel tank. I just got the tank and it has a Welbro 255 LPH internal pump that sits in a tub/baffle inside the fuel tank. It was $366 from Amazon. The part I don't on the setup is the supply and return fittings are just like a standard low pressure tank. I am going to use some short length of Gates Barricade EFI fuel line to connect the tank fittings to -6AN barbed fittings that will connect to the -6AN hose fittings I already have.

Also, I have been waiting to see when "TanksInc.com" releases their TCR9C-T EFI B-Body fuel tank? I like how the pump and float are mounted separate and the pump has threaded fittings.

Just noticed the edit about valve springs.
I am using Isky 8005A springs with comp retainers (I think 748-16?) and 10-degree locks.
The springs are 400 lbs/in rate, 135 lbs seat pressure @ 1.875 install height.
I think these springs were 5 lbs/in stiffer than the Comp 925 springs with 14 lbs more seat pressure (when installed at the same 1.875".)
I used these because I originally was using a stainless CAT 1.7:1 ratio rocker arm, but had issues with the cheap CAT rockers, and replaced them with 1.6:1 Harlan Sharpe rockers.
Anyhow, I am at 0.581" lift vs 0.617" with the 1.7:1 rockers.

Im in Chicago and have 93 oct at pump and even 100 oct. if needed. pistons are even deck with valve reliefs

It does sound like you have more compression. My heads were 84cc, pistons have 17cc dish, 0.040" head gasket, around 10.3:1 compression.
If you have flat top pistons with say 5cc valve reliefs, zero deck, 78cc heads and 0.040" head gasket, you compression should be about 12.2:1 !
I think the compression may be too much with such a mild cam and pump gas?

The big Comp Hydraulic roller XR292HR-10 (242/248@ 0.050) installed straight up at 110 icl might work? The idle vacuum should be fine, but you may still need the higher octane, or use E-85?

Your best bet is to call some cam grinders and let them know what your doing. I think they may recommend a larger cam (294-296 advertised, and around 250@ 0.050") with a wider 112 LSA to reduce overlap?

Buy a used junker engine and put it in the Coronet until you can rebuild the original engine. You are trying to pound a square peg into a round hole.

For your own good, please consider the compression ratio FIRST. The small gains from running your compression ratio real high are often heavily outweighed by the hassle of using octane boosters, race gas, reducing ignition timing and all to avoid detonation.
I struggled for years to make my 440/493 run strong and NOT knock. I was at almost 11.0 to one and tried several things to get it to run like I wanted. I think I have found a winning setup now though. I lowered the CR to 10.07 and went with a MP 284/528 solid cam with 1.6 ratio rocker arms. The car idles nice with 13" of vacuum in gear and will blow off the 295 series tires easily. This is a streetable setup that idles nice, revs nice, never overheats or fouls the plugs. I have a 2500 stall converter and 3.55 gears and I absolutely love the car now.

Kern Dog said:

I absolutely love the car now.

Click to expand...

I kinda love your car too Greg - looks great!

440NME, High CR and a small cam to keep vacuum up just ain't gonna work short of using race gas. Like IQ says - square peg/round hole.

I have the Lunati xxxx703 hydraulic flat tappet in my 512 with 12.4 static and Stealth heads, M1 intake. It gives about 12 inch vacuum at idle, which is minimum for my power brakes to work in town.

Very basic recommendation for a driver: 9.5:1 CR and a 114 LSA cam for the stroker. The 114 LSA cam will idle well and have great vacuum and with 500 inches you will have gobs of low and mid range power, which is exactly what you want for a street car.

Rhoads lifters also help with idle vacuum. They are a little noisey but do work.