I'm getting ready to build a 493 for my 70 RR coupe. The car currently has a TRW based 440 with ported 915's, TM-7, 1" spacer, HP950, MP590 solid w/1.5 rockers, and 2" Super Comps into 3" exhaust (Old School!). 727 / 3.91 8 3/4 3800# with driver. On 275/50/15 Drag T/A's we ran a traction limited 11.95 at 117.5 last fall in cool air at 600' altitude. The car was driven 80 miles to the track (Muncie, IN) and run as driven. Chassis dyno says 392 HP at wheels, I'd guess 520 at the crank.

We are upgrading to new Moser axles and will be going to a 28" tall tire. I also have a new A&A 727 and 9 1/2" Dynamic converter (3800 stall) that we are installing now.

For the 493, I have a set of "stealth" heads, CNC ported by Jeff at MCH, and a port matched Street Dominator intake (to get some hood clearance). I'd like to re-use my headers and carb on the 493. Springs on the heads are the 440 source outers with some Comp 974 inner springs, 10 degree steel retainers and lash caps. 150# on the seat, 420# at .650", bind at .720". Heads milled to 82.5cc.

Flow Numbers:

Intake Exhaust Exhaust w/tube
.100 75.0 71.0 72.9
.200 156.7 120.4 124.8
.300 218.8 158.6 166.4
.400 264.2 184.7 198.1
.500 296.8 200.3 219.3
.550 308.2 206.2 228.6
.600 315.9 210.9 233.3
.650 320.7 215.8 238.2
.700 322.7 218.9 243.8
.750 325.6 220.8 248.2


I'm thinking zero to .005" deck height for quench with the closed chamber heads and standard gasket thickness ( .039"), static CR between 11.25 and 11.5, .030 over 440 stock block with 4.15 crank and 6.76 rods. solid flat tappet cam with about 290 duration, .650 lift ( with 1.6 rockers).

Use is 50% street / 50% strip, with trips up to 150 miles at a time. The current combo is fine for me as far as drivability, even with the .590 cam.

Objective is 80-100 HP more than current combo with equivalent drivability and good reliability.


Please offer your comments on the following:


RAS 1.6 rockers

1) Not too heavy for the RPM ( < 6800RPM) range for this engine?

2) Pros/cons to selecting the type of adjuster end ( ball versus cup)?

Camshaft

1) Comp MM solid 6587 lobe:
Dur @ .050” @ .200” Lobe 1.5 1.6

289 263 181 .404 .606 .646

2) Your recommendation on a cam

3) Need for lifter face oiling ( EDM hole) for these types of cams

Overall Buildup

1) Main studs?

2) Steel Caps?

3) 1/2" pickup?

4) oil passage mods?


Anything else you would like to mention!

I'd say main studs and alum caps and 1/2 pickup.Is the Cam 290 advertised and 263 @.050 correct?The intake carb will hold you back from making max power for sure but should still net you over 100hp over the 440 for sure

Sounds like a well sorted out deal. Your not going to run that one suggested Comp cam on the street (MM lobes) That cam is very, very aggressive its hard enough to get it to not eat lobes anyways. Better hope the factory lifter bores are square and have good clearances etc. Valve springs will be replaced about every season. Better keep a close eye on the 440 Source Outer springs
I would be very surprised if you can get that kind of RPM out of that combo.
I would run the EDM Howards style lifters, use main studs.
If your wanting to drive back and forth to the track, and really be street friendly, just reuse the MP 590 cam.
I built this very same combo, except my heads weren't CNC ported, but did have some port work 590 cam etc. 5800-5900 rpm, you could stick a fork in it, she was all done. Your port work might net you another 200-300 rpms maybe.

I would say your old engine would be lucky to have made 450 HP realistically.
New engine should make a real 550+ hp though.

I was thinkin the same thing as for the cam. I'd almost think the 590 cam maybe step up to the 1.6 rockers would be a much more street friendly cam

I would use the SQ lobe for the .875 lifter. They have a similar lobe but it is easier on springs and not as crazy as the MM. I agree on what was said. they simply are too hard to keep alive in a street application where idle time is common.

For the lower end... you dont need the 1/2" pickup. I would run simple main studs and stock caps. Modify the main feeds and radius the intake passage, and make sure the holes are fully exposed in the cam bearings so the top end gets good oiling and the oil system's fine. I also think the rpm is excessive. Using the parts, i'd think max power will be closer to 6200ish.

My 505 motor made 680 hp using similiar components. I was using the CNC ported Mopar heads but they are exactly the same as the CNC Stealth heads since Jeff uses the same program on them. I ran a small street roller cam with 260/266 duration at 050 and 1.6 rocker arms. I was using the Super Victor intake rather than the Street Dominator but I also ran the M1 intake and made similar power.

http://www.moparmusclemagazine.com/techa...lock/index.html

I have a Holley St Dominator manifold but I just didn't get around to running it during that set of dyno tests. My guess is that it would have been down a few hp from the M1 but I doubt it would've dropped much.

The 950HP carb is really only about a 750 cfm carb so it will be a bit small for a 500 inch motor. Should work great on the street though but for the strip I'd switch to the M1 with a 4500 carb if you can afford it.

"I would use the SQ lobe for the .875 lifter. They have a similar lobe but it is easier on springs and not as crazy as the MM. I agree on what was said. they simply are too hard to keep alive in a street application where idle time is common."

Moper-

Something like the 7260 SQ lobe? About the same performance as an MP 590 but less duration due to a more aggressive ramp? That lobe looks to be similar to the street roller AF used in the 505 buildup in the cited article.

Nobody has commented on ball versus cup on the rocker adjusters. Comments pro/con either way?

I agree that the max power will likely be somewhere between about 5900 and 6200, but we currently run the 440 (for which HP peaks at about 5850)up to 6500+ in the traps due to the tire size/speed and I was asking about the weight of the RAS rockers being a problem at that RPM versus the lighter aluminum 1.6 rockers (we have Crane 1.5's on the 440). I suspect we'll be running well over 120 with 493 (we're at 117.5 now), and even with the taller tire we'll be at 6300+ through the traps.

I was actually looking at the 7263 lobe, but we're on the same page. I like ball adjusters and cupped pushrods BTW.

Although I run a MM intake lobe on my race car, I agree with the posts saying not to run it on a street application. I would run the EDM lifters with those spring pressures with whatever cam you choose. It is not all race, and with the CR, a solid cam with around 265 at 0.050" sounds about right. The milder the lobe profile, the more duration at 0.050" you can stand.

The headers and carb will be fine, but I would run whatever carb spacer you can fit on the Street Dominator, it is low so you should be able to run at least 1".

I also like 1.6 rockers, but to make your life easier (pushrod clearance) you might consider just 1.5s. So check it if you go with 1.6. The 1.6 intake and 1.5 exhaust technique can also be considered.

I also believe in the common block mods, but that is a choice you need to make. The more you race it, the more risk without doing them. But anything can break at any time, even street duty (stop light hot rodding). I run aluminum main caps on my production blocks.

Everything is a trade off, especially with a bunch of street duty.