It's been a long time since I've posted here but I feel this latest project is Moparts worthy. Especially since there are so many G2 Hemi guys in here. While I'm certainly no Hemi guru I have been working on a 572 cube Hemi as of late. The story begins with a customer that has a '70 Challenger that he wanted a big bad Hemi under the hood or in this case through the hood. He had a local builder supply him with an ex race 572 Hemi which he swapped out the high compression pistons and big solid roller for pump gas street duty. Installs it in the car with elephant ears, crank trigger, external oil pickup, aluminum oil pan, 4-5 piece headers, electric waterpump, custom fabbed aluminum valve covers, and cross ram intake with Holley carbs. The engine he is told is good for 800-900HP buy the builder and off he goes. While in the car the customer never can seem to get it running very well and I don't think it ever went above idle. The carbs seem very rich and the whole car goes to a Holley carb tuner and this guy is truly awesome with a Holley. He goes through them and while he does improve the tune, a host of other problems really prevent the car from being driven. It is suggested that the engine should be sorted out on the dyno before going any further. Here is where I enter the picture.

On the dyno the engine looks every bit the part of a believable 800-900hp piece. It sounds crazy and looks crazy. I added dual wideband O2 sensors to my dyno recently and that was one big reason it came to me in order to sort out the fuel ratio/curve with the help of the Holley expert-GB. As expected it is very rich but we have to get a baseline so the first test is from 4500-5500 rpm. The carb linkage makes it tricky to open the throttle to WOT smoothly but the engine makes 700+ tq @ 4500 rpm. What happens after that is a bit of a head scratcher. The power falls off a cliff and makes less than 500HP with the little air cleaners installed. A backup pull is performed with no air cleaners and 740tq and a 40hp gain is seen but with the same power curve. I check timing and see it is @ 36 total and back it up to 32 and it picks up another 30hp with the same cliff jumper curve. I wanted to see what cylinder pressure was and performed a quick compression test =165 psi. We could hear some misfiring through the RPM range so we thought fresh plugs would help while I checked valve lash. The engine has a Bullet solid roller and RBRE rocker system--very nice stuff. New plugs were installed and no real changes to the power or curve is observed. We try a pull to 6500 rpm just to see and right at 5600 rpm the power makes a U-turn and heads upwards as the design of the crossram starts to shine-a best of 670HP is observed. I think we tried a few more pulls but we could not really get rid of the misfiring and time was running out as well. This was my second day working on it as it took me 6 hrs to hook it up on the dyno the previous day. The engine leaked oil at multiple places, I observed more blowby than I would like and the headers leaked too. Options were discussed with the owner and he was unhappy with several things so basically we were given the green light to pretty much start over.

He never liked the headers, the elephant ears, the external oil line system, the crank trigger,the gear drive or the valve covers, the sparkplug wires and nobody present was happy about the way it ran. I was given the greenlight to go through it and make the necessary changes. As I took it apart some interesting discoveries were made. In short we are keeping the block/crank/rods/heads/rockers/camshaft and maybe the pushrods. The block has a sleeve, the head ports were raised so radically that no intake will fit without some custom spacer work, the exhaust ports are welded to radically raise the floor, the pistons featured a very small dome, the lifters are Comp's entry level rollers, the water pump would barely turn by hand, the swinging pickup in the pan was jammed up, the crossram intake had lots and lots of work on it internally etc.....

Getting very very close to putting this back on the dyno and I think it will be a much different story. Some pics for your enjoyment. J.Rob

Promised pics, J.Rob

I elected to fill the intake port roofs. If you look closely you can see the previous port shape. J.Rob

More cylinder head work. I didn't think the heads looked right without a frost plug. J.Rob

Nice Diamond pistons with Total Seal AP/Napier ring pack. J.Rob

This intake is up for grabs if anyone wants to take a shot at it. J.Rob

Nowhere to go but up with that one.

Pretty much-a lot of low hanging fruit. J.Rob

I’m trying to figure out what the shiny ring around the chamber is?

Witness mark from the pistons contacting the heads?

Is the target to have it be in the 800-900hp range when done?

Heads and intake are old Super Stock stuff. I'd say that's why it became such a turd after changing the pistons and cam for stuff that was more street friendly. Looking at the heads and intake, plus your location; I can guess where the stuff came from... and everything you said/found with the motor makes much more sense.

I think its just the photo-No contact from what I can tell.

No 800-900Hp is not really the goal--Just a properly running engine. I'm sure anything over 700HP will be a win. J.Rob

Sounds like the valve springs are shot.....When ever the power falls off a cliff like that, its always been valve springs.

Was there something bolted to the underside of the intake ports?

I was thinking valve springs didn't sound happy as well. What are the pushrod specs?

The last pump gas 572 hemi I built made 800 HP at 6500 RPM on Oregon 92 octane non ethanol pump swill. it had around 10 3/4 to 1 compression ratio and a top end kit from Stage V heads from FHO along with one of there cams for EFI, Stage V single plane dual 4150 flange with a set of 1150 CFM dry throttle bodies with a Holley EFI kit from Rich at Fastman EFI
Nothing special in the motor as the car will have air conditioning, cruise control power steering and power brakes
This motor is going into a 1971 Challenger street and local drive to the local car shows car, customer wanted a "Hemi"
I call the 426 Hemi motors Hemiroids for a reason
Good luck on yours, they are basically a internal combustion motor after all

Yeah, looks like a bunch of obsolete super stock parts. The valve springs might be shot or perhaps that cross ram was just so messed up that it shuts the power off for a big chunk of the curve. Depends what the customer wants but a good single plane intake would probably solve most of the issues. Or something like the Stage V intake. Good luck sorting it out. Customers usually aren't too happy about spending money to fix the last guy's mistakes.

It did have hacked up self tapping screws in the runners--Maybe to hold port floor fillers? I dunno but they are gone and plugged now. J.Rob

Normally I would agree but this was different. I put the air hat on to see if CFM fell off at higher RPM's it didn't. I have also never seen valvesprings go away and then come back 500rpm later and hold on a further 1000rpm. J.Rob

Looking forward to seeing how it does after you fix it up! Seems like a typical thrown together w/ leftover obsolete race parts car show hemi. Looks good and sounds mean, but won't pull a greasy string out of a hog's butt.

That's a picture...

That is a new one
I'll try and remember it to use as a good example in a proper discussion on HP and torque