512 low deck street engine

We just finished dyno testing a low deck 512 that was built for a 1967 Dart street car. The owner wanted something that made decent power, but was smooth enough for street driving and had a small enough cam that he could use a factory HP type torque converter. The engine has TF240 heads, 9.8 compression, a hyd roller cam, a TF intake and a Holley Sniper EFI unit. The cam is a Comp Xtreme hyd roller shelf cam. The specs are 236/242 which is close to the same specs that I used in my 496, but this cam made significantly less power than the custom roller that I used. My cam was a custom QXX/QXI lobe cam selected by Dwayne and my engine made more than 600 hp. This engine made right at 600 torque and 550 hp.

I had forgotten about the last minute cam switch so I updated the thread with the correct numbers. I couldn't figure out why this engine was down 50 hp from my 496 but now I think it is the cam. My 496 had the same compression, same heads, same intake, etc. but it made 630 torque and 610 hp. The only difference was the cam lobes. My engines used the higher lift QXX/QXI lobes. Sometimes lift doesn't matter, sometimes it does. I guess in this case it matters.

Here is a short video showing us warming the engine up on the dyno. I didn't have time to shoot any videos when we ran the engine.

https://youtu.be/1kIZ09ysWR0

Awesome! That's some incredible torque. And looks and sounds great.

I've got 99% of the parts to have someone build my 508" RB. I went with TF270's. What size carb is on the 512? Using DynoSim 6, with a 10.2 compression and slightly more aggressive cam, it predicts 660 HP at 6500 and 563 Torque at 5500. Time will tell.

Nice. What’s the cam specs?
Thanks for posting

building a 512 atm from a rb, 440source kit. plan to use a similar cam (Howards 723445-08) for the same intended purpose.....the owner has got a indy dual plane intake i planned to use....do you think it will restrict it too much?

Michael

Excellent results for what the customer asked for. As i recall, a stock , 340,383,hemi, type converter will flash over 3000 with that much torque, and drive like a stocker on steroids! Fine build for a driver.

Andy? not to interrupt your thread. What did you seal your valve covers with? I been using a gasket on my 499 bracket motor, wonder if there is a different option? [leaks a little] Thanks! Happy Thanksgiving!

Comp Xtreme hyd roller shelf cam. 236/242 duration but not a ton of lift. We had a custom cam on order but it never shipped so we switched to the Comp shelf cam at the last moment since it was in stock. I think that decision cost us power but the customer wanted to get the engine finished. He is happy with 550/600 so not a big deal.

The blue gaskets in the picture are from Moroso. Not my favorite valve cover gasket but they work with a good valve cover and a machined valve cover rail.

A dual plane intake isn't really required with a 512 since you can make 600 ft-lbs with a single plane. But on an engine like this it won't restrict it. Power peaks early on these engines anyway when the cam timing is small. I say try it and see how it works.

We used a Braswell 750 hi flow for break in and then switched to the customer's Holley Sniper for the dyno pulls. The Sniper made a little more power than the Braswell but that could be due to ring seating.

Thanks for the answer. BTW, I believe I purchased your timing chain cover that allows for cam swaps. This is yours right? https://arengineering.com/products/timing-chain-cover/

Very nice!

The cam is the same one I was looking at for my 541. Dwayne brained up a similar duration stick for my 541 but with different lobes on a wider lsa. I'm not sure how the TF270 compares to my KG ported Eddy heads but it's likely a step better.

It is interesting to see the torque coming in a bit later than mine. The HP is a bit higher than mine with no valve float so you one upped me there.

Wilson called to say my intake is under the knife this week. With luck, it'll be home and ready to dyno again before Christmas.

This engine has Gaterman lifters in it, same ones we use on most of these builds. Never had any issue with bleed down or pump up and they don't seem to have any excessive noise issues.

Goof to hear. That's what I run, too.

I like that cam size for the street car even in a 500 inch motor.

Did you check the idle rpm vacuum? My cam is a little bigger, but on a wider LSA. It works okay with my tight 11" factory convertor, but it does tug a bit in-gear at idle.

What is the rocker ratio?

Thanks

Just to help keep everyone on the same page......
The low deck 512 build Andy posted about used 240’s, not 270’s.

The 240’s are a bit better than KG RPM heads on my bench(316@.600 vs 303@.600)
The 270’s are a pretty big jump up in flow from either(348@.600)

The test I’d find interesting would be the same low deck 512 Andy has here....... but with the 270’s in place of the 240’s

That would be interesting. I assume the curves would shift over to the right a bit but I don't know how much. I think the Comp shelf cam is too small for the 270 heads but I'm not sure about that. It would be interesting to see if a 512 with 270 heads could be configured to make lots of torque like this engine but still pull high enough to make an interesting amount of HP.

In my mind you’d do the head swap first(240’s to 270’s, “port matched” TF manifold)....... then start adding duration to see what it took to get the HP number to start exceeding the TQ number.

The 505 that was recently on the dyno here(10.5cr, HR, EZ295’s, Indy 2D) made the same TQ/HP.......640/640.
That combo had about 10deg more duration along with heads that flowed 344@.600.

The Indy 2D was used primarily for hood clearance reasons.

That plan would work great for a customer who wanted a square engine. (torque and power same peak values) A square engine typically has pretty good street manners, especially when coupled with the right converter but this customer wanted a smooth engine and didn't want to put a high stall converter in the car so we went with a smaller cam.

Making power isn't a problem with these Trick Flow heads, finding the right balance between power and street manners is more difficult. I've been wrestling with cam duration vs. manners for awhile now. Manual transmission cars are the worst, automatics have a much wider tuning window as long as the customer is willing to play with the converter. In my experience, almost every customer asks for more power than they are actually willing to live with!

I've notice that all the street and strip motors I've built for pump gas with less than 10.5 to 1 compression made more torque than HP with aluminum heads, no matter which cam, intake or carb size,
Motors above 10.5 to 1 compression made more HP than torque

I’d agree with that.

That is just because they didn't have a big enough cam in them. A pump gas engine can be set up to make top end power with the correct cam, intake and carb. About the only people who build engines like that are NHRA stock or super stock guys since most people would just add compression to make more power.

Yeah I'd say that we have several customers every year asking for 700 hp street engines. Once we ask them if they really, really want a 700 hp street engine they usually back off to "well, perhaps I'd be happy with 600 hp". We did do a 700 hp street engine for a guy with a four speed car. The car wasn't driveable so he pulled the four speed out and swapped in a 727 with a high stall converter and then he could drive it. He drives it to work on nice days. It is a bear of an engine but he makes it work.

I generally look at the final overall gear ratio and the cruise rpm.
Then talk with the customer about their tolerance for poor drivability, and try to come up with something of a compromise between the desired power and street manners.

Sometimes the goals and the combos are really too far apart to fix with a cam.

It’s certainly better/easier when all the parts for the combo and the goals for the car are on the same page.

I really should have listened to you guys when I swapped cams a few years ago. You both thought my choice was a little to rowdy for a 10 second stick shift street brawler.
So now I'm changing springs and putting a smaller street roller in my engine now so it's more drivable on the street.
I appreciate your input and now I'm heeding your advice

Gus

For me, time has changed what I feel is “streetable”.

Something I might have thought was “acceptable” 30 years ago......... is a often a no-go for me now.

I guess I was a bit of an odd ball (again) when I called up asking for torque instead of power and had a vacuum number in mind.

As for the heads, the numbers you got are about what I expected.


The heads are still a sticking point in my mind. I kinda backed myself into a corner with the pistons. Better heads would likely wake up the 541 nicely but the smaller ports I've got might make it feel a bit more responsive on the street. Just what a 5300 lb cruiser needs.

Not me, I like a lot of power, at the track and on the street

Better heads would likely wake up the 541 nicely but the smaller ports I've got might make it feel a bit more responsive on the street. Just what a 5300 lb cruiser needs. [/quote]
My guess is where the crossover point is for best torque between small and large port heads would be a big deciding factor. Look at the size of gen3 hemi ports compared to thier engine size. An example would be your current heads versus a 440-1, and fuel injection to help level the playing field. I bet a ported 440-1 head with a short duration cam and 1.7 rockers might be killer on a 541. Another example is the factory heads for hp 383 and hp440 were the same, along with the same cam!

Come to think of it, i have a set of killer 440-1 heads, 1.7 jesel rockers, and most of the parts to build a 580 inch street bruiser! Ok, now to find a perfectly clean Chrysler Imperial, 😁

Come to think of it, i have a set of killer 440-1 heads, 1.7 jesel rockers, and most of the parts to build a 580 inch street bruiser! Ok, now to find a perfectly clean Chrysler Imperial, 😁



Something similar to our street/strip combo 589ci wedge motor @10:1cr, a small .625" 260/270@.050 s/roller motor, 440-2 intake but with race 365cnc -13 heads, made 720ftlbs@4400 and 694hp@5500 at 33 deg.total and with a small old 950DP,....runs on pump V-power and should last well as its shifted@5800 and traps at just over 6000. Potential there for at least another 100hp with 2+points cr, more cam or even 1.7 jesels and a Dominator.

What about part throttle response and low rpm cruise?

That's where peak numbers mean nothing. Gotta make solid vacuum for power brakes and to keep the EFI in its happy place.

Feets........I’m looking forward to round two of the 541 dyno testing.



The ones I had here were CNC’d by KG, but I did the valve seat work and assembly.

Throttle response is excellent, can't get into it at all without lighting the street tyres up though which I've never seen him do, car has 11" drums and no power, stops the car good, owner goes to shows with it, low rpm cruise is fine, we adjusted the carb using vac guage once at the track, it had 15" if I remember correct@around 900>1000 for what its worth. Its driven to the track and raced with full exhaust to bumper, I don't think he could've got a much better deal (£10k for the fresh motor) as its fulfilled all his requirements and more on track, but with that came the added expense of a Dana, a race 727/converter etc. etc.

That cam is pretty close to the bullet cam I have more 505 truck motor, 10.2:1 compression, but 270 heads and indy dual plane. Still waiting for dyno time.

That cam was a custom grind comp Cams solid roller cam made for Benshoff racing that I was able to buy from the owner before he used it.
It is 260 @.050 on the intake lobes with .420 lobe lift and 266 @ .050 0n the exhaust lobes with .409 lobe lift ground on a 108 LSA, I installed at 107 ATDC on the intake lobes and I ran 1.65 Harland Sharp rocker arms on it with the low deck Eddy six pack intake on my old pump gas 505 C.I.400 stroker motor in my old street Duster. It ran a best of 10.12 at 127. + MPH with that cam and standard port440 heads,. Switching the heads and intake to a set of Indy SR M.W. port heads and an Indy 400-3 intake with a stock Holley 9375 non HP list 1050 CFM carb pickup that car to 9,993 at 134.7 MPH cork up with the air cleaner on weighing 3450Lbs. with me in it at Woodburn in July at the Mopar race back when.
Those 75.0 CC Indy heads did change the compression ratio from 10.31 up to 10.78 to 1 and made it have more HP that torque with the same cam install the same with the same rocker arms and valve lash, I'm sure they flowed more air than either set of the standard 440 port heads I ran on that motor but the smaller CFM of the 1050 CFM Dominator carb versus the 1350 CFM of the six pack may have not made up for the increase by itself, it did make peak HP move up in the RPM range (peaked at 7300 RPM) and peak Torque at a higher RPM (5200 RPM) than the six pack set up did That motor with the six pack and 906 heads made 644 Ft. Lbs. torque at 4500 RPM and 612 HP at 5500 RPM
on the carb shop DTS engine dyno using CA91 octane pump swill back in 2002 in Ontario, CA in the spring before it got really hot down there.
That motor and car exceeded my wildest hopes every time I change a part on it

10:1 446, Bowl ported RPM heads, SFT cam, victor, ported 850, dyno headers- 526tq/558hp

10:1 410, bowl blended RPM heads, mild lobe SR cam, Victor, 1-3/4” headers, QFT 850 carb- 524tq/538hp

Thanks for posting them, you have probably built and dyno tested a lot more BB Mopar motors than I have
Keep up the good work
BTW, do you mind sharing the cam specs on those toe motors? I hope so

The cam in the 446 for that test was 264/264-109.
This was the second cam. First cam was 254/254-110.
Essentially no difference in power.
In the original configuration, both cams made about 520-525hp with 1-7/8” headers, SD intake, and ProForm 750 carb.

The bigger headers, victor, 2” super sucker, and ported 850 picked up the motor over 30hp.
That was just a test to see if we could exploit the bigger cam after seeing the first combo didn’t respond to the added duration.
If I had to do it over again, I would have used a slightly shorter cam than the first one.

The 410 cam was 251/259-108.
The target was 500/500....... so no changes were made.

I agree ^^^^^^^^^ with that said, on my 512 when it was carbed it was really to much cam for a comfortable driving street car 255,258 109 lsa, BUT with the individual 8stack it is like driving a bone stock 440, I can lock up the converter as low as 1200 rpm & smooth as glass.

The 440-2D when ported to max wedge is a very strong intake especially when the lower plenum is radiused from the plenum to the individual port runners. The average lower plenum runner is down 30cfm from the upper but with some sensible port work they can all flow much closer to even.

I had the ported dual plane on my 517 Low Deck with the chapman cnc'ed Stage 6's which are on par with a mildly worked set of TF270s. Motor would rev to the upper 6000's with ease even with the dual plane. I run a ported 337 intake on it now and it's even better.

i know that's a low deck but maybe a ported Street Dominator or a deep ported Performer RPM might work even better with that mild of a cam. I can run an RB manifold on mine because of the Stage VI's that dont have the cast-in spacers like the victors and TF's do.

That should be a tire frying monster with a tight converter and all of that torque available at 3000 rpm. Should be an awesome, nice driving street car!

My tolerance is pretty high for poor manners, my car has 4.30's, a loose converter and the 590 mp cam with 270* @ 50 duration so it's soggy down low and can't run power brakes, but I enjoy it overall. For something that gets limited use I appreciate the level of obnoxiousness, it's part of the fun of old musclecars to me. Assume it'll only get better with more displacement and similar duration too. New stuff has more potential and is so much quicker stock but it's a totally different experience.

Fast,

Was the 410 a BB or a small block?

That cam is exactly the size and spread in used in my 440 W2 SB (4.06" x 4.25") which is also 10:1.

It's ridiculously easy to have fun with a reliable motor combo like that.

Pump gas no fuss big torque street motors are really the way to go IMO. And on a HP/$$ ratio the BBM can still hold it's own.

It's sad to say with the rising cost of racing and just towing to the track that very few people (relatively) are still building full-on Mopar race motors in these days of 700HP small blocks and turbo LS motors.

Settle for going just a few tenths slower and just drive your toy to and from the track!