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512 low deck street engine #3096692
11/23/22 11:12 PM
11/23/22 11:12 PM
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AndyF Offline OP
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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.

IMG_1158 (Large).JPGIMG_1141 (Large).JPG
Last edited by AndyF; 11/24/22 11:33 AM.
Re: 512 low deck street engine [Re: AndyF] #3096694
11/23/22 11:15 PM
11/23/22 11:15 PM
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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

Re: 512 low deck street engine [Re: AndyF] #3096708
11/24/22 12:07 AM
11/24/22 12:07 AM
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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.

Re: 512 low deck street engine [Re: AndyF] #3096741
11/24/22 08:02 AM
11/24/22 08:02 AM
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Prospect, PA
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Nice. What’s the cam specs?
Thanks for posting

Re: 512 low deck street engine [Re: AndyF] #3096742
11/24/22 08:16 AM
11/24/22 08:16 AM
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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

Re: 512 low deck street engine [Re: AndyF] #3096747
11/24/22 08:33 AM
11/24/22 08:33 AM
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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.


8.77 153 mph best, 3055 lbs 528 indy 440-1 alky
Re: 512 low deck street engine [Re: AndyF] #3096762
11/24/22 09:53 AM
11/24/22 09:53 AM
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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!

Re: 512 low deck street engine [Re: BSB67] #3096792
11/24/22 11:10 AM
11/24/22 11:10 AM
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Originally Posted by BSB67
Nice. What’s the cam specs?
Thanks for posting


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.

Last edited by AndyF; 11/24/22 11:31 AM.
Re: 512 low deck street engine [Re: dare_dude] #3096793
11/24/22 11:11 AM
11/24/22 11:11 AM
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Originally Posted by dare_dude
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!


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.

Re: 512 low deck street engine [Re: MichaelF] #3096794
11/24/22 11:13 AM
11/24/22 11:13 AM
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Originally Posted by MichaelF
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


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.

Re: 512 low deck street engine [Re: GTXMEX] #3096797
11/24/22 11:15 AM
11/24/22 11:15 AM
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Originally Posted by GTXMEX
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.


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.

Re: 512 low deck street engine [Re: AndyF] #3096832
11/24/22 01:28 PM
11/24/22 01:28 PM
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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/

Re: 512 low deck street engine [Re: AndyF] #3096912
11/24/22 07:34 PM
11/24/22 07:34 PM
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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. biggrin

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.


We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
Re: 512 low deck street engine [Re: feets] #3096925
11/24/22 08:52 PM
11/24/22 08:52 PM
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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.

Re: 512 low deck street engine [Re: AndyF] #3096937
11/24/22 10:43 PM
11/24/22 10:43 PM
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Originally Posted by AndyF
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.


We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind.
- Stu Harmon
Re: 512 low deck street engine [Re: AndyF] #3096996
11/25/22 10:24 AM
11/25/22 10:24 AM
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Originally Posted by AndyF
Originally Posted by BSB67
Nice. What’s the cam specs?
Thanks for posting


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.


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

Re: 512 low deck street engine [Re: feets] #3097012
11/25/22 11:27 AM
11/25/22 11:27 AM
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Quote
I'm not sure how the TF270 compares to my KG ported Eddy heads but it's likely a step better.


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


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: 512 low deck street engine [Re: fast68plymouth] #3097057
11/25/22 01:39 PM
11/25/22 01:39 PM
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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.

Re: 512 low deck street engine [Re: AndyF] #3097062
11/25/22 01:53 PM
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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.


68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123
Dealer for Comp Cams/Indy Heads
Re: 512 low deck street engine [Re: fast68plymouth] #3097084
11/25/22 03:24 PM
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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!

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