512 low deck street engine
#3096692
11/24/22 12:12 AM
11/24/22 12:12 AM
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Joined: Jan 2003
Posts: 31,050 Oregon
AndyF
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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.
Last edited by AndyF; 11/24/22 12:33 PM.
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Re: 512 low deck street engine
[Re: AndyF]
#3096747
11/24/22 09:33 AM
11/24/22 09:33 AM
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Joined: Jan 2003
Posts: 10,011 Frostbitefalls MN (Rocky&Bullw...
gregsdart
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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..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: 512 low deck street engine
[Re: BSB67]
#3096792
11/24/22 12:10 PM
11/24/22 12:10 PM
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Posts: 31,050 Oregon
AndyF
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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 12:31 PM.
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Re: 512 low deck street engine
[Re: dare_dude]
#3096793
11/24/22 12:11 PM
11/24/22 12:11 PM
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Joined: Jan 2003
Posts: 31,050 Oregon
AndyF
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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! 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.
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Re: 512 low deck street engine
[Re: MichaelF]
#3096794
11/24/22 12:13 PM
11/24/22 12:13 PM
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Posts: 31,050 Oregon
AndyF
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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 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.
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Re: 512 low deck street engine
[Re: GTXMEX]
#3096797
11/24/22 12:15 PM
11/24/22 12:15 PM
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Joined: Jan 2003
Posts: 31,050 Oregon
AndyF
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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. 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.
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Re: 512 low deck street engine
[Re: AndyF]
#3096912
11/24/22 08:34 PM
11/24/22 08:34 PM
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Joined: Jan 2003
Posts: 28,068 Irving, TX
feets
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Irving, TX
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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. 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
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Re: 512 low deck street engine
[Re: AndyF]
#3096937
11/24/22 11:43 PM
11/24/22 11:43 PM
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Joined: Jan 2003
Posts: 28,068 Irving, TX
feets
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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. 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
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Re: 512 low deck street engine
[Re: AndyF]
#3096996
11/25/22 11:24 AM
11/25/22 11:24 AM
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Joined: Feb 2005
Posts: 4,316 Prospect, PA
BSB67
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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
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Re: 512 low deck street engine
[Re: feets]
#3097012
11/25/22 12:27 PM
11/25/22 12:27 PM
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Joined: Jan 2003
Posts: 14,506 So. Burlington, Vt.
fast68plymouth
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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
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Re: 512 low deck street engine
[Re: AndyF]
#3097062
11/25/22 02:53 PM
11/25/22 02:53 PM
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Joined: Jan 2003
Posts: 14,506 So. Burlington, Vt.
fast68plymouth
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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
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