Posted By: pleasantk
512 build suggestions - 06/16/10 11:31 PM
Looking to build my first stroker motor for the GTX and looking for some suggestions on a few items. This is a street/strip car. I will be adding a set of Edelbrock heads. I have a 727 with full manual reverse pattern and a 4200 stall PTC converter. My question is how much compression can it take and still run on pump gas? Also I have a MP .557 cam laying around,could I get away with this cam or do I need to look for something bigger? Not looking for the fastest stroker around, just want something that can hold it's own at the track and still be able to cruise up to the local car show. Thanks in advance!
Posted By: ahy
Re: 512 build suggestions - 06/17/10 12:32 AM
A few comments based on building a 496. The 512 will like to breath; any porting you can do on the heads to increase flow will really help. With a cam like the .557 I think you would be fine up to 10.4 - 10.5. Maybe a bit more but personally I'd build for 10.2-10.3 to have a little margin.
On the cam, it depends on what you want and like. The .557 would work great on a street strip car. It would be fun to drive with lots of torque. You would give up some on the top end vs a more radical cam... but the more radical cam may reduce the fun of driving it. The 557 should work fine with standard Ed springs.
With the 557, torque should start building pretty fast starting below 2500 RPM. 4200 stall may be a bit much. I'm not an auto guy but would guess 3500-3800 would be more than enough.
Posted By: 383man
383man - 06/17/10 04:23 AM
I have a .030 over 440 in my 63 right now with the MP .557 cam and I really like that cam in my street/strip 440. I am only using 906 heads I did some porting on. My self with a 512 I would look to use more cam then the .557 as it will handle a larger cam with ease. You can still have a nice driver and as was said I would have the Eddy heads ported. With the right cam and quench you could run up to 11.0 comp on pump gas. I would also use a zero deck flattop piston. That way with a closed chamber head you can use a .039 head gasket and have nice quench. I have 10.0 comp in my 440 now which is iron heads and the aluminum heads can handle about 1 point more comp. Good luck , Ron
Posted By: Cab_Burge
Re: 512 build suggestions - 06/17/10 04:36 AM
I have several pump gas street stroker motors, one is a 518 low deck with 10.29 to 1 compression and the other one is a 464 C.I. 440 motor(3.9 stroke with 4.50 bore) Both motors have Eddy RPM heads.
The big motor has a set of the CNC ported Eddy RPM by MCH and the little motor has a stock set of Eddy RPM, the big motor has a Comp Cams solid roller that is 260@ .050 intake and 266 @ .050 exhaust, both have over .700 net lift at the retainers. The little motor has a Comp Cams XE295HL cam and lifters, that motor has 10.46 to 1 comp, ratio. Both motors run well on the local pump swill with the total timing set at 34 to 37 degrees, depending on the track altitude and weather
Don't forget that big C.I. motors eat big duration cams and need big air into and out of them
Posted By: gregsdart
Re: 512 build suggestions - 06/17/10 11:12 AM
A set of higher ratio rockers will work well here. The .557 is .631 with a 1.7 rocker if you can find them. Almost roller performance with a flat tappet cam. Sig Erson made a high ratio cast steel rocker years ago in 1.75 advertised. I used it with a .590 cam and L88 chev valve springs. I was shifting below 6000 rpm. Worked great!
Posted By: gregsdart
Re: 512 build suggestions - 06/17/10 11:24 AM
Found a part number, but no longer in the catolog.
Erson rockers, 1.75 bb, e918010
Posted By: Twostick
Re: 512 build suggestions - 06/17/10 12:07 PM
My 9:1 493 made 600 ft/lbs at 4000 with a .509 and 1.7 rockers so your converter should be pretty close. On the dyno mine started swinging the needle at 1500 and by 2000 it was doing 500 ft/lbs. Does it on 87 regular. Just the ticket for my New Yorker.
Kevin
Posted By: Dabee
Re: 512 build suggestions - 06/17/10 12:46 PM
For a street/strip engine you don’t need a lot of lift. I have the below cam in my 511 wedge and it is a hand full on the street. Compression is 10.5, with out of the box Indy EZ heads. Tons of low end torque. I would think your .557 would work in a 512. My 511 runs 11.74 in the ¼ mile in a 69 Super Bee and that’s with P/S, P/B, A/C and full interior.
Posted By: Dabee
Re: 512 build suggestions - 06/17/10 12:54 PM
A couple things I forgot to mention. I’m using a 2400 stall PTC converter, 727 trans with a reveres manual VB and Gear Venders OD.
Posted By: Thumperdart
Re: 512 build suggestions - 06/17/10 02:42 PM
Now we`re talkin................You say you want a respectable street/strip car? That has different meanings to different people and no dissrespect but a 512 running 11`s doesn`t cut it in my book(havn`t written it yet)and I only have 470 cubes and 12.11 comp but my car purrs like a kitten w/275-280 degs of dur @ .050. Not saying you need THAT much but as Jim stated you need way more than those baby cams and STREETABLE well, that too is a matter of opinion..........go big!
Posted By: TonyS451
Re: 512 build suggestions - 06/17/10 02:58 PM
I ran a 10.5-1 512 with Stage 6 heads, indy dual plane, 950 carb and a 238 @.050/.540 Solid flat tappet through exhaust manifolds and it went 11.55 at 117 at 3800lbs. Although your engine might like more cam, I think the .557 would work fine and should be extremely nice on the street.
Posted By: pleasantk
Re: 512 build suggestions - 06/17/10 05:46 PM
Just wanted to say thanks to everyone for all the suggestions. It has definitely given me some more to think about!
Posted By: tboomer
Re: 512 build suggestions - 06/17/10 05:50 PM
If you haven't bought a kit yet...Try Muscle Motors....Mike and Eric were great to deal with and answered all of my questions!!
Posted By: Cab_Burge
Re: 512 build suggestions - 06/17/10 06:46 PM
I am contenplating switching heads on my 518 from a set of CNC ported Eddy with 84.0CC to a set of Indy 44-1 with 75.0 cc, that change will make my compression ratio go from 10.29 to 1 to 10.84 to 1. I'm thinking that will still be pump gas freindly with my camshaft, the bigger the cam duration at .050 the less the dynamic compression ratio ends up being. my new dynamic comp. ratio will be 7.862 according to the on line calculator
on KB web site, United engine and machine. My message is build your motor with flattop pistons with valve reliefs and shoot for at least 10.5 to 1 compression
Look at using a bigger, and better designed, cam than the Mopar "557" or "590" also
Posted By: 451Mopar
Re: 512 build suggestions - 06/18/10 05:32 AM
Compression ratio really depends on the entire combination. My old 451 ran on pump gas at 11:1 compression, with a mild 251/251 duration roller cam and Brodix B1 B/S heads, 3500 stall converter and 3.91:1 gears. The new 500 stroker is 12.4:1 compression, and I have been running it on 100 octane pump unleaded. I have not tried it on lower octane. I really built this engine with the intent to run E-85, but I need to update my fuel system for the E-85.
I also, have a 440 source 512 kit that I plan to put into my convertible. I want this to be a pump gas engine that is easy on parts, idles like stock, and good power up to 5,500 - 6,000 max.
I am using the 440 source 17cc dished pistons #5070, and with the Stealth heads 80-84 cc? the compression ratio will be about 10.0-10.25:1 depending on the actual chamber volume.
With 512cid the Stealth and RPM heads are actually on the small side and could use some porting, but should work fine on a street car.
The big engine will really want a good sized cam. I think about the smallest cam I would use would be 230 duration @ 0.050".
I have not decided on a cam for my engine yet, but I have the old 251@ 0.050" roller cam from the 451 I was thinking of using as a baseline, but I really would rather have a milider hydraulic roller than the solid roller to reduce valve train noise. Because i don't plan to race the car, I am leaning towards a smaller cam, and looking at something like the Comp #3122 hydraaulic roller cam lobe profile with only 236 @ 0.050" duration, 0.608" lift with 1.6:1 rocker arms, but the ramps must be pretty fast because the 0.200" duration is 160 degrees which is about the same as some of the larger 244(158&161) and 248(161) @ 0.050" cams?
Posted By: Bubba
Re: 512 build suggestions - 06/18/10 12:37 PM
My Suggestion is to look up AndyF 's Mopar Book.. ASAP
AndyF's BOOK
Posted By: Streetwize
Re: 512 build suggestions - 06/18/10 01:46 PM
11:1 will work well with the 557 and it will make great power even with mildly ported E-heads. Think about a 2.19 intake valve and concentrate primarily on getting the mid lift numbers up, don't worry so much about the peak numbers.
I like the Indy dual plane (I run a ported Max wedge version on my 4.30 stoke 12:1 517 B) or the street dominator, the performer RPM is also a great intake but it is tall and limits your hood clearance and doesn't flow as well as the Indy 2D on a big inch motor.
Your short block makes the torque, the cam tunes the curve and the HP potential is the heads....get the powerband where you want it and if you want more HP upgrade later to some 360+ cfm MW ports and you'll make more big end and not lose any torque, only gains.
557 is a great cam, it will be very mild in a 511, at least the way I build them. 590 would work even better with no real downside on the street.
For street strokers I like a tighter (3500-ish) FB stall with a ~4400 flash...but your in a "race only" forum so the opinions are going to skew to the high side. The tight FB allows you to get more use out of the great torque but the flash puts you right into early side of the flat Torque Peak so even from gradual part throttle 'roll-on' the power comes on fast with great tractibility on street tires....plus it's more predicable and easier to modulate in all weather conditions.
PM me if I can help with any 'real street' combo type questions.
Posted By: Blakcharger440
Re: 512 build suggestions - 06/18/10 06:41 PM
None of these 10.5 to 11.5 combos would run very well on the 91 pump gas that they sell around these parts and that is the best you can do here unless you go to E-85 and then you would have to travel 200 miles to get that.....so pump gas friendly is very relative to where you live at.
