Weird Stroker Build, Looking for Input

2245 Views 8 Replies 3 Participants Last post by monte1go, Jul 2, 2010

monte1go

Discussion Starter · Jun 30, 2010

Hey guys, bear with me as I think alot of you guys may question what I'm thinking, but here it goes.

Car: 1970 Mercury Montego Approx 3500 lbs.

Trans: C6 rebuilt with shift kit, stock converter (small pilot)

Rear: 2.50 9"

The car currently has a tired D0 blocked 429 with rebuilt D0VE heads (standard sized valves/no porting, but less than 10k miles on them). 1 7/8" headers, Stealth, Holley 770.

Now, for my desired build...

5xx stroker (to replace tired 429 SB) small overbore (prob .030 over) with 4.5" crank. H beam rods (for upgrade later)

Here's where things start to get weird...

I want to reuse pretty much everything from my current combo due to being um....not rich. This means Stock D0VE heads, Stealth, 770cfm carb, 1 7/8" headers, and ...really weird... Stock 1970 positive stop rockers/valvetrain.

Custom cam from RHP with ~220-230* @ .050 intake, ~230-240* @ .050 exhaust and ~.510" lift intake/exhaust so as to work with stock valvetrain.

My priorities are basically to spend the bucks on the shortblock now, and then run it for 10-20k miles in this form, and add aluminum heads/bigger cam/ etc. etc. later. 2.50 gears must stay, carb, intake, stock converter (may have to find a larger pilot one to work with stroker crank) etc. must stay due to budget/driveability concearns. I'm thinking 5k RPM MAX, due to cam size/valvetrain.

anyways, I'm looking for input on what kinda power it'll make (I'm thinking ~450 hp, 550 lb-ft), how'd you think it'll run (mid to low 12's?)/anything else you would change or would/wouldn't do. I'd eventually like to make ~650 hp with different heads (prob P51), and bigger cam, so shortblock will be built accordingly.

Thanks!

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TorinoStyle2

· #2 · Jul 1, 2010

Well, a .030" overbore combined with the 4.5 crank will give you a 545 cubic incher...plenty big to make great power & torque.
Your plan sounds good, build a strong shortblock, then upgrade the top end later.
The only thing I'd do is go with a bigger carb than a 770 CFM, as even the unported D0VE's can fit a little more thru them, although the cam you are proposing will be very mild in such a big displacement motor.

Also, the 1-7/8" headers will be a restriction with the big displacement, I'd move up to at least a 2" inch primary, but they'll work for now.

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monte1go

Discussion Starter · #3 · Jul 1, 2010 (Edited)

Whats The 'Power limit' for 770 cfm carb and 1 7/8" headers? I thought they should support ~550 hp. With a VE of between 80-100% suggested CFM ranges from about 600-800 on a 545 @ 5000 RPM. I'm probably gonna be shifting at 4500, which I'm OK with, In order to stay within the airflow limits of the carb.

Maybe I should go about it like...we'll, the carb and headers have to stay, and then size my cam accordingly. Basically just reduce my airflow requirements with a milder cam/reduced rpm.

I'm just trying to make something that's fun to drive, while maximizing my power within my limitations (Carb, intake Valvetrain, Exhaust).

What cam specs would make a 545 peak at 4500?

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CarsByCarl

· #4 · Jul 1, 2010 (Edited)

Given the restrictive heads and limits on lift, you're going to need way more duration. Figure 244/254 on a 112 with .295 lobe lift. This should get you 450+HP at 4500 and 575+lb/ft at 3500. You'd want to shift at 5000 with the 4500 peak.

An 870 carb and a cam with more lift (aka Lunati 31605) will net you closer to 500HP and 600lb/ft, but won't increase the rpm range. The carb change doesn't account for much at this point due to the extreme exhaust restriction.

I would suggest making the required mods to run the cam you plan to use with better heads. It'll be cheaper in the long run. Won't have to buy a weird custom cam now, won't have to buy a second cam later. Won't have to do two break-in's, etc.

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monte1go

Discussion Starter · #5 · Jul 1, 2010

I guess I should try to explain a little bit about what I'm trying to do. I am not really looking to make power with this motor, that's for later and as such, the shortblock will be built with that in mind.

I'm not really concerned about hitting a "number." What I am concerned with is idle (stock converter/livability), fuel economy (not expecting 20 mpg, but if I could get 13-15 that'd be nice), and budget with regards to all the top end stuff. This is why the carb/headers/stock valvetrain has to stay.

Carl,

I def. Get what your saying, and I would tend to agree with you. However like I said, not trying to hit a 'number', at least not right now. just trying to get a new stroker sb to replace the oil buner, and make it work as best I can within my limitations.

The custom cams from RHP are within 50 bucks of any cam/lifter kit I would get, so that is a reasonable upgrade To get something more matched to my off-the-wall combo.

Also, I plan on eventually going to Fuel Injection, So I don't wanna get a 1050 carb to use for a year or two. Hopefully you see the reasoning behind what I'm trying to do.

Thanks in advance

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CarsByCarl

· #6 · Jul 1, 2010

monte1go said:
What cam specs would make a 545 peak at 4500?

I think I answered that question. If you aren't concerned with it peaking at 3500 or 4000, by all means do something else.

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monte1go

Discussion Starter · #7 · Jul 1, 2010

Yeah,Maybe I mispoke about wanting to peak at 4500, Probably want to be shifting at 4500.

Carl,

would you recommend your Street Brawler or All American shortblock in this application?

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CarsByCarl

· #8 · Jul 1, 2010

monte1go said:
Yeah,Maybe I mispoke about wanting to peak at 4500, Probably want to be shifting at 4500.

Carl,

would you recommend your Street Brawler or All American shortblock in this application?

If your goal is to eventually make 650HP, a forged rotating assy (Ultimate Fighter package) would be a better choice. The cast cranks will get you there, but will also be getting into the grey area of what they'll handle reliably.

Also, if you're considering a switch from D0VE to SCJ/P-51 heads, don't forget to have pistons made with valve reliefs for both designs. Another option would be TFS Streets which use the same angles as D0VE's and won't require special pistons.

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monte1go

Discussion Starter · #9 · Jul 2, 2010

Good point about the p51 valve reliefs, I'll Have to keep that in mind. Thanks for the input guys.

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