Can someone ballpark a good engine rebuild?

[Bens69PlymouthSatellite]

I have had stuff written in here before about what direction I should go with a rebuild and you were all very helpful,so here comes another one, I have a 69 440hp magnum.If the engine needs to be bored over,.30 over is all im doing if I can,the stock engine should make 10.1 compression right? I wanna stay on pump gas and around that compression,how would this work out,Edelbrock performer rpm heads 84cc, 2.14 in.,1.81 ex., stock crank,and rods, speed pro pistons,3.73 gear,2800-3200 stall torque converter, comp hydraulic roller cam,rpm range 1800-5800,274in. 282ex. @.050 224in. 230ex. lift .538in./.534ex. 110 lobe sep. and 1.5 rockers,and edelbrock performer manifold,1500-6500 rpm,holley 770cfm, does anybody have any suggestions,any help with cam selection? If I dont go with this im gonna use the eddy top end package,looking for about 500hp,wont complain about a little more,or less,I would be happy with a stock rebuild,with slight cam and eddy heads,any help with estimated compression? I appreciate all of your tolerance for my questions,I am pretty new at this still.

 

[Meep-Meep]

Don't count on the factory Magnum 440 to be at 10:1. I am building a mild 440 now using the KB 237 pistons, 915 heads and a shim gasket and it CC'd at 10.0:1 (79.5 CC chambers). Now, the KB pistons have some large valve reliefs in them but they are at the six pack compression height - 2.065" vs the Magnum pistons, which are 1.990" I think. I recommend you CC everything so you know what you have.

Where do the 3.73 gears come from? It's a non stock ratio so I'm just curious.

I assume you will use the Performer RPM intake.

I would think that roller cam should work well with the Eddy heads.

 

[Bens69PlymouthSatellite]

The 3.73 gears were motive gears alot of people told me to go with 3.55 gears,or 4.10,not really sure what my real logic was behind the 3.73 except maybe with a little taller and wider wheel in the back they may bite a little better,and still maintain some level of fuel economy and not be revving so high on the expressway cruising at 65mph like a 4.10 or 3.91,do you think they are a bad idea? I actually think I may end up going with the eddy power package,just saw a video of it making 520hp on a dyno and 560ft lbs of torque,and its the easiest to work with,no real guesswork,I would still cc everything as you suggested,I dont need a 11.5.1 12.1 compression on this car 93 octane is expensive enough,should I go with 3.55 or keep the 3.23 I have now? And will the 741 rear I have take that much power?

 

[Meep-Meep]

The gears will depend on how you plan to use the car and should be tied to the engine power band. For strict 1/4 mile use you want to be going through the lights right at the top of your power peak. For freeway flying at low RPM you want 2.73's. Personally I think 3.73's are leaning toward the 1/4 mile side of the equation and minimal freeway driving.

I knew a guy that used to run his 67 Formula S 383 Barracuda on the bottle with slicks on a 3.91 741 case. Although he had no problems I still wouldn't go out of my way to install one, but assuming you will use the car with street tires the 741 should be just fine.

Yeah, 11.5 - 12:1 is too much so I'd shoot for a max of 10:1. Using the Eddy package will take a lot of guesswork out of the build since all components were selected and tested on a dyno.

 

[Propwash]

Hey Ben,

Try these Calculators out, maybe they'll help you make up your mind a bit more.

http://www.richmondgear.com/101032.html

http://www.tciauto.com/Products/TechInfo/Calculators.asp

good luck

 

[Bens69PlymouthSatellite]

I really selected the gears based on what a friend of mine who has a 528 Hemi charger explained to me about how he has 3.91 in his right now and hates them with a torqueflite trans, wishes he went 5 speed, so instead he is going down to 3.73 gears so he has a little more *** off the line and can still just cruise decent.He said based on the fact that I do race a little on and off the track(If it$ worth It!$$) He said at 550 estimated hp and 580 tq I should maybe look at the 3.73, If I hate them I will drop down to 3.55! thanks for all the help Meep and Will!!

 

[rumblefish360]

I've had a 741 w/4.10's for the last 18 years with 360's rated at approx near 450 HP/400 lbs. of torque pounding it over the years.

New engine is in and expected to see over 500 HP / 470 lbs tq next year. IF I break it, you'll read about it, though I doubt it. LOL!

 

[Revhendo]

OK, I can't stand it, I tried to restrain myself, but.....

My engine builder gave me a good ballpark, but he was off by a couple grand...:rolling:

I'm so sorry.....

 

[Bens69PlymouthSatellite]

Thanks for the help so a 741 case will be fine im sure. Why do people refer to it as the crappy 8.75, The same guy I refered to with the 528 hemi is making 630 hp rear wheel hp and he has a 741 says he has used a ton of them,never had an issue even laid down a 9.8 second car on one,is that pure luck? I knew the 8.75 was tuff but never thaught it to be that tuff,Thanks for the help!!

 

[rumblefish360]

The 741 has the smallest pinion.
Sorry, I should have noted that I have 742 gears in the 741 case. A 489 is the biggest pinion gear -8-3/4 rear. In theroy, the larger the gear, the more power it will hold.

I have a buddy that used to have a all steel 69 Dart w/a BIG roller cammed, Indy headed 500 cid engine laying down a best of 9.2 in the 1/4. This is when the rear finally gave out. The rear was also stock, no bracing on it, no nothing added, just S/S springs moved inboard and a pinion snubber.

 

[Bens69PlymouthSatellite]

Mine is all 741 posi so I will most likely end up going with the Eddy power package,which I am sure will test the tensile strength of the 741! I will let you all know if it becomes an unsightly hood ornament for some POS Chevy or Ricer!

 

[Meep-Meep]

Sorry, I should have noted that I have 742 gears in the 741 case.

That's interesting info! New life to 741's!