building 440 with 915s. HELP appreciated

[goose69]

I'm building a totally budget 440 for my Saturday night cruiser/race car (1966 Belvedere, primer black, mini tubbed, probably nitrous). Well here is the deal. I bought this car so I can have something to drive and thrash a bit while I build my Roadrunner. I have a nice pair of 915s with some heavy springs and nice valves in them that I'd like to use. The motors I have to put them on are as follows (all stock bottom end motors by the way and that's what I want to stick with): 1)1969 440, 1)1970 440, 1)1975 440, 1) 1978 440. I am looking for suggestions on a combo to put together here and not wanting my compression to skyrocket (so I can run pump gas)or have detonation problems. I know ideally people say not to use these heads on a 70's motor but will it really hurt or has anyone done that combo with success of failure?
Thanks for the help.:cool:

 

[696pack]

Your 915s will work the same on any of those 440s you have listed.

 

[daredevil]

assuming deck heights are the same

 

[Meep-Meep]

Good choice. I'm running a set right now on a 440 and details of the build are posted here somewhere. Assuming the engines you listed have the standard pistons the compression distance is low enough to not cause an issue. I'm running pistons with a 2.065" comp height (same as 440 six pack) and figuring in the RB deck height, stroke and rod length that puts the piston nearly at zero deck. The compression height for a Magnum piston is 1.990" I believe and the later model engines are lower than that. Also the closed chamber head will provide better quench, which tends to reduce the possibility of detonation. I'm at 190 PSI of cylinder pressure and that's about the limit for pump 91. Pulls like a freight train though!

 

[goose69]

All the motors have the standard pistons in them which is why I'm asking this question. Being the 69 motor's pistons are at deck height doesn't that cause a situation where I'm hitting about 12.6-13 to 1 compression? I know the 70's motors are way deeper in the hole (maybe .80?) and have no problem running that set up if it doesn't cause any problems. I've also been told to look for a camshaft with a lobe serparation over 110deg if I run the 70's motor. True?? I've built a couple other motors with the cylinder pressure at 190-195 and they ran awesome but you are right Meep-Meep, that was the highest we dared to go with pump gas.

 

[goose69]

Oh yea, I believe the 1970 motor is a little lower in the hole than the '69 motor but would have to put the pistons back in the motor to verify. Maybe a better choice than the '69?

 

[SUPERSTOCKRACER]

I RAN those heads with great success with a str-14 crossram intake.
those close chamber heads when done right make very good power.
i went 11.58 in my 63 plymouth max wedge savoy back in 97.

 

[goose69]

That I don't doubt. I'm just trying to put something together inexpensive to run for now while the bird gets worked on. The expensive motor is going into my roadrunner. thanks

 

[696pack]

See my comments in your other post about these heads.

You should have kept all of this in your first post rather than starting another about the same basic thing.

 

[goose69]

Sorry, I was just trying to reach the largest amount of people with their opinions that I could. Some may not have seen the post in the other section. Thanks though.

 

[Cranky]

I have a 1970 440 from a Chrysler and the pistons are .050 in the hole (stock) and with closed chambered heads and a steel shim gasket, the compression is 10.3-1. Too many worry about static compression but like Meep-Meep says, better quench will help...and will do more for you than low compression and little quench will. The auto industry produced a lot of low compression engines in the mid to late 70's that did little more than pinged themselves to death. And keep in mind how many are running 11-1+ engines on pump gas.....it's all about cylinder pressure....like you mentioned.

 

[goose69]

Ok guys & gals, I've finally got some things together for my 440 motor many of you gave me good information about. I ended up using my 1978 block and crank. I found a guy who sold me a rotating assembly (forged trw pistons #2355f-30, LY rods that were ground smooth, and a steel crank all balanced) for $200! I'm using the cast crank because my Dynamics converter is for a cast crank motor. Had my block bored, new cam bearings put in, and took them my heads in to do a valve grind. While doing the heads (915's I bought for $125) they did the 3 angle grind and told me someone had put in oversized manley valves, hardened seats, bronze guides, double valve springs, machined out for the nylon positive seals, lightly ported them and blended the bowls. I about fell off the stool! So I ended up getting another deal for a new comp cams double roller timing chain, comp cams xe274 cam and lifters, and a summit 110 gal per hour electric pump with regulator for $100. This all aught to go well with the barry grant 750 speed demon carb I have and the holley street dominator intake I'm looking for (if anyone has one for a decent price let me know).
Started my assembly last night ans filed the rings for a gap of .028-.030 to allow for the nitrous I might be squirting on it.
Well thats all for now, hope to have more soon!!!!