[baddbob]

If you want to try extending the rpms a little with the cam you've got (I'm assuming it's a hydraulic) you can adjust your lifter preload to a minimum and sometimes see an extra 300-400rpms before valve float. Adjust your rockers to zero lash and then only add 1/8 turn just to set the lifter plunger below the c clip in the lifter bod. You can also run them at exactly zero lash but this is really hard on the c clips. This way when the lifters pump up at high rpm they will only hang the valves open a minimal amount. If you've been setting them at 1/2 turn or more preload I guarantee you'll see more rpm.

All of the tests I've ever seen reguarding roller vs ball pivot style rockers show very very little in HP gains, way cooler oil temps though. Bob

[66pontiac]

Bob - The heads are the 461's. If you have a chance check out e-bay, item number 7996670863. I have been thinking about those. Thanks again for all the info. Gary

[xntrik]

Originally Posted by baddbob

The 4.56's are perfect for a high winding tunnel rammed 327 IMO, with 4.11's or higher the rpm drop between gears would really put the 327 out of it's power range after the shift.

RPM drop between gears has nothing to do with how low the rear end gear is..... Drop is determined by the transmission gear ratios. The RPM will drop the same regardless of the rear gear.

[rrmccabe]

Originally Posted by xntrik

RPM drop between gears has nothing to do with how low the rear end gear is..... Drop is determined by the transmission gear ratios. The RPM will drop the same regardless of the rear gear.

I have to agree with Bob. Drop is caused by the total ratio of gearing which includes transmission+rear axle. RPM drop is multipled by the axle ratio.

[xntrik]

Originally Posted by rrmccabe

I have to agree with Bob. Drop is caused by the total ratio of gearing which includes transmission+rear axle. RPM drop is multipled by the axle ratio.

For example: If the transmission gear ratios drops the rpm 20% from first to second gear, say from 6000 to 4800 when you shift, are you trying to tell me that if you change the rear gear from 4.56 to 3.50 , shifting it will change the rpm drop between those gears a different amount???? Try it and watch your tach.

Why do race people want close ratio transmissions..?..

... think about it.

[orian]

I wouldn't call this high horsepower, but it is respectable. Recent rear wheel dyno numbers were 301 hp and 335 torque at 5800/4200rpm with a very flat power band up to 6200 rpm. With 461 heads it dynoed 33 hp less.

327 ci SBC bored 0.040 = 333 ci
Edelbrock RPM Alum. heads 2.02/1.60, 64cc chambers
KB156 pistons, 7cc valve reliefs
9.6:1 SCR
8.1:1 DCR
Performer RPM intake
Carter AFB 600 cfm carb.
CompCams XE262-10, 218/224, 110 lobe sep., .462/.469 lift
CompCams roller rockers 1.52:1
Block decked to 0.010
Head gasket 0.028
1 5/8” Heddman full headers
Flowmaster series 40 mufflers
Stock Muncie 4-speed
3.73 posi rear end
27.5” 235/70-15 rear tires
1964 Impala SS, 3450 lbs curb weight, 3660 with me in it

[chrisflock]

Originally Posted by rrmccabe

4:56 with an automatic? Yikes.

If you are going stronger I think you are going backwards. I am a 60s GM muscle car fan and love small blocks. You are taking a techology car that would probably kill the 327 if you put the same efforts into the late model motor.

There is a reason that these little Hondas with big fart tubes on the back (my new favorite term) are killing hemi cudas. So if you are thinking "stronger" then I think you should rethink. Just my opinion of course.

If you think that those can really take a hemi cuda, you need to take a look under some of those hoods. Because 90% of those cars have bone stock motors, maybe with a "cold air" filter sitting right behind the radiator and some red spark plug wires, and occasionally a painted cam cover.

And of the ones that do have some motor mods, most are minor things like bigger injectors. Most of those guys just played to much NFS underground or watched Fast and Furious too many times and they think new rims, a wing, a 4 inch muffler tip on a 1.25 inch exhaust, and chopping their springs so the car bounces all the time will make their car run 10 seconds.

Heck, we had a kid here in town with a Honda he claimed made 500 horse power when he hit the NOS. He dyno'd the thing, guess what? 185...

Not to say that there aren't some fast compact tuners out there, but most are show and sound. You'll probably find as many, if not MORE, modified Hemi Cuda's that'll whip those modified honda's than visa versa.

Now, you give me an RX-7 or a Miata or Supra, maybe we'll talk...

Chris

[baddbob]

Originally Posted by xntrik

For example: If the transmission gear ratios drops the rpm 20% from first to second gear, say from 6000 to 4800 when you shift, are you trying to tell me that if you change the rear gear from 4.56 to 3.50 , shifting it will change the rpm drop between those gears a different amount???? Try it and watch your tach.

Why do race people want close ratio transmissions..?..

... think about it.

Yeah, you're right by saying the rearend gear difference isn't going to change the differences in gear ratios within the transmission and I shouldn't have worded it that way. The rearend ratio has no effect on how the transmission cuts up the overall ratio but it does effect how easily the engine's output can overcome the rpm changes. Basically the engine will have to overcome less resistance between gears with the 4.56's because of the added leverage they provide. As an example think of the differences between say 2.56's and 5.13's, the engine sure would labor after the shift with 2.56's compared to 5.13's.

[baddbob]

Originally Posted by 66pontiac

Bob - The heads are the 461's. If you have a chance check out e-bay, item number 7996670863. I have been thinking about those. Thanks again for all the info. Gary

I checked out those heads and yeah I'm sure they flow more air than your 461's, they've got larger valves and look to have been cut for larger springs. Be carefull though as they might need a complete rebuild with new guides, seats, and valves which would add up to more coins than a new set of aftermarket heads would cost.
I just went through this with a set of bigblock 049 heads, by the time I added hardened seats, bronze guides, stainless valves, roller springs, new guideplates, studs, locks, retainers, plus the porting and all the machine work I would have been quite a few dollars ahead if I would have just bought some aftermarket heads and sold the 049's untouched. Live and learn.

[rrmccabe]

Originally Posted by xntrik

For example: If the transmission gear ratios drops the rpm 20% from first to second gear, say from 6000 to 4800 when you shift, are you trying to tell me that if you change the rear gear from 4.56 to 3.50 , shifting it will change the rpm drop between those gears a different amount???? Try it and watch your tach.

Why do race people want close ratio transmissions..?..

... think about it.

I think we agree on the merit of close ratio transmissions. I guess I am going to have to think about the rear axle deal. I know the final ratio is 1st gear ration x rear axle ratio, 2nd gear ration x rear axle ratio, etc.

Might have to get a pencil out and think about that one.

Rich

[xntrik]

Originally Posted by orian

I wouldn't call this high horsepower, but it is respectable. Recent rear wheel dyno numbers were 301 hp and 335 torque at 5800/4200rpm with a very flat power band up to 6200 rpm. With 461 heads it dynoed 33 hp less.

327 ci SBC bored 0.040 = 333 ci
Edelbrock RPM Alum. heads 2.02/1.60, 64cc chambers
KB156 pistons, 7cc valve reliefs
9.6:1 SCR
8.1:1 DCR
Performer RPM intake
Carter AFB 600 cfm carb.
CompCams XE262-10, 218/224, 110 lobe sep., .462/.469 lift
CompCams roller rockers 1.52:1
Block decked to 0.010
Head gasket 0.028
1 5/8” Heddman full headers
Flowmaster series 40 mufflers
Stock Muncie 4-speed
3.73 posi rear end
27.5” 235/70-15 rear tires
1964 Impala SS, 3450 lbs curb weight, 3660 with me in it

*********

Respectable????? Holy Cow, Man.......

That's about 375 flywheel horsepower out of a 327 !!!!!! That's 1.16 hp per cubic inch..... with that streetable cam.

Ya, that is doggone respectable....... and only 3450 pounds.....

[maddogskip]

Originally Posted by steve t

327 are already screamer, add a good 4 barrel 650, headers and intake, and some 373 gears

I stumbled across this while surfing the net and could not help but want to comment. I love my 327 because I can rev her up to 5k with no problem and she just screams.

This is what I did with my 67 Camaro. I had a 283 (not stock) then put a 68 327 block in with a th-350 tranny. Was good but not what I wanted considering I put everything into the block I could think of to get a whopper of a road monster. high rise Edelbrock, 650 thunder series, dome top forged pistons, aluminum roller rockers, hi RPM lifters, 462 double hump heads, 3/4 race cam, Headers, 2" dual exhaust with some magnaflow muffs and so much more. I still had the stock limited slip rear end and couldn't even burn the tires.

I went from a 67 10 bolt mono-leaf to a 68 12 bolt 5 multi-leaf in with 373 gears and a Detroit Locker with some Wilwood 4 Piston Brakes (because I had to eventually stop) and now, I need to carry IBProfin in my car because of the whip lash factor. I could have gone with 411 gears but why. I cannot even keep my new 295's from spinning when I put the hammer down. Plus this way on the freeway, I am not thrashing the motor as much.

I get Zero to Now as opposed to having my car so long legged. Who wants to drive a older car 150 MPH anyway (except maybe in a 1/4 mile if possible).

So I guess the moral of this story as it relates to your question. Check out your rear gear ratio, get that to where you want it and then make motor changes if you still need to.

Thanks...

Tom

[ap72]

rear axle ratio causes the the gear spread chart to shrink like squeezing an accordion)- in essence tightening up the rpm drop. The RPMS are measured relative to speed, and when you change the rear axle ratio it does indeed affect the way the car resonds to shifting. In essence the car will only need to pull up to 30MPH instead on 45MPH with a higher axle ratio in 1st, then 60MPH vs 90MPH in 2nd. Its hard to explain without an excel spreadsheet or a pencil and paper, but axle ratios do affect shifting.

Also from the looks of it you need to upgrade your heads, AFR195's would be about perfect. also your ignition is suffering from spark spatter at your top RPM's and a solid cam would be a good move if this is a strip only car.

[DoubleVision]

This thread is 3 years old.

[1970ssnova]

helpfull info. i dont know what kind of horespower your engine is putting out, but i have a 327 out of a 67 corvette. its the 365 hp block. its small journal obviously, i just finished the new build. i ran the stock steel crank, 6.125 crower rods, 6.0 rod length .30 over 350 pistons, 10.5 to 1 forged ross pistons, solid lift roller cam in the low .700 lift range, edelbrock e force ported aluminum heads, victor jr. intake with a little port work and a 750 holly dp. it dyno`d out at 667 hp at 7500 rpm. talk about big power out of small cubes. 3.73 rear end gears and a 4 speed muncie in my 70 ss nova. talk about a screaming little bastard...... BIG BORE SHORT STROKE ALL THE WAY BABY.