how to know where to set the RPM redline ?

[BSeery]

I have a '74 Vega that I am racing. I didn't build the car or the engine, I purchased it complete. From what I know the engine was rebuilt back in 1993, run a few times in 1994 and then not raced until I bought it. I've run it 4 good runs and right now it's running 10.67 @ 126 .

I want to know how many RPM's I should be spinning the motor before shifting and where the absolute redline should be. The car came with a MSD 2 Step and the top chip is set at 7000 RPM. Bottom chip is at 3500, but I will probably try higher as it seems like a soft launch at 3500 RPM.

Here are the specs on the motor:

454 BBC block - .060 over with 427 crank. 4.311 bore 3.760 stroke.
pistons: 12.5 forged TRW for 427 engine - L-2308a
rings: Speed pro chrome moly
Rods: Chevrolet stock 427 rods
Crankshaft: Steel (that's all it says). Guessing that means stock.
cam: Competition cams solid roller: 708 lift, 306 duration, advanced 2 degrees.
lifters: competition cams solid roller
rocker arms: Sig Erson Roller 1.7 ratio
Push Rods: Sig Erson
Valve Springs: Competition cams
stud girdle and windage tray: Moroso.
Heads: Chevrolet polished oval port 353049 (passenger car from 1973 I think).
headers: Hooker 2" primary , 3 1/2 collector.
Carb: Holley 1050 CFM Dominator.
MSD 6a ignition, billet distributor.

Transmission: TCI Powerglide full competition.
1.96 low gear, aluminum hubs, trans brake.
TCI torque converter 8" 5000 stall

Rear: Ford 9" 4.88 gears, spool, 35 spline axles



From what is listed can anyone see where I should be shifting and what my max RPM should be?

Also, can anyone see an easy way to get some more power from this combo (NO NOS)? There are guys running 383's in similar cars getting better times than my BBC 440. I suppose I should be happy, I guess if I go much faster then the rules and equipment will get really expensive.

Thanks for any information or suggestions.

[John_Heard]

First thing I noticed is that duration, is it @.050? IF so, WAY to much for that motor.. Post your cam card, let's see what the specs are.

[BSeery]

First thing I noticed is that duration, is it @.050? IF so, WAY to much for that motor.. Post your cam card, let's see what the specs are.

Here ya go:

Part # 11-710-9
Chevy Big Block 396-454
Grind number: CB 306b-R8
Duration at .020 tappet lift
Intake 306 Exhaust 306

Valve timing:
at .020 intake - open - 43 btdc / close - 83 abdc
exhaust - open - 79 bbdc / close - 47 atdc

106 intake center line
duration at .050 intake 275 exhaust 275
lobe lift intake .4167 exhaust .4167
lobe seperation 108.

[John_Heard]

I have a feeling that's a "little" bit too big for that motor. Have you ever done a cranking compression test on this motor? What kind of numbers is it making?

Bob West - Get in here, this is a somewhat similar combo to your old motor right?

[BSeery]

never done any cranking compression on it. I will have to get a gage for that. It turns over with no problem at all with 40 degrees fixed timing, fires right up (better than my old dodge truck).

I would like the car to get into the lower 10's consistently so I can then set up the throttle stop and run 10.9 class.

By the way, the carb is a 1050 Dominator, running down into a Holley 4150 pattern adapter then into a 1st Stop throttle stop (4 butterflies) and then into a 4150 style Holley Strip Dominator intake manifold. I don't know if that restriction is much of a concern or not.

Also, any ideas at the RPM limit of these pieces? The stock crank and rods concern me and I wonder if they will take anything over 7000 RPM. I am hitting just over 7000 RPM at the line.
4.88 gears, 1:1 powerglide 2nd gear, 31x13.5x15 tires.

[sunsation540]

the rods are the killer how old how many laps 3/8 or 7/16 bolts the crank even if it's a factory steel shaft the 3.76 is tough the 2308 trws are bricks easy way to make the rod twice as strong is to make the piston weigh half as much. a steel rod 427 with good bolts should go 7000-7500 and recon the rods each yeay if the move or grow more than 0.0015 in the big end replace them as a set this cam would be good to 7800 in a 427 something like 292-302 adv and 256-264 @50 would be good with o port heads 427 and make power to 7200.

[BSeery]

So if I go with some good rods, lighter pistons and up the compression I should be good for some more HP and good till around 7500 RPM ?

I think for now I set the upper RPM limit at 7200, shift at 7000 RPM. That should keep the engine safe until I pull it apart. I am hoping to get all of next year on the engine before opening it up (knock my wooden skull).

[hsutton]

So if I go with some good rods, lighter pistons and up the compression I should be good for some more HP and good till around 7500 RPM ?

I think for now I set the upper RPM limit at 7200, shift at 7000 RPM. That should keep the engine safe until I pull it apart. I am hoping to get all of next year on the engine before opening it up (knock my wooden skull).

Going faster seems a waste to me if you want to run the 10.90 index. Your already half a second too quick as it is. I'd drop the rpm and discontinue using a throttle stop so you can find a place the motor would not need the stop. Less RPM, less likely to hurt the motor. You can always jack up the leave RPM if you need more 60'. These motors will live forever at 6500 RPM.

[Bob West]

John, its alot more motor than my old motor. Mine was a .030 over 454, .548/.559 lift 233/239@ .050 300/310 adv and only 10.5-1, same heads, dual plane and current 950HP. I do think he's got way too much cam and gear. That car can't weigh but what? 24-2500 with driver? compared to my 3850 w/driver per Tulsa scales. The best I got out of my old motor was 11.78.

[BSeery]

John, its alot more motor than my old motor. Mine was a .030 over 454, .548/.559 lift 233/239@ .050 300/310 adv and only 10.5-1, same heads, dual plane and current 950HP. I do think he's got way too much cam and gear. That car can't weigh but what? 24-2500 with driver? compared to my 3850 w/driver per Tulsa scales. The best I got out of my old motor was 11.78.

I think we are close to 2900 with driver. I am a BIG guy and the car is all steel (except hood).
Too much cam and gear ? What would you suggest?

I am hitting 7000 at the 1/4 with a 4.88 / 4.86 gears, 5000 rpm stall TCI converter and 31x13.5x15 tires.

[fishman]

My set up is in a 74 pinto with a 383 stroker
cam is 633 lift and 272 duration and 268 @ .050
heads r edelbrock victor flowing around 295 cfm 2.08 valves
intake is a hurricane opened up with a 1 inch spacer by trandapt with a 850 cfm holley
12.5 pistons
headers stepped and 1 3/4 tube
torque is 8 inch 5000 stall glide 1.74 first gear
gear is 5.14 with 32x14x15

time is 10.21 at 132 mph car weight is 2450
altitude is 2360 feet

what r your 60 foot times

showing the comparsion between cars and with your setup u should be running faster for sure not sure of elevation u r at....i agree for them heads u have to much cam...take it to the dyno to find out rpm max......just sharing info hope it helps

[BSeery]

altitude - Google Earth says 450 feet. unfortunatly our track does not print correct temp, pressure, wind or D.A. on the time slips.

60 foot times are around 1.51-1.54, but we are still working on getting good burnouts for traction and figuring out the correct launching RPM for the transbrake.

I am guessing that you must be turning about 7400-7500 RPM at the lights in the 1/4 mile from your setup.

I am going to try and find a dyno that will let me put the car on and get me a wideband 02 as well.

[fishman]

I am turning just over 7000 rpm at the finish line...i could be going faster but i had changed the cam to a roller cam for the last race of the season and the old cam was good for 4000-7000 rpm so i had set the shift light at 6800 rpm and i forgot to change the pill so i had short shifted the car and also i use to come out of the hole on the transbrake at 4200 rpm and with the new cam i still haven;t found the sweet spot but i am guessing around 4600 rpm..........there is next year i guess no racing here up north with 19 inchs of snow already and temperatures of around 5 above.........my sixty foot r 1.40..........the dyno will be the best bet to find jets, valve lash, timing. if the carb is the right sizes and ohhhhh ya horsepower........hopefully everything works out for u..............my set up should be running around 10 flat or in the nines so i have some fine tuning to