Where did I go wrong?
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Freshman User
Joined: Jun 2006
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From: Houston TX
Where did I go wrong?
My truck is a dog off the line. I have an 82 f150 long bed with a 302 .30 over, stock crank and rods, flat top pistons, Edelbrock RPM heads with 202 valves and 60 cc chambers, Crane Energizer roller rockers Clevit cam with a 512 lift on int. and exh., Edelbrock RPM intake, Edelbrock 600 vacume secondary carb, Flamethrower distributer and coil, Hooker equal length headers dualed out with an H pipe, AOD tranny with a 2300-2600 stall convertor (stalls at 2100), TCI Streetfighter valve body, 3.25 rear end with 16" tires. It boggs bad until 2500 to 3000 rpm then ***** ***. I've got timing set at 14 with 20 mechanical coming in by 1500 rpm plus the 10 from vacume giving 44 degrees total. My assumtion is it's the rear end gear ratio. Where am I going wrong?
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do you race the rtuck or daily driver?or both? i personlay think you ger ratio is way to high i would recomed 3.73 ratio if you drive it and race it in the 1/4 but if you run the 1/8 4.10's or even lower also maybe try a differnt carb i am not a fan of vac carbs i like manual that way i know it is gonna work and work faster if you know of someone or even have a a diffent carb like a holley 750 try it out
Logistics Pro
Joined: Jan 2002
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From: suburban atlanta
Check with the cam guys to see if you should index the cam different. Sounds like you are 'coming onto the cam' at 2500, and you'd like it a little lower. They might be able to help you re-index the cam.
tom
tom
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From: Houston TX
Wow, you guys are great. I'm new to this forum and didn't expect this fast of a responce. A 3.73 or close to that is the gear I'm looking for. I had an Edelbrock 750 vacume on it for a while but it ran too rich and I called Edelbrock and they said swap to the 600. I have a Holly Street Avenger 650 that I'm going to try.
Is re-indexing the cam basically re-gringing it to differant specs? Or is it more of a tweek?
Is re-indexing the cam basically re-gringing it to differant specs? Or is it more of a tweek?
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More information would be helpful in diagnosing the problem but your overall combination is mix matched and that is probably were the problem lies. You have heads and an intake designed to maximize the performance of a lightweight vehicle. You're '82 longbed is not a lightweight vehicle. You didn't list your cam specs but it's going to be a challenge to make the low end torque you need to get your truck moving with your heads and intake you're using, even if you use the stock cam. Your rear gear is wrong for the engine/converter combination. You're going to have to set a goal for your truck and then try to achieve it with the right combination. It sounds like you have the bulk of your build money invested in high RPM and high horsepower equipment so maybe you should continue to go that route. You may want to get a 2nd truck to drive on the street and save the '82 for the track. A shallower gear would definately help. With your converter a 3.73 - 4.11 would make a big difference. You list your tire size as 16", however that is not a tire size that is a rim size. Your tire size will affect your overall gearing. The more infomation you can give the easier it will be to arrive at a solution.
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My apologies, Fordziller. The whole time I was reading and then replying to your post I was picturing the Victor intake and heads in my mind. Then I went to run your basic combo in the dyno sim and realized my mistake. You can actually make good torque with what you have with the right cam and tune. How about more details?
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From: Houston TX
No problem, Twinscrew. The things you said in the first post is what the little man in the back of my head has been screaming. I really don't want to get another truck, I just don't want to get beat so bad by the newer trucks. The specs on the cam are 0.512/0.512 lift - 230/230 @ 050 duration - 110 lobe seperation. Tire size is 265/70/R16. Do you know about what compression I have?
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Logistics Pro
Joined: Jan 2002
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From: suburban atlanta
From what I understand, you can advance or retard camshafts (intake & exhaust are both affected) by some degree to optimize them (especially aftermarket with added equipment like headers and manifolds) for your setup. Either advance or retard will raise or lower the torque curve relative to rpm.
I am not a pro, but the cam grinders should be able to tell you how to optimize for your setup.
Perhaps the computer simulation can tell you if this will help.
tom
I am not a pro, but the cam grinders should be able to tell you how to optimize for your setup.
Perhaps the computer simulation can tell you if this will help.
tom
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From: Houston TX
I've seen that option on gear sets and chains also. The chain I have now has an option of 4 degrees retard, stock and 4 degrees advanced. I couldn't see the advantage of setting it with the chain instead of the distributor so I installed it in the stock position and set the timing to 14 advanced with the distributor.
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Just posting that made me think about what you just said. Advancing the timing chain or gear 4 degrees, changes when the valves open in relation to the piston reaching TDC and has nothing to do with the distributor, which controls the fire in relation to TDC. So that being said, does opening the valves 4 degrees sooner or later help low end torque or top end or am I way off base? Thanks tom.
Last edited by Fordziller; Jun 20, 2006 at 08:53 PM.
Logistics Pro
Joined: Jan 2002
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From: suburban atlanta
You have the idea, but I don't have the info. I *think* that if you advance the cam timing, it comes into power later in the rpm range, if you retard the cam timing, so it opens a little later, it will have more low end.
Again, call your cam supplier for their input. THey grind the things, after all...
tom
Again, call your cam supplier for their input. THey grind the things, after all...
tom
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Actually, advancing the cam will increase the torque at lower RPM's. I have built or helped build several truck engines for guys who just had to have a lopy cam. I would avance the cam 2 degrees at a time until the torque started falling off, then back down 2 degrees. In the couple that I did I ended up with the cam being advanced 4 degrees. This will definately help with the cam you have. Your duration is a little long for a good low end torque cam but the lobe seperation angle is whats really hurting you. Also you're gearing is simply too tall. You could address your gearing problem first and see what the results will be, but to get your truck to pull really hard down low you may end up needing a different cam. I will check my files to see which cams I've used in trucks and post them later.
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From: Houston TX
I've got an edelbrock Performer Plus cam that I can put in.
Duration at 050 inch Lift: 204 int./214 exh.,
Advertised Duration: 270 int./280 exh.,
Valve Lift: 0.448 int./0.472 exh. lift,
Lobe Separation (degrees): 112,
I also have a 302 Performer Intake to go with the cam. Would that be a better setup for the low end torque. Would I need to advance it 4 degrees?
Duration at 050 inch Lift: 204 int./214 exh.,
Advertised Duration: 270 int./280 exh.,
Valve Lift: 0.448 int./0.472 exh. lift,
Lobe Separation (degrees): 112,
I also have a 302 Performer Intake to go with the cam. Would that be a better setup for the low end torque. Would I need to advance it 4 degrees?
Last edited by Fordziller; Jun 21, 2006 at 12:14 PM.
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The Performer Plus cam would be an excellent choise for your truck. It would make great torque down where you need it most and with your heads and intake should pull cleanly to 6500 RPM. Advancing this cam will boost low and mid-range torque but it will take some power from the top end to do so. Best of all your gearing will not be nearly as much of an issue and you may be able to stick with what you have. I believe that you will be more than satisfied if you try the Performer Plus. Your engine will have excellent throttle response and still have a slight lope. On a final note, keep your exhaust pipes on the small side with high flow mufflers. Believe it or not 2" duals with an H pipe would be ideal for your combination. They would also give your truck a very crisp sound and people will think that you engine is alot hotter than it actually is. Trust me on this and you will not be dissappointed. Keep us posted as to your results. Cheers.