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  #1  
Old 09-10-2001, 11:44 PM
FURY 66 FURY 66 is offline
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Question rear gear and cam

hey all,i'm still running that stock 318, and it is really starting to suck being passed all the time.what i need to know is #1 what gear am i running w/a stock 904 locker in 2cd gear(85 'Chrysler 5th ave)my rear ratio is 2.94, the rpm's just hit 4200,when i let off.tire sizes are 215/70's @84" on the left side,and235/70's at about 87 " on the right side.#2 Will a cam get me the rpm's ?or should i find a diffrent rear?,will the motor take it?these 318's are becoming plentiful and really want keep them if i can find a way (for now)to use them.any good combinations needed. they aren't blowing me away as one would expect,but they do have more motor for sure,coming off the turn.everything helps.thanks Mike P.S.-
-----still the only mopar at my track----
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  #2  
Old 09-11-2001, 07:44 AM
daveashsr daveashsr is offline
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hi i'm no expert for sure but unless i'm mistaken 2nd gear is 1.45 in that tran so u have a final of 4.26 if your using 2nd !! unless your racing on a pretty big track thats pretty tall !!
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  #3  
Old 09-11-2001, 09:05 AM
AVENGER29 AVENGER29 is offline
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My 2 cents worth, we run a final ratio of 7.02 on 1/4 mile dirt track with some banking, our rear gear is a 4.86 ratio, we also run in 2nd gear. On a short track like ours, your final ratio should in the mid 6's, probably 6.5 to 6.8. They are definitelly going to pull away from you coming out of the turns with so little gear. We normally turn our engine just under 7k, your 318 in somewhat stock configuration probably will not live long at that rpm, however it should survive fairly well up to 6,000 rpm, assuming you have a decent valve train.
Im not sure but i would guess the rule of thumb is to have enough gear so that your engine is at uptimum performance at or near the end of the straight away.
340 & Sanborn please jump in!!
avenger
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Old 09-11-2001, 02:59 PM
Racedude_5 Racedude_5 is offline
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Default 318

I don't know what class you are running or what your competition is running but that little 318 is preety tough. It has the stoke of a 340 with a smaller piston so it will really turn the rpm and as you say there are a bunch of them around. If that is what you have to run I would get a good cam ground for about 7000 rpm tops and try to gear it so it would turn at least that at the end of the straight. Be sure to get good pushrods and rockers so they will stand the abuse and if you can get a good set of heads and the little 318 will surprise you, That s not to say a bigger motor wouldnt be better but if you are going to run the 318 this will definately help
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  #5  
Old 09-15-2001, 01:18 PM
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cageman cageman is offline
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Default been there

I run an 88 fury that now has a 360 but for 3 1/2 years I ran a 318 with lots of luck. One thing I can tell you is that it will have to be geared right for the track or it wont keep up. I ran 2.94 308 and 243 and i got an 8 3/4 out of a 68-70 b-body and it is a perfect fit. I then got 391 gears for 3/8 mile and 410 for 1/4 mile. Easy to find and change like a ford nine inch. My mid pack 318 went to the top 5 every week.
I only ran the 340 cam that mopar makes and it made good power too. I think it was a 455 lift cam.
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Old 09-28-2001, 10:33 PM
FURY 66 FURY 66 is offline
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Thumbs up

hey thank you guys,at least i can come back here and try a different suggestion if i come up short. i started to taper off on my racing ,i sponsor myself and the budget was already out the window.i'll try to make a few more out of eight,but the info will come in real handy for my old fury which i intend to race in an enduro.but have two 318's i will put some money in for next year. i do have a question though,what kind of car should i look for that would have the gearing that i need? i usually just throw a nother rear in,because the one i race is welded.85 fifth ave.tough question prob right.thanks guys.the hardest part about racing is the time it takes and money to build up a parts supply,lol. MIKE
3/8 mile and also a 1/4 not sure which i want to run next year.
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  #7  
Old 09-29-2001, 01:05 AM
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cageman cageman is offline
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pickups have the gears to look for. Older trucks(74and older) had 8 3/4 in them with 355, 391 and 410. Newer trucks can have 8 1/4 and 9 1/4 with the same gears usaully.
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Old 09-29-2001, 11:38 PM
FURY 66 FURY 66 is offline
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Default thanks cageman but...

will the whole rear change out,leaf springs line up ,shocks.i have no idea.thanks
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  #9  
Old 10-01-2001, 01:41 PM
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cageman cageman is offline
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Default well lets see...

You will need the housing out of the 68-72 b-bodyand the axles and backing plates and brakes too. Now find a pickup with an 8 3/4 and take the gears out of that, it is like a ford nine inch. The leafs and shock mounts will be reused, you just have to cut the hole in the spring perch on the axle tube a little bigger.
where Im from, I buy the older trucks for 50 -100 dollars and take the gears out and sell em if there a posi and make a box trailer out of em. and sell them for 250-300dollars. easy money and I sell them all the time.
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  #10  
Old 10-01-2001, 11:03 PM
FURY 66 FURY 66 is offline
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thanks cageman,winter is almost here and its time to go shoppin.hope to have a bad car for next year.thanks again. Fury66
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  #11  
Old 10-02-2001, 06:50 PM
340king 340king is offline
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Default Gearing

You are correct in connecting the two together. The gearing will depend on the camshaft or the rpm that the engine works at which is controlled by the cam. The prefered method for gearing would be to dyno the engine, pull it past peak HP and determine the tq and HP curves. Then figure the gearing that will get you the most average HP on the entire straight. This is usually 300-500 rpm over peak. The little 318 doesn't drop off as fast as some larger engines do, so it may be closer to 700 rpm over peak for the best acceleration.

Another way to look at it is to gear as deep as you can without over revving your engine components. This has the advantage of giving you more torque multiplication coming off the corner. This is one key area that you can use to make up for a smaller engine. That little 318 will rev quite quickly, so deeper gears won't hurt you under acceleration as much as it would a 360. In other words it takes some HP to spin up an engine, slowing the acceleration of the car by using HP to spin up the heavy engine components instead of powering the car. It is like having air conditioning on. Properly geared, a 318 might keep up quite well against some larger engines depending on the class rules. Typically, in 2 bbl classes, you can get away with running a smaller engine more easily than in others.

I had a 318 in my B body street stock. I had it geared @ 6.17:1. I ran at two big 1/2 tracks. I was at peak rpm by the middle of the straights. This allowed me to run a 318 against 351C and 350 engines. It worked well if you ran good valvetrain.

The last one I raced came out of a guy I worked with's backyard. It was laying there, upside down, when he moved in. It was free. I used it for one whole season until I ran it out of oil and pulled the pin. I killed them until the valve springs gave up about half way through the feature. I restricted the oil to the heads. The valve springs couldn't cool properly and were down to 35 -65 lbs at the seat when it broke. It floated the vavles all the way down the straight.

In my defense, I was in college and didn't have enough money to buy food, let alone race. The promoter told me to get my car out of the tree strip and he would take care of me. I made money for the first and only time racing that year.
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  #12  
Old 10-02-2001, 10:22 PM
FURY 66 FURY 66 is offline
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Smile thanks all

cant say it enough ,thanks again.allthis is so helpful for now and the short future.helps shrink the learning curve getting quality ,learning experience,pointers.will have many more? to come.dont have the help ,mostly am a one man show at the track. cya
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  #13  
Old 10-09-2001, 08:47 AM
sscarbrough52 sscarbrough52 is offline
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Do you run Citrus County Speedway?

My father ran latemodels there in the early to mid 80`s big block 383ci in a 70` cuda ran constant top 5`s.

See what you have in a 2.73-1 rear and use 1st gear in a 904, 2.45-1 this will give you a 6.68 should keep you from scattering the valve train but give you more out of the hole. That track is two drag strips and two hair pin corners, always liked it though.

If your are looking for a new car I may have one for you, it is a super stock aphalt car 75`charger with a 10.5-1 flat top 360ci. It has been well gutted and you would have to check your rules, but it is a good safe car and runs well.

Good luck to you!!

If you are interested check out (no more breaking up) for a photo.
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