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TF 904 street strip tips

Posted By: Tig

TF 904 street strip tips - 02/14/18 10:14 PM

I'm going to rebuild the 904 in our street strip 68 'cuda. It has run a 14.2 & 98mph but it doesn't get into 3rd gear. I want to keep the rear at 3.23 so would a low gear set help here?
How would you build yours?
Posted By: A/MP

Re: TF 904 street strip tips - 02/15/18 12:12 AM

It will give you you a better launch and a better 60' but you'll still be hard pressed to hit 3rd gear. That 2.74 will test your suspension. Have you tried a 26" tire maybe even a 26" tire with a 14" rim. That could be like moving to a 3.55/3.73.
Posted By: MoparBilly

Re: TF 904 street strip tips - 02/15/18 03:13 AM

Low gear set is the only way to fly in a mildly geared street car, especially with modest cubic inches.
Posted By: RMCHRGR

Re: TF 904 street strip tips - 02/15/18 04:58 AM

A low gear set drops the RPMS more between the 1-2 shift than a standard set because of the wider spread. Probably not a huge deal but something to think about.
Posted By: Tig

Re: TF 904 street strip tips - 02/15/18 09:44 AM

Thanks for the reply's The car does have a 26" street tyre and a higher stall converter. Seems to stall around 1800 - 2000. The car is a bit doggy until it hits 3000 rpm or so then it picks up. Shifting at 60000 so as long as the shift rpms don't drop below 3000 we should be ok.
Any body tried a low gear set up?
Posted By: Streetwize

Re: TF 904 street strip tips - 02/15/18 04:41 PM

Low gear set will help, in first it will basically turn your 3.23 rear gear to something closer to 3.65, Yes the gear spread is more but you can compensate for that by shifting the motor at a bit (a couple of 100) higher RPM. Put a good (Street/strip) shift kit in it, just a bit higher line presures will help firm the shifts as well. Might as well put new bands and clutches in it. Higher stall converters with low torque and 3.23's is probably not a good recipie, but the deeper gear set will increase your instantaneous torque alone and your final stays 1:1. Cuda A bodies are fairly light.

Recurving your distributor for a little more initial and less mechanical would probably help your acceleration as well. Switching to a set of bowl ported late model '302 casting number heads (heart shaped chambers) are worth a bunch without having to go into the short block.

With the right parts you can make a 318 perform very well and get very good MPG. Even swapping to the OEM replacement 360 cam (single pattern .410 lift moved up 4-6 degrees) works fantastic in a stock/near stock 318.
Posted By: WheelsUp73

Re: TF 904 street strip tips - 02/15/18 07:48 PM

When changing to a low gear set it will also have a lower 2nd gear ratio. Stock is 2.45/1.45 and Low gearset 2.74/154. The A&A gear set is 2.77/1.57
Posted By: gregsdart

Re: TF 904 street strip tips - 02/15/18 11:03 PM

You do have some room to increase stall speed and still have respectable slipage at cruise speeds. I would go both low gear set and a better converter. You have a relatively short tire which makes the 3.23 gear seem like a 3.55. A good converter builder can tell you just what you can do.
Posted By: vindicator

Re: TF 904 street strip tips - 02/16/18 12:51 AM

I agree with gregsdart, I think a low gear set would help for sure. I also think a convertor with more stahl speed would not only help at the track but would also be better in traffic.
Posted By: crlush

Re: TF 904 street strip tips - 02/16/18 02:55 AM

I would definitely look into a higher stahl convertor.
Posted By: Tig

Re: TF 904 street strip tips - 02/16/18 09:11 PM

Hi All.
Thanks for the replys, a little more info. The motor I'm guessing is around 300hp, we run ported '302 heads with the 360 (1.88 1.60?) size valves. Air gap intake with the ports opened to 360 size and a 600dp carb (I think it could go bigger here too) Compression worked out at around 10.5:1 with the .030 over bore and KB 167 pistons. (We built it a few years ago I have all the specifics written down somewhere but i forget where it is.... old age sucks!) These UK RHD 'cudas are heavier than the US counterparts, they come with all the H/D suspension and brake stuff it also has chassis ties and a big stereo! Converter is a hughes street / strip but it doesn't seem to stall that high.
OH the Cam is a comp 268 XE.
EDIT. it also runs the billet distributor with the lightest springs but I'm thinking it could do with more advance sooner too.
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