Drag Racing Discussions > Front Engine Dragsters

Rear Tire selection

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codysisson:
Hi Dave, nice to talk with someone else with a Worm Chassis! I only put 6 runs on the tires but each launch I felt as it shifted ever so much to the side. I played with tire pressure from 7-8 pounds but no difference. My first run the track was cool and at the 1000' foot mark i felt the tires break loose as the the car started to walk to the side and for the first time I had to drive the car back to the center. My times were very close to my Hoosiers 31 x 10.5. The Hoosiers launched and drove just as straight as a die. The only reason I went to the 33's was to to raise my gear ratio which it did.
The highest RPM i have left so far is 4000 Rpm. I finished the car last September and was only able to get 10 runs on it so I wasn't trying to push it hard. My wheelie bar height is 2", My Hoosier tires, CO7 ran the best with 7.75 pounds air pressure.

THe engine is a 366, 13:1 compression. .680" valve lift, ported Dart Pro II heads, filled block. The engine dynoed at 535 Hp at 7000 Rpm and there was more left  but I didn't want to push it too hard. All my runs I made I had the engine tuned according to my dyno data around 485 HP so there is quite a bit left.
Right now all I want is seat time. I plan to rent the track in a few weeks to do a bunch of testing.
I sent my converter out to be checked and what I was sold was a 5600 RPM stall but what I actually had was a 7800 RPM stall converter. Needless to say that should change things up a bit!!
Call me on my Cell anytime if you want to talk and let me know if I can help any other way.

JrFuel Hayden:
I have a set of M/T 33x10.5x15 that I got to try from a Heritage A/FD, he didn't like that they don't grow, which is what he was looking for. He tried tire pressures from 6# to 8#, and didn't like the way they handled. I know some racers want to try a narrower tire because they are not making 700-850 HP, and GoodYear is not making a 11" tire now, so on paper it looks like the 10.5 would be worth trying. In a way it's too bad the 10.5 tires are not made for FED's.   I was interested in trying them after seeing how much Matt Hadford from Total Seal Rings improved his B/DA [ before he went to Pro Stock] when he replaced his 33x14.5x15 GoodYear and Hoosiers. Matt picked up about 2 tenths with the M/T on 14" wide wheels. After talking to slick manufactures and some racers that pointed out all the 10.5 tires are designed for the 10.5 door car classes. So I think the biggest difference in those tires is a lot stiffer sidewalls to handle 3000+ lb door cars and softer compound to work with "dead-hook, shift, dead-hook, shift," etc. Most FED's are looking for more tire speed to keep from pulling the motor down out of it's HP range. 
 I never ran the 10.5's because I was advised that to make them work, I would have to run a 14" wide rim, not legal for Heritage JrFuel. Also they weigh 44 lbs, a whole bunch more than the 22.6 lb D2585 GoodYear 31x12x15 we run now. You know it takes power to turn rotating weight. A common idea is one pound of rotating weight is equal to 9-10 lbs of static weight. so if your car is over weight now, and your car weighs less than 3000 lbs, you might be better off trying the GoodYear 31x12x15. We started out running the GY 31x12x15 slicks on 10" wide wheels, and as we made more power we had to go to wider rims, 1'st 11" now 12". The wider rims also helped with 1/2 track traction, but the with the wider the rims the tires grow less, ie higher trap RPM and/ or lower top speed.
There are allot of Heritage and ANRA NE-1 [ 7.60 bracket] FED's running GY 31x12x15 on 10" rims.
Jon, Hayden Wheels, 800-624-3803

JrFuel Hayden:
Opps I forgot, yes I have a special order in with GoodYear for 170 of D2585, 31x12x15 slicks which are being made now, so we should be getting them soon. Call me if you want any. The reason they are on a special order is GY put that tire on an "inactive list" in 2012 because of low sales, but this is the second pre-sold special order I submitted to GoodYear.
BTW, I also have a special order in for GY D1288, 33x12x15 which they will be making next month. 

Cody, who made your 7800 stall converter and what size is it, 7" or 8" or 9", and who's fixing it for you ?
We run a 7" A-1 converter in JrFuel, matter-a-fact, all but one JF teams are using A-1. I helped a SWJFA racer by letting him use one of my tighter 7" and he picked-up almost two tenths with his all iron SBC injected alky 700-725 hp FED. It's all about letting the motor run in the RPM range it's happy. A rule of thumb is stall should be 1000 to 1500 below your shift point.
Have fun !

dusterdave173:
Love this conversation and feedback!
I put the 33 MT's on because John Worm said so-- and because I have a killer deal at my business on MT's.
Since I have brand new car-- have never had a dragster-- all of it is brand new to me-- though I have drag raced for over 25 years now--I love a door car because when you get it right it Stays right. I feel like by seasons end I will get a handle on the dragster. I jumped in and made full pass on my first run and it went pretty darn good. Now after visiting the track 4 times total 8 runs I see I have a long way to go. The big deal for me so far has been lack of good feedback after each run--I am yet to have same crew help. I got a video camera on for my last pass and learned more from that one run than all others so far. I feel like that will be a BIG help as the year goes on--My car hates a poor track, like test night minimal prep--It seems fine on good tight track--I started out at 11 lbs per Johns instructions and have had folks laugh at that so I have come down little at a time to now--8 lbs--car 60 ft'd the best at 11 lbs and high RPM launch --I like leaving at 2000 RPM range --I am foot braking--no interest in trans barke at this point--keeping it as old school as possible--I always loved foot braking --just the way I am. It did rattle the tires one time at the gear change on a very slick track--don't want that to happen again--Geeez! Can't afford the dental work--it was not fun!!
The more I talk with other dragster owners and the more I watch it seems that even the guys that have raced an FED for years will have issues from time to time concerning launch, tires, shake, etc
These cars seem mercurial at best. I am sure there are some vets that have one running like a Swiss watch but most seem to all fight same issues.
I am a rookie, need seat time and experience. I understand that I need to ask and listen --the only reason I throw out anything I am doing is in order to get a response from folks with experience so I can learn and Be safe.
I really appreciate this forum and the positive help.
I am having a ball and look forward to making lots of runs this season--My club Southern Slingshots is chock full of good guys--we have lots of cars--they have been super helpful.
I have strung the car several times--seems ok--rollout is within 1/4 inch at same pressure-have centered the wheelie bar several times-the video showed my last run making that slight "side step" that Cody mentioned on the leave so I am going to concentrate on good solid evaluation of each run, keep good records and hopefully get zeroed in.
keep the advice coming boys! Thanks
Cody , that is one NICE looking car--congrats! I know you are proud of it!

masracingtd1167:
I was just looking in the Goodyear tire specs and they make a 29x12 d5 tire . I wonder how this would work . I guess ground clearance could be a problem . They also make that tire in a 13x31 .

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