1/4 mile gearing?

Made a few 1/4 mile passes today, best was a 8.36 @ 165 mph. Car has a SCJ headed 547, 300 on a plate leaving at 30 percent full on at 2sec. We tried to bring it in faster, but it puts the car on the bumper. We have a 3.50 gear on a pro radial, the car goes threw the traps at 7200 rpm. Do you'll think a 3.29 gear would bring the RPM into better range or stick with the 3.50 gear. I'm thinking at 7200 the SCJ head is out of steam??

329 gonna make it lazy down low, turn up the juice imo

that's pretty stout as is that had to be a low 5sec 1/8th what transmission and converter is in it?

I'm a firm believer that you gear for trap speed.

7200 isn't stupid rpm, have you looked at having the convert or worked on? Maybe tighten it up a little on top.

Larry T wrote:that's pretty stout as is that had to be a low 5sec 1/8th what transmission and converter is in it?

Glide 1.80 str cut. Ultimate 10" con. With 3.89 gear we couldn't make the 1/4, it would trap the 1/8 at 6800 car went 5.36 in 1/8th. Changed to 3.50 gear and went 5.35 at 131mph in the 1/8....... That change didn't kill it in the 1/8th, it did drop the rpm to 6600. Car weighs 3270 with driver.

dfree383 wrote:7200 isn't stupid rpm, have you looked at having the convert or worked on? Maybe tighten it up a little on top.

We shift a 7000, drops 1000 after shift change.. Lenny said he could tight the con. A little bit if needed.

1.76 first 3.60 rear gear -6% 10.5 converter on a half assed 500 shot I went 5.47@138 1/8th.im just throwing out some numbers my converter is too tight at that hp level.I would like to have the 1.80 first gear that would help my deal.

Larry T wrote:1.76 first 3.60 rear gear -6% 10.5 converter on a half assed 500 shot I went 5.47@138 1/8th.im just throwing out some numbers my converter is too tight at that hp level.I would like to have the 1.80 first gear that would help my deal.

Your mph is good enough for 5.0s.......what your 60ft? A nitrous car has to get after the 330 to run a number. I would like to get our system 100 percent by the 60 foot if I could. We 2step at 3800, it flashes 5800.

the 1.80 may be your issue, all the radial guys Ive seen are using 1.69 or 1.58 gear sets, hell Ive bought like 3 sets of lightly used 1.80 gearsets from radial guys here lately dirt cheap.

chuck wrote:

dfree383 wrote:7200 isn't stupid rpm, have you looked at having the convert or worked on? Maybe tighten it up a little on top.

We shift a 7000, drops 1000 after shift change.. Lenny said he could tight the con. A little bit if needed.

Have you tried shifting at 7,200?

richter69 wrote:the 1.80 may be your issue, all the radial guys Ive seen are using 1.69 or 1.58 gear sets, hell Ive bought like 3 sets of lightly used 1.80 gearsets from radial guys here lately dirt cheap.

We've been selling 1.58 gear sets and transmissions like hot cakes. We do get used 1.80's some but depending on which brand they are makes our decision on how to sell them if they are still in good shape. If they come out of our builds they have Winters gear sets but most people use lower cost bte gear sets.

chuck wrote:Made a few 1/4 mile passes today, best was a 8.36 @ 165 mph. Car has a SCJ headed 547, 300 on a plate leaving at 30 percent full on at 2sec. We tried to bring it in faster, but it puts the car on the bumper. We have a 3.50 gear on a pro radial, the car goes threw the traps at 7200 rpm. Do you'll think a 3.29 gear would bring the RPM into better range or stick with the 3.50 gear. I'm thinking at 7200 the SCJ head is out of steam??

Personally, I would think that a 3.20 something gear would help you all the way around in the 1/4 mile.

what is your tire size?  

and what kind of car is this motor in? like to know more about this machine!  

nitrous.f wrote:and what kind of car is this motor in? like to know more about this machine!  

\
Same motor......different cam from Lem.

https://www.429-460.com/t12622-car-pics

nitrous.f wrote:what is your tire size?  

Pro 275.

Chuck sounds like you got it running purty good you still own it I was thinking you sold it bought another one ?

basicly running the same combo, but mines a d1ve block 545 with pg trans 1.80 str cut gears, with nos plate system
anywhere from 150-200hp shot! man your car is alsome looking and running! hope mines run close to yours! all the chevy boys
were I live will be running for the hills!  

69F100 wrote:Chuck sounds like you got it running purty good you still own it I was thinking you sold it bought another one ?

I was building a 2002 Cobra with a A headed 598 for a friend......he wanted to trade. I still help with the car. I going to post my new car in the build section, I'm in the process of 25-5 the chassis now.

Got you

any video of the car! would be nice to see!  

nitrous.f wrote:any video of the car! would be nice to see!  

I seen the car in person and I will say the pics don't do any justice for the looks IT LOOKS SUPER NICE IN PERSON Chuck builds some nice rides

69F100 wrote:

nitrous.f wrote:any video of the car! would be nice to see!  

I seen the car in person and I will say the pics don't do any justice for the looks IT LOOKS SUPER NICE IN PERSON Chuck builds some nice rides

Thanks Jim, I don't have any video from saturday. I have one from a while back when I crushed oil pan and headers. I'll try to post later. Here is a video of the car I built for my brother, same motor as the one in my car. This was the first time we fired it off.

https://www.youtube.com/watch?v=cWfmI_H96ao

chuck wrote:

Larry T wrote:1.76 first 3.60 rear gear -6% 10.5 converter on a half assed 500 shot I went 5.47@138 1/8th.im just throwing out some numbers my converter is too tight at that hp level.I would like to have the 1.80 first gear that would help my deal.

Your mph is good enough for 5.0s.......what your 60ft? A nitrous car has to get after the 330 to run a number. I would like to get our system 100 percent by the 60 foot if I could. We 2step at 3800, it flashes 5800.

with good track prep and fairly new 275 radial or 28x10.5 slick 60ft 1.1 range,not so good prep 1.2-1.3 range.