400 SBC NOS

[helicoil]

I am new to this site but not to the street legal drags. I have enjoyed reading through these very informative threads! I've done lots of racing but don't have alot of experience when selecting combo's for a NOS SBC package. I have a CNC Bowtie block and a set of Track 1 heads done by Ron's Porting. Last season I ran 11.28 @ 121/7.20 @ 97mph 1/8th in a 3300lb 8.5" tire 66 Nova. On spray the car went 9.66 @ 144.83/ 6.29 @ 116 1/8th. This was done with a 100 shot thru low gear and 225 HP in high gear on top of the 100HP. I am freshening my combo and planning to spray it more regularly this year. My questions are in regards to a few items, camshaft and rods/pistons. This engine is an older R/M Super Series type build. It has a Carillo H-beam w/ SPS CARR 3/8" bolts and a JE SRP 5cc dome piston. The camshaft is a Erson 272/282 @ .050" and the IO is 28*BTDC, IC is 64*ATDC, EO is 69* BBDC and EC's @ 33*ATDC. Lobe lift is .450". Lobe Sep is 108* and it has a int and exhaust c/l of 108*. I use a 1.5 ratio arm. I thought picking up almost 24 mph on the spray was good, but this is definitely no N20 cam. Is there room for improvement with a N20 grind? Is it worth the money? I was somewhat disappointed with the NA performance at 11.20's. The car has a 4500 9" converter (launched at 3800)/ 4.11 gear/ 26" tire - no spin, except on N20! I had 1.54 60' on N20 and 1.68 on motor. Compression is 12.48:1 and I use a Super Victor with a BG 1090 dominator. 1 3/4" primary tube with 3 1/2 Flowmaster Super 40's. My questions to some of you knowledgeable and experienced builders and racers are about cam selection for this package. I am not wanting to change my spring package on the head, so max lift is limited to .725" or so. The MAX RPM now is around 7500 with the .272/.282 cam. I like the specs, just wondering about a wider lobe sep?? Is it worth the money with those performances above. What about the 4/7 swap. Comp wants 378.00 for a N20 grind with it. Are there better options? 4/7 or no? As far as the pistons I am a little worried about the SRP's, but after seeing signs of detonation on some rod bearings (like loss of crush), they appeared to have lived O.K. A 4.125"/3.75"/9.010" deck with a 6" rod combo piston for N20 from JE is a custom (not shelf), they make 1.145" CD for NEW 9.020" (finished) blocks as a shelf piece but not for my arrangment. This piston is expensive. If I need it, I'll get, but I question to the experienced. Do I need it? I am frugal, but not unwilling to spend some money. I would like to run 9.0's in this fairly stock appearing car.
Some proven p/n camshafts fdr this combo with N20 would be appreciated? also your experiences with these rods and pistons in similar applications.
Thanks for reading my long winded post, but I know detail is worthwhile......
Other specs on heads are @.300" 226int/148ex @.400" 268int/187ex @.500 302int/210ex @.600 314int/224 ex @.700 317int/234ex - 2.08/1.6.
What should this car be running? It appears it is a little lazy on motor alone leaving the line. It acts like it would benefit from a 5000RPM converter and at least a 4.56 gear??
Thanks

[h]

ttt

[sbchevy1]

i dont know about your nos recomedations but your on motor runs are way off the mark i would think you should be running in the low 10s at 128+ mph

we have a 383 in a 3400lb car with way less head less comp at 11.3 to 1 a lot smaller cam at 242 at 50 solid roller only 3800 stall converter and 3.54 gears has been 11.02 at 123+ mph this is in a total street car
with everything you say is in your car you should be easy bottem 10s
we have another car with a 12.5 comp 357 with box stock brodix ik200 heads that do not flow more than 260 cfm it weighs at 3300 lbs does have 4800 stall and 4.56 gear but on a 32 inch tire and it went 11.00 at 122= mph
i would start looking at your current combo very carefully before changing anything out

[85Iroc]

I agree. You definitely have something not right. Maybe the cam is a little too big. My 355 has 10.8:1 compression, Canfields ported by Mike that flow very similar to your heads, Victor jr. intake, .626/.626, 255/264 @ .050 on 109 lsa lunati cam, powerglide, 4.88 gear on a 26x10 slick. It goes 6.90s @ 100 mph in the 1/8th w/ a 1.46-1.47 60' leaving off the brake at 3500-4200 rpm. Car weighs ~3100 with driver. You definitely should be leaving harder that what you are. More converter might help with that big of a cam and more gear would help launch but it might not like to run the 1/4 with much more gear, especially on spray. I think I'd look at a smaller cam and make sure the fuel & electrical system is up to par. Also make sure the tranny & converter are working like they should.

[helicoil]

Thanks for you replies. Input is appreciated. My feelings also revolve around motor et being low, most likely do to the 1.68-1.71 et, indicating the the 'laziness' of the engine combo. Spray is my focus, I also play quite often on the street with this car. It is a stock suspeneded (Fab 9 rear), Caltracs, and 26X10.5 ET streets. My thought was BIG manifold and carb along with camshaft and PG ltall 1st gear and 4.11 rear would allow the car to leave on slippery surfaces (ie street) with a baby street tire. It does work against the tubbed Pro Streeters at local cruise nights. LOL But at the track, it is boring! I honestly belive if I had a 4150 carb and manifold, maybe a Victor Jr. or comprehable Wilson it would respond much better on a holeshot with this converter. Couple it with a 3-spd (TH350 or 400) and I could get 60's in the 1.55 range, same engine. Anyones thoughts......I don't know many racers with similar combos in my area. I see alot of SBC racers on this site and value everyones input. anyone with thoughts on the SRP pistons in a 300-350 HP N20 plate SBC. JE says 250HP max, but i sometimes notice from my perspective (parts manufacturer) that we can be a little over protective. Thoughts? Also, I have talked with many racers who say that camming an engine for N20 is not always the best approach, I know of several guys who cam an engine to produce max HP, and then add spray with good results. I kind of believe I have an example of this result, at least half of it (good N20 results), the other half of motor performance does not seem to be there. But maybe on a dyno it is there??? Possibly I am just not using it or applying it correctly in this car with the setup. Surely some of you have ran into these situations.... input is welcomed. thanks again, enjoy reading this site!! I hope some others give input and experiences

[Gary]

You said you checked with comp on a custom cam have you cheacked anyone else? I run a cam motion nitrous grind and love it. I run a 360 in a 3300 lb car with a th 350 and a 4500 nitrous converter. It runs 6.20's at 114 with a 1.40 sixty foot with a 250 shot and foot brake. I have dart 230 heads ( way to big on the motor but work for the spray )motor runs 7.60's on motor and 6.20's on the spray. Last cam ran 7.40 on motor and 6.40 on spray changed only the cam and gained 2 tenths on the spray but lost it on the motor. But it is more mild mannered on the street. Give cam motion a call and have them recomend a cam for your combo. Gary

[strokedTA]

I ran a 406 Dart block sbc. Had a baby cam, 250-260 dur @.050, about .660 int / .696 exh, 112 LSA, Comp grind, 11:1 comp. Heads were Brodix T1X's, flowed about the same as yours. Ran an 1175 Pro System dominator and brodix 1002 intake, BME N2O pistons, tool steel top rings.
Motor made 653 horse at 6700 rpm's on Steve Schmidt's dyno.
Ran best of 6.69 in 1/8 (don't even remember mph), 1.42 60's on motor, leaving off brake (TH400) at 4500rpm, stall was set to be around 4800 on motor and 5400 on spray (Coan built it off my dyno sheet) that was when I had 28x12.5 ET Streets, @ 12#'s, 4.11 gears @ about 3500 #'s, not sure because didn't weigh the set-up until after the season. Afterward weighed 3420 with me in it
Later (following year) when I sprayed, had 1.30 60's best, with 29.5x10.5 ET Drags, and ran a best of 6.01 (hitting 2nd gear right off line). Last run with that set-up.
Later found out all my connections with my nitrous system were corroded (fricken nice!!!!! ).

Car should have ran 5.80 I think, but hey I didn't do it, not enough time at the track!

I would in no way go to a lower gear, especially if you want to run the 1/4.
If you aren't spining a 26" tire then you either aren't hitting it hard enough or you have a hell of a track.

It would be a great idea for you to dyno the set-up and see what's up.
I wouldn't use the SRP's for a 300 shot, and use Hellfire rings. I gapped my tool steel rings at .008 per inch of bore, on top.

Where do you live?

Good luck!
Dave Brown
www.wheelsupracing.com

[helicoil]

David-
I live in St. Louis.
i would like to dyno the engine to dial the carb in better. I use an Innovate A/F meter and really don't like the constantly dancing numbers I see.
I think I will try leaving somewhere in the 4500 range next season. I can't really explain the weak 60's. I suppose the camshaft is just too big to leave that down low.
I have bumped the compression to 13.25 with the NEW JE N20 pistons and Iwill run the Hellfires again this year. I gapped them at .007" per inch last season. I am still up in the air on the 4500 carb vs. a 4150 and smaller intake.
Do you have any experience running a glide vs. a TH400 or TH350. Is it worth the change. I street drive the car alot and think the 3-spd would be more fun to drive. The glide is kind of boring.
What manifold do you guys reading along think makes a better 4150, Dart Wilson or HV1000 Brodix?
Thanks,
Tim

[strokedTA]

I'm probably going to a glide? So, no comparison, sorry.
Glide is lighter, don't have to shift as quick, get smore power to ground.
But cost more than twice as much to handle the same power as a TH400. Mainly from the $1100.00 gears you have to buy for the glide.

Dave