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Need help with track times

6K views 41 replies 8 participants last post by  spinn 
#1 ·
I have 1986 Monte Carlo SS stock suspension with 90/10 shocks and drag radials I have a 355 afr 190s xfi280 .576,.570 cam rpm intake with 1inch spacer 650 edelbrock carb 1 3/4 headers timing set at 36 total 2400 stall 350th trans my slip was an 9.2 1/8 mile 79mph with 2.1 60ft
 
#6 ·
I would swap the carb for a 750 vacuum secondary Holley type, preferably with a metering plate on the secondaries. It will be substantially easier to tune it that way. Get the spring kit for the secondaries and a jet kit with 1 of every set.

That's a healthy cam for 355 cubes and you have pretty good heads. It will want to run with a converter higher than what you have now. I'd rock a 4k converter with a set of 3.73's and a 26 or 27" tire.
 
#7 ·
I would consider a 3800 stall or there abouts,750 hp double pumper,and what ever manifold is one step below victor Jr.your 60' times needs to be 3/10 quicker at least.
do the manifold/carb swap first and see where the power is,then re determine the stall you need for racing.

what gears are you using?that also can be optimised after carb/manifold swap
 
#8 ·
You should be running low 8's high 7's at least. Your 60 is pretty bad as well
.... a 355 with 9:1 and a summit 234/244@.05 Hyd flat. Rpm intake and a 750 Holley Dp with 373:1 and a 3000 stall in a 69 chevelle runs 8.2 with mildly ported 462's and will go faster he just ran it 2times to get a time slip...with nitrous he blew the tires and ran mid 7's with a 150 shot...
 
#11 ·
How did you figure out your cfm requirements? Did you factor in VE and rpm? Real test is to hook up a vacuum gauge and watch your manifold vacuum at WOT and if your vacuum goes above a couple inches you don't have enough carb. The article I read that on was more race oriented so idk how far off that is for a street/strip deal.
 
#12 ·
Intake and carb isn't killing it that bad unless the a/f ratio is whacked. The 60' is s l o w. You should be in the 1.7-ish range. Unless you are spinning the TC is too tight so the new converter should help unless the car's spinning.

Pay close attention to the shift points. Most guys over rev the engine thinking they'll go quicker if they tach it out to 7K rpm. You want to shift about 10% past the power peak.
 
#13 ·
its funny, there was a guy who had a ford truck with a 429 CJ built nicely with cam, intake, headers, ignition and a 800 cfm edelbrock, and it did run good...or so he thought...I at the time had a 68 cougar with a 357W about a 400hp build with world products heads 1 3/4 headers weiand stealth intake and a 750 hp series holley... he liked the look of the carb and was astonished at how good it ran and wanted to try my carb, well after several weeks of asking i let him borrow it...HE DIDNT want to give it back... :drunk: lol and you know I traded a mustang was an 89 for a 79 f-100 with a mild 460 and with msd ignition upgrade and yes I swaped that same 750 hp holley on that truck with 33's ... i did outrun the same mustang in the 1/4 i traded with a TRUCK! >.< whitch did yea it had a edelbrock on it beforehand as well, they are good carbs but you dont see many FAST cars running edelbrock carbs...wonder why?

you have really good heads, decent intake, and you try for gas mileage from an edelbrock? i just i dunno....i wanna be mean but there are so many people that do the same thing....so ill just say to each there own but the proof is in the pudding, if you want to go faster start thinking more of performance than gas mileage...


Id rather use a holley avenger vac secondary series carb than a edelbrock anyday they are really good carbs vac secondary the 770 works really well on 450hp builds.. even as small as 347 cid...and that is TRACK proven performance...
 
#14 ·
I thought the intake rpm performer was good since I don't rev to high and I shift at 6k since after that I have valve float and I don't spin off the line at all but this is not my daily driver so I could move to a 750 but I'm pretty sure my a/f is pretty good with the 600
 
#16 ·
example of mine: My car,when I bought the car,ran a best time of 13.9 at 101 mph. All I did was swap in a 750 double pumper for a 600 double pumper and I ran 13.4 at 105.

Also of note,,, 650s/750s/850s used to work better than 600s/700s and 800s. I put a 700 double pumper on a 327 and it was a dog. I got my 750 double pumper off a 283 powered chevy2 I had before I got the Camaro. 600 cfm is not enough for a "good" 350
 
#17 ·
You want track proven? I've posted this so many times now that I'm sick of it but here goes. All steel '81 Camaro w/0.030" over 455 Pontiac, ported 6X, Performer intake, cam, TH400, 3.08 rear gears- 12.7 @ 107 mph. Carb was a Holley 4777. Picked up almost 2 tenths by changing to 3.31's.

Would his car pick up using a bigger carb? Possibly. But not by enough to compensate for the amount of missing performance- especially the lack of 60' time. A smaller carb could even help the 60' time.

I'm waiting to see what happens w/the new TC.
 
#22 · (Edited)
You want track proven? I've posted this so many times now that I'm sick of it but here goes. All steel '81 Camaro w/0.030" over 455 Pontiac, ported 6X, Performer intake, cam, TH400, 3.08 rear gears- 12.7 @ 107 mph. Carb was a Holley.
You have to be joking.

You guys have really fast cars. These are full weight normal driving vehicles? My mothers accord weighs about 3600lb with the 4 cylinder, It is a aluminum can. It is hard to get an old GM full size down to 3600. Almost inpractical.

Using the scale at the land fill. It weighs your car at its actual weight. No door sticker, or advertised weights.

When I did the drag only build with 4.56 gears it would be at the hydraulic limit around 6300-6500rpm. Taking it up before the traps it would run out, and had to let off. Made it to 13 flat using the Mopar direct connection book 13sec 440 reciepe. Mopar 509 cam 3600 stall 4.56 gear in a 3800lbs 70 barracuda. I thought that was a fast package. Using a demon 750 DP.

A 600cfm never made more than 300hp NA.

I built a 355/th350 with the rpm complete heads and cam and intake and 750 carb 3000stall 4.10 build. It supposedly made 420hp, according to the mph it was about 268 rwhp.

My truck is super charged vortec sbc and probably makes 350hp at the flywheel. If you can get 1hp per inch NA that is fantastic. My NA stuff was around .8 to .85hp per inch, figured from the mph.

To dial in the carb we use a 4-5 gas probe at the collector. You turn the car wheels resting on a rollers with 500lbs of resistance strapped down with a fan . O2 Co's Nox A/f in parts per millioin ppm and tune accrording.
 
#18 ·
using 4781 base plate on a 4777 carb can make a very big improvement on a low powered car.Takes some tuning and possible booster venturi changes to optimise.I did that before.The dyno time cost more than just buying a race prepped carb.I also used a 660 center squirter and it had fabulous wfo performance but it was grotesque as a street carb.
 
#20 ·
put the convertor in first and get fresh numbers.

I personally would use a single plane intake and a 750 double pumper.750 cfm is 750 cfm.same size carbs make similar amounts of HP.More racers will be able to help you tune a race oriented carb like a 750 double pumper
 
#23 ·
why would anyone aspire to get .8 hp per cubic inch? I feel 1.15 to 1.2 horse power per cube as being a decent and achievable goal with good road manners,like any modern engine offered here in north america. I believe 1.5 HP/cube is about the most I want to deal with and still drive it on week ends.Im talking normally aspirated engines,,,
 
#24 ·
V , its not like I was trying to limit my builds to that. It is how much they made.

A .85 hp per in NA engine is a hot engine. 1.2 hp per inch NA is not even realistic. It can be done at a premium. That 375hp/327 never made 375 real hp. Some people became dreamers, instead of builders/creators . I do like to read your reciepes.

Peaky power and a flat curve power are diffrent. You may get 400+ hp with a 350 single plane, single carb, big cam. A supercharged 350 with a mild cam is gonna walk it from the line. You will not catch up, off the line is were it is won.

So what increase the stall to 4000 shift a 6000+ and remove all driveability. Could be but thats not my way.
 
#41 ·
V , its not like I was trying to limit my builds to that. It is how much they made.

A .85 hp per in NA engine is a hot engine. 1.2 hp per inch NA is not even realistic. It can be done at a premium. That 375hp/327 never made 375 real hp. Some people became dreamers, instead of builders/creators . I do like to read your reciepes.
.85 hp/cubic inch is NOT a hot engine. Most factory engines can do that sipping 87 octane. Take the new Camaro with its 312hp V-6. It's a 3.6 liter or 220 cubic inches. 220ci=312 hp or about 1.41hp/cube.

Peaky power and a flat curve power are diffrent. You may get 400+ hp with a 350 single plane, single carb, big cam. A supercharged 350 with a mild cam is gonna walk it from the line. You will not catch up, off the line is were it is won.
Not necessarily true. Yes the supercharged engine will make more torque and more power down low, but the ENTIRE combo comes into play when MOVING the car. A high revving 350 with a single plane that can go to 7k, will s**t all over a supercharged engine that can't go to 6k at the track. RPM is everything at the track. A car that can spin to 7k+ can run a big converter and a steep rear gear. The 350/single plane car can run a 4.56 rear with a 4500 stall, versus the supercharged engine running 3.23's and a 2500 stall. The single plane car would crush the supercharged car out of the hole.

So what increase the stall to 4000 shift a 6000+ and remove all driveability. Could be but thats not my way.
Driveability is a relative term. What is deemed driveable to you, might be too mild for someone else. There's more to a stall than just the stall speed. A tight converter will drive much better than a loose converter. I have a 4400rpm tight converter in my car that drives very much like stock under light loads.

As far as your own engines, you have to take into account the DA (density altitude) where you live. If your car is running 13.0's, but you live in Denver, it would run MUCH better, if you lived in say, Maryland.
 
#25 ·
Spin,my latest project might fit what you describe,,,,might?My street car is a 1981 vette,so far changed almost everything.256/264 @ 050 roller cam.drive ability is very good after 1600 RPM.I can drive @ 45 MPH in O/drive and accelerate smoothly and very quickly. below 1600 rpm I need to go down a gear.The reason it will still respond well with that big of cam is the intake centre line is only 108 degrees. Im very very sure this engine exceeds the 1.2 horse power per cube that I feel is normal.If you have a calculator,plug in the numbers and see what you get?
specs,,10.75:1,cam 256/264@050,,420 lift x 1.6 intake/1.5 exhaust,,950 modified hp,vic junior(instead of super vic for lower RPM and smaller cam) 4.155 bore/4 stroke,dart 227 cnc ported heads with minor polishing,2.07 int valves/1.6 exhaust,,rocker shafts.callies light crank,wiseco pistons,cam is solid roller and 108 separation(square cam,more for road race)

let me know what you think it makes?
I am making a few changes and painting the car.I will chasis dyno it after all that.The engine has been on a dyno before installation,which is just a ball park because my headers and carb are different and I run full exhaust
 
#27 ·
specs,,10.75:1,cam 256/264@050,,420 lift x 1.6 intake/1.5 exhaust,,950 modified hp,vic junior(instead of super vic for lower RPM and smaller cam) 4.155 bore/4 stroke,dart 227 cnc ported heads with minor polishing,2.07 int valves/1.6 exhaust,,rocker shafts.callies light crank,wiseco pistons,cam is solid roller and 108 separation

let me know what you think it makes?
I am making a few changes and painting the car.I will chasis dyno it after all that.The engine has been on a dyno before installation,which is just a ball park because my headers and carb are different and I run full exhaust
Calculator? You mean the track mph, or a engine dynometer. Anything else is bogus or close to. That is all race, and you could be making more than 1.2 per.

I like the cam 256 at .050 with .42 lobe , man that is not gonna work on the street with even a 454. Yes you can probably drive it . My oppinion that the valves do not stay closed long enough to have anything under 3-4000rpm.
 
#28 ·
rofl,I lope along at 65 mph at 2100 ish rpm. That is not a huge cam. thats .420 lobe lift btw if you missed the info. so just over 600 lift exhaust and close to 640 lift intake. If you have used any roller cams you know how nice and smooth they are. This cam idles smoother than any 500 lift 300 (advertised) hydraulic flat tappet cam
 
#29 ·
also forgot to mention,the headers are step headers with 1 7/8" stepped to 2" with 3" collectors. Primary tubes that big require adapters to bolt them to the heads. I use Jere stahl headers and his adapters are different than hooker big tube headers,just in case someone needs to regasket their headers there are 2 sizes depending on adapters
 
#32 ·
454 chevy bb has a 4.25 bore and 4" stroke

small block 434 has a 4.155 bore and a 4" stroke
so spin? why would my camshaft selection be much different from a 454?
ask people here that have actually used a solid roller camshaft how the engine idles? Its a lumpy sound ,but they idle a reasonable levels.My car idles at 950.

what does your V-6 idle at?probably 900 rpm.
I invite other solid roller cam users to post.
 
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