Hot Rod Forum banner

1/4 mile 16????

5K views 25 replies 14 participants last post by  DoubleVision 
#1 ·
OK I built the motor in my truck and its running alot slower than I thought it would.. does this seem right??? its a 350 4 bolt flat tops over 40 with 487x heads milled 10 lunati 60102 cam 1.6 roller rockers rpm performer intake 1406 carb stock manifolds accell ignition module msd cap coil th350 transmission stock converter with 308 gears and 22 inch rims in an 86 chevy shortwide... I figured the thing would run at least low 15's high 14s but the best i got was a 16.5.....
 
#3 ·
the truck is bagged so I can't run long tube headers but shortys would be better than nothing. I'm wanting to put different gears in it but the truck is going to be daily driven so I think the 410s would be a lil bit much. I'm also looking around for different heads. would you recommend a holley or edel carb???
 
#5 ·
A TCI Breakaway converter (2200-2500) or similar would work well with 3.73 and not put you at too high an RPM .Like you said about the headers,shorties are better than stock.Those heads are one the best flowing smog heads made.Yes, I know you could buy aftermarkets but not everyone has that kind of budget and if frogs had wings,they wouldn't bust their butts when they jumped :D
 
#10 ·
1/4 in 16

Troy,
could you be mistaken, I think the frog should be fine when he jumps. But when he lands, now there might a some concern as to him well being. :embarrass
 
#11 · (Edited)
4500lbs and 300HP (stock exhaust manifolds and your CR?) is about/roughly a 14 (with a strong tail wind at sea level)....

calculator link:
http://www.tciauto.com/Products/TechInfo/Calculators.asp

it's a very long list of possible/probable (minor and major) causes that are likely acting together to make your ET so so slow....

my first test would be to do a compression and/or vacuum test to verify the whole rotating assembly is working properly, rings and valves are infact sealing....
(a 16 indicates next to no HP power if the motor is the problem)

one small item is the 1406 carb is set up more for (lean) economy as delivered (98/95 jets 75/47 rods, it wants 5.5psi fuel pressure max), you are likely too lean WOT=.2-.3 slower???

edit add:
another effective way to test how well the rotating assembly is sealing is mount a vac guage so you can read it driving....
on a 3rd to 2nd downshift at 50mph your motor should read about 25Hg....
here's a link on how to diagnos the rotating assembly with a vac guage (caution they are referencing typical stock motor readings results)
http://www.users.bigpond.com/ergoff/vac1.htm
 
#12 · (Edited)
Drag Basics

1- Be sure your throttle is opening all the way. Have some one hold the pedal down, and look at the blade(s) (engine NOT running) .
2- Basic tuneup - Is there slop in your distributor? Chevy distributors are bad about having too much wear vertically, between the drive gear and the housing. I have heard that each thousandth of movement changes your timing by 1 degree. Moroso makes shims for this (cheap fix) Shim kit is PN 26140. If your distributor is then too tall, bottoming on your oil pump,it may cause spark scatter. Use PN 26150 to space the housing up off of the manifold a little.
Is your engine running on all cylinders. I had a 455 Olds that was arcing one cylinder, only under power. I had a friend power brake it and saw the spark plug wire arcing to a vacuum hose.
3- Is your fuel system up to snuff? No kinked lines, if it has been sitting, check your fuel tank vent (darned dirt dobbers). If you are running good on the first half of the track, but not picking up at least 15-20 MPH on top, look hard at your fuel system.
4- Does your truck roll fairly easy? Check for brake drag, have the alignment checked.
Hope this helps, Charles
 
#13 ·
what was the trap speed?

How much total ignition timing?
Done any carb tuning?

A "350 hp" engine out of tune can easily lose 100 hp.

22 inch rims doesn't mean anything. How tall are the tires?

Your cam is about 10 to 15 degrees too big for a truck with a 3.08 gear. Drop a few sizes on the cam and it will go faster.

My c10 (4500 pounds) runs high 14's at 97 mph with a set of 3.08. It has a 468 cid engine (exhaust manifolds, 206/212 degree cam, 8.75:1 cr, some head work).

Takes around 380hp to make a 4500 pound truck run 97 mph in the 1/4 mile. And a 380hp 454 big block can use a 3.08 gear. A 380hp 350cid needs at least a 3.73 gear.

Maybe you should consider using a 4.11 gear with a 700r OD transmission. Comes out to be the same gear ratio on the highway.
 
#18 ·
F-BIRD'88 said:
Your tires are 29" diameter. Very tall. You need a (very) high gear ratio to use the engines raised power/torque curve. (camshaft timing)
The thing is going 16's cause what you have is a mismatch. (big cam,low compression, low (stock)gears, tall tires, heavy vehicle. restrictive exhaust and cylinder heads.)

What is the problem with using long tube headers? ???("Bagged")???
A pick up truck is about the easiest vehicle to accomodate headers.
If any vehicle can truly benefit from the increased torque made by good long tube headers, for acceleration its a slug/tank pick up truck.

If you are going to run 29" tall tires and stock gearing (2.73-3.08), the cam is all wrong for both daily driving and acceleration.
That cam needs some compresssion ratio (more than stock) and doesn't get busy till near 3000rpm) If you want the motor to cruise along at low rpm all the time (low gars and tall tires), you want a small cam (short .050 duration).

When you ran 16's in the quarter what was the MPH from the time slip?
The long tube headers will hang too low and drag the ground.. What heads would you recommend? I'm tight on cash so what would a good gm head be other than vortec cause I don't have the money to get another intake. Also what carb should I run?
 
#20 ·
Sounds like my old P/U Brick

I got an education after camming, headering,manifolding & carbing my 350.

I would tromp on the go pedal.....all I got was more noise than before. :drunk:

I listened to F-BIRD'88... read some of his past posts... went for the gold!

His builds based on Vortec heads & Isky "Lift Rule" camshaft, are almost an overdose.

When I tromp on the gas now, the truck does not leave the line quicker than before, but to be truthful, I believe it is because the tires are spinning and smoking & squealing so much! :thumbup:

NONE of my trucks have ever had the throttle response, nor bottom end that his build offers. Perfect street manners.

I have not quite gotten the balls yet to open it up and feel it rev past 65;

1. still a fresh motor, less than 100 miles.
2. this is the fastest truck I have ever been in, ever.

Listen to what this guy has to say, he no speak with forked tongue.

He's a smart guy.

My 2 cents.
 
#21 · (Edited)
Caution:
on your PU, because of the tall gears and heavy vehicle you do need to road test and be extremely careful listening for detonation when tuning the dist ign timing....

your cam duration needs 14-16*'s plus of base timing to make decent low end TQ to launch the truck.....
at only 8* base it is likely your all in WOT timing is only 28-30* at 3,000+....
(some truck dist do have 26* of centrifugal so you need to test with a timing light to know what you have!!!)
your camshaft wants 36* all in timing, which, with the base at 16* it will have if the dist does has 20* worth of centrifugal....

the motor combo wants the timing all in at 2800-3000rpms for best possible ET/MPH at the strip....
BUT...
with those tall gears(!!!!).....
I don't recommend all in at less than 3200-3400 on your truck....
there would be to much risk of detonation on a steep road grade (or the bed is loaded with something) when the motor is "lugging" at low rpms at part throttle....

just changing the timing to more correct WILL make a major TQ and HP improvement

here's a excellent timing article link to study:
http://www.gnetworks.com/v4files/barrygrant/Ign timingwithimages.pdf
read it carefully....
 
#25 ·
bodydroppedsquare said:
the truck is bagged so I can't run long tube headers but shortys would be better than nothing. I'm wanting to put different gears in it but the truck is going to be daily driven so I think the 410s would be a lil bit much. I'm also looking around for different heads. would you recommend a holley or edel carb???
Some people use the 3/4 length chevelle headers in lowered trucks. The 22s aint helpin either.

Shane
 
#26 ·
I agree with Nairb. Simple fact, your running way too high gears and you need less cam with the combo you have. just a gear change or a much shorter tire would be a step in the right direction. You have to understand also, when you change tire diameter, you change the gear ratio, the taller the tire the higher the ratio, the shorter the tire the lower the ratio. This is why when 4x4 pickups install 36 inch tires in place of the stock 28`s they came with, it`s recommended the gears be swapped to a lower set. Example 3.42`s to 4.11`s.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top