mcbchild

iTrader: (1)

Ok guys, I am in need of your ideas again.
I went to the track again last night and running like 12.1x
I know that there is more power in her and just can't get it out. Maybe could this be something as simple as the tune needs playing with and I see listings on here that are running 10s with similar setups. Also shifting at 6800 rpm and around 6200-6500 thru traps
Here are my specs:

350 .060 (388 sbc)
11to1 forged flat top pistons, with zero deck
Eagle cast-steel crank
6" I-beam rods
Isky mech flat tappet cam 251-259 (284-292 dur .541-.547 lift 108 LSA) installed straight up
1.6 roller rockers
Super victor intake
Dougs 1 3/4 LT headers
Brodix track 1 heads
830 Holley race carb
Pertonix race HEI dizzy
t-350 trans w/4500 stall
4.10 rear gears
Race weight 3450Lbs.
Eibach drag launch rear springs w/pass side airbag
Lakewood LCA w/lcarbs in the next hole down from stock
28x9x15 Hoosier slicks
Removed front sway bar

1st
60' 1.74
330 1.744
330 5.031
1/8 7.760
mph 89.41
1000 10.175
1/4 12.21
mph 111.78
Kind of let off the gas a little on this 1st run

2nd
60' 1.67
330 5.021
1/8 7.758
mph 90.31
1000 10.125
1/4 12.13
mph 112.20

Orr89RocZ

iTrader: (20)

Lets start with the simple and obvious things here.

Are you spinning on launch? Was this on footbrake? If so, how are you launching it? leaving off idle, leaving at slight foot brake stall or leaving off full foot brake stalling?

Then lets go with how much timing you running at WOT? What rpm does it come in at? Try setting full timing at 3500 rpm or so, so it hits the top of the converter hard.

That setup should be sixty footing alot harder than that. Thats a good bit of gear, stall and good motor on paper.

Tune comes to mind here because I think you should be trapping alot higher than that MPH indicates. What was the weather/DA like at the time of these runs? Could have huge influence in how that motor runs.

1/8 mile trap and 1/4 mile trap seem to go well together. I have a buddy that traps 89-90mph in the 1/8 and has hit 113's in the 1/4. Runs 12.0-12.2's with same 1.7 60's as you but on a good air day has hit 11.7's I think it was at almost 115.

It could be in the tune, the air quality or whatnot but still seems like it should get up and go abit quicker than that.

skinny z

Orr asks all the pertinent questions. I agree the tune and the air make a huge difference.
I'm a little suspicious of the soft 60' time. My combo will lay down a 1.7 and I don't have half the setup you have. The TH350, the 4.10's and the 28" tire doesn't give you as much gear as you might think. If you could trap in 3rd at 6200 rpm you would be near 125 mph! At 112 you must be close to 5500 so from a STRICTLY drag racing point of view you don't quite have enough rear gear. Traction permitting I would think you should be low 1.6 in the 60'. That'll get you 11's. One observation I have is that the dedicated drag cars never seem to have enough gear. I'm always surprised at the number of 4.56 and 4.90's being used.
Gears notwithstanding, I'd double check the condition of the engine with a compression test. A healthy racing engine should be in the neighbourhood of 200psi cranking pressure. I see you've listed an 11:1 piston. Have you calculated the compression ratio? A quick check with the DCR calculator indicates that cam would like a true 11:1 SCR.

Atilla the Fun

Your 60' time is too slow.
I doubt you can hope for 10s with that combo at that weight.
I'd go to 29x10.5W slicks, front skinnies, a low-ratio gearset, ( 2.75/1.57 rather than the 2.52/1.52 ) a trans brake, and AFR's best 195 heads. The version that's over $2,000 / pair.
And install a '91-'92 WS6 rear anti-roll bar. The biggest tubular version.
Is the car caged? It'd help. Gut the interior.
ALL of that together should get you high 10s

mcbchild

iTrader: (1)

You guys are the best with these 383-388 sbc and that is why I really wanted ya'lls opinions.

Orr, I am using foot brake and bring it up to about 3000-3200 and not spinning on launch. Full timing is at 36* at 3500 rpm, weather was around 78 degrees and very little humidity and not sure what my DA is here in milwaukee, wi.

SkinnyZ, I am around 6200 rpm going thru the traps in 3rd gear. Also should I go with maybe a smaller tire and the block was just rebuilt with new file fit rings and the builder stated that I can use NOS on this motor and said to use around 150 to 200 shot which I did a 150 shot on my last run after losing timing 2* and hit 11:40s at 121 mph with a rt 1.6x still but I hit the nos on 2nd and 3rd gear not on take off. With the tune and 150 shot hit after 60', I can hit 10s, but would like to hit at least low 11s without the nos first. But seems like you are also saying I should go with a smaller cam?I remember you had help me before figure my scr and dcr which at the time i think was around scr 8.6:1 and dcr around 10.7:1 with the cam advanced 6*.

Atilla, I am running 28x9x15 slicks at the moment and front skinnies and not sure I want to put a transbrake in a t350. Would it be better to get the track 1s ported instead of purchasing a new set of AFR 195 or would they cost about the same price for a pro port job on the brodix heads as purchasing new afr 195s. The car is not caged which I know will add more weight back. Maybe I'll go with a 6pt rollbar after the season anyway and you think that will actually help?

So far I am looking at tuning, possible cam change, different heads or porting my existing Brodix track 1s, does that sound about right?
I am really not ready to change heads as I spent close to $1500 on these heads I have now. Is the cam really maybe too much for this engine ?

Orr89RocZ

iTrader: (20)

You bring up a good point. If the tach shows 6200-6500, then your converter is slipping alot. Your getting almost 13% at the low end and upwards of 18% on the high end of the scale if you trapped 6500 rpm. Might be blowing thru it, may just be a softer spec'd converter. Definately sounds like its a milder converter off the line, just because the car isnt 60 footing but could be in the tune.

Fast 383

iTrader: (2)

I feel that something is still way off. Lets go back to basics.


1.What is different from the last thread we had going where you were running high twelves and couldn't figure out why? I remember you saying that you took the motor apart and maybe found a/the problem. What became of that?

2. A car at 3450 will need to make 500 Horsepower to go 11.0 @ 123 or so. There's no reason your combo shouldn't make 480-510 when tuned properly.

3. Providing that you are making the 500HP than obviously your setup is the restriction. When I say set up I mean everything around the motor. Ex....Converter, gear, tires,


Here's what I would suggest. Start with the converter. Because obviously your 60ft's are no good. 4500 is a good number in a ten inch or 9 inch converter. But if it's an 8 inch that is to tight and potentially a restriction. Tell me where you bought it from. Do you have the reciept? a part number. Let's find out what you have and make sure it's not holding you back. If your converter is too tight and not creating any slippage than your not going to be opperating in your powerband. Ex. Your racing from 4500-6200. Throw in the fact that your footbraking and only launching at 2500 or so....You should be F/Braking to 3500using the 5300-6800 window.

Once you get that out of the way you can concentrate on the fine tuning issues such as Gear ratio and tire size.

I personally feel like the car is just far from it's powerband and needs a converter/gear change. But just remember this...

500HP + 3450 = 10.99 @ 123


My car had an almost identicle set up accept 3180 lbs and less cam. My car made 485 HP and was dyno tuned. It ran high tens consistantly. If I put less gear in there and less converter it would have pulled the car out of it's opperating range and probably ran high elevens/low 12's. Right where you are.

Ask yourself ...

Am I Tuned in and making the HP.

Is my chassis capable of putting my HP and weight into is powerband?

Atilla the Fun

Okay, I was still working on my first Pepsi when I typed that.
Lemme try again:
First, my calculator says your converter slippage is about 500 rpm, which isn't bad for such a small converter in such a heavy car.
Second, I was thinking lower gearing, but now I'm sure I'm fully alert, it should be in the axle, not the trans. 4.56 gears.
Yes, I'd sell the Track 1 heads.
Look, the close ratios of the TH350 help keep the engine in the powerband. The 4.56 will give you a proper combined ratio in first, proper rpm through the traps, and will help everywhere in between, too. The smaller intake ports in the AFRs, as opposed to probably 220 cc in ported T1s, will give you a harder hit to the converter, but not hurt the top end.
The heads plus the gears plus the cage plus the rear sway bar will require more traction. 29x10.5W slicks will give you that. That should drop your 60' times to the 1.3 range. That alone would be an 11.7.
But the AFRs giving you more power everywhere, and the 4.56 gears, the rear bar, and the cage combining to let you use it, a 10.999 should happen.

mcbchild

iTrader: (1)

fast383, The problem when the motor was taken apart was that 1 or 2 cylinders had really weak rings on the pistons and that was caused from my engine overheating twice on me with my fan belt kept slipping off. The issue has been fixed since then with a different belt set up, but the damage must have been already done to the rings. I think 2 of my cylinder compression test came out to about 175 psi and the rest were around 190psi. One of the cylinders I was informed looked like it was burned is what my builder told me and he was able to fix that by honing the cylinder he says. Put new file fit rings and bearings in the block and this was the first time I had the car out since I got the motor back installed.

I am running a 9.5" 4500 converter that I purchased from ******* performance and I included the link below of this converter had heard nothing but good things about their converters. I am back at the track again in 2 weeks and will foot brake to 3500rpms and see if that help and maybe start playing with my total timing by starting at 34* and work my way up to 38 or 40* in 2 degree increments. Does this also sound like a good starting point?

http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWNX%3AIT

Fast 383

iTrader: (2)

Well, it's not the best converter out there ( just an average 9.5 inch High stall street strip converter). But people all over have had very good luck with them. It really shouldn't be your problem, however, I think it is.

I'm thinking your problem is this. Your engine combination isn't making any low to mid range torque because of the way it's set up with the larger cam . I'll bet if you dyno'd it you would see that it's making the power but all above 4500 to 6800.
The fact that you can only get that car out of the hole at 3k or 3500 is letting you out on the track where there is no torque or real horsepower. Thats why your 60 ft's arn't there. Than your going down the track and only crossing at 6300-6500? Thats no good.

Think of this.... Put in a transbrake, launch at 4500 or higher with a 4.30-4.56 gear and watch your 60Ft get to 1.59 or better. Than shift at 6800 and hope your rpm's fall back to 5000 or more. Shift again and cross the traps at 6800-7000.
Thats has to be good for a seconed.

Other options would be to try out a smaller cam. Something like a 246/251 @ .050 to level out your powerband and match the rest of your combo. Your converter would adapt quickly to that.

Another option would be to get a super loose 8 inch converter with a fat cut stator that will spin to 4200 or higher on footbrake. The extra RPM/Slippage would also equate to higher trap rpm's which will be higher trap MPH.

These are just my opinions.
My car made a beutiful flat line of torque from 3000 and up with my combo and worked great with a lower stall converter(3300) but probably could have benefited from a 3800-4000 stall for maximum 60ft's.

mcbchild

iTrader: (1)

Thanks for the quick replies ya'll. I'll start working with the launch and tune in 2 weeks when I am back at the track. All of ya'll have given me some great advise and I'll start working from those right away. If this still doesn't work out right, I'll start with replacing the cam to something in the 246/252 @.050 range and work up from there. Heads if needed, will not be an option this year as the season is almost done and will just try and work with what I have now at the moment. I also have a set of MT ET streets 27x10.5x16 that I can also tray since they are a smaller tire and still pretty new, just figured I would get better traction with the bigger slicks.

Orr89RocZ

iTrader: (20)

That combo if making the power it should be, will 60 foot just fine with less converter and less gear if the car is in the 3450lb range. I had a good bit of power on my 383 with just 3.42 gear/3600 stall and cracked off 1.55 60's without trying to hard.

That combo with the current gearing and stall should easily match that. Its not trapping that fast mph wise which would indicate its down on power.

I'd start looking at the fueling/air delivery.

Use only as much tire as needed. Some like to go with throw as big as tire under the car as you can fit, then gear to match. That works ok, but the whole system needs to match the rpms you intend to run.

Fast 383

iTrader: (2)

What was your cam specs and powerband? 251/259 indicates a much higher powerband than something in the 230's/240's which would work well with a 3600 stall.

mcbchild

iTrader: (1)

Orr, So I should play with the air/fuel delivery after getting my rpm launches up then the timing would be a good starting point?

Fast383, I don't have my cam spec card right now as I am at work and will be home in about 2 hrs, but I thought this cam power band was around 4000-7000. I will post the cam spec card then and also i have tried several different cams from crane cams hyd-flat tappet 244-252 @.050 to Crane Cams mech flat tappet 248-258 @.050. So I should have held on to one or both of these cams.

mcbchild

iTrader: (1)

Ok, just talked with isky and they said the power band range on this cam is about 3000-7000. So I guess I don't need to change cams at least or should I anyway?

Orr89RocZ

iTrader: (20)

I dont think that is too much cam being a solid flat tappet. My cam was basically a 3000-6800 rpm cam. It peaked torque around 4000 but held flat to near 5000 rpm, and peaked hp at 6300 and held to well out to 6500 where dyno stopped, even tho the rev limiter was hit on the run and I had that set to 7000 rpm. I shift at 6800 with that combo.

My L98 with bolt ons was easily 1.7x all day long with 2800 with peak torque in the 3200 range.

I think your combo is good for a peak torque in the mid upper 4000 rpm range and hold well to low mid 5000 rpm range, so 4500 stall is worth while.


Next time at the track, try bump up a jet size and run it with same 36 deg timing. Run it 2 times to get a feel for the change in fuel and then see how it compares to the old times. Got to match weather/DA conditions to get a comparison

Jet for best MPH and go from there.

Another plan of action is to vary rpm shift point. I'm curious what springs are in the heads and do they match teh requirements of that cam?

loneroad

iTrader: (3)

[quote

Orr, I am using foot brake and bring it up to about 3000-3200 and not spinning on launch. quote]


have you tried launching a little above idle?

depending what pump cam you have in, you might be half way thru your pump shot at 3200 and leaning out.

Orr89RocZ

iTrader: (20)

Good point with a carbed car they may like leaving just off idle or mild foot brake stall to 1500 or so.

Also whats your exhaust like? 3" true dual into what mufflers?

Atilla the Fun

Smaller cam might help the launch, but smaller cam with your sucky heads means you will lose top end. Just because it's a cheaper option doesn't make it the best.

mcbchild

iTrader: (1)

Orr, yes I have dual 3" exhaust into dual summit race chambers mufflers (Summit Racing SUM-638230) with an "X" pipe in between.

Orr89RocZ

iTrader: (20)

I wonder what the flow capability of those mufflers are? They could be holding back power some if they dont flow well. Can you try a run without them on?

mcbchild

iTrader: (1)

Orr, yes I have with my mufflers off the car. Also, i had the springs replaced in the heads for the flat tappet mech cam. They came with roller cam springs good for up to .700 lift.

88IROC350TPI

I have to ask... why do you always recommend people spend thousands of dollars to change their combo that already have the parts needed to go a lot faster? 1.3x 60fts and only 11.70 ET's? Is that a typo? a car 60ft'ing in that range should be into the 9's. 29x10.5W tire? Those tires are designed for Outlaw classes... why would a 10-11 second car ever need such a huge and expensive tire? Not to mention to fit a tire like that would require a ton of modifications. Paying $2,000+ for AFR heads when he already has a head that with the right combo would run him into the 9's also seems like extraordinarily bad advice to me.

His 60ft is clearly not his problem here as the timeslip shows almost no inconsistencies... His entire timeslip matches exactly the timeslip of a 12.10 car which would lead me to 3 possibilities:

1) He doesn't have the parts he thinks he does.
2) He has a tuning problem (carb, timing,
3) He has a mechanical problem (slippage, bad cylinder, etc)

Just for reference, my car is 3490lbs... motor is only a 10.9:1 350 with a "huge" cam in the 260's @ 050 on a 110LSA, cheap Canfield 195 heads out of the box, tight 9.5" converter (stalls around 3500RPM), 3.92 gear with a 27x10.5" tire. Carb is a 750 Speed Demon with the jetting and squirters up 2 sizes from factory and the timing is locked out at 35*. Shifting at around 6500RPM the car has been low 11's at 121mph with 1.60-and-worse 60fts. His combo should definitely run similar to mine, if not better.

mcbchild

iTrader: (1)

88, I definitely have the parts that I have listed and installed myself. All except for the short block and I even installed and degreed my cam. Checked compression in all cylinders and all reading 195 psi. So apparently we are all in agreement that this is all pointing to a tuning issue. I really appreciate everyones feedback here and will start with jetting my carb up and work on mph. Then will start on timing. May even need to try launching at different rpms and off idle. Somewhere I have to find what I am missing.

Fast 383

iTrader: (2)

I don't know. I think the combination is definetely there. 480-500 HP shouldn't be a problem? Anyone disagree? A dyno tune would explain.

With the powerband being 3000-7000 The converter should be getting the job done. Especially since it's footbraking to 3000+. As suggested try a low RPM launch, some cars benefit from that, some cars do not. I feel the car could benefit from a 4.56 gear to get it crossing the line at 6800-7000.

I have a question. What does the car feel like going down the track.
A.
- Does it launch soft and come to life about 200 ft out?
- Do the RPM's drop a lot or a little when your shifting.
- Does the car feel like it could keep pulling way past the traps?

or..

b. Does everything feel pretty seemless out of the hole, normal shift drops and crosses the traps with everything is has?


I guess what i'm asking is....Does it feel like a low 12 seconed car or a low eleven/high 10seconed car all out of wack?

Fast 383

iTrader: (2)

lol. Read my mind


This happens all the time. When something is wrong with a combination and it's only capable of so much, the timeslip will reflect it as if it were really a true 12 seconed car. IMO, only time you'll see inconsistancy's is a situation of spinning the tires. I see this 5 times a week with converters being wrong. The timeslip will read like 10.60/127 w/ 1.49 60ft with a 4800 stall converter and 9.70/138 w/ 1.33 60ft with the correct 5800 stall converter.

Good info. It tells us that mcbchild doesn't have to much cam for his combo.

It also tells me that if you had a higher stall converter you would cut 1.5x
60's and go some high 10's.

mcbchild

iTrader: (1)

Car seems to come out of the hole normally and shifting is pretty seemless. Also feels like it is reaching it's peak power around 6800-7000 rpms. Seems as though is should come out of the hole harder and during my shifting point, the rpms are not dropping very much, maybe drops to around about 5500 rpms, maybe a little higher. It does not seem like it's got more pull past the traps, it seems pretty steady past the traps. SO I think that is telling me that a tune and maybe bigger jets in the carb would be needed. I am installing new jets in the carb today and only going up maybe 2 or 3 jet sizes and will try different launches a week from this wednesday at the track. WIll try off idle and also try loading up the converter as much as possible with footbrakes. I believe I should be able to load up the converter to about 3500 to 3800. At first I was running high 12s and even cut a mid 12 when I was running with a 3500-3800 stall and with the exhaust open. I just switched to the 4500 stall and then I was running low 12s and with a good tune, I know it can run high 11s., but just seems like it should run low 11s at least with the parts I have now.

Maybe once I start playing with the carb jetting and timing, it will hit low elevens and I was just missing something like that all along.

88IROC350TPI

Are you sure your timing marks are correct? Are you sure that you are getting full throttle with the pedal to the floor and both sets of barrels are opening? I know these questions may seem stupid but it's easy to overlook the little stuff.

I would try locking out the distributor and seeing how the car likes it - Chances are you will wonder why you ever played with springs/weights again and the car should definitely leave better. A lot of people will tell you locking out the timing on a street car is a bad idea, but in my experience it is fantastic: car drives down the road great, idles perfectly, and my Walmart battery and CSR mini-starter have no trouble starting the motor on even the hottest of days.


My car would definitely run in the 10's with some slight changes but I'm too cheap/lazy to improve it. The car runs better than I ever hoped for so I'm happy... This year I think I'm just going to see how much spray it'll take and shoot for a 9.999.... Might just be a dream though cause there is no way in hell a 3500lb car with $1,000 heads, bone stock suspension/chassis, and a non-outlaw class tire can run those times

Orr89RocZ

iTrader: (20)

No hesitation off the line? Just wondering if it has a slight overrich pump shot or something that may be slowing down engine acceleration. My turbo car does this and I havent had a chance to tune it out. Feels like its leaving normal and just takes time to spool up, but its really just going to rich on WOT snap, so its hesitating and building rpms slowly.

mcbchild

iTrader: (1)

Definitely no hesitation and not running rich as I have already checked the plugs. Leaving out of the hole does not worry me too much, what worries me is that somewhere all the power that should be in the motor is not coming out and somewhere there is a bottle neck blocking the power the engine should have. You guys have put me on the right path I would think between the carb jetting and timing, is the issue.

The timing marks are correct as I have dialed the cam in an verified the timing marks on the balancer. It is a steel sfi balancer and no separate ring on the balancer to spin loose. I think 78s are in the carb now and will pick up some 80s and 82s since I already have some 74s or 76s sitting around in the garage.

skinny z

You said yourself that you have run a 1.60 60'.
If the OP could cut a 1.60 then he too would be in the 11's.

88IROC350TPI

He would but for instance, my car has run as slow as a 1.71 60ft and still an 11.25 @ 121. My car 60s like crap because my convertor is too tight and my suspension is all stock. It trips the timer and then the chassis/suspension spend a tenth or two flexing and trying to figure out what's going on before the car starts moving forward again.

What im trying to say is that his car is consistently slower than it should be throughout the entire 1/4 which means his 60ft is not really the problem here because he should still be able to run in the mid 11s with those 1.67 60s he's pulling. Sure, improving his 60ft will definitely improve his overall time but there is still some other reason that his car is missing around 100HP.

Fast 383

iTrader: (2)

I agree with the above. Seems to be down on 100 HP. But the fact is that post after post he has just about everything we throw at him covered. There are some small areas like carb jetting and a degree or two of timing but we all know that The motor seems to be functioning properly.

I still believe this drivetrain needs an adjustment.

Fast 383

iTrader: (2)

It's telling me that your 9.5 converter is a tad loose. You ran a 3500 stall and went to a 4500 stall. Maybe your prime is a 3800-4000. Paired with 4.56 gears to get you across at 6800-7000 could be the trick. Again, these are just ideas.

Orr89RocZ

iTrader: (20)

i wouldnt say 100 shot down. That would put him at 122 mph traps. I think he should have 117-119 in it which is closer to 50-75 hp down

A good 30-40hp can be found easily with the tune if its currently too lean. maybe even more. I picked up 2 mph from going from 14.5 air fuel at peak torque to 13.0 air fuel ratio on the dyno. gained about 25-30lb ft torque right there and 10 or so hp peak. I was close on my tune with peak hp, but missed mid range by a few points air fuel ratio, yet the car still felt and ran fine. Right after the tune however, it really picked up. 2-3mph increase and 1 tenth right there on same 60 foots (Slight spin on old slicks)

The rest may be eaten up by the converter...hard to say

mcbchild

iTrader: (1)

I also forgot to mention that on my last run, I just backed my timing down 2 degrees and hit my NOS 150 shot. Car was like a bat out of hell and probably could have hit the 10s if I had used it on take off all the way thru. I used it on 2nd gear and hit is again on 3rd gear and ran an 11.40 with 121 mph. I know I should not have used the NOS, but I had it for 2 years now and just wanted to try it once to see the difference.

88IROC350TPI

I did some playing around with Engine & Drag Racing Analyzer Pro and it says pretty much what I said... Assuming good weather and at sea-level shifting at 6500RPM it says you should run an 11.11 @ 121.10mph with a 1.63 60ft.

I know computer programs should only be used for ballpark figures but this one is very accurate when it comes to the combos i've put into it. For example it says my car in street trim should run 11.40 @ 118mph with a 1.66 60ft. In reality it runs 11.50-56 @ 118-119mph with a 1.60-65 60fts through the crappy single 3" catback.