What is wrong with this combo

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19DART66

19DART66

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A few of you asked me about my combo in my Dart. Well I am kind of sick over it, I have spent a lot of money to keep going slower. I had an 80 Mirada with a W2 372 inch engine, 11.3 comp. 590 lift mopar solid cam,victor jr intake, 830 holley, 4800 converter, 999 trans, 4.88 gears, 11.5-29.5 slicks, and a ladderbar coilover suspention,car ran 10.8 at 123 to 124, it wieght 3360 with me in it. My Dart combo at this time is 416 with 10.4 comp. indybrock heads ported by shady dell( they flow 313 at .700 int. 222 at .700 exh. the W2 flowed around 290 int. 190 exh. at .600) they also ported the victor jr intake to match the heads, and spec out the cam for the combo,.668 lift int and exh,[email protected] int,[email protected] exh,108 cl 104 installed roller cam, a tricked out 850 annular booster holley, 833 4spd, 4.10 dana 60, cal trac bars and springs, 8.5-26 slicks(both cars cut 1.50 60ft. times). Best time so far with this combo is 11.15 at 119, at the track sunday the car slowed to 11.5 at 116, 60ft were off poor traction. The car went 11.14 at 120 with unported heads,rpm air gap,the 590 cam,and 750 holley,3.90 gears. The car is run through 1 7/8 headers and 3 inch full exhaust. Do you guys think the cork in this thing is the exhaust or some thing else!
 
19DART66 said:
A few of you asked me about my combo in my Dart. Well I am kind of sick over it, I have spent a lot of money to keep going slower. I had an 80 Mirada with a W2 372 inch engine, 11.3 comp. 590 lift mopar solid cam,victor jr intake, 830 holley, 4800 converter, 999 trans, 4.88 gears, 11.5-29.5 slicks, and a ladderbar coilover suspention,car ran 10.8 at 123 to 124, it wieght 3360 with me in it. My Dart combo at this time is 416 with 10.4 comp. indybrock heads ported by shady dell( they flow 313 at .700 int. 222 at .700 exh. the W2 flowed around 290 int. 190 exh. at .600) they also ported the victor jr intake to match the heads, and spec out the cam for the combo,.668 lift int and exh,[email protected] int,[email protected] exh,108 cl 104 installed roller cam, a tricked out 850 annular booster holley, 833 4spd, 4.10 dana 60, cal trac bars and springs, 8.5-26 slicks(both cars cut 1.50 60ft. times). Best time so far with this combo is 11.15 at 119, at the track sunday the car slowed to 11.5 at 116, 60ft were off poor traction. The car went 11.14 at 120 with unported heads,rpm air gap,the 590 cam,and 750 holley,3.90 gears. The car is run through 1 7/8 headers and 3 inch full exhaust. Do you guys think the cork in this thing is the exhaust or some thing else!
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First thing I would do is pull all the plugs and see if she's running to rich or to lean. I'd also round up a off the shelf 850, get her lined out jet wise, and swap it for the annular holley just after running a set of numbers. Also install a fuel pressure guage that you can see from behind the wheel and make sure the system is keeping up all the way to the lights.
 
60' are missing about .10-.15 depending on where in the 1.5x you are.

Try to get a good known carb and try out like Demon suggested. Lots of "trick" carbs are total junk.

Make sure the timing is set to optimum. Get the basic set up right, MPH.

Wouldn't be the first time those heads don't work like the numbers suggest.
 
Wouldn't be the first time those heads don't work like the numbers suggest.
Click to expand...

Do tell you speaking from experience??...


As for the orginal question,go over everything something is wrong.that combo should be well into the 10's...
 
At what engine temps are you making your passes?I have a new AED 850HO carb(930cfm)if looking for new,these carbs are the ticket.Very responsive and easy to work with,it,s a reworked Holley 850 dp.
 
I have gone through this tune up with a fine tooth comb, the timing is at 35 total all in at 2000(tried a few degrees ether way 35 seemed to be the best). Fuel system is set at 7# does not drop below 5#, fuel pump pushes 3 gal. in a minute through the regulator. I have optimized the carb jetting through changes in main jets,idle jets, powervalve restricions,and powervalve changes. Plugs come out a light,light tan at the end of a run, run at a golden tan on the street( I own a honda cbx 6 cyl. motorcycle after jetting this for best performance with 6 small k&n filters and a 6 into 1 competition header, holleys are simple).I am thinking now that the exhaust is holding it back( 3 inch mandrel bent from headers to rear bumper, dyno max hemi turbo mufflers). The Mirada only lost 2 to 2.5 tenths with the same setup, but the car feels like it has a cork in it and it is holding back, what do you guys think about that. Thank you for your thoughts.
 
This is where an engine dyno really helps. I've done quite a few engines and if they go on our dyno, and perform flawlessly then once in the chassis they faulter, you can bet it's not the engine itself.
I would pull it out, dyno it and look for problems. That engine should make at least 550HP on ANYONE's dyno! If it does, and it's healthy, then put it back in the car and start looking for things.
If you think it's the exhaust, pull it and run it. I bet you only lose a .10! That's what my duster lost when I ran my exhaust.
Brian
 
yep, there are chassis dynos around here locally that will only charge 30.00 a pull , with the sniffer it will tell you if there something wrong with the carb. take a extra carb with you. check all valve springs for a broken one. spin them around to get a good visual. that dyno will show at what rpm the power is falling off. just my 2 cents
 
So your heads flow 313 at .700 and your cam is netting out somewhere around .650, you aren't using all the head. Secondly as Moper asked what are the mid lift flow numbers. These can be more important than peak flow, W2's are good mid lift flowing heads.

Thirdly you are running a four speed with a very small tire and leaf springs albeit with CalTracs. This can't compare to the ladder bar car.

Fourth the 4 speed is heavy and bulky, how are you shifting it and what RPM, you may be winging it to high or not high enough. Lots of variables.
 
Ok the full numbers on the heads are, int. side 70.2 .100,149.8 .200, 205.6 .300, 255.6 .400, 274.3 .450, 286.1 .500, 294.3 .550, 300.1 .600, 306.2 .650, 313.1 .700 The exh. side is n/a .100, 110.2 .200, 150.1 .300, 192.2 .400, 200.3 .450, 206.8 .500, 212.4 .550, 217.8 .600 ,220.1 .650, 222.3 .700. When I made the exhaust I never intended to take it off, so I welded all of the connection except the slip fit at the headers, but there is'nt enough room with the tall pipes to slide the exhaust back far enough to clear the collecters( my mistake).The car 60 foots with in a couple of 100th of the ladder bar car with alot smaller tire I give the knod to the cal tracs. I hold the rpm around 3500 and on the third yellow the right foot goes to the floor and the left comes up the right does not come off the floor till the end of the 1/4. When I leave the line the car leaves clean no bogs no hesitasions no drop in the rpms(borg beck long 1200# pres. plate, sinterd iron disc, steel flywheel,and trans is slick shifted with a 3.09 first gear) I shift at 6200 this seems to be where the engine lick to be shifted at.
 
You aren't running a two-step? You should.

Leaving with the throttle blades all the way open is worth ET. Plus you don't have to worry about the transitional parts (squirters, etc) causing problems.

Also, launch RPMs seem pretty low for a stick car.

Did you degree the cam or "dot to dot" it?

I agree with these guys that the valve train should be checked. Make sure the springs are tested, and that none of them are messed up.

Definitely do a leakdown on the motor also.

Clutch slipping on the top end?
 
Well, that should be a lot of flow from those heads to go through the restrictive exhaust and quite frankly it should 60' better than that. You have a big cam and big carb it should want to rev higher than that. The carb and exhaust sound like they are both holding you back. I never liked annular booster 4150 carbs for high RPM use.
 
IMO, that static ratio is at least a full point low, and if this was a race car first with those heads I'd build it with closer to 12:1. Next.. What was he thinking with that cam? He's got some lift but for what you're doing 256°@.050 is barely there. I think the ports are lazy as it's built right now.
 
the victor should move more air than the air-gap for sure.
 
He's running a Vic Jr now. Was running an Air Gap on the previous combo it says.
 
I have been told to put a 1050 dominator on it by at lease 3 different racers at the track. One had a spare in his trailer but could not find the manifold adapter.As far as the cam goes he was trying to build cylinder pressure with the lower compression and keep the lift high for the head flow, when I built the short block I ordered flat top pistons from wiseco and after 3 months of back order I end up getting there reverst dome pistons so I could get the finished machine work done before stock car season started(if that happend the car would have been down for the summer) thats the reason for the low compression. Ryan even told me it needed more compression, but that will be the next short block. The short block was built 3 years ago and the heads,cam, and intake were done last spring.
 
Does that thing actually HOOK with a stick and little tires?? Amazing!!

Back on point: We all (you, too) can Monday Morning Quarterback this thing to death. Yea, the CR is a little low, but big whoop; should still be deep in the 10's if it hooks. That said, being you've been over most obvious things, I would make sure through a compression test and leakdown that the moder is healthy. If it is, a chassis dyno session would be where I'd go...

Ideally, the motor out and on a dyno is good, but dyno's don't get time slips. Too many varibles in the car. I have seen MANY good "dyno" motors not run to their expectations, only to find out they might like something completley diff in the tune up.

I went back and re-read your post. It LOST 1 mph with ported heads?? Is that in the SAME weather conditions?? If so, "houston we have a problem". Actually the MPH tells me it's just NOT making the power to be a 10 second player. I would expect to see the MPH for that combo up around 123-125 easy. Chassis Dyno time!! I would also bring along a regular ol' 750 and 850 DP to try, as I am not a fan of those annular carbs either. Better yet, I'd bet that a 750 HP will out perform that thing. Case in point, I once found 21 HP and 18 ft lbs on the dyno swaaping a "trick" 830 AD for a "tuned up" 3310 VACUUM SECONDARY Holley.

Also those muffs might be holding some power back. I'd sure try it uncapped and see what happens. You can do that on a CHASSIS DYNO, too!

By the way, that is a WAY COOL car!!
 
So instead of milling the heads to make the chambers smaller and getting compression back he just half-assed the cam? (pardon my French but that looks to be the case) Nice compromise there.
The heads need duration, not lift. The lobe must look like a hydraulic lobe with that much lift and no duration, not to mention slow ramps on both opening and closing. That cam would be much better with a set of RPMs and an M1 rather than the 360-1s fully ported with a Victor. Dished pistons are not a big deal but he should of accounted for that change with something other than leaving the heads and getting an oddball cam. If he wanted flat tops but couldnt get them he should have made the chambers smaller.
My fix armchair quaterback fix: Pull the heads and have them cut .100 to bring the chambers down to 53cc and that will yield just under 11.8:1 static. Get pushrods .100 shorter. Replace the cam with something like the Comp RX302S-R6. Your heads are too much for what you have for the cam. At your level, you can't just stick more lift in hoping to get the pressure with low duration. You end up with what you've got... Sluggish low end, and not enough air for top end. I respect Ryan but I think he missed the mark with that compromise.
 
I am sorry mopar I guess I did not exsplain it right, I built the short block 4 years ago(looked in my paper work, thought it was 3 but I put it together in spring of 06). Ryan milled the heads back to the intake seat to up the compression but with all the work he did on the chambers to unshrowd the valves the milling gave us 62.5cc and that was the reason for the cam.( the heads came with 2.05 valves took some work to clean up the chamber flow). Ryan had nothing to do with the short block he did the heads, intake, and cam in feb. 09. The heads are not 360-1 they are the indy edelbrock t/a heads, sorry for the confussion .
 
I was thinking that wasn't much duration for a cam too but since it was a roller it might be alright. You'd think it would make more torque down low with that. But either way I'd do the easy stuff first before I swapped camshafts. Exhaust and carb.
 
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