needing to make some changes cam? heads? carb?

[willtow]

im considering doing a cam swap and upgrading carb to a 750cfm e85 by horsepower innovations or mark sullens on my 79 malibu bracket car (street legal but driven very little) i built this motor early last summer and there something thats holding this car back its not running the numbers it should .....here are specs as of now...

car weighs approx. 33-3400? full body/interior/6 point cage/ racing buckets/deleted heater/ac box/removed inner bumper structure
350 .40 over
11.1 compression
aluminum 58cc / 210int. runner heads set up w/ hyd .550 lift springs
488/507 lift hyd. flat tappet cam adv.duration .288/.297- @.50 .235/.243
1.6 crane full roller rocker arms
performer rpm air gap intake
650cfm double pumper no power valve jetted 77 square
running a 50/50 mix of 93pump gas and 110 sunoco race fuel
msd billet hei dizzy advance locked out at 39 degrees (thats where it runs its best)
mallory 685 ignition box
350 turbo transmission
stall converter will hold on footbrake at 2500rpm and flashes around 3600rpm
4.56 gears spool with 28/10.0/15 slicks
90/10 shocks on front 50/50 on rear
rear sway bar
1 5/8 tube headers 3 in flowmaster exhaust

im wanting to keep this simple as stated above im running 1.6 ratio rockers with .550 lift springs so after the math my max cam lift will be .516 ive been search the net on comp,crane, howards,lunati etc.... reading and trying to figure out what im needing in a cam by what most recommend the cam im running should be close the only thing that concerns most is the large 210cc runners on my heads ive even been told i need a smaller lift with more duration? idk very confusing also as i said above im planning to go to a e85 carb and ive been told to up carb to a 750 instead of the 650 im running now the car is running around a average of 8.15 in 1/8th 60ft in the 1.74 range at 83mph i think the mph is fairly close but the 60fts/330ft are a lot less than i think it should be ......the cams im considering but still looking and listening to what everyone is saying
lunati -.515/.515 duration adv .300/[email protected] .246/.246
comp -.510/.507 duration adv .296/[email protected] .246/.253

any ideas or recommendations.................

 

[willtow]

ive talked with all the cam companies and everybody says i need a whole lot bigger cam with my heads also been told to leave it alone and up the carb to the 750 .....ive given alot of thought and took everything ive been recommended about this ive got a chance at a set of aluminum heads that are similar to what i have now same valves, springs etc but they are 190cc would this smaller head bring my current combination around as it seems the 210cc heads are the problem as most say.....i can swap heads for less than i can swap the cams......whats your thoughts?

 

[Redline396]

up the carb to a 750 with a 1 inch open spacer first....with those gears and converter you may be running out of steam at the top end with that manifold...i personaly like the vic. jr or the team g myself for top end power with alot of revs.......you did not give the specs on your current cam....with a flash of 3600 i would have run closer to a 4.11....at what rpm are you shifting?is it still pulling when you shift or is it falling flat?

 

[Damon]

Buh buh buh...... OK, what's it run?

Where is it you think you are missing out on the fun? I agree the 210 heads are possibly a little big for the rest of the combo, but not ourtrageously so. The combo seems reasonably well matched.

The converter holding 2500 on the brake but flashing to 3600 might be a red flag under normal conditions, but with 4.56 rear gears it's tough to really load up against the converter at the line. So that kind of difference in RPMs isn't really all that crazy.

I'm scratching my head looking for anything that stands out as an obvious problem but I'm not seeing it. So..... let's see a timeslip. The whole shebang from 60 foot throug the stripes. If something's seriously whacked, it'll show on the timeslip.

 

[willtow]

Buh buh buh...... OK, what's it run?

Where is it you think you are missing out on the fun? I agree the 210 heads are possibly a little big for the rest of the combo, but not ourtrageously so. The combo seems reasonably well matched.

The converter holding 2500 on the brake but flashing to 3600 might be a red flag under normal conditions, but with 4.56 rear gears it's tough to really load up against the converter at the line. So that kind of difference in RPMs isn't really all that crazy.

I'm scratching my head looking for anything that stands out as an obvious problem but I'm not seeing it. So..... let's see a timeslip. The whole shebang from 60 foot throug the stripes. If something's seriously whacked, it'll show on the timeslip.

sorry its been awhile since ive checked in here.....
i did make a cam swap and a e85 750 carb left it the same as above but the new cam is a .507/.530 lift .297/.307adv .243/.253 @0.50 with 1.5 rockers but im still running 1.6 so those nubers will be slightly higher.....heres what the car ran last pass last year
1/8th mile-
8.195
1.825 60ft
5.243 330ft
83.24 mph

ran the car last weekend with best pass of
7.784
1.665 60ft
4.954 330ft
86.68 mph

the car is doing better i think its still got a 10th or so in it that needs to be tuned out scaled the car it weighs 3470 with me in it.....

 

[lilbowtie]

Something isn't happy and like Damon I don't see it - you seem to be soft across the board. I would say the E-85 and carb change would account for the performance increase (+ you need to keep tabs on the weather your running in) I can see the heads causing you to be soft on the bottom(should still be in the 1.5's) but you should show more MPH on the top. I hope you changed springs cause that .530 lift with a 1.6 rocker has you over .550 (your earlier calculation was right). It would be nice to have an O2 sensor and record what the fuel is doing. What's your RPMs at thr traps?? Still thinking!

 

[bracketchev1221]

Have you changed the valvesprings yet? I am a little worried about your math. You say that the springs are rated to .550 lift.

.507/1.5= .338 lobe lift X 1.6 = .541 on the intake
.530/1.5= .353 lobe lift X 1.6 = .565 on the exhaust

 

[willtow]

Yep I'd already done the math on the rockers I was misinformed on springs after getting part # there actually good to .580 so I'm good there ..... I do not have a 02 sensor but checking plugs and talking to my carb builder I'm running a lil rich at wot and idle I'm gonna back of a couple of #s on jets and lean out the idle a bit ....the car is around 5200 at traps ....

 

[bracketchev1221]

Ok, if they say .580, that is one thing. Sometimes that just means that the clearance to coil bind is sufficient to .580. Doesn't necessarily mean to have enough pressure to .580 lift. A .580 lift cam with higher .050 duration will open the valve faster than a cam with equal lift and lower duration. Also they don't know if it is a 1.94 valve or a 2.08 valve. 5000 rpm or 6500 rpm. Lots of variables to make sure you have the right spring.

 

[willtow]

Ok, if they say .580, that is one thing. Sometimes that just means that the clearance to coil bind is sufficient to .580. Doesn't necessarily mean to have enough pressure to .580 lift. A .580 lift cam with higher .050 duration will open the valve faster than a cam with equal lift and lower duration. Also they don't know if it is a 1.94 valve or a 2.08 valve. 5000 rpm or 6500 rpm. Lots of variables to make sure you have the right spring.

Springs where checked by local engine builder and said they would be fine with my combo