Is my engine performing as it should??

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J

jonnyboy1617

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Hey, just getting some opinions if everything is going smoothly...
Here are the specs
73 plymouth duster
360ci, bored .30, decked, honed
K&N HiFlow filter
Holley Street Avenger 670cfm w/ vacuum secondaries
Edelbrock RPM Airgap (port matched)
Fully ported J heads, stinken heavy dual springs -(maybe lost cam?)*
CompCam [email protected] [email protected] (original cam timing)
Speed Pro hypernuetic pistons, 9.3:1 overall CR
Hedman Full length headers
X-pipe setup with flowmaster 40's
Taylor Spiro-pro plug wires, 8MM
Mallory 6A MSD
Summit Racing coil (up to 65,000 i think)
Autolite platinume spark plug gapped at .060 (Good or bad?)
3350 with me in it
727, stock converter
3.23 posi in a 8 3/4
Street tires, P245/60R15

The engine pulls good till 5550rpm and then it lets off a little.
When shifting at 5500rpm the time slip reads...
R/T - .358 (I know, kinda crap)
60ft - 2.33
330ft - 6.14
1/8 - [email protected]
1000ft - 11.93
1/4 - 14.22@98mph

With my engine setup, I was expecting somewhere around 380-410hp as a medium. But with the car only running at 98mph, some people don't think it has anywhere NEAR that amount. Can the trap speed really help guess the HP? Because I tend to believe its bogus. And is the car running like it should at the moment? Or does something not add up? Or do you think I might be doing anything wrong? I will be putting the car on a dyno in a little less than a week, but I just want to get your opinions.

* I said I might of lost the cam because before the car was started, my brilliant dad had me crank the engine without spark to set the timing, which I thought was a big No No with the new cam. Because it lasted a total of like 30 seconds. And I'm hoping the car will drop into the 13's after I put in a new torque converter and slicks.

Thanks for any help, I'd appreciate it.
 
Should be faster, your 60' times are crap. Stock converter is probably killing you. Trap speed is a good indicator of HP, not perfect but far from bogus.

Others will direct you in what needs to be done to fix it....
 
do you mean it stops pulling after 5500 rpm or it loses power,you should pull right up to at least 5700 or 5800 rpm shift points with that cam.
 
I think you should lessen the plug gap. I'm running a similar ignition system (Mallory HyFire 6A) on my slightly-warmed 318 and I have my plugs set at .040". Using an online calculator those times indicate around 240 HP at the flywheel (net) which is a bit low. Make sure your ignition advance is dialed-in properly as well as your A/F ratio and the secondaries on your carb (if they are somehow adjustable, I only know Carters). If that doesn't help too much a looser converter might knock off a few tenths; do you happen to know if the converter you have is from a stock HP car (340, 360, etc.) or just a regular smallblock 727?
 
You have heavy valve springs, ported heads, and a stock cam. I'm impressed it revs to 5500. I think you may want to try shifting at 4500 and see what it does. The heads hurt 60', as does the stock convertor and gearing. I would replace the springs with a set of Comp 901s (single with dampner) or remove the inner spring from the heads, install an XE268H and try again. It's making decent power for the cam. But you put in a stock cam. Now it's wasting power opening against the big springs and the ports are not moving air well at low rpms. Typically porting sacrifices low lift flow for mid and high lift. Good portting minimizes that effect. Average or poor porting exagerates the effect. Minor mismatch... address those two and see what it does...
 
I am haveing very similar problems with a 340 j heads port matched purple .450 .455 268/272 670 avenger hp manifolds tti2.5 15.2 1/4 2.2 60 ft 3.23 gear It quit pulling at 5500. so far i found i used a dial back timeing light. bad. it was off. i thought i had 36 total and it was more like 40. I`m going to change plugs corect timeing to 15 initial 36 total. and wile the plugs are out do a compreshion check and give it anouther test. If i forgot anything i would appreciat the help. I did check to make shure the carb is wide open and will do it again.their were times on the street in 1stgear it went up to6200 easily but not that knight.
 
To me, it looks like it is running just fine for what it is. That is a pretty small cam and carb, so the motor nosing over at 5500 is to be expected.

Are you sure you have double springs, or is it a single with a damper. If it is a double spring, then it is way more than that cam needs. Also, if the heads are fully ported you could really benefit from a bigger cam.

Sorry, but 380-410 hp is not realistic for the motor as it sits...maybe 300-320 hp. When you go to the dyno, be prepared for a shock (most people think there motors make WAY more power than they really do). Just remember, the dyno is nothing more than a tool for tuning.

Yes, trap speed is a VERY good indicator of how much hp you are making.

13's are not out of reach. You could probably get there with some tuning (sticky tires would be a big help if you're spinning them off the line).
 
Sounds like you have a lot of good parts but may need a little more cam. I'd switch to something with a bit more duration and lift to help the motor pull stronger up top. Something like the Comp 20-224-4 Extreme Energy XE274H would work well with a 2400 stall converter. Use the springs Comp recommends. I'd consider a vacuum secondary 750 cfm carb too that is jetted properly. Maybe the Street Avenger 770. Make sure you have a performance curve in your distributor. Good Luck, you're gonna need those sticky tires!
 
once you get the cam changed or spring changed...

you will be fighting the stock converter and 3.23 gears....

duster in sig has same problem stock converter and gears...and small tires..

in las vegas, trap speed was 101.26 but with eddy heads...and it is not a 340 but a 360.
cam is a hughes 230/237 with .515/.535....eddy air gap, holley 750.
 
That weight and MPH shows about 225hp at the wheels.

If the hook was right and you could maintain the MPH, it should run 13.40-13.60's. It would take some gear and a converter.

My Dart 4 speed is a basic 70 340, cam 214/224 445/465, LD340, 750 Vac, headers, MSD, 3.91's and 245/60/14 tires. Best runs 13.30's at 102.00. I'm guessing it makes about 320-330 at best. No way your engine is making 380. More like high 200's-low 300's at best

My friends Demon is a 360 w/340-350hp, car weighs in at 3375 with him in it according to the Vegas scales. It ran 103 at vegas running a 14.10-14.20, pegleg 2.76 gear rear. We figure, car hooking with some gear, it should run about 12.70-12.80's

I think your car is running pretty decent for what it currently is.
 
"once you get the cam changed or spring changed...

you will be fighting the stock converter and 3.23 gears...." I agree. 3.91's ( or even 3.55's)with converter will make a big the difference.
 
Well, for what it's worth, they never run as fast as you think they will. Take it from the guy who has a 13 second dart that runs 15s. Hahahahahaha
 
I dunno whats holding it back, but something isnt right.
360's can easily make 1 hp per cubic inch.

Your 60ft time is crap, but still you should have stronger mph to
show how much power your making.

Let us know how you go when you dyno tune it...
when i done a 14.5 my car was making 200hp at the tires
an i crossed the line at 93mph an i have 3.23's behind a 318.
Whats funnier is when i took it to race it,it wasnt when
it was going as good as it did.

I hope a dyno tune can sort some things out for you.
 
Thanks for the answers, I know the cam is kinda dinky, but at the time it was all about saving money, because with the bigger cam I would need new rockers arms, I think I read the max for those were like .475 lift or so. I've wanted to have a bigger cam now that I have more money, but how much HP should I gain from switching to something like a purple Cam "P4120231" and added a 1.7ratio rocker arm? It would give me .549 lift, but 'm not sure if that's too much ramp rate, and how would it act with only 9.3:1 compression? And one person recommended the Comp XE274H. How would it compare to the purple cam I'm looking at?

And I would like to have a lower gear, but it is a daily driver (I'm in highschool) and I drive down a highway everyday.

And I'm afraid i might of sounded a little on the cocky side with the numbers I mentioned, but I was not for sure what to say Because CompCam's "Camquest" showed 525hp??? Which did sound wayyy high to me, and Desktop Dyno showed like 460-480 from what I remember. I'm never trusting those again, because i'm pretty sure I gave them accurate data. I used flow numbers from another set of ported J heads. Which may or may not be accurate.
 
if you are staying with the stock converter and gears I would not use the .508 cam....

that cam has alot of duration and will kill you bottom end torque.
 
70aarcuda said:
if you are staying with the stock converter and gears I would not use the .508 cam....

that cam has alot of duration and will kill you bottom end torque.
Click to expand...

I wouldn't do the 508 either.

A 484 will, 95% of the time, outperform a 508 cam except for the last 5-800 of usable band. With the carb you have the top end is going to suffer, so the 508 is a mismatch. I think you have some mismatched stuff.

If you are going to run stock rockers, stay with the 484 or a XE268H cam or something similar as the max lift range. Putting 1.7 rockers on this is an absolute waste of money, IMO. Try to find a flowsheet for the heads if done by a shop, without it, camming it is a guess at best. Plus, what they flow at .600 lift means nothing to you because the cam you are running is only accessing about .400-.420 lift ranges.

IMO, figure out what you want out of the engine. There are plenty of solid 350-400 hp builds for a 360. The current compression may be a bit of a hinderance, but, you can work around it with smart parts selection.
 
crackedback said:
I wouldn't do the 508 either.

A 484 will, 95% of the time, outperform a 508 cam except for the last 5-800 of usable band. With the carb you have the top end is going to suffer, so the 508 is a mismatch. I think you have some mismatched stuff.

If you are going to run stock rockers, stay with the 484 or a XE268H cam or something similar as the max lift range. Putting 1.7 rockers on this is an absolute waste of money, IMO. Try to find a flowsheet for the heads if done by a shop, without it, camming it is a guess at best. Plus, what they flow at .600 lift means nothing to you because the cam you are running is only accessing about .400-.420 lift ranges.

IMO, figure out what you want out of the engine. There are plenty of solid 350-400 hp builds for a 360. The current compression may be a bit of a hinderance, but, you can work around it with smart parts selection.
Click to expand...

From a flow chart i saw for fully ported J heads, it flows best somewhere at .500lift.
CFM numbers are... .400lift = 240int./159ex. .500lift = 258int./183ex. BUT! This is someone elses head work, So it's just a guide.

But why is it a waste of money putting on 1.7 rockers? If a found a cam with enough duration to peak at 6,000 (where I would like to have it), and then slap some rockers to bring the lift to the low .500's, wouldn't it outperform a cam with the same profile but with 1.5 rockers? Since The 1.7's cause the valves to lift faster, so they hold fully open longer. Or is it hardly a difference in power? And you mentioned the carb would suffer up high, but how high are you talking about? And how much loss would there be? And what would be a better size? And I don't think i would have to add a ton more duration, (but I may be wrong, I'm still new at this), so I'm thinking the current compression (9.3) would be fine.

I know I have mismatched parts right now, the cam and head aren't matched the best and the torque converter is still being decided, but it will be changed. Im guessing somewhere in the 2800 - 3,000 stall range. But I have to decide on what to do about the cam first. Because now that I'm aware of the HP numbers of the engine, I don't think anything under 300 is acceptable, and I hope it's not under right now. So this thread might of turned into cam selection, haha.

And one more question, the engine was out of a 77' Dodge van, I do not have clear evidence of what kind of crank it has, I should of done more studying when the engine was torn apart. Im thinking it's a cast iron, so would it be safe spinning at 6,000? And I do have ARP rod bolts BTW.
 
And I found out the Camquest was bugged, I re-entered everything and it came up with 411hp@5000 and 455ftlb@4000, which I guess still looks pretty high from what you all have told me.

And I said earlier that DynoSim (2003) calculated somewhere around 430hp... Well it did again, BUT! Thats before it puts friction and everything into calculation. If you look at a different hp table chart, it predicts the engine peaks at 363hp@5000rpm at the flywheel, and 357@5500, and starts nosing to 331@6000, just like I said the car felt like. and after taking out power from chassis loss, it ends up just about 300hp@5000 peak... I don't like the sounds as much, but I'm proud that DynoSim seems pretty reasonable. If anyone wants to give some accurate specs to see how well it works, I'll be happy to enter them. It's kinda fun. Im bored, that's why i've typed alot.
 
The cam you have is capable of 350HP.

I did a camquest and came up with something around 370hp 420 tq which is still pretty aggressive. Those programs also assume a perfect tune. It was almost spot on with a couple of recent builds compared Dyno numbers.

1.7 rockers are a ***** to use, cause all sorts of problems. Adding lift doesn't equate to making a ton more HP. Sometimes it's negligible. On your style, desired build engine, they flat aren't needed. There are valid reasons to use 1.7 rockers, IMO, none of those are present here.

That engine could run with a 950hp on it. I wouldn't run one with your converter/gears. Some say it's crazy, but, they work. Done it more than once. The carb you are running will make it weeze up top IMO. Driveability will be good, max power won't. SB chryslers tend to love carb.

Good luck with it.
 
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