HP Peak at 5000? Somethings wrong for that much duration. What is the LSA? DId you degree the cam?

is that 750 a DP or vacuum secondary?

You had a full 34+ degrees of advance?

Those numbers using STD dyno correction?

[This message has been edited by 89rs400 (edited 11-04-2002).]

 

That's a lot of cam to have a power peak at 5000 rpm. What is the intake centerline?

Did you have an exhaust system on the engine? You didn't mention one, and it's attention to little details like this that will make the difference.

------------------
1967 Nova coupe daily driver
406, 10:1, 224° cam, Q-jet, 700R4, 3465# w/driver
11.75 @ 117 thru the mufflers
18 mpg on the road

 

How were the flow #'s on the heads? Cleaned up, fully ported, or 'as cast'? Personally I'd throw a Victor Jr. intake on it and see what it does. Given that you have steel heads, you've probably got the compression about as far as you want... aluminum could tolerate a bit more. My 350 has a similar build, a little bigger roller; 260/264 @ .050" and .634 lift; but since it's a 350 I need to spin a little harder... CHA aluminum heads, 215cc; 285cfm @ .700 intake flow; 220 @ .700 exhaust; ultra light weight bottom end, gas ported pistons 10.2:1, etc; on a 750 "out of the box" 4150 it made 517hp @ 7000; 442ft-lb torque at 5200. With a moroso vac. pump and a VDL prepped 750HP series carb it made 542hp and a little over 450 ft lb torque. (So what I'm getting at is you should be able to beat me at least torque, if not get the HP #'s quite a bit higher.) The dyno is pretty honest-- lines up with 2 other independant dyno's and with the Moroso speed calculator. Let me know if there is anything off my build that can help you in yours-- I have pretty good notes around. -Dan

 

<BLOCKQUOTE>quote:</font><HR>Originally posted by 89rs400:
HP Peak at 5000? Somethings wrong for that much duration. What is the LSA? DId you degree the cam?

is that 750 a DP or vacuum secondary?

You had a full 34+ degrees of advance?

Those numbers using STD dyno correction?

[This message has been edited by 89rs400 (edited 11-04-2002).]<HR></BLOCKQUOTE>
The Cam was degreed in with a 102 CL and it has 106 LSA. The carb is a 4779DP. Timing is @36 degrees and the numbers on the dyno are corrected numbers.

 

Another item of concern is that the cam is a small base circle cam and when Asked if longer pushrods were used the builder said they checked and thought the stock length would be fine. From what I have read you need a longer pushrod to compensate for the smaller base of the cam. I have ordered a pushrod length checker and will see if geometery is correct. Could too short of pushrods be doing some of this? Thanks for the response!

 

If the push rod length is off, you could be losing some lift, and it can lead to valve guide wear problems.

Also it might not hurt to check the timing mark to the balancer- (make sure "0" on the balancer to timing tab is top dead center on #1, otherwise the timing light setting would be off. I don't know if you are using a GM balancer or a Fluidamper-- but GM made several different timing mark locations, and the balancer key to timing mark relationship changed. (I know if at least 3 different locations used...) -Dan

 

You might want to try backing the timing off a few degrees. Most people around here, including me, have found that 383's and 400's like 33-34 degrees of advance the best. Yours may be different, but its a quick, easy, and free adjustment that may free up some horsepower.

 

brake specific fuel curves in line?
I don't think the dual plane is causing a restriction that low.. but if you have a single you might want to install it and confirm that. Intake port matched and port alignment good (should not kill 40hp..but).

Compression is a little low.. but that should not reduce hp too much.
Shorter/incorrect length PWs should not reduce lift as such.. just cause the valvetrain lash to not remain consistent. Was that changing a bunch?

 

Is this dyno on the engine or the wheels? Too many unknowns here. If your geometry is off you could have a number of power robbing things happening such as rockers hitting the rods and/or binding elsewhere. If this is not on a engine dyno and you are running an exhaust system you may have a big restriction. Headers? Manifolds? old exhaust? with your components I would have expected you to peak at a lot higher RPM and get better #s. If this is rear wheel numbers then you did not too bad other then peaking at too low of a rpm. Tell us more!!

 

The numbers on the motor are from an engine dyno not a chassis dyno. It had 1 5/8 Dynomax headers. My pushrod checker came today, compared to a stock 327 I have my pushrods appear to be about .120 short. A co-worker suggested I do a compression check. He felt the 106 LSA was bleeding off too much cylinder pressure with my 9.4 compression and that might be killing my power. He thinks I need 110 LSA.

 

Ok, get this:
I entered this all into my program and I got 399HP at 5000RPM, and 425LB-FT at 4000RPM. Man, that's pretty close!

I am assuming you are using a 160 thermostat, 1.6 roller rockers, and guessing those headers have 36" primaries.

Since the computer program agrees with the dyno reading, that leads me to believe you have a less-than-optimal combination. By the way, your dynamic compression is too low.

I found if you install a Victor Jr. intake, that alone will get you about 22HP and 10LB-FT of torque. You can do 1-3/4" headers, but it wont be a very large gain (7-10HP)...and the power will go up even more (including your idle vacuum) if you raise your compression to 11:1 or so. Part of the problem is the Iron Eagle II heads don't flow too well out-of-the-box (compared to others). Do some careful porting and it should show some good results.

If you do all the modifications I listed above (except porting), that should get you around 448HP @ 6000RPM and 455LB-FT at 4500RPM. Porting on those heads could be worth 45HP!

Just curious, but what was your idle vacuum anyway?

------------------
1969 Base Camaro
Vortec 355, Perf. RPM, Demon Carb., TH-400
All sheetmetal is NOS GM
See my webpage at: http://www.geocities.com/compuboy007/

 

It sure feels like the cam is the main issue. Even if the heads aren't quite as good flowing as the premium Al heads out there, you should easily get 450 HP, and I'd say even more torque from a 383. Might be a good idea to poke around the archives and see some other combinations, there are tons.

Regarding compression, gas in my part of the world is getting pretty bad, and you will definitely lose power if you have to retard timing to eliminate detonation.

I'd try a different cam. By the way, with that tight of a LSA, what was the idle vacuum? Must have been really low, tough on the street for power brakes and idle quality. Is this a circle track cam? What are you doing with the engine? Street/strip? Race only?

I recently puked a Comp Extreme Energy hyd roller (distributor gear), and replaced it with a slightly milder Crane. The lift and duration were about the same, but the LSA was opened up to 112 versus 110 with the Comp. I got at least 2" of idle vacuum, better idle, and the car still scoots as good as it did before, from a seat of the pants feel. Made me happier.

Good luck,
Mark

------------------
69 SS, ZZ430 Look-alike, Tremec TKO, Hotchkis Suspension

 

9.4:1 compression + big cam = unexpectedly low power output. Low compression with a big cam kills both low end power and top end power. I seriously think Silver69Camaro is onto something.

It might help if you advance the cam some but I honestly thing a smaller cam and/or more compression (along with a Vic Jr) will fix her up.

 

I agree with Mark. The 215 iron Eagles flow 264/172 @ .550" valve lift. 450 HP at the flywheel with these heads and your big cam should not be a problem. As Eric mentioned the low compression is going to hurt you to the tune of 25 HP or so, and the bottom end is probably going to feel soggy on the street. If you can post the timing specs for your cam, I'd be happy to run your combo on Desktop Dyno. To be in the ball park, your timing should be around 12 degrees initial with 24 degrees advance. As posted above, I think you are going to want less cam or more compression to make everything work.

Good Luck!

Chris

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[This message has been edited by Fuji (edited 11-06-2002).]

 

If it helps, I have a fully ported and ceramic coated victor jr intake that I should sell. It's for a big runner set of 23 degree heads-- 1206 or 1207 felpro gasket size (I'll check to be sure), Either isn't what you'd say small. Email me if interested - dan@automationdevelopment.com

 

Chris-
Desktop dyno will not be able to give an accurate output due to the fact that it is 'guessing' at many of the variables. It doesn't know primary tube length, intake manifold flow, cylinder head flow EFFICIENCY (read: flow and combustion swirl), rod length (necessary for dyn. comp.), etc.

Like I've said before, Desktop Dyno is only good to determine where on the RPM scale the peak HP and TQ figures should be.

67Cam-
I don't know what this engine is for, but that cam with the 106LDA is a good drag cam. It will produce high PEAK HP figures. If this is a street motor, I would suggest moving to a 110-112LDA cam, as this will produce more AVERAGE power figures. In other words, it will have a broad power band, and you will have more idle vacuum also. However, in this case, it is possible that you will lose some peak TQ, but gain peak HP and more average TQ & HP.

You've got a good long-block setup right now. If you want to keep the current cam, then increase the compression, use a single plane (Weiand Team G is excellent), and do a little port work on the heads. That could get you to 480+HP.

------------------
1969 Base Camaro
Vortec 355, Perf. RPM, Demon Carb., TH-400
All sheetmetal is NOS GM
See my webpage at: http://www.geocities.com/compuboy007/

 

Sorry I have not been responding more frequently to all your post. I have read them and there is a lot of good info. What I found out today may be causing some of my problem. My cam was degreed in at 106 which is my LSA, it should of been 102. My engine builder and the cam company had some mis-communication. After a lengthy talk I decided to put my motor back on the dyno, the cam will be degreed correctly, my push rod issue will also be resolved. I am also going to try some 1.6 rollers on my intakes to see if that helps offset my low compression issue. Howard Cams tech person said with my cam retarded like it is my power is going to be way off and the motor will be lazy thru the entire rpm range. Also my 1 3/4 headers arrived today and we are going to try them. I am hoping this will get my output up. If not, I will be changing cams.

A little more info on my car and the motors application. It will see the drag strip a couple times a year but for the most part it is a hot street car. The chassis has some upgrades that should work with this power. I have frame connectors, CE Slide-A-Link bars, CE shock crossmember and adjustable shocks. The rearend has Moser housing ends and big bearing axles, 4.10 gears and BFG drag radials. I am running a turbo 350 with a manual valve body and a JW 10" converter with about a 3500 stall. The car is a frame off that I am into the fourth year of work on. There is hardly a piece that hasn't been replaced. I went for a good clean factory appearance that will run good and strong.

Thanks for all your responses!

jjc

 

Be sure to post back and let us know how it goes.

------------------

 

I think the compression is a minimal factor. There are Stock (and superstock) class motors with 9 to 1 compression and have much more duration than your running (and their hp peak is not at 5000).

In the early 90s, when 9 to 1 became the max for some nascar classes, they found that going with more duration would help offset the hp loss by the reduced compression (a company named bo-laws comes to mind). Longer time to fill the cylinder more completely to offset the reduction of net cylinder pressure.

If possible, fix cam phasing first and rerun dyno. I think that will be the most significant benefit.


[This message has been edited by 89rs400 (edited 11-07-2002).]

 

It seems to me that you are going in the wrong direction with the cam and headers. There is little you can do to make up for the lack of compression by moving the cam a few degrees, advancing the cam 4° will have the effect of reducing the upper rpm power and boosting the low end. With your compression ratio, I would go with a cam with about 20° less duration, something around 230° @ .050". I ran a 385" motor in my daily driver 67 Nova with 9.5:1 compression and a 228° cam successfully to 12.1/112 on 89 octane gas. With my current motor I run 10.2:1 compression with a 224° cam on 92 octane gas.
Another consideration of a 'hot street car' is that you spend 99% of your time below 4000 rpm, and 1-5/8" x 40" primaries with a 2-1/2" collector would work extremely well there. I built a set like this for road racing a 331" Nova in Mexico and we ran away with the class, enormous torque from 2500 to 6000 rpm. I'm making a similar set for my 406, and I'll post the e.t.'s when they happen.

------------------
1967 Nova coupe daily driver
406, 10:1, 224° cam, Q-jet, 700R4, 3465# w/driver
11.75 @ 117 thru the mufflers
18 mpg on the road

 

Onova: You ran the Mexico deal? The 1k mile deal?! COOOOOL! Don't drink the water.....

Good info on the cam advance issue, no question the motor will come alive with the right baseline degree, but I am still convinced that this is too much duration, and as importantly, too little LSA. Dude, you will be SO happy with a high lift, shorter duration cam. With that much displacement, your engine will rock out.

 

<BLOCKQUOTE>quote:</font><HR>Originally posted by Mean 69:
Onova: You ran the Mexico deal? The 1k mile deal?! COOOOOL! Don't drink the water.....

Good info on the cam advance issue, no question the motor will come alive with the right baseline degree, but I am still convinced that this is too much duration, and as importantly, too little LSA. Dude, you will be SO happy with a high lift, shorter duration cam. With that much displacement, your engine will rock out.<HR></BLOCKQUOTE>

It's actually just over 2000 miles covered in 7 days. It follows much of the original Pan Am highway through the central highlands of Mexico. Most of the racing is done above 6000', so the 400 horses you had at sea level are now about 300. You can see the route at http://www.panamrace.com. We finished first in our class and 8th overall out of 81 cars.

------------------
1967 Nova coupe daily driver
406, 10:1, 224° cam, Q-jet, 700R4, 3465# w/driver
11.75 @ 117 thru the mufflers
18 mpg on the road

 

Onovakind...With the compression you`re running in your 406 coupled with a relatively short cam, have you ever done a compression check?
If you have, could you post what you have for pressure?
Just curious...doing some adjusting on our 406 and thats something that we`re into at the moment, thanks

------------------
78 Camaro hyd cam 406
TH350-3.23 gear
11.86 ET
116.7 MPH

 

We use KB125's at zero deck with a .039 gasket and a 74cc Sportsman head to get 10.3:1. I'll do a cranking check this weekend and post some #s. The cam is a Comp 12-430-8 280HR hydraulic roller.

------------------
1967 Nova coupe daily driver
406, 10:1, 224° cam, Q-jet, 700R4, 3465# w/driver
11.75 @ 117 thru the mufflers
18 mpg on the road