Worst AFR 165 dyno ever

[hcetretsam]

Just dynoed my 302. Reached 241 max hp and 256 max tq.

Here is my setup.

Manual trans.
1986 Short block with notched pistons. Calculated compression to 9.8:1
Holley 670 street avenger carb
Weiand 7515 xcellerator intake
AFR 165cc 58cc Heads
Scorpion 1.6 roller rockers
E303 Cam advanced 4 degrees
1 5/8 Hot rod style shorty headers
Full dual 2.5" exhaust from headers back with an x pipe and bullet style mufflers

Mallory unilite distributor

Made over 250 ft lb of torque from 2k rpm to 5krpm
Made 150hp at 3k rpm peaking at 241 at 5.5k and holds till around 6k

After checking my timing I found at idle it was at 20 degrees and around 44 above 3300 rpm. I have since adjusted it to 14 degrees at idle and 36-38 above 3300. I have not been back to the dyno. The car feels stronger but it is so light its hard to tell.

I was expecting around 280 hp at the wheels and at least 300 ftlbs.

Thoughts?

[hcetretsam]

Attached picture of the dyno sheet. I know custom cam, but, before I spend any money there has got to be something wrong here..

[streetbeast]

Is that SAE or correctored H/P?????????SAE will be lower .but its a true reading.

[hcetretsam]

Corrected, 1.05 correction factor. The curve looks right just low. My buddy put down 308/331tq with his rebuilt chevy 355 lt1 with longtubes full exhaust stock heads on the same dyno about a week prior with similar conditions for comparison.

[DeaconBlue]

Was that a Dynojet or a Mustang dyno? You want to target a WOT a/r ratio of about 12.9:1. Was the wide band O2 sensor attached to the tail pipe or in the header bung? What gear did you make the pull in?

That is a decent combo of parts you have there and it should be making more power. Did you dial the camshaft in when you installed it to make sure it is correct?

[SCracer]

i swear i couldn't get my Holley 670 Street Avenger carb to open the secondaries with this light car. i'm running a Holley 4150 600 CFM mechanical secondaries now!

almost the same set up as yours (see my sig line) but with GT40p heads...dyno'd at 279 HP.

i was seriously considering buying a set of ARF 165's.

i'll be watching this thread...

good luck with the tuning.

[hcetretsam]

I know its a bit lean once im all the way in the throttle, but 40-50 hp? The cam was in the motor when I had e7 heads on it and I used a degree wheel then. Dynojet, made the pull in 4th. I am planning on switching to mech secondary. Found that the secondaries are not opening much when on the road..

[DeaconBlue]

One last question - have you done a compression check on the motor lately?

Good point about a light weight car and the vacuum secondaries being a bit slow to react. You can always swap in a lighter secondary spring. Good tech info here;
Holley Performance Products Frequently Asked Questions

Remember that the engine will only breath in what it needs with a vacuum secondary carb, which is what gives you such great throttle response.

With a mechanical secondary carb, you will always be a bit too rich.

[hcetretsam]

Already have the lightest spring in the secondary. I dont ever hear them open when im driving it thats for sure. Have not yet checked compression. Kind of a basic thing to overlook I guess.

[hcetretsam]

All cylinders have between 145-155 psi. Less than 6% leakdown on every cylinder.

[DeaconBlue]

Okay yes the numbers are very close, which is great, but to me they seem a bit low. You noted you are running a E303 cam, with IIRC, 282 degrees of duration and 220 degrees or duration at 0.050". So a couple more "dumb" questions when you checked the cylinder pressures; Was the engine nice and warm - up to normal operating temperature? Did you remove all eight plugs? Did you block open the throttle plates on the Holley carb?

One other possibility - when you adjusted the initial timing, did you happen to adjust the Mallory distributor by changing the advance curve springs? The reason I ask is that a lighter weight vehicle needs a faster rate of ignition mechanical advance - so you would want to use a set of lighter weight springs.

http://www.jegs.com/InstallationInst.../650-29014.pdf

[bstuke]

If that is RWHP, that is about right.

I would put in an F cam, and 1.7 rockers on the exhaust...

[hcetretsam]

Originally Posted by DeaconBlue

Okay yes the numbers are very close, which is great, but to me they seem a bit low. You noted you are running a E303 cam, with IIRC, 282 degrees of duration and 220 degrees or duration at 0.050". So a couple more "dumb" questions when you checked the cylinder pressures; Was the engine nice and warm - up to normal operating temperature? Did you remove all eight plugs? Did you block open the throttle plates on the Holley carb?

One other possibility - when you adjusted the initial timing, did you happen to adjust the Mallory distributor by changing the advance curve springs? The reason I ask is that a lighter weight vehicle needs a faster rate of ignition mechanical advance - so you would want to use a set of lighter weight springs.

http://www.jegs.com/InstallationInst.../650-29014.pdf

Not a dumb question, just something I should have thought of. Engine was warm. Throttle open. The distributor has light spring in it. I put those in when the motor had e7 heads on it. Double checked, all advance in by 3200 rpm.

[hcetretsam]

Originally Posted by bstuke

If that is RWHP, that is about right.

I would put in an F cam, and 1.7 rockers on the exhaust...

It is rwhp. The curve itself doesnt look bad, and power drops off just as it should with an e303 4 degrees advanced. Ive just seen people put down 30-40hp more with the same combo. Not to mention the torque being so low (30 40 ft lbs.)

[John Card]

A lot of aluminum heads with efficient chambers like that will tend to make best power with advance in the 28-32 range. I think you may still have too much timing. Timing is HUGE - way more critical than AFR to making power. Also, when the car is on the dyno, pull the air filter off and have someone shine a flashlight down into the secondaries. Make SURE they are opening fully at WOT under load. I've picked up 15hp just by reaching over with my finger and flipping the secondaries open the rest of the way, and I've picked up 30hp by pulling out 4 degrees of timing. Verify everything - dont assume anything.

[bstuke]

Originally Posted by hcetretsam

It is rwhp. The curve itself doesnt look bad, and power drops off just as it should with an e303 4 degrees advanced. Ive just seen people put down 30-40hp more with the same combo. Not to mention the torque being so low (30 40 ft lbs.)

Did you do the runs without an air cleaner?
Does the throttle blades open all the way at full throttle?

[hcetretsam]

Found some vacuum leaks and recurved the distributor. Switched to a 600 cfm mech secondary. Havent been back to the dyno yet but I think I found the missing power.

[bstuke]

Good to hear.

[Oldtymeflyr]

You should be between 320 and 350 rwhp.

It could be a lot of little issues. My suggestion is to add 1.7 rockers to that E cam.

Advance the timing to right about 30 to 32 degrees, be sure and try the low side. See what happens.

With GT40P heads I am at 293 rwhp/tq you should be well above that. A friend with a little different cam and a good solid block is at 340+ rwhp with about your setup.

Good Luck. Just put it together.

Rick

[Butch B]

350 rwhp? Hummn? 290ish-320ish rwhp maybe with that cam IMHO. Still, that set-up should produce more hp than where it is now--Good luck
Butch

[hcetretsam]

I rechecked the compression with 2 other gauges and found the motor has actually 125psi compression. What do you think I should expect?

[SwiftDB4]

125psi is definitely low IF the engine is truely hot when you tested it. 9.8-1 c.r. should give 160psi+. Engine temp has got to be 180+ degrees and without too much delay in removing all the plugs and testing.

[hcetretsam]

I removed the rockers and performed a leak down. Less than 5% on every cylinder. I am stumped.

[hcetretsam]

Engine was at temp.

[trevor]

your timing is way off with an E cam. Go with 12 initial, 32 final. A 600 cfm mech sec. should be perfect. Between those two changes you will be around 300rwhp. Double check for vac. leaks. That can throw everything off. Shoot for a 12.5 - 13 to 1 AFR.

I would go back to the dyne with those changes. Do the leak down if you still have low numbers. I doubt it is the cylinders.

I made 260rwhp on the lower result mustang dyno with a 120,000 donor motor, X cam (not a good match - got a good deal on it), gt40P iron heads, edelbrock rpm dual plane, 650 DP mighty demon. With those heads you should be at 300rwhp

You are lucky you didn't burn the pistons up with a 44 degree advance. 20-44 final is a nascar motor.

[Bob Cowan]

If you have minimal leak down, then the cylinders are sealing well and should be making good compression.

The common cause of something like this seems to be improper valve adjustment, leaving the intake and/or exhaust valves to stay open.

You installed your cam 4* from straight up. It could be you moved it in the wrong direction, and now the intake valve stays open too long.

Try this:
- adjust the rocker arm to zero lash by turning the adjuster nut with your hand only. When you can not turn it any further, that's zero lash.
- Loosen the nut 1/2 turn.
- repeat the compression test. If the numbers go up, you've found your problem.

[vector1]

you did the cranking compression test with the butterflies open on the carb?