Dissapointing performance

[340demon72]

Yeah, WOW! I'M Dutch and I thought I was stubborn <grin>


You need to listen to these guys or figure it out for yourself. You don’t have a big enough carb, you need bigger exhaust, converter stall too low (should be 2800-3000) and if you showing 20” vacuum at idle something is way off with your cam…..


The fact you can't smoke tires really points to the converter and cam. Good luck.

 

[Dusterguy]

I have listened all of you. What you want me to say?

 

[Dusterguy]

My meter has something differet scale than US thing. After looking my meter my vacuum at idle is 7 inch/hg. Does that sound right?

 

[racerdan80]

Et and speed difference with a good converter to a mismatched one can be quite a lot. For instance, my dad's chevy nova with a small block and nitrous was over carbed with 2 holley 660's, only a 3500 stall and 3.5" exhaust. Went high 12's on motor and 11's on nitrous. Lazy dog off the line. Single 830 carb, 5500 stall converter, no change to exhaust, would leave on the wheelie bars with a 1.54 60 ft. Ran then 11.10 @ 120 on motor, 10.35 @ 130 on nitrous. The combination was way off originally. You have a ton of potential with those heads, but everything in your combo must agree with each other

 

[Cuprum-74]

I have a stock bore 360 (4 inch) with stock 308 cast iron heads. speed-pro pistons with 9.7:1 compression ratio. A Lunati Voodoo 270/279 Roller Hyd. Cam. (replaced that comp mutha thumpr cam)
A dual plane air gap manifold.
Edelbrock AVS 650 carb.
Dual 2.5 exhaust with X pipes, a hughes 2400 converter in an A999 trans converted to non-lockup with a Cheetah valvebody.
I have 3.21 gears and I can easily do burnouts with 255/60 tires...
I now have 15 hg of vacuum. I was getting 9 hg with a Comp Mutha thumpr 311 duration cam (that sucked!)
Oh and I get 16-17+ mpg highway...
Listen to these guys. "Don't burn the bridges to the library if you want to learn."

 

[Dusterguy]

Et and speed difference with a good converter to a mismatched one can be quite a lot. For instance, my dad's chevy nova with a small block and nitrous was over carbed with , only a 3500 stall and 3.5" exhaust. Went high 12's on motor and 11's on nitrous. Lazy dog off the line. Single 830 carb, 5500 stall converter, no change to exhaust, would leave on the wheelie bars with a 1.54 60 ft. Ran then 11.10 @ 120 on motor, 10.35 @ 130 on nitrous. The combination was way off originally. You have a ton of potential with those heads, but everything in your combo must agree with each other

What trap speed was with 3500 converter and 2 holley 660's?

 

[Cuprum-74]

Here for reference...

 

[racerdan80]

110 on motor, 120 on nitrous. After converter and carb change 120 on motor and 130 on nitrous and bouncing off the limiter @ 7500 rpm. The dual carbs and tight converter made that combo run like crap. It was very mismatched

 

[Dusterguy]

Is there availlable higer stall converter for lockup 904? (in usa) or is only option to change non lock up trans?

 

[racerdan80]

Cope, ATI, dynamic racing may be able to make you a custom one. Not sure if they'll deal with a lockup thou.

 

[Cuprum-74]

With lockup you are severly limited when it comes to aftermarket. Plus they're more expensive. I converted my A999 to non-lockup as I got tired of dealing with poor TQ converter selections (as well as constantly burning out the lockup TQ's). I was lucky I had a spare 12,000 mile non lockup 904 to pull parts from, and then I purchased a Cheetah non lockup valve body.

Done a few 1,000 mile road trips and never had an issue.

 

[racerdan80]

I would try to upgrade the carb and exhaust first. With the bigger carb it is going to need to be re jetted to dial in the a/f ratio and a free flowing exhaust. After the motor is dialed in, you may be able to figure out what your motor requires in stall converter. Stall will also have to agree with the axle gears and tire diameter

 

[jbc426]

Stock or ported heads? I assume ported ones. What carb you have?

Hughes Super Prepped Edelbrocks with a few hours of hand blending in the bowls etc. Gaskets matched to an Airgap intake with the center plunuem cut out. It's fed by 49lbs Ford Racing injectors and a Hughes Big Gulp throttle body.

TTI step headers with a Full TTI 3" H-pipe exhaust with Hooker Aero Chambers and ovalized tips. It's quiet until you hit the throttle more than just cruising, then it gets loud! 3.91's, a 4 speed auto overdrive with a 3400 stall/ 3-carbon fiber disc - lock-up converter. It hooks up hard on the street using properly adjusted slapper bars and Nitto drag radials. Heck, it beat a Hellcat in a drag race a few months back.

It took over 10 years to dial my car in. It is a process, and it is still evolving. Keep at it and you will get it where you want it. My problem is that point keeps moving.

 

[crackedback]

Ede carbs suck unless you are running two of them... JMO

Something is WAY off. 20 initial is little light IMO. Probably should be in the 24 range. 7" of vacuum is low as well. Is that at idle in N/P or in gear.

It's NOT the heads that are the issue.

 

[SGBARRACUDA]

I am totally amazed! You ask for advice, but have all the answers? Are we not telling you what you want to hear? Ok try this, you need to grease the frequencies on the flux capacitor. I think that will do it. You'll be running 5 sec passes in no time!

 

[GeorgeH]

I am totally amazed! You ask for advice, but have all the answers? Are we not telling you what you want to hear? Ok try this, you need to grease the frequencies on the flux capacitor. I think that will do it. You'll be running 5 sec passes in no time!

You send them to school. What do they do? Eat the pages!

 

[straightlinespeed]

That is a nice combo right there for street use and probably has a great "seat of the pants" feel.....

JW

Your darn right it does! The car is so much fun to drive with the new engine, that the transmission decided to crap out so it could be just as cool!

 

[SLOPAR72]

Your darn right it does! The car is so much fun to drive with the new engine, that the transmission decided to crap out so it could be just as cool!

Lol..... atleast have a good story about how you broke it.... Nobody wants boring details.... You motor should have some nice low end Torque which is great for weekend parts replacement lol....

JW

 

[Lustle]

Ok look. You keep saying you have "good attitude" but then we tell you whats wrong (small exhaust, small carb, etc) and you tell us we are wrong.

We are NOT wrong.

That exhaust is killing 50HP ALONE. AT LEAST.

No. I'm not kidding. Yes, at least 50HP. No, really, 50HP. YES exhaust matters THAT MUCH. Engines pump air. Period. If that air has no where to go, engine doesn't pump. Period.

That carb will probably give you great crisp throttle, but you're losing out on power. Period.

So I'll say it again.

2-1/2 inch exhaust. 750 double pumper.

Do these first. Then see what it reacts like. Figure out the engine before you start messing with converter and such. Which, BTW you need a lot more of.

Why are you fighting all these suggestions then saying you don't know whats wrong? If everyone is saying it, that MIGHT be what it is.

Oh, for your reference, he's my build:

340 .040 overbore
KB Pistons 10.05:1 compression
J heads - 2.02 Intake/1.60 Exhaust - bowl/port work (mainly cleaning up that terrible turn into the bowl) stock stamped steel rockers
Comp XE274H Cam - 230/236 @50 488/491
Street avenger 670
Edelbrock rpm air gap
Hi pro manifolds 2-1/4 exhaust with turbo style mufflers
B&M Torq master 2400 stall
3.55 gears

Builder rated engine at 380 horse with the manifolds. The thing ROASTED tires at will. Had 205's on there originally and it had no problem. But even 245's it could roast whenever it wanted. On the brakes, not on the brakes. Off the line. Etc. Now I'm putting on Hooker headers with 1-5/8" primaries into 3" collectors. Full 3" exhaust with Dynomax bullet mufflers and turndowns at the muffler. 4.10 gears. New custom PTC torque converter, 3000 stall. And FItech efi. I'm expecting to pick up at least 25 horse. But every desktop dyno I've done says anywhere from 30-40 horse. Once again proving, exhaust matters.

 

[Coronet 500]

I truly believe you need to do an 8 cylinder warm compression test first. Diagnose this step by step.

 

[Riff Raff]

Guys. For what ever its worth. I agree with all of you and all of your suggestions. I think this fella's comments and replies are being taken out of context. Just like texting its easy to misinterpret the point someone is trying grasp and/or make. I think his grammar and english translations make him sound combative. Just saying...

 

[fishmens67]

cam timing ? something is wrong and your right, it is not the exhaust size limiting the lowend torque. if anything 2" would make the 360 have more lowend torque and suffer at higher rpm.

 

[MopaR&D]

Yeah guys go easy probably a bit of language disconnect going on like he said... I think he is willing to try the carb and exhaust (right?), I think that's what you need as well. And do a compression test at least to see what your cranking compression is, that will tell how good the performance will be at lower RPM in general.

I know you think 2" exhaust isn't hurting much but it's probably becoming a restriction before the engine starts making peak TORQUE, let alone HP with that cam. If you increase the flow with 2 1/2" pipes it will probably increase torque slightly even down to 2500 RPM and it will just pull harder and harder from there on up. Try unhooking the headers and running them open, I bet it screams and/or the carb runs super lean lol.

 

[skrews]

Years ago I went from 2.25" exhaust to 3", cut 3 tenths off my 1/8 mile ET (8.8 to 8.5) and gained 3mph. Do the exhaust first.

 

[Dusterguy]

Hughes Super Prepped Edelbrocks with a few hours of hand blending in the bowls etc. Gaskets matched to an Airgap intake with the center plunuem cut out. It's fed by 49lbs Ford Racing injectors and a Hughes Big Gulp throttle body.

TTI step headers with a Full TTI 3" H-pipe exhaust with Hooker Aero Chambers and ovalized tips. It's quiet until you hit the throttle more than just cruising, then it gets loud! 3.91's, a 4 speed auto overdrive with a 3400 stall/ 3-carbon fiber disc - lock-up converter. It hooks up hard on the street using properly adjusted slapper bars and Nitto drag radials. Heck, it beat a Hellcat in a drag race a few months back.

It took over 10 years to dial my car in. It is a process, and it is still evolving. Keep at it and you will get it where you want it. My problem is that point keeps moving.

Sounds like you got very healthy engine.

I have also had this car long time 15 years and when I bought this it was almost stock 318 engine and that was really slow. So looking that I have made some progress, but problem is I constantly want more performance.