paulmoore

Got the engine running finally and everything is hooked up. At idle(about 770-790 RPM) I have 12-13 inches of vacuum, 6 PSI fuel pressure. When I hit the gas, the car feels like it has no power(should have AT LEAST 420HP!! with my setup). I don't hear any detonation or misfiring. If I am at a steady cruise speed/RPM, and I gradually give it WOT, I can hear the motor bog when the secondaries open. Also, I was in second gear at about 1500 RPM and tried to give it WOT, the car reved up till it hit 4 grand, and then felt like I let my foot off the gas even though I had the gas pedal buried!!! Something is definetely off. Maybe I'm running rich?? The girlfriend was driving behind me, and she said that the car smelled, but couldn't describe it. Nothing comes out of the tailpipe though, so I don't know. Any ideas??? Thanks, Paul Moore

V6sucker

easiest way I know to tune is like this...

get an external vacuum guage.
Hook it to a constant HIGH vacuum source (like brake booster port)
Get idle to around 8-850
Start with one bleeder and turn until you get the highest vacuum reading.
Adjust other bleeder and then go to other, back and forth always aiming for highest vacuum reading.

After that you should be good to go.

I had a holley I did this with and it would bog off idle, almost die it was so rich. And I only got 12-13" at beginning. I got it up to 16" with above meathod and it ran like a raped ape.

paulmoore

Well, I am running the Edelbrock Performer RPM Package- RPM Air Gap dual plane manifold, 1407 750 CFM manual choke carb, and their cam. The cam specs(I .410 E .510 @ I 234* E 244*) show that it is only supposed to get about 10-12 in Hg at idle. Now, I'm already at 12-13 in Hg so I'm not sure that the vacuum method will work for me. Right now, the mixture screws on the front of the carb are screwed almost all the way in(which should be lean if I'm not mistaken) Is it possible that running excessively lean could cause my engine not want to rev past 4000 RPM? Possible fuel starvation at that RPM? I'm new to carbs so I'm open to any advise or suggestions. I would *assume* that everything mechanical in the engine is working ie. cylinder pressures, valves opening and closing properly otherwise the engine vacuum would be lower or jumping around. I think that I will still try to adjust the idle with a vacuum gauge and see what I get with the mixture screws. Maybe play around with the timing also....

MaxxMitchell

iTrader: (4)

Bringing this back up. Did you ever fix your problem? Im running a decent set up with a 1411, and it just lacks power. It hits a wall around 4000-4200, but idles, and drives around great. Just wondering what else you had to go through to fix your problem.

paulmoore

Well, as of right now the engine is blown. The number 4 intake valve hit the piston and broke off and pinballed inside the motor- cracked the piston in half, gouged the head and the block. It's all pretty much useless now so I had to start over and this time I'm going with a 383 stroker. But as far as the old motor was concerned there were more MAJOR issues with it. But after the teardown, I was able to get a better idea of what happened...

I had a problem iwth the idle. I would get it set to about 800 RPM. It would sit there for a minute or two, and then start to load up, and run rough. Idle dropped down to about 500. At this point, I would go up front, raise the idle speed back up to the 800(still running choppy), and then give up some throttle to let it set. Once I gave it some gas, the engine would idle at 1500 RPM!!! So after a minute of two, I would lower the idle speed back down to 800 and then it would get choppy, and go back down to 500- this was a continous issue.

I also had another problem with engine RPM range. Once I would start to drive the car, and give it gas, usually 1/2 throttle or more, it would not rev up past 4000 RPM. When the engine hit that RPM, it physically felt like you lifted your foot up off of the pedal, but I have it to the floor!!!

It also ran super rich, and I wan't able to get it tuned right either. I tried every adjustment on the carb without having to tear it down, but to no avail. Even if I would have changed the metering rods, it wouldn't have made a difference and I'll tell you why......

When the motor finally went south for the winter, I jerked the heads off later that afternoon. EVERY single intake valve except for the #8 was bent(but #4 was broken off), and all the pistons except for 8 and 4(which was cracked in 1/2) has hit marks on them from the intake valves. This tells me that I either had too little piston to valve clearance, or something else happened. But the bent valves would cause the whole nothing past 4000 RPM thing, and could also cause it to run rich and mess with the idle due to dynamic compression loss. But hindsight is 20/20, and I know that I am the one that messed it up, but not intentionally. I'll tell you how....

When I first started to build the engine I was inexperienced. After all the machine work was done, and I installed the heads and stuff, I knew that I needed custom length pushrods because the block had been decked. So I bought a pushrod length checker, mocked it up with my hydraulic flat tappet lifters/camshaft/rocker arms, and finally got the length I needed. Did you catch the problem with that? I used the hydraulic flat tappet lifters instead of solid. So, the stress of the vlavetrain was pushing down on the lifter cup, causing it to compress. Because of this, I ended up using a pushrod that was longer than I needed. Longer pushrod caused the initial piston to valve contact, and I was fighting with it the whole time. But like I said, it was my fault. Live and learn right? Anyway, these are the things that I will be taking my time with on this new motor. I won't make the same mistake twice. Hopefully, someone will read this and think twice to check those clearances. It could same them alot of time, money, and aggrivation.

mw66nova

iTrader: (13)

hey paul, do yourself a favor next time and degree in the cam. my first engine build i did all by myself (no pops to help me, he was outta town.) i managed to get the cam gear off a few teeth from the crank gear...just a thought. damaged was similiar, though it didn't last through break-in and i was able to salvage everything but the cam/lifters.

BigDreams92

iTrader: (1)

This is exactly what my 1406 edelbrock would do, I messed with it for a month then bought a real carb. I couldn't be happier now.

mw66nova

iTrader: (13)

see, now that's weird cause we put a 1406 on my buddies lt1 cammed 305 and it works great! i mean, we had to rebuild it(bought it used) but once we found that one of the floats had sunk and we set it all up with a new acc. pump and put a rebuild kit in her, it ran GREAT. though the 305 we've got it on is only 9.5:1 compression and the lt1 cam has a 117lsa, so it's got GREAT vacuum, lol! it runs decent though. i know with a 600 double pumper the car would run better though.

paulmoore

I agree, there alot more things that I could have done the first time to ensure that something like that wouldn't happen. Unfortunately, I'm under a HUGE time constraint(I live in a kind of deed restricted community) and with all the hours I spend at work it would end up taking too long. So instead, I am having the short block built by a machine shop. They did everything, assemble the short block, install the hyd. roller cam and degree it in. everything in the bottom end has been taken care of. It is being shipped to me as we speak. When I get it, I will do the checks for piston to valve clearance, pushrod length, etc. so this catastrophe won't happen again. If all goes well, I should have the new engine together and in the car and running in a couple of weeks.

mw66nova

iTrader: (13)

yay!

BigDreams92

iTrader: (1)

My cam is either 110 or 111 LSA, think 111. Vacuum isn't horrid, but it's not THAT good lol.

Paul
Gratz, sounds like everything is going to work out fine
What heads are you running on the new shortblock? Another set from edelbrock?

mw66nova

iTrader: (13)

i think he's gonna be running AFR 195's.

BigDreams92

iTrader: (1)

I'm gonna be like the only one with vortecs I need to invest in some better heads!

MaxxMitchell

iTrader: (4)

LOL you might be alone where you are, but I'm not here. Then again, mine arent true vortecs, just modeled after. Well Im just fine on the Pistion to valve clearence, im just trying to dial her in. I do have a pretty good exhaust leak, and stock manifolds to a open Y pipe. Headers will be ordered this week some time. The car pulls pretty good in 2nd and 3rd, but the RPMs just arnt there, and it really starts to slow down around mid 4000. Oh well everything takes time.

BigDreams92

iTrader: (1)

I'm sure everything will pan out for ya. I'm not real good at the tuning thing, but switching to my proform mainbody 750 was the best thing I could have ever done for my 383.

MaxxMitchell

iTrader: (4)

The car is hesitating when I take sharp turns, mostly lefthanders. Thought it was gas being low, untill I got the gauge working, and put in another 5gallons, and it still did it. Im guessing the float on my carb are set too low. Funny its a rebuild from Edelbrock, oh well nobody is perfect.

paulmoore

Yes, I will be running the AFR 195's with the new engine combo. I actually called around a few places to talk to some people to get some ideas about what kind of power levels I could realistically achieve with any given setup and still be reliable enough for everyday use. That's when I found this...

http://www.airflowresearch.com/dyno/chevy_dyno.htm

Anyway, I'll probably end up running about 10.2:1 compression with the 68cc heads, so that should give me just a tick over the 500HP mark. Once you factor in all the parasitic losses from the water pump, power steering pump, alternator, transmission and rear end, I would like to think that I could still end up with roughly 380-390HP at the wheels. I feel that this is a more realistic goal, and should get me into the high 11's ie. 11.9x. Once all the major kinks get worked out, and everything is tuned to where it needs to be, I might just throw the bottle to it and see what she does. With the forged bottom end, she should be able to handle about a 200 shot safely, and if I'm right that would put me in the mid 10's. That is all that I ever really wanted from this car anyway. The best part is that peak torque occurs at 4500 RPM, and peak horsepwoer comes in at 5500 RPM. So, I don't even need to spin the engine up that high to make max power, and when I grab the next gear, the RPM's should drop right back down to the 4500 RPM range or so. That way, I am taking full advantage of all that torque.