Amidst all the talk of electric fuel pumps, regulators, etc, I thought I'd share a testament of the old style fuel pump...

Truck's finally running pretty decent, carb's still not perfect, but yesterday I eased out into the old gravel road, pulled the C6 down into first, got her straightened up, still rolling a bit, matted the pedal and the right rear instantly gave in as tire smoke just billowed behind me. I usually try to shift up before it hits 6000, but this time it snuck up on me and 6000 was there before I knew it, so I bumped her on up to second. Tire kept spinning profusely and the only change was the sound of the motor winding the rpms back up. It spun effortlessly all the way through second, and didn't stop spinning until I shifted up into third. Cool.

The main thing I noticed was that right about 6000 rpm, just as I was trying to gather my senses enough to make the 1-2 shift, it sounded and felt like it was hitting a rev limiter, but I'm running the MSD 6A box, so there isn't one. So I reckon this was the motor beginning to starve for fuel?? It's the only think I can think of anyway.

Even though the cam is supposed to be good to 6500, I really don't like turning her up that high anyways, so it seems to me that if the old stock style fuel pump is good for 6000, that's probably about good enough. Maybe?

 

What valve springs did you use? Sounds like valve-float.

 

Edel heads, pre-assembled. Not sure what springs they use. I wondered about valve float. I guess if it was that, then I was pretty close to messing up and should try even harder to stay below the 6 grand mark, huh!

 

Heh. Yep, sounds like valve float. Try it on pavement next time, much more fun.

 

Oh, it WAS solid pavement, alright. Just the old rough type, not smooth blacktop. That's all I meant by gravel road. Definitely pavement, though. There's a very long black mark to prove it!

 

The Edel valve springs "should" be good for 6500 rpm, with the RPM cam anyways.

 

Yeah, you didn't do anything funky like go to a roller cam, right?

 

The Edel springs are similar to the Cranes I once had. I wouldn't push a cam over about .570" lift with those springs (at least not at those RPMS). They struggled with my .600 lift roller at much lower RPMs. I guesss I do have a little more volume to feed. What size carb are you running?

 

I agree with Greg, those stock Edelbrock springs are way over rated!!

And Randy I cant see you pushing your motor up to 6500rpm just cause crane "says" thats what there good for...with that cam and Stock Edelbrock heads...your going to run our of breath up there anyway... It doesnt do much good to push the motor past were it has made the most hp...

Even with the T-Ram and a Solid Roller at 246*/246* @ .645" lift.. the HP tops at 6100rpm...And that with Ported Heads.....It drps of a couple hp at a time up to 6500rpm but none the less without more Head flow and Intake flow..it still runs out..

JMO.....

Russ

 

No roller cam - just a Comp 292h (.560 lift/244 duration @ .50). Comp says that the operating range is from 2500 to 6500, but I really don't have any desire to push her past 6000. That's getting on up there in my opinion. It sounded just like it was hitting a rev limiter just as it was right on the 6000 mark. I got it out of first right about the same time. I guess that was a close one.

Greg - the carb I have on it right now came off of a bud's hot rod - a Proform modified Holley 650 DP, jetted out to about 830cfm. If I'm just cruising around, there's a little stumble, but when I mash it, boy does that motor really love it. Whenever those back barrels kick in, she really comes to life!

 

I am running the Edel RPM cam, 232/232 @ 0.50 and 0.572/0.572 lift. My rev limiter is set to 6K.All I was saying is that with a flat tappet cam that has less than 0.580 lift he should not be floating at 6K.
Greg, The Edel springs are not setup for anything at or above .60 lift or roller cams either I suppose.
But like stated before, some people have had issues with the Edel springs. Maybe it is a quality control problem. but my setup straight from Edelbrock works just fine. No mods or tweaks of anykind. Although the Erson roller rockers may help with that.

Fuel starvation or valve float I can't say. But like Russ said not much reason to be past 6K anyway.
Damn I've gotten long winded. LOL.

 

Randy, I you and one other guy in this forum have gotten by with 6K on the springs...I think Crane claims there good for .600" lift ..but I have my doubts!

Russ

 

Russ, I'm not running Crane springs. I am running the springs that came with the Edel RPM heads.
Are you saying they are made by Crane? Confused.
Did I miss something in the above posts? I am going to reread the thread.

 

Either way, 6K and above is probably a bit of a stretch for these FEs, if you ask me, and I only got there accidentally anyway (too busy looking at tire smoke in mirror). Lord knows I don't want to blow it up... I was just curious as to what it might have been doing - valve float or fuel starvation.

 

Did it come back with full power as soon as you upshifted and got back under 6000RPM?

If so, it's not fuel starvation. If it was, it would run crappy for a few seconds until the carb filled up with fuel again.