So here's my problem, I can't get my motor over 5000rpms on the street....history is it's a 2014 Butler 461 built, broke in and dynoed by them at 472hp @ 5500rpm, it never got installed just sat wrapped up then I bought it last year and installed it this spring, specs are...9.75 comp, Butler grind cam 282/288,230/236, .510/.521 114LS, ported polished iron heads, MSD, ready to run dist.(no box)Holley 110 gph pump. I put my Edelbrock Performer RPM and Holley Street Avenger 770 vac secd, and my 8mm Taylor wires on it from my other motor a 455 that developed a rod knock. I have the original tank pickup, new 5/16 braided fuel line, in line Edelbrock 40mm screen filter removed the stone filters from the carb, new Accel can coil and a wire from the battery to a relay so there's over 14 volts to the coil now thanks to Pontiac Bobs post, I purchased a new harness not knowing about the resister wire, you think NPD and American Autowire could put in there description NOT FOR ELECTRONIC DISTRIBUTORS after four coils and calls to MSD,Butler, new battery, ground wire Bob had the answer and I thought for sure that was my rpm problem but I only got 500 more rpms more. Set the limiter twice once at 5800 then 6000, revs past 5000 in neutral but not under load and feels like something is breaking down at 5000 no surge or bucking just feels like a rev limiter, also put the rear float over the half way mark that's what Jim Butler suggested but have another call into them to say it didn't work. Sorry for being long winded just want to get everything out there, so any help would be great before all my hair is gone,thanks,Randy

"...new 5/16 braided fuel line..."

Is that 5/16 number a mistake ? I think most factory line was 3/8. Most recommend 1/2" line, for high performance engines.

What's your max total advance(with the vac advance unhooked & vac source plugged), & at what rpm is that max achieved ? Most(not all) Pontiac engines seem to like somewhere between 30° & 36° advance, all in by 3000 rpm. Obviously, if your max timing advance is much less than 30°, it'll reduce power. If it's much higher than 36°, detonation becomes more likely.

A timing light should show whether your ignition system is firing all cylinders, at the correct time, up to 5000 rpm & beyond. Cranked my 455 a couple of day ago. It had a fairly loud "pop" every so often. Hooked my timing light up to several different plug wires. Would get steady fire, for a few seconds, then would miss a couple of beats. So, I have to track down my problem. I suspect the rotor. This is the most common HEI problem I've had, thru the years. A new rotor usually fixed the problem, for a while. The rotors would appear to have carbon tracks, all around where the rotor button(bushing) in the cap contacts the metal tang of the rotor.

I'm not an HEI expert. I always used points in all my bracket cars, back in the old days. So, I hope I can get this HEI fixed. If not, I'll consider either trying a different HEI, or switching to something else, maybe even points, or a points dist with Pertronix Ignitor 3 points replacement.

It's a 6AN which I think is 5/16th id that's the size Butler used from the pump to the carb so I thought it would be ok for up to 500hp but maybe not, I would need to change the pickup to 3/8 if I'm changing the line to 3/8 right? And there's no vacuum advance, Butler said they don't like using them, I'm at 14 degrees initial and about 34 degrees at 2500 that's what Butler set up. I wonder if an electric pump in back would help, had to put one on my 67 years ago to feed the mechanical with a 428 tri power. Just trying to determine if it's electrical or fuel, kind of hard to rig the fuel pressure gauge so I can see it driving.

-6an is 3/8in

Looked up my purchase it was 6AN which is 5/16 ID 17/32 OD according to TT Racing's description.

Thinking of raising the float levels beyond the recommended level to see if I get some more rpms, maybe that would determine if I'm running out of gas, just an idea.

Baaad65 said:

Looked up my purchase it was 6AN which is 5/16 ID 17/32 OD according to TT Racing's description.

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The closest fuel line to -6an is 3/8 in. Try to stick a -6an fuel line on a 5/16 barb and see what happens. Most stock cars in the late 60’s and 70’s have a 3/8in feed line and a 5/16in return. I wouldnt put a 300hp small block on a 5/16in line let alone a 461 stroker. If you have a -6an line that is equivalent to you using a 3/8in factory feed line. -6an will support up to 650hp n/a.

Well that's good to know because I thought I screwed up and would have to replace the line and worse the pickup, maybe I need an electric pusher pump like I said my 67 428 tripower needed that then was fine, or the pickup sock could be clogged because it looks like the tank has never been out and the car was in a field for a while I'm sure by all the crap I've been finding in every place imaginable. That's if my problem is fuel not electrical, still unsure.

Not sure if your issue is fuel related or ignition related but i will say ive had some recent issues with the Holley 110 gph mechanical fuel pump... with multiple failing within days of being installed. The build quality has really gone down hill. I would suggest if you dont already have a fuel pressure gauge put one inline going to your carb setup... then see when you experience the issue at 5000rpm if it corresponds to a drop in fuel pressure. If pressure is solid at 6-7psi then you can rule out fuel as the issue. I would also check vacuum and see where thats at. If its normal only thing left it can be is ignition.

Ya the pump sat on the motor for 4years and I did have to pull it apart to index the fuel port but have a gauge on the dual feed and I'm getting 4 -5 at idle but a little difficult to see the gauge going down the road. Vacuum gauge in the car reads 16-17 at idle, new Accel super stock coil but maybe that's breaking down? And like I described I have a couple wires crossing through the distributor cap to reach but idk think that would be a problem always not at high rpms. Also new cap, just feels like a rev limiter but don't know how to deactivate it unless I unplug the tach then I have no reading in the car unless I go by sound and feel which I could probably feel if it's pulling past 5000.

When I figured out I had a resister wire and corrected it and got 14v to the coil is when I picked up 500rpm, used to quit at 4500rpms now it quits at 5000. Thinking of trying an Edelbrock low psi inline pump to feed the mechanical for 40-50 bucks and an easy install instead spending 150.00 on a new mechanical, if that doesn't help I can just leave it with no harm. That's what cured my 67's problem back 30 years ago.

Well talked to MSD all they said try a 12 gauge wire from the battery to relay and relay to the coil instead of 14 gauge if that doesn't help look at replacing the valve springs, the motor did sit for 4 years without loosening the rockers and probably wasn't turned over so is that a possibility? Sqaushed springs? Any thoughts anybody?

Baaad65 said:

Well talked to MSD all they said try a 12 gauge wire from the battery to relay and relay to the coil instead of 14 gauge if that doesn't help look at replacing the valve springs, the motor did sit for 4 years without loosening the rockers and probably wasn't turned over so is that a possibility? Sqaushed springs? Any thoughts anybody?

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In my younger days I had bought cars that had not been started in 10 yrs and after a little oil in the pistons ,fuel clean up, oil change,and a pump prime they were of to the races.

Everything looked and moved good and rockers seemed fine with no excessive movement, I'm calling Butler on the valve spring idea and will run a bigger battery wire to the coil but I'm stumped. Still not sure if it's fuel or electrical.

Baaad65 said:

Well talked to MSD all they said try a 12 gauge wire from the battery to relay and relay to the coil instead of 14 gauge if that doesn't help look at replacing the valve springs, the motor did sit for 4 years without loosening the rockers and probably wasn't turned over so is that a possibility? Sqaushed springs? Any thoughts anybody?

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NO, springs don't "squash" from sitting. If the rocker arms were set too tight, you might experience a rough running engine, back firing, or even a "no start" engine as a valve (s) would be slightly held open and not seat.

Since the engine was dyno'd and broken in at the higher RPM's, I would assume there is no problem mechanically.

My questions are these - Did Butler dyno the engine with the same distributor and carb that you are now using? They may have their own ignition/carb set-up that they use to do the dyno and them supply the engine less these parts for the owner to install their items.

I would be looking at the fuel issue and a possible ignition issue.

I assume you are driving the car and have taken it for a drive and experienced this problem. If it is a fuel delivery problem, when you reach your 5,000 RPM mark, you should feel the car "nose over" when the carb bowl goes dry - meaning the power pull stops and it almost feels like you applied front brakes slightly to pull the front of the car down (acceleration causes the rear end to squat a little and pull the front end up).

You mentioned it will rev past 5,000 RPM in neutral, so my money is on a fuel problem because under constant load sucking up gas for a good long blast is different than a quick revving of the engine under a no load condition.

If it was the MSD, and it was faulty, then I don't think you would have the difference in rev points with no load vs under load conditions.

What did you gap your plugs at? Might sound simple, but maybe the gap is too large for the spark to jump. Often with the aftermarket ignition is will suggest a wide gap on the plug which requires a lot of energy to jump the gap. Check the plug gap and set them at .032-.035" like factory plugs. Let's make sure you are getting a good hot spark.

Next, gas cap. This is often overlooked. Put a non-vented cap on a tank having no vent and you are creating a huge vacuum in the gas tank that is pulling back on the gas going through the line as the fuel pump is pulling back to supply the carb - doesn't work. With the position of the filler neck on these cars, hard acceleration with a full or near full gas tank will cause the gas to slosh right out the filler neck. Then someone gets the idea to install a different non-vented cap and that's when problems start. Might not be as pronounced with a stock engine, but with a built/bigger cube engine it'll show up quick. Cap should be a vented cap.

Also ensure that the hose on the tank has been replaced with ethanol friendly hose. The original rubber type can deteriorate and dry rot. You could simply have a split in that hose and not even see it allowing your fuel line to suck in air as the fuel pump demands additional fuel on those long hard pulls.


Although you installed a 3/8" line from the fuel pump to the carb, the factory gas line from the tank to the fuel pump may only be 5/16" line - as will be the sending unit at the top of the gas tank where your rubber line connects. As I recall that is what was used on the '65 cars. 3/8" line was not standard line until 1968. So if you still have the 5/16" line, it is too small and is creating a restriction on those hard pulls.

You can remove/install 3/8" steel lines and get a matching 3/8" fuel tank sending unit. The other option that may work with the smaller lines is to install an electric fuel pump back at the tank to aid in fuel delivery, but I say "may work" because it may not with the fuel demands of the 461 cubes.

Check out those things first before pulling stuff apart or doing more mods that you don't need and probably won't solve the issue. :thumbsup:

Butler dynoed it with the MSD dist. and the rockers weren't loosened but I replaced the stock manifold with the Performer RPM and they had a Q jet on it but I put my Street Avenger 770 vac sec. on it also replaced the MSD wires with my 8mm Taylors that were cut to fit, plugs are gapped at .035. The throttle plate is opening all the way when pedal is to the floor, and I raised the rear float level over half way up the site glass, it doesn't nose down just feels like a rev limiter. I did replace the hacked up original line with a 5/16 ID braided line from tank to pump and the same size line is what Butler used pump to carb, used an Edelbrock 40 micron filter right before the dual feed and removed the stone carb filters so only have the tank sock and 40 micron as filters. Gauge on the dual feed reads about 4.5-5 lbs at idle but haven't rigged anything where I can see the pressure at 5000 rpms, like I said I gained 500 rpms once I got 14 volts to the coil but haven't changed the battery to coil wire yet to 12 gauge like MSD suggested, not sure that's going to make a difference over my 16 gauge wire. Gas cap is a good idea I'll check it but looks like an original gas cap, they should say "vented" on it correct ? I was thinking of installing an Edebrock 4-7 psi electric in line pump in back and like I said I needed that on my 67 428 tri power back in the day, maybe history is repeating it's self.

Ok I have a "not vented" cap but there's a small like 1/8 " elbow coming out of the fill neck has a little piece of hose and then steel tube in a fish hook shape with a clip holding it, so that should be the tank vent and it's clear, so I assume I don't need a vented cap because I've read where they leak when you take off. Also my fuel pressure is around 7psi at idle cold not 4-5 like I thought but I think it drops a little when hot. And my wire from the battery to relay and relay to the coil is 14 gauge not 16 so I'm not changing it, doubt if that would make a difference. Did try revving it in park a couple times and I feel the limiter kicking in at 6000 like I set it, idles great at 750-800 with 17 inches of vacuum and great throttle response and rolling 20mph just shreds the tires in first and pulls hard until the 5000 mark then breaks down. Just frustrating.

Baaad65 said:

Ok I have a "not vented" cap but there's a small like 1/8 " elbow coming out of the fill neck has a little piece of hose and then steel tube in a fish hook shape with a clip holding it, so that should be the tank vent and it's clear, so I assume I don't need a vented cap because I've read where they leak when you take off. Also my fuel pressure is around 7psi at idle cold not 4-5 like I thought but I think it drops a little when hot. And my wire from the battery to relay and relay to the coil is 14 gauge not 16 so I'm not changing it, doubt if that would make a difference. Did try revving it in park a couple times and I feel the limiter kicking in at 6000 like I set it, idles great at 750-800 with 17 inches of vacuum and great throttle response and rolling 20mph just shreds the tires in first and pulls hard until the 5000 mark then breaks down. Just frustrating.

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You are good on the non-vented cap with the vented filler neck and hooked hose.

What does it do when you get up to about 4,000 RPM's - easy throttle - and then bring up the rev's?

Pull the rev limiter back to 4,500 RPM's if it will drop that low. See if it works.

If you max the rev limiter out, will it climb past 5,000?

Bad coil. This was another member's experience.

Wrong gas pedal cable? Does putting the pedal to the floor fully open the carb? We have seen this problem come up. Cable too long or incorrect parts from another year used. Have a helper and put the pedal to the floor and look down the carb to ensure the throttle blades are vertical and secondaries wide open.

Call the carb manufacturer. They may have some suggestions. Perhaps the vacuum secondaries are adjustable? Any air bleed tubes which may be too small" Incorrect jetting? Need larger needle/seat?

7 PSI is fine at idle. The need to know is what it reads at 5,000 RPM's.

Okay I have any extra standard can coil I could try and yes the throttle blades are opening all the way, had my assistant push the pedal to the floor and watched them open straight up, have vacuum secondaries so can't tell but I did try the yellow spring with same results so I put the plain steel color one back. The carb was new and I put it on the 455 that was in the car when I got it but only made one pass at 4500 rpm and then it developed a rod knock so I babied it the rest of the summer and the 461 went in this winter, replaced the power valve and has a #25 squirter and #71 /#76 jets in it.Maybe it is a fuel problem and I'm just not feeling the nose down effect since I'm concentrating on the road and the tach, so maybe I'll try that Edelbrock 4-7 psi electric pump for 50.00 can't hurt leaving it in and it's pretty easy to install.

Okay well swapped out the coil with the same results, bringing up slowly to 4000 goes good, I keep going and hits a wall at about 5000rpms then backed off to 4000 feels good, didn't notice any nose down feeling. Electric fuel pump might be here Monday if that doesn't help then I'm out of ideas except valve springs but if they were bad or miss adjusted I would think it would run bad at idle or pulling it up to 5000rpms but it's perfect.