Did someone throw a boat anchor behind my car at 4500?

[max71]

I'm posting just to clear this up with Steve.

I want the power band to be what the cam is advertised for: 1200-6200 Not 1200 - 5000.

That's it. In a nutshell. The Huffaker cam allowed me to bury the tach. Don't need to do that. 6200 is enough.

And yes, I need a break. It just is frustrating driving the car knowing it doesn't work properly. Its not like its a Sunday car and oh well. Its a daily driver thus a daily reminder.

[malcolmr18zoy]

Hi Gary,
Thankyou for your long and detailed reply. I guess I misunderstood what it is that you're sick of, but I'm disapointed after scratching my head for so long that you don't want to even discuss it any more.
You still haven't answered my two questions, and they are relevant to your case. I guess you really don't want to discuss it any more.
Malcolm

[max71]

I would've hoped my long thread gave you every answer.

The engine wasn't rattley before I freshened it. It was performing ok. If you trace back to the start of the thread you'll see why I did the refresh. I found large metal chunks like ring chunks in the sump when I pulled the engine to have the transmission syncho's redone ( Oh I forgot Reed hosed that one too - it will have to be redone eventually). Saw the chunks and saw all the lifters were bad and sending the lifter shots to Joe resulted in him telling me the cam was bad which it was.

BUT I never intended to touch the engine because it ran great. That's the rub. I took a great running engine even with bad parts and decided I would make the 100K engine and never pull it again.]

I had a long talk with Guillermo who was doing the paint and he pointed out that if I was going to need future engine work now was the time to do it rather than risking damaging the paint later. Does that clear it up for you?

Is there something else I haven't answered? You and Steve have been the most active and I want to close this with you both being satisfied. I think I cleared Steve's confusion.

[max71]

In respect for Malcolm wanting answers I did the following:

Carl Heideman sent me a check list of what he would if he got the car in the shop. He works closely with Dave Anton. Carl has a very respect shop in the midwest. The following is what I did with no change in performance. I think it clearly points to cam issues:
I checked compression 1=194, 2=194, 3=200, 4=194
I rechecked and adjusted timing (minor)
I reset the plugs to .030 (as per Carl)
I double checked the carbs thoroughly - adj float height to proper 1/8" - fast idle, idle mixture, balance idle air flow, ensured throttle linkage balanced above idle, ensured choke linkage balanced and adjusted for proper high idle. I used a digital caliper to check balance in jet height. Rechecked A/F
Distributor cap is new, checked wires
Throttle opens all the way
PCV working fine
Checked air filters and made sure vents were aligned

The only thing I did not do on his list is I didn't check valves and re-torque. I will, but I had checked torque and set valves 1000 miles ago.

Aside from #3 50 pounds higher (valve need to be reset?) everything checks out.

I believe this clearly points to the cam or something in the low-end.

[malcolmr18zoy]

Hi Gary,
I'm sorry that you feel so down hearted about your car, but I think that you should dial in your camshaft timing in order to cure your problems.If you're relying on the factory markings on the sprockets you could be way off, I mean 6 to 8 degrees from experience. Since you've had this problem since the new camshaft was installed, I think that is where your problem lies.
Malcolm

[max71]

If its off I have no clue how to time the cam. Been there, maybe screwed it up. I/we did it according to Vizard's instructions.

[malcolmr18zoy]

Just as a point of interest, there is no danger in revving a long stroke engine. The only reason that most high revving engines have a high bore to stroke ratio is that it allows for bigger valves, which allows a bigger charge, which makes for more revs. That is why older, longer stroke engines favored hemispherical combustion chambers. The domed roof of the chamber allowed for bigger valves. These days it's considered more efficient to build in more squish. In the quest for more power, however, with a short stroke engine, there is usually a lower torque to power ratio.
Sorry for high jacking your thread, Garry.
Malcolm

[max71]

No hijack Malcolm. I'm glad you cleared that up. I always understood and enjoyed the MGB because it was a relatively high revving engine. I have a friend in Florida who was a mechanic at a BMC dealership then their service manager. Even he said the cars worked best when revved high and lasted longer. He said what I always was lead to believe that not revving these engines leads to carbon build up and eventual issues.

This is crux of my disappointment. While I get it that most member see no point going above 5000 RPMs I've lived with this car doing it and it was a ball. The engine once balanced and in spec did it with ease - with Huffakers bits. I rarely shift below 4000 RPMs unless traffic is crawling an inch at a time.

Anyway, thanks for confirming that Malcolm

[Martin Keller]

Hi max71,
I have been following this thread and started woundering if you have checked your tach to see if it is operating correctly.
You have never said just how fast your going and in what gear your in so it is just an idea that you might want to check especially with an electric tach..
Just a though.

[max71]

Hi Martin,

This is such a long and meandering thread but I did cover that. I took it to a rebuild shop and they said its off very little.

[Martin Keller]

Hi max71,

Did not catch that but I due remember reading that you had gone to a insturment repair shop, just figured I would mention it just in case it had been overlooked.

[max71]

That would solve it if my tach is off 1200.

But I just go by what it read before the rebuild. Some day I need to have Steve put his Snap on RPM gauge on while I go into the car and cross check. We were going to do that several times...

[Larry Kluss]

A couple of points related to the discussions here, though not related to Gary's engine concern, as he has already addressed them.

First, from my days in the drag racing engine industry, I believe it's rod ratio that generally dictates the mechanical RPM limits of an otherwise correctly prepared engine. That is the ratio of stroke to rod length. A long stroke and short rod creates a more severe rod angle, piston side load, big end load on the rod, limiting its capability of handling high RPM. An example of this in a small block Chevy is a 302ci vs. a 400ci. The 302 has a good rod ratio of I think 1.5:1 allowing the highest RPM of all small blocks. It was used in TransAm racing in the late 60's. The 400 is I think 1.8:1 and is the worst of the small blocks. It was used in the biggest, heaviest sedans and wagons for it's better torque characteristics.

On tachs, when I bought my E-type, the owner (original owner's son) said the motor ran about 4500 RPM at 65 MPH on the freeway in top gear! It idled at 1500 on the tach and would not run at 700 RPM. I quickly figured out that the electronic tach must be off so i checked it against an auxillary digital unit and recalibrated it at various RPM. The point is, it is possible tachs can drift or get out of calibration over time.

[Jimmy]

Right you are, Larry.
I need to learn that all the rules I'm used to also apply to "half-engines", not just V8s.

[malcolmr18zoy]

I think there are a few more factors involved in being able to build a high revving engine than rod ratio. I think that most manufacturers try to make their engine blocks as short as they can for manufacturing purposes, and weight. Therefore the conrod has to be long enough to allow the piston to reach the top of it's stroke, but short enough to allow the crankshaft to sit as near as possible to the bottom of the cylinder. I think one of the most important factors in the quest for high revs is the metallurgy of all the components. That is making a crankshaft that is resistant to twist, and flex, and conrods that are resistant to stretch, and flex. Also the engine block needs to be strong enough to hold everything together, and dozens of other factors.
I don't know anything about small block Chevys, but I'm interested in what you said about the varying rod ratios on these engines. I guess they must all have different length strokes.
Malcolm

[Jimmy]

Malcolm,
One good place for you to start learning about Chevy engines would be an outfit by the name of Jaguars That Run.
Just Google it, sit back, and enjoy.

[Larry Kluss]

Malcom, I agree with your points. There are many factors that go into it and modern materials and manufacturing methods of hi-performance replacement parts (cranks, rods, bolts, bearings, etc.) have enabled previously unrealized high RPM limits in older engine designs. Even with all the best components, an engine is still limited by its design and one with an optimum rod ratio will be able to safely rev higher than one with a poor ratio. Generally speaking, long stroke motors have lower rev limits than short stroke motors.

To answer your question, yes, small block Chevy engines have various strokes (and rod ratios), desite the fact that a 265ci block has the same physical dimensions as a 400ci (as do all the versions). Also, virtually all of the components are interchangable.

[Kelvin]

Gary.

For giggles, check the gaskets between the carburetors and the air filters. If these are installed upside down, the port in the face of the carburetor leading to the area below the piston is obscured. This prevents the carburetor piston from rising correctly under load. The engine will idle fine, but when under load the venturi suction on the top of the piston is working against a vacuum under the piston. So no go.

Just a thought.

Your symptoms indicate problems under load, which could be ignition, or could be a problem with fuel flow. Is there any chance that you can get a sniffer on the tail pipe?? This would tell you if the problem was fuel related very quickly.

A failing fuel pump, or intake line to pump air leak will also give the symptoms you are describing.

[max71]

Thanks for responding Kelvin. I did check that and they were fine. When it was dyno'd the APT dyno person said A/F was fine. I would like to get a sniffer but haven't had any luck.

My next task is to figure out what the cam is degree'd to since my peak torque is so low 2200RPMs.

If you have a sniffer I'd gladly make the drive up to SB.

[Kelvin]

Gary. Your post under another topic, gave me pause.

You stated that you had two fuel pumps in the system. I'm just wondering if you have done a flow test to make sure you have adequate fuel flow under load?

It's possible that the secondary pump, or it's associated hoses/fittings/filter could be restricting flow. Just a thought.

I've had similar symptoms caused by fuel starvation that were caused by a conical filter inserted into the throat of an aftermarket in line fuel pump. The filter got plugged with debris from the dirty tank and would not allow adequate flow under heavy loads. This was in my Jaguar 3.8S and was a bitch to fault find, as there was no indication that there was an integral filter. The give away was that the car ran great on the left fuel tank (and pump) but would die when pressed hard using the right hand fuel tank (and pump).

[max71]

Kelvin. Good pick up. That was one of the reasons I mentioned that in the other post. But don't the dyno information I updated show proper fuel pressure? http://www.hipnoticinc.com/dyno/

I always wondered about that setup although the car has been running fine including the old engine that didn't have any issues like this one at high RPMs.

[Steve Simmons]

But did the problem occur while the car was on the dyno? If not then the fuel pressure readings on the dyno are meaningless. Flow and pressure are different things anyway, although related. If flow drops then pressure should also drop downstream of the restriction. Pressure would remain however before the restriction, unless the problem is the pump itself.

[max71]

The dyno numbers are what they are and show where the car runs out of power. Without putting a gauge on it to measure pressure I do not know. I have clear clean lines as far as I know and a new clean filter.

[Steve Simmons]

So I take it the problem happened on the dyno then? Not just where the power band ends but it actually "hit a wall" the same as it's doing now? That's an important part of the puzzle IMHO.

[max71]

The car always hit a wall. I took it to the dyno because he was suppose to be the man who will not only dyno but correct any problems. I guess I hit him on a bad day as he was very grumpy and his conclusion was its the wrong cam for the car. I was disappointed because previously Dave Anton said this guy is so good he would know if the cam was off by a degree or two. Had he told me hey, this is not running the in the typical power band that I have seen from the VP-11 I think you better recheck your cam timing I think I would've saved 3.5 years of aggravation.