Warm engine misses

[Bo Dillingham]

To RestoCreations and all,

After all this turmoil, before I do ANYTHING else, I have made an appointment with a local shop (where I have done business over the years) to drop the car off over the weekend and have them check out the electronics next week. They have all the equipment and expertise, and I told them about the last few weeks of my efforts, and explained that the idea is to confirm whether or not the electrical system is at fault. As much as I like working on my own car, I'm certainly not above asking for professional help.

As the weekend approaches, weather permitting, I plan to drive around a little so that I can give the best information to the shop (its name is "C.A.R.S." for Cortland Auto Repair and Service). "My mechanic, Matt" (see post numbers 30 and 36) confirmed that he thought it was the carb all along, and he would happy to rebuild it for me, or help tune it up if I do the rebuild myself. He is not happy about the fact that I am taking the car to a shop just to have the electronics checked, as I think he is insulted, but I'm in the "better safe than sorry" mode right now.

Meanwhile, I'll be reading and rereading all these posts and all the literature that you have recommended (I downloaded copies, so they're handy).

As usual, I'll keep you posted,

BoDill

 

[Bo Dillingham]

To All,

First, I have left a notice on my other thread, "Holley Help", and told people to look at this thread, as it has begun to encompass all the problems (both fuel and ignition).

As of this afternoon, I just drove around after doing a carburetor rebuld on my Holley 650 Double Pumper Spreadbore. So, as of now I have replaced the points, plugs, coil, wires, distributor cap, rotor, resistor, and rebuilt the carb. By the way, the carb looked like new inside before the rebuild, and I used a Holley rebuild kit and put in the 8.5 power vavle (the power valve I replaced had a number "8" in one corner and a number "5" in another corner).

(Forgive me for repeating myself here, but I don't expect everyone to want to sift through all the previous posts) The car still "misses" at driving speeds. Ironically, it starts amazingly well. It fires and is running in what seems like about a half a turnover, and it ides well, and accelerates just fine. Sadly, once I get up to around 40 or 50 MHP and just cruise along, it starts to missfire. I use the word "missfire" because that is what it feels like. Also, it doesn't feel real regular, as if it was a spark plug; it feels random, but I have tried a few different sets of points.

Since the car idles and accelerates well, and seems to have a problem only at cruising speeds, I plan to ask around locally if anyone can recommend a shop that might be able to solve this problem because I've been screwing around now for weeks with no luck.

In the meantime, if you have any suggestions or advice, please let me know......and thanks,

This is an edit (3:18 PM) that just occurred to me; Is it possible that a wire could not be the right gage? Not a plug wire, but something else in the ignition system? Also, years ago a friend of mine was told by a race car owner to "Just replace your carburator!", as he said that rebuilding it is a waste of time. Since a Holley 650 SB DP is less than $500 new from Holley, perhaps this is the better solution. As I said, any help is welcome....

BoDill

 

[65TripleBlack]

I just got here after reading the notice in your other thread.
For me and any others that don't have a few hours to study all posts in this 6 page long saga, please give a quick synopsis of what's going on, including all things you've tried, rejected and had success with.
You can also include any of the predictable stuff that was said/rejected by anybody from that Corvette website with the wierd looking alligator mascot.

 

[Bo Dillingham]

To 65TripleBlack and all,

About a month-and-a-half ago, my 65 Vette started "missing", after about 12 years of trouble free service in a northern climate, where it is stored all winter and driven mildly all summer. It has a small block with an Edlebrock intake manifold and a Holley 650 Spreadbore Double Pumper. The "miss" doesn't show up during start-up or idle, nor during initial acceleration, but once I get up to speed it starts to "miss" erratically. For me, "up to speed" is anywhere from 25 to 70 MPH, or normal highway speeds. I am 70 years old, and long past drag racing, etc. My normal driving rate is around 50 MPH in open country, as it relaxes me.

I started by replacing ignition components and the fuel filter, and later rebuilt my carburator, and so far nothing has worked. The previous 80+ posts simply discuss various possibilities suggestions and procedures along the way.

At this point I am totally discouraged and frustrated beyond sanity. I have taken the car to a reputable shop to get their opinion, and they basically told me that the ignition system seemed fine to them, and wished me luck with the carb rebuild.

Now, I think I did a reasonably good job on the carb, but if there is a super-complicated blocked passage inside it, perhaps I didn't find it, or my cleaning just plain didn't touch it. If there is a good mechanic with the tools and expertise to troubleshoot a problem like this in Upstate New York, I would be happy to pay for the proper help. Naturally, I don't intend to drive the car very far because it doesn't run right, but I also feel that I am way out of my league (unless a carb replacement is the solution).

I can't think of anything else necessary to sum this up, but I will be paying attention and will do my best to answer any questions.

BoDill

This is an EDIT: Does any of this sound like it might be caused by a fuel pump?

 

[Bo Dillingham]

To All,

As a courtesy to all who are following this thread, this post is simply information that may take awhile to have an effect; I just bought an electric fuel pump and a cover plate for the hole in the block where the old fuel pump is mounted. I am certainly not sure that the fuel pump is the cause of my problems, but I like the idea of an electric fuel pump (I had one on my 68 Chevelle back in my "Gearhead" days).

Also, in a fit of frustration, yesterday I typed, "Engine misses at cruising speed" into Google, and the first article that came up said that a common cause is the fuel pump. The actual truth is that I want to install an electric fuel pump for the reason mentioned above (my Chevelle).

It might be a week or two before I get this installed, and I will post the effects good or bad.

BoDill

 

[65TripleBlack]

I seriously doubt that it's the fuel pump and it's easy enough to check it first. Put a pressure gauge in line, run it inside the car or tape it to the cowl where you can see it, and take it for a cruise...the fuel pressure should not drop more than 1-2 psig below the 5-6.5 that it was during idle. I assume the floats are set properly. If the engine pulls freely under a load without falling on it's face, then you can immediately eliminate the fuel pump, float level, fuel sock, fuel line and fuel filter. Try this in 1st or 2nd gear up to about 5500 RPM.

Be careful with an electric fuel pump...........you don't want anything more than about 7 psig fuel inlet pressure otherwise your needle/seats won't seal. You'll need a regulator. This setup is a complete waste of time and money for anything less than a dedicated race car or a car with electronic fuel injection.

That said, your problem is more likely ignition. If carbon tracking and wire shorting have been eliminated (especially between 5 & 7, which fire consecutively), then I'd look for weak spark. It might also bee too rich a mixture fouling one or more plugs. A hotter than stock spark will fire fouled plugs, no matter how bad they are. Stock spark is not tolerant of any fouling at all.

Have you tried this yet:

1. Get engine to op temp and drive it at cruise speed until it starts to miss.
2. Release the clutch, shut it off and coast to a safe place, preferably a rest stop or parking lot.
3. Let things cool off and remove all 8 plugs keeping them numbered and in order. Mark them 1-3-5-7 and 2-4-6-8.
4. Take pictures of all 8 and post here.

 

[Bo Dillingham]

To 65TripleBlack and all,

Since it may be awhile before I get to this stuff, I thought it wise to let you know what's up now.

First, I don't have a camera (or a cell phone!), so posting photos might take awhile. In the meantime, there are multiple websites concerning the "reading" of spark plugs (NGK Spark Plugs for example), so I might try to learn something from them.

The electric fuel pump thing is just personal, and is not expected to solve my "missing" problem. As I said, I put an electric fuel pump in my 68 Chevelle (many years ago) and liked it a lot. No particular reason, I just liked it. May be it was the sound of the fuel pump that I used to hear before the engine turned over; I'm not sure why, but I just plain liked it.

As I said, it may be awhile before I do any of this stuff because the rest of my responsibilities (like mowing the lawn, etc. etc.) have been grossly neglected for weeks.

As always, thank you for your attention and advice....

I'll be back,
BoDill

 

[c5vetter]

I am confused! Thought you indicated you had changed plugs and wires at the same time!? Now, maybe not so!?

 

[Bo Dillingham]

To c5vette (it's about midnight my time, but I want you to know that I'm paying attention),

My number 1 post regarded changing the plugs. During the next month-and-a-half or so of posts, I tried new plug wires and they didn't change anything. Since my old plug wires appear to be in excellent condition, and are cut to proper lengths so that they don't drape over the exhaust pipes, they are back on the car. I did a few things with the new wires on the engine, taking great care to keep them off of the exhaust headers, etc. and when no change was forthcoming, I went back to the "old plug wires" which look like new and fit the engine. Certainly, if and when I make some headway in solving these problems, I will likely cut the new wires to fit and install them. Right now, I am confident that the old wires are good, and I am focused on finding out why my car idles so well, starts in an instant, but "misses" at road speeds (and returns to a smooth idle at stop lights?).

As usual, thanks for your attention, and I'll keep posting as I learn........

BoDill

 

[Bo Dillingham]

To All, especially 65TripleBlack,

Today I pretty much discouraged myself from installing an electric fuel pump.

With that in mind, I started reading articles on the Internet regarding mechanical fuel pump failures and quickly found this; "Warning signs of a bad fuel pump. 1. While driving at a consistent high speed engine jerks or gives a sputter sound.". This sounds a lot like my Vette!!!! Since I am totally discouraged and burned out from the last weeks of working on this problem, it might take me awhile to do the proper testing, etc. but again I thought it would be courteous to let everyone know what's up and why there may be a delay in putting more information here.

BoDill

 

[Bo Dillingham]

To all,

It's been about three weeks since my last post on this subject, because I finally turned the Vette over to a reputable shop (C.A.R.S. in Cortland, NY) and told them what I had done so far, including a half-hearted "rebuild" on the carb, AND I gave them the Holley Rebuild kit that I used. One of their mechanics took the Holley 650 Spreadbore Double Pumper completely apart and rebuilt it, doing a much better job than I did. When I picked up the car I was told that he did more than "just a simple carb rebuild". Since I visited the shop while the guy was working on the carb, I did see the carb spread out all over his workbench, and he mentioned that not all the stuff necessary to do the job right are in the rebuild kit that I had.

So, now I have the car back in running condition, but I'm not satisfied that the 650 SBDP is the best choice for me anyway. My manifold is an Edelbrock 2101, which is designed for the spreadbore configuration, but I think that other carbs would fit on it and do just as well if not better. I'm also disappointed that the Speadbore does NOT have external float adjustments, so I am considering getting myself a new carb for Christmas. I have not made a positive decision on that yet, but am looking at other Hollies such as the 570 CFM Street Avenger and the 600 CFM Double Pumper. This is a 327 small block, so if you have any advice, let me know....

Thanks for you attention and support,
BoDill

 

[Tom Bryant]

So how does it run warm now?

As for a replacement carb the purpose of a double pumper is to give a larger than usual squirt of fuel when you hit the gas for situations where you have a large volume intake plenum. Think tunnel ram, where a normal squirt wouldn't supply enough fuel to feed the plenum volume and all of the cylinders causing a stumble at initial throttle opening. You don't have that problem. A 2101 is essentially Edelbrock's aluminum version of a stock cast iron manifold. You don't need and really can't use that extra shot of fuel with that manifold. Stay away from the double pumper or manual secondaries for your application. Use a vacuum secondary spread bore or even a square bore in the 600 range and you will be a happy camper.

 

[Bo Dillingham]

To Tom Bryant and all,

First, thank you Tom for good advice.

Next, to all, since my Vette is running at the moment, and there is not much sunny driving time left in Upstate New York, I will drive it for now and have plenty of time to decide on what to do next over the winter. I would like to keep the Edelbrock 2101 manifold if possible and practical, but I am going to spend some time reading and discussing carburation (as it has been such a long time since I've done any serious work on a car).

The sad truth is that I am seventy years old, and my nephew will undoubtedly inherit the car. He is not mechanically inclined, so I want to outfit the Vette with a carburator that will provide some get-up-and-go, but can be worked on by local mechanics in our small town. With that in mind, I think that Holley products would be a better bet than something more sophisticated or less common (like an Edelbrock carb, for instance).

Again, your suggestions and advice will be greatly appreciated, as it has been so long since I've been active in "Hot Rodding". Recommendations for particular carburators will be more than welcome.

ALSO, now that I have this particular problem (Warm engine misses) under control, do you think that I should start a different thread regarding selection of a carb for local casual cruising around? After all, this 327 does have tube headers, and I want to have some fun with it before my nephew gets it!!!

By the way, I have been looking at the 600 CFM Holley Classic P/N 0-1850S (or 0-1850SA if there is any advantage to aluminum). Any comments??

BoDill