Grapejuice1998
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Posts posted by Grapejuice1998
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So the other day my tach decided not to tach out, lol. It'll go up to about 3k and hang right there. Get below 3k and it reads again.
Any ideas?
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This is my first BBC, but the spark plugs were relatively unusual. They had the 13/16 base, but the were extended tip R44XLS. These were the only style of plug that would fit. How do I find out for sure which heads are on it?
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with stock heads , yes
if you have raised exhaust ports, no
I am considering a set of the American racing headers, my 17 year old hookers are getting pretty bad
Dan....have any pictures of those headers?
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Sorry, there was an attachment at one time. Here is the graph of the 3 sets of curve springs.
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Alan, you might get quicker/better answers if you provided more information with your questions.
Which engine do you have (assume 454 from your avatar)? Is it stock or modified with cam/intake/carb enhancements (important for manifold vacuum levels)? If stock, you should have base timing info on a sticker in your engine compartment. What vintage of HEI (assume it pre-'75 if it has manual vacuum advance)? What type of driving will you be doing? Is performance or economy more important?
When I rebuilt and installed a pre-'75 HEI on my modified 402, I messed with an adjustable vacuum advance unit for awhile. Basically, you aren't changing the total range of advance because that is fixed and the degrees (i.e. 20) should be stamped on the advance linkage arm in plain sight. You can limit the range a bit with properly sized bushings on the "L" of the actuator arm, but that is another subject.
If your vacuum advance unit is adjustable, you can only adjust WHEN the vacuum unit begins introducing that amount of advance into and out of your timing circuit by adjusting the level of vacuum required to operate the advance unit. It would be most helpful to put a vacuum gauge on your intake manifold or carb port (where ever the vacuum advance hose normally connects) and see how many inches of vacuum your engine pulls at idle and partial (i.e. cruise) throttle (should be zero at WOT, of course).
IMO, there is much more art than science involved in "curving" a distributor and setting up your overall engine timing so be prepared for a LOT of trial and error if you really intend to optimize engine performance. If you are going to use your vacuum advance (it's optional in some cases), you need to disconnect it and securely plug/cap the vacuum line or port. You need to look up base timing specs for your engine but it will usually be between 4 and 8 degrees BTDC. Your big block will idle terrible at this setting until you connect your vacuum advance unit again. Be sure to remember that each timing mark on your stock degree tab is 2 degrees or you will set your base timing too advanced. Check your timing at idle with the vacuum connected to see how many degrees the unit is adding to your base timing at that vacuum level. It really helps to have a digital read-out timing light so you can always bring the timing mark on the crankshaft back to align exactly with the "O" mark on you timing tab and accurately read the degrees of advance on your timing light display panel.
Basically, your vacuum advance should be operating at idle and during steady throttle cruise conditions. During acceleration, your engine vacuum drops and your mechanical advance (controlled by the springs and weights) take over. So you can basically tune them independently for those two conditions. The adjustable vacuum advance theoretically addresses the TRANSITION of timing control between the vacuum and mechanical advance modes. By adjusting your vacuum advance unit (mine used an allen wrench up through the vacuum port) through its range you are changing it's reaction to the level of vacuum your engine is creating at that time. One end of the range will kick it in or drop it out at a somewhat lower vacuum level than the other end of the range (I don't know which end of the range your instructions are giving you initially).
Any change in transition from vacuum to mechanical advance will be far more applicable to normal driving around town so that is where you will want to test the results of any adjustment you make. You want your total advance (base+vacuum+mechanical) to stay in the upper part of its 34-36 degree total range for best performance, operating temperature and economy but it must not be too high or you will get detonation (pinging) on acceleration/load. The quickest way eliminate detonation is to back your base timing down a couple degrees at a time but you may also need to change to heavier springs so your mechanical advance does not come in too quickly under load.
"Curving" a distributor is an old school art and I looked far a wide before I found someone who could do it for my new HEI. My friend is a NHRA Pro Stock driver and speed shop owner from Sweden. He worked with the adjustable vacuum advance for quite awhile and concluded that completely eliminating it was best for my modified engine and style of 4-speed driving. He went with 14-16 degrees base timing with 20 degrees added by the mechanical all in by 2800 rpm. He used a combination of springs to get a smooth advance curve. Note that you do not have to use the springs in matched pairs so you can experiment with a medium and a light spring or a medium and a heavy spring, etc. The other variable you can change is the mechanical advance weights - there are many to choose from - different profiles and weights. He didn't change mine but I had just put new bushings on the weight studs and you surely did also in your rebuild.
Not sure any of this will be helpful to you. For many of us, I suspect engine tuning is one of the best places to seek professional help. Good luck.
While I knew quite a bit of it, some of it I didn't, so all of it was helpful and appreciated.
I kinda thought the title stated the motor size, but it's mostly stock. It has Hooker headers and an Edelbrock intake (still has a QJ though), but as far as I know, it's otherwise stock.
I daily drive it for the most part (N. Texas) and I do like to get on it from time to time. The car was really running badly when I got it earlier this year, so I set about fixing things as I found them. I went to put a timing light on it recently, an found it had NO timing marker, or scale. It had the required hash mark on the balancer, but nothing to reference the timing off of. Nothing. Can you beat that?! Anyway, I marked the distributor base with a sharpie and advanced it a bit and it ran a whole lot better, which led me to a complete distributor rebuild and the installation of a proper timing pointer.
All of that is done now, so I thought I'd get some timing advice from people who have already been there and done that. I could have looked up the base stats online, but all that would have given me was a starting point. I was hoping for (and got) some base and total timing numbers to try now.
The adjustable advance instructions said to go all the way clockwise to start with, so that's where it is now.
The advance curve tables and associated springs, are each very different in how much total timing comes in and how quickly. Take a look at that attachment, please.
Thank you so much for taking the time to explain in such detail. I truly appreciate the effort.
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*crickets*
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If it has a single wire and a ground then the regulator on the core support should be by passed. The original connector was removed on mine. There's a video about the procedure on YouTube.
Thanks Rock!
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I like the Hooker 2455, but it is best to move the proportioning valve
No doubt! The old Hookers (lol) on there now are right up against the proportioning valve. I automatically thought of moving it up on top of the frame.
So the 2455 clears the steering shaft ok?
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Your alternator has an internal regulator. I am guessing the regulator has been deleted or by passed.
Doesn't it look as though there was part of that taped up wiring (about 2 o'clock) that used to plug into where that black plastic filler plug is now (12 o'clock)?
Is that the difference between an internal and external regulator alternator?
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Recently I was swapping out my alternator and noticed it has some wort of wiring conversion, or deletion.
What's happening here and why?
Thanks!
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I have just completed a rebuild of my hei distributor and have a couple of questions.
First, base/initial timing.
Where do I need to be on that?
Next, it has 3 different sets of springs, so it will advance in 3 different curves. (see: sideways attachment)
Which curve works best for a mostly stock 454?
Last, it also has an adjustable vacuum advance. The instructions say to turn it all the way clockwise to start with.
How do I go about the fine adjustment?
Thanks!
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I have just completed a rebuild of my hei distributor and have a couple of questions.
First, base/initial timing. Where do I need to be on that?
Next, it has 3 different sets of springs, so it will advance in 3 different curves. (see: attachment)
Last, it also has an adjustable vacuum advance. The instructions say to turn it all the way clockwise to start with. How do I go about the fine adjustment?
Thanks!
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What's the best fitting header out there? Mine has a set of ratty looking Hookers on it right now. They were painted silver, along with the entire exhaust at one time, so now they are flaking and rusting. The drivers side was dinged up severely too, so it would clear the steering shaft. The drivers side also hangs too low, so it's the first thing to hit if you happen to bottom out.
Surely someone makes a decent fitting header now?
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I ended up with a new motor from NAPA, but I plan to go back and open up the Delco to see if it just needs a good cleaning.
Thanks you for the help.
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Looks like my drivers side power window motor decided to retire today. I did a little trouble shooting and checking, so I know for sure the motor is getting power from the switch. My question is, are these readily available anywhere and/or is there someone who rebuilds them? I really want to get this fixed as quickly as possible though, as it's definitely windows down temperature here in Dallas right now.
Thanks!
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I can not remember what my 4.11 with a 28" tall tire turns at 70 but at 60 I think it is around 3200/3300 with a non lock up converter. I have a gearvendors overdrive on the back of my TH400 so it has been awhile since I turned it off to see what it would be.
I would love to hear more about the GV o/d installation. Do you have a thread about it?
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Had a similar problem in my camaro. Turned out the float level was too low so if I got on it enough, I'd eventually starve for fuel.
My thought is it just isn't getting enough fuel. Runs fine on 2 but when that 4 barrel kicks in it is starved for fuel. Either the pump isn't working properly or a line is kinked or the needle and seat and float problem. Should be interesting to see what it actually is.
I pretty much have no other choice at this point. I will start with a carb rebuild, then I'll work on the distributor. I just wish I had a spare carb to swap on it first.
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fuel volume. verify pump is putting out correct gpm and make sure all fuel hoses are the right size and not kinked (saw a lot of new lines get kinked when tank is installed) I had a van come in the shop once that would do that and I stayed on the gas until it stalled, pulled over and pulled the top of the carb off and found it empty. here the body mounts were sagging and pinching the fuel line closed. ran fine all day until you "got on it" also saw cam lobe for fuel pump wear...
The car had the same problem before I changed out everything. I did verify that the fuel lines aren't kinked though. The carb is the only other unchanged item in the entire fuel system.
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I would guess your advance is malfunctioning. Keep us posted on what you find though. Dale
It's a long shot but maybe a distributor problem advance may not be working properly
It's worth a look. I had planned to blueprint the distributor anyway. Thanks!
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Sounds like what my Nova was doing when the fuel pump went bad. Is your fuel pump electric or mechanical?
It's brand new mechanical and the proper p/n for the car. It was doing this before I swapped pumps though.
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I have 3.73's with 28" tires, th350, and at 70 mph my autometer tach reads right at 3400. Could be a inefficient/ incorrect converter. Like Sam stated the factory tach could be well off. Hook up a temporary tach to confirm the rpm.
David
It sure sounds like 4k though!
After talking with a fellow who owns a 69 Chevelle SS, he said his tachs about 3,800 @ 70 with 3.73's.
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When I got this car several weeks back I knew about the fuel system problem and thought, yah, no problem. I can fix that. Well, I guess I can't. At least, not without the help of someone more knowledgeable than myself.
Here's the deal:
When you go w.o.t., it will start to run pretty hard and then it will act like it's run out of gas and just fall over on it's face.
Here's a short video of the bog out.
What I have done, so far:
The fuel system is mostly new. Everything has been replaced, except the carburetor (QJ). This includes a new tank, which was a single line in/out at the time. It was suggested that perhaps that was the problem, so I bought a dual line pickup and pump and installed all new fuel lines (except the metal ones, which I blew out with an air hose). I also tried removing the paper filter in the carb, as well as running without a gas cap (the new tank doesn't have vents like the old one did).
As I said, the only piece that hasn't been changed, out is the carb. A local builder said there's nothing wrong with it though. Has anyone ever seen this type of thing happen due to a carb problem? If so, does anyone here build a good QJ, or is there a better option out there?
Thanks y'all. This is really starting to get to me. I really want this thing to run like a 454 should!!
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It was 3/8 line. The paper filter is still in there though.
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Speedometer not work?
That would be a 28" tall tire.
If you did it correctly and it came out to 3.73 (which it sounds like you did) yes it is impossible to be revving at 4k.
So either your GPS is not accurate, you messed up on the old school way of measuring the gears, your tach is not working properly, or your transmission is slipping bad.
The speedometer works. I just verified it's accuracy with my gps app.
'70 SS 454 tach
in Interior Tech
Posted
Isn't there a company that rebuilds all three instruments to factory spec? (tach, speedo, clock)
I could have sworn I browsed such a website recently, but I'll be darned if I can find it.