General advice

[Aaron jackson 87]

idle screw changes idle. The idle will increase when you add timing. Use the idle screw to lower it.
Get a bigger carb.
I run mine about 10-12 advanced. My 454 likes alot more then that.

Ok, so as a example. I start the engine, check timing that reads 8° and decide i want to advance to 12°. That in turn raises my idle rmp to "1200" and i adjust it back to 800 with idle screw. I double check timing to varify and now view that is again at 8°. Is that normal operation? Is it the case that if i advance the timing bact to 12° it would increase idle speed again, and i would adjust again with idle screw? That seems like an endless cycle. Not sure if im over thinking, or if i have a problem with something. Thanks for your reply!

 

[Bent77]

Sounds like the timing might be coming in very quickly

 

[Aaron jackson 87]

Sounds like the timing might be coming in very quickly

Am i correct in assuming that i should not be having that much timing change with such a small amount of rpm change from idle? Maybe the weights in dst. Are not correct?

 

[Bent77]

This might be
Can you watch the timing while you operate the carb? Slowly open the throttle and see how much/fast the timing moves

 

[Aaron jackson 87]

This might be
Can you watch the timing while you operate the carb? Slowly open the throttle and see how much/fast the timing moves

I did notice it changes pretty much instantly even with just adjusting idle screw, vaccum advance is disconnected and pluged.

 

[Bent77]

Sounds all mechanical, probably fairly aggressive it sounds.

How does it drive?

 

[Aaron jackson 87]

Sounds all mechanical, probably fairly aggressive it sounds.

How does it drive?

It drives pretty well i would say, no miss fire or anything, does have a slight bog off idle, not sure what kind of power i should be making with my combo but feels like its lacking some, that being said i havnt had it much past 3500 rps yet.

 

[Bent77]

It drives pretty well i would say, no miss fire or anything, does have a slight bog off idle, not sure what kind of power i should be making with my combo but feels like its lacking some, that being said i havnt had it much past 3500 rps yet.

The bog off idle is likely the accelerator pump as was mentioned

 

[Aaron jackson 87]

The bog off idle is likely the accelerator pump as was mentioned

Agreed, my biggest concern is the timing issue, is there any way to verify if it is accurate, or malfunctioning? Thanks again

 

[kgblazerfive]

Most of the time it means it is to lean. Pump needs to pump quicker.

 

[scpaul]

Someone that knows today's specs. and is familiar with the effects of altitude should weigh in on this, but we used to set timing with the vacuum advance disconnected and the vac. line plugged. Could he have a bad vacuum advance actuator. We set the idle speed at Idle around 600 to 650 at idle in neutral with a manual trans. and 750 to 800 in park at idle with an auto. trans. and it should drop to around 650 in drive held with the brake and down to about 600 rpm's with air con. on.

Have you checked the condition of the mechanical advance weights, springs and play in the bushings in the distributor? This is depending on the newer ones still have springs and weights. We used to play with them. In engines that we wanted to rev faster we would change the get lighter advance springs and go heavier with the advance weights. Since you are at 4700 ft. and probably want to operate more at lower engine speed most of the time, you need to ask someone that knows the newer specs. and about what works there. The various settings settings including jets, back barrel settings (timing, jetting, vacuum or mechanical back barrel activation, accelerator pump etc.) and I guess they still have a power valve. I don't know how much and/or what the computer does if it has one.

I know that almost all of these things have been mentioned, but all of them work in concert with each other. Someone that can help with all of the things at one time really needs to help him in person (No Offense Intended To Anyone). Trying to get all of the settings right at the same time can drive a person nuts. I think he said that he had a cam in it.

I think someone has already said something "about several of the members around him". Somebody should make arrangements to get together with him. His house would probably be better, just incase y'all run into something that you don't expect. An "Experienced (read older) mechanic" would probably be a perfect fit. I really hope that I'm not parroting someone else. If so, please excuse me.

Just my "old" opinion, Paul

 

[Aaron jackson 87]

Someone that knows today's specs. and is familiar with the effects of altitude should weigh in on this, but we used to set timing with the vacuum advance disconnected and the vac. line plugged. Could he have a bad vacuum advance actuator. We set the idle speed at Idle around 600 to 650 at idle in neutral with a manual trans. and 750 to 800 in park at idle with an auto. trans. and it should drop to around 650 in drive held with the brake and down to about 600 rpm's with air con. on.

Have you checked the condition of the mechanical advance weights, springs and play in the bushings in the distributor? This is depending on the newer ones still have springs and weights. We used to play with them. In engines that we wanted to rev faster we would change the get lighter advance springs and go heavier with the advance weights. Since you are at 4700 ft. and probably want to operate more at lower engine speed most of the time, you need to ask someone that knows the newer specs. and about what works there. The various settings settings including jets, back barrel settings (timing, jetting, vacuum or mechanical back barrel activation, accelerator pump etc.) and I guess they still have a power valve. I don't know how much and/or what the computer does if it has one.

I know that almost all of these things have been mentioned, but all of them work in concert with each other. Someone that can help with all of the things at one time really needs to help him in person (No Offense Intended To Anyone). Trying to get all of the settings right at the same time can drive a person nuts. I think he said that he had a cam in it.

I think someone has already said something "about several of the members around him". Somebody should make arrangements to get together with him. His house would probably be better, just incase y'all run into something that you don't expect. An "Experienced (read older) mechanic" would probably be a perfect fit. I really hope that I'm not parroting someone else. If so, please excuse me.

Just my "old" opinion, Paul

Thanks paul, i definitely agree wit the "drive a person nuts" part! Just to clairify i am running with no computer, the owner before me hacked everything out when he converted the 305 tbi to carb... and i do mean hacked lol. I set the timing as u stated, vac disconnected and pluged. Have not done much tuning to carb at this point orher than idle screw, fast idle for choke operation, and setting the mixture screws to a "base" setting. Thanks again for everyones input!

 

[scpaul]

You really need someone to help you. There's so many things that send you in so many directions. Have you checked your vacuum advance to make sure that it's working. It generally won't cause the truck to not run, but it can cause performance problems especially when there is another problem of most any type that affects the performance too. The problem is that usually you're going to need an old time mechanic that knows the old systems. Have you got a service manual like a Chilton's, there's other ones too, I just can't remember the names.

Maybe you can talk to somebody at a parts house and he can suggest which manual for the years that will help you the most. The new manuals aren't going to be of much use since you said that the other guy cut the harness up. Does the distributor have points or has it been converted to a magnetic or some other type of pick-up? You said that it had been cammed, carbed, heads and intake changed but still running stock exhaust manifolds (?). What all else has been messed with and what year would you call the engine thinking about the distributor and what type of system it has.

Good luck, Paul

 

[Aaron jackson 87]

You really need someone to help you. There's so many things that send you in so many directions. Have you checked your vacuum advance to make sure that it's working. It generally won't cause the truck to not run, but it can cause performance problems especially when there is another problem of most any type that affects the performance too. The problem is that usually you're going to need an old time mechanic that knows the old systems. Have you got a service manual like a Chilton's, there's other ones too, I just can't remember the names.

Maybe you can talk to somebody at a parts house and he can suggest which manual for the years that will help you the most. The new manuals aren't going to be of much use since you said that the other guy cut the harness up. Does the distributor have points or has it been converted to a magnetic or some other type of pick-up? You said that it had been cammed, carbed, heads and intake changed but still running stock exhaust manifolds (?). What all else has been messed with and what year would you call the engine thinking about the distributor and what type of system it has.

Good luck, Paul

The block is a 1995 350 tbi motor, that i bought to replace the blown 305. I completely disassembled measured clearances on everything. Had a little scoring on rod journals that i was able to polish out with some 600 grit and a leather strap. I put the mild .420/ .440 summit cam and lifters in with my ported 193s and performer intake. Transferd the 1403 carb and standard hei distributor that was on the 305. And yes it has factory exhaust from the 305 still, money was the deciding factor... to my knowledge the vac advance is working, at least the diaphragm is good tested by sucking on the end of vaccume tube and it holds the suction. My biggest question is should my timing advance when i turn my idle screw, even with advance line blocked? If i raise idle by 100 rpm, the timing on balancer increases a degree, and vice versa. I can find no info ANYWHERE on line about it, and as far as an old time mechanic the best i personally know is the guy who does my machine work. Overall tuning is not a problem for me, but its all pointless if i cant trust my timing right?

 

[scpaul]

You checked the vac. advance right. You might want to do it for about 30 sec. to make sure that it doesn't leak down because of any pin holes (pinch hose with pliers), but there probably isn't. The reason that you see the timing change when you increase/decrease is a combination of the vac. advance starting to have an effect, but most of that is the advance weights in the dist. turning faster and centrifugal force causing them to sling out further and turn the advance plate in the distributor, which moves the position of the points or pick up, whatever you have. That's why when we wanted the motor to rev faster we would change the advance springs on the advance weights in the distributor. I'm not really familiar with the H.E.I. distributors, they were coming out and being used as I was getting out of it. If that dist. is still setup like I'm used to, the advance plate is what you see when you remove the cap and rotor, under that plate is where the advance weights and springs are located. The advance weights are shaped strange. There's 2 of them opposite of each other. I can't remember weather the springs are on the top of them or under. If you mess with the springs, be careful and have a magnet handy. They have a bad habit of getting away from you and going all the way down in the distributor. I can't be sure but, I'm thinking that stronger springs bring the advance later and lighter springs bring it in earlier. For some reason, that doesn't sound quite right, so ask somebody to be sure. Remember that I said that I'm not real familiar with the H.E.I. distributors, so you might ask somebody to make sure about them too. Yours does have the Ginormus size dist cap with the coil in the cap itself, right? Can you adjust the dwell on that dist. through the little door in the front of the cap, or do you adjust dwell at all?

Get a manual that goes back to engines that had distributors with points and comes up to the H.E.I. distributors. I don't know what years that would be if it has the H.E.I. distributors and goes back a few years from there, it probably has the years that you need.

I might be wrong but, when we quoted cam specs. something like .420/.440, we were talking about the intake and exhaust lift specs for the intake and exhaust. Cams have been described several ways including stock,mild,warm,race, full race. There was degrees of overlap which has alot to do with economy and how it chopped. The numbers on the cam that you quoted, if I'm right means that going through 1.5 to 1 rockers gave you (.420 x 1.5 = .630 lift at the valve and figure .440 the same way).

Hope that I'm right about enough of this to be useful. Please do check with someone that is more up to speed with the new technology. I've been out of cars and racing for about 25 or more years. I'm just now trying to get help to understand some of this new stuff. I have a '90 GMC Jimmy 1500 that I parked about 8 years ago, and it was still running. Gas mileage was killing me.

If you think that I can help you, send me e-mail, I check it most often. ([email protected]) By the way, where are you?

Best of luck, Paul

 

[Aaron jackson 87]

You checked the vac. advance right. You might want to do it for about 30 sec. to make sure that it doesn't leak down because of any pin holes (pinch hose with pliers), but there probably isn't. The reason that you see the timing change when you increase/decrease is a combination of the vac. advance starting to have an effect, but most of that is the advance weights in the dist. turning faster and centrifugal force causing them to sling out further and turn the advance plate in the distributor, which moves the position of the points or pick up, whatever you have. That's why when we wanted the motor to rev faster we would change the advance springs on the advance weights in the distributor. I'm not really familiar with the H.E.I. distributors, they were coming out and being used as I was getting out of it. If that dist. is still setup like I'm used to, the advance plate is what you see when you remove the cap and rotor, under that plate is where the advance weights and springs are located. The advance weights are shaped strange. There's 2 of them opposite of each other. I can't remember weather the springs are on the top of them or under. If you mess with the springs, be careful and have a magnet handy. They have a bad habit of getting away from you and going all the way down in the distributor. I can't be sure but, I'm thinking that stronger springs bring the advance later and lighter springs bring it in earlier. For some reason, that doesn't sound quite right, so ask somebody to be sure. Remember that I said that I'm not real familiar with the H.E.I. distributors, so you might ask somebody to make sure about them too. Yours does have the Ginormus size dist cap with the coil in the cap itself, right? Can you adjust the dwell on that dist. through the little door in the front of the cap, or do you adjust dwell at all?

Get a manual that goes back to engines that had distributors with points and comes up to the H.E.I. distributors. I don't know what years that would be if it has the H.E.I. distributors and goes back a few years from there, it probably has the years that you need.

I might be wrong but, when we quoted cam specs. something like .420/.440, we were talking about the intake and exhaust lift specs for the intake and exhaust. Cams have been described several ways including stock,mild,warm,race, full race. There was degrees of overlap which has alot to do with economy and how it chopped. The numbers on the cam that you quoted, if I'm right means that going through 1.5 to 1 rockers gave you (.420 x 1.5 = .630 lift at the valve and figure .440 the same way).

Hope that I'm right about enough of this to be useful. Please do check with someone that is more up to speed with the new technology. I've been out of cars and racing for about 25 or more years. I'm just now trying to get help to understand some of this new stuff. I have a '90 GMC Jimmy 1500 that I parked about 8 years ago, and it was still running. Gas mileage was killing me.

If you think that I can help you, send me e-mail, I check it most often. ([email protected]) By the way, where are you?

Best of luck, Paul

Thanks again paul, your the man. You have givin me more of your time then i ever expected and it is VERY appreciated! Those were the intake/exhaust lift nimbers yes. And i live in the grand valley area, fruita to be exact. I will pick up a book as you sugest and will do the bleed down test on vac. As sugested. Maybe its worth me starting a new thread on this issue to hopefully get more insight! Again, thanks for all of your time!

 

[6872xtc]

@bent72 should have tagged me in this thread...
I couldn't figure out how he knew that you are close to me!!



Anyway, I live in Palisade, and work in GJ.
I have a good timing light too...
Sending you a P.M.

 

[Bent77]

@bent72 should have tagged me in this thread...
I couldn't figure out how he knew that you are close to me!!



Anyway, I live in Palisade, and work in GJ.
I have a good timing light too...
Sending you a P.M.

Figured sooner or later youd get on it

 

[scpaul]

Aaron,

It makes me very happy to be able to help someone with the achent (real old) info that I can remember. You're lucky that you caught me on one of my mentally good days. After I hit the enter button, I started having second thoughts. I'm notorious for over explaining things and getting into details that don't matter or believe it or not, getting side tracked and chasing my tail (imagine that). I'm a retired technician and details were my whole working life, retired 2009.

My opinion is that you get a set of headers when you can. They are some of the cheapest horsepower that you can get and each time something else gives you a little more, they usually do to. It's hard to get more air/fuel (power) in unless you get the exhaust out. For your best use of headers you need to think about getting the exhaust gas moving fast enough to create a vacuum so that it pulls more. If you have too small of a tube (primary) it causes restriction (no vacuum, usually restriction) and if they are too large you don't have enough exhaust volume to create the vacuum. The diameter And the length of the tubes, especially the primaries affect how well the headers work for you. There's alot to consider, cubic inches, speed that you will be turning the motor, restriction in getting the air/fuel mix into the cylinder with the proper air/fuel ratio, altitude and probably a bunch more after all of these years.

I would guess that the better header companies still do it as a service. It used to be that if you had the info that they needed; probably call first and talk with a tech to find out what info he needs. Then they probably can run it through, I guess a computer program now, and can suggest the size primaries, both diameter and length, collector diameter and length and now days they probably have learned more specs that help the headers work better for your particular set-up and will help the most. If you have DEEP pockets, they could make a custom set made just for you (DEEP Pockets!!!)

What state is that?

Well, I did it again, good luck, Paul