Throttle linkage and ecm
Thread Starter
Heel & Toe
Joined: Aug 2009
Posts: 21
Likes: 0
Throttle linkage and ecm
Greetings Vette-heads,
After having sorted out the driveshaft nightmare (with y'all's expert advise and information,) we have reached another point of information gathering. Big brother's monster-motor has a Holley 750CFM double pumper on it and it appears that the current throttle cable it too long. I know that I can buy the "button" to go onto the carburetor for the accelerator and kick-down but does anyone know if there is a shorter cable made for this or will I just shorten the "pedal" end of it.
The other question is that the original L48 had a pretty prehistoric ECM and the Q-jet had some involvement with the ECM, I think, in some instances. Is there any need for us to try to "trick" the ECM or shall we just pretend that this new engine is sitting in an a remote engine stand?
We've got the ignition wiring and tach and the gauges all likned into the existing wiring harness and all seems to be working properly at this point. The timing is done and fuel lines are attached and working properly. We fired it up yesterday and YAHOO, it is one mean-sounding motor !
I'm just not sure of we need to concern ourselves with the on-board computer or ignore it.
As always, thanks for all you folks' assistance.
And, by the way, the driveshaft will be corrected this next week.
After having sorted out the driveshaft nightmare (with y'all's expert advise and information,) we have reached another point of information gathering. Big brother's monster-motor has a Holley 750CFM double pumper on it and it appears that the current throttle cable it too long. I know that I can buy the "button" to go onto the carburetor for the accelerator and kick-down but does anyone know if there is a shorter cable made for this or will I just shorten the "pedal" end of it.
The other question is that the original L48 had a pretty prehistoric ECM and the Q-jet had some involvement with the ECM, I think, in some instances. Is there any need for us to try to "trick" the ECM or shall we just pretend that this new engine is sitting in an a remote engine stand?
We've got the ignition wiring and tach and the gauges all likned into the existing wiring harness and all seems to be working properly at this point. The timing is done and fuel lines are attached and working properly. We fired it up yesterday and YAHOO, it is one mean-sounding motor !
I'm just not sure of we need to concern ourselves with the on-board computer or ignore it.
As always, thanks for all you folks' assistance.
And, by the way, the driveshaft will be corrected this next week.
Former Vendor
Joined: Apr 2009
Posts: 766
Likes: 3
From: Charlotte North Carolina 704-394-5150
First off, try modifying the pedal assembly to get the accelerator cable to function correctly. I have done this time and time again when dealing with changing to a Holley.
As for the ECM....due to not having the TPS and M/C solenoid in the new Holley, I would delete ECM and not worry about it. If you have changed distributors and no longer use the original one that was in the car...I would delete the ECM. If you have modified the exhaust and deleted the oxygen sensor...i would delete the ECM and not worry about it.
Is the engine able to run WITHOUT the ECM connected to the wiring harness? Need to know what you did and did not do so I can help.
"DUB"
As for the ECM....due to not having the TPS and M/C solenoid in the new Holley, I would delete ECM and not worry about it. If you have changed distributors and no longer use the original one that was in the car...I would delete the ECM. If you have modified the exhaust and deleted the oxygen sensor...i would delete the ECM and not worry about it.
Is the engine able to run WITHOUT the ECM connected to the wiring harness? Need to know what you did and did not do so I can help.
"DUB"
Thread Starter
Heel & Toe
Joined: Aug 2009
Posts: 21
Likes: 0
Dub,
Sir, the ignition is MSD plug-n-play distributor with an MSD "Blaster" coil. The only hook-up I used was the hot from the ignition switch which I picked up from the previous HEI wire. I also picked up the tach-drive wire from the old HEI wire. I've not hooked up the "bat, b+ or C-" from the three-wire plug as I believe that is computer-oriented. The new engine will not have an O2 sensor and no TPS at all. My biggest concern was that there may be some little somethin'-or-other related to the ECM that I'm not aware of which could cause us a hitch of some kind. (As you know, I'm good at overlookin' some of the little things ie. the driveshaft fiasco.)
Thanks so much for your help. Big brother just registered as a member yesterday and his user name will be freddybear. He'll have have some questions, too.
COPCO
Sir, the ignition is MSD plug-n-play distributor with an MSD "Blaster" coil. The only hook-up I used was the hot from the ignition switch which I picked up from the previous HEI wire. I also picked up the tach-drive wire from the old HEI wire. I've not hooked up the "bat, b+ or C-" from the three-wire plug as I believe that is computer-oriented. The new engine will not have an O2 sensor and no TPS at all. My biggest concern was that there may be some little somethin'-or-other related to the ECM that I'm not aware of which could cause us a hitch of some kind. (As you know, I'm good at overlookin' some of the little things ie. the driveshaft fiasco.)
Thanks so much for your help. Big brother just registered as a member yesterday and his user name will be freddybear. He'll have have some questions, too.
COPCO
Former Vendor
Joined: Apr 2009
Posts: 766
Likes: 3
From: Charlotte North Carolina 704-394-5150
COPCO,
The ECM used then is no longer like what is used today. There were not that many functions for it to monitor to keep the engine running correctly in regards to emissiins and performance. Try unpluging it and if you have wired up components and not used the factory computer wiriing due to not needing it....the engine should run. The ECM was very basic...and I can not think of anything that will cause you to have aproblem with the "check engine" light coming on....or the engine and car not running without it. The power to the HEI ...that is now going to your MSDis fine. That is not controlled by the ECM. Tach wiring also is not controlled by the ECM. I will double check my books tomorrow but I think you are fine.
"DUB"
The ECM used then is no longer like what is used today. There were not that many functions for it to monitor to keep the engine running correctly in regards to emissiins and performance. Try unpluging it and if you have wired up components and not used the factory computer wiriing due to not needing it....the engine should run. The ECM was very basic...and I can not think of anything that will cause you to have aproblem with the "check engine" light coming on....or the engine and car not running without it. The power to the HEI ...that is now going to your MSDis fine. That is not controlled by the ECM. Tach wiring also is not controlled by the ECM. I will double check my books tomorrow but I think you are fine.
"DUB"
Thread Starter
Heel & Toe
Joined: Aug 2009
Posts: 21
Likes: 0
GRANDMASTER CORVETTE,
Holy-moly, it sounds like we got part of it right, then. Of course, I didn't take time to get a complete schematic but from perusin' the Chilton and Haines, it seemed like we were close to correct. I know we still have to hook up the vacuum stuff for the pop-up headlights but all of that seems pretty simple. My fear was, that not being really "up" on these on-board computers we might get into some trouble. However, when we fired that thing up there was no doubt at all that it's running RIGHT !
Thank you, again, for your guidance.
COPCO
Holy-moly, it sounds like we got part of it right, then. Of course, I didn't take time to get a complete schematic but from perusin' the Chilton and Haines, it seemed like we were close to correct. I know we still have to hook up the vacuum stuff for the pop-up headlights but all of that seems pretty simple. My fear was, that not being really "up" on these on-board computers we might get into some trouble. However, when we fired that thing up there was no doubt at all that it's running RIGHT !
Thank you, again, for your guidance.
COPCO
Former Vendor
Joined: Apr 2009
Posts: 766
Likes: 3
From: Charlotte North Carolina 704-394-5150
COPCO,
Glad to read that it is "running right"!
Depending on how much cam you have in this engine....you may want to hook up a vacuumm gauge and check...due to if this car still is going to have power brakes...you may have an issue with it or that the vacuum required to raise and lower the headlights may take longer than normal due to the vacuum the engine produces. I have had to install electric assist vacuum pumps on a very few car due to radical engines.
Last but not least...when you are tuning your engine...and you get it RIGHT...do it WITHOUT any of the vacuum that controls your inside ac/heater controls and headlights and brake booster. Just block off the vacuum fitting during tuning....THEN when you start to add these parts into the vacuum system...see if your engine reacts differently...especially when you connect the vacuum hose for the headlight system the reason being...the vacuum actuator relays that are mounted between your headlight assemblies can leak vacuum, along with the #10 tin can reservoir also that is mounted behind the front bumper. The actuator realys are real bad about leaking vacuum due to age....also MAKE SURE that the vacuum check valve that goes in the hose that comes off your intake fitting is a good check valve. It should only work in one direction (duh). They are known to also go bad along with the white plastic filter that goes between the check valve and the intake fitting. Just thought you might want to know about these issues that can occur so you are not tuning your engine with ALL of the vacuum for other systems connected to your engine at the time of tuning....it can create a "hair pulling" situation....been there....done that...now I know what to do...
To check and see if your headlight actuators relays are good or bad is easy... When looking at the relays you will see three large hoses that plug into the relay anolg with one small hose.. at the bottom of the relay you will see a squared portion of the relay that is made into the plastic. Putting a hose to your ear...while the system is all connected...and engine running....and put the other end up into the squared area...you will either hear vacuum leaking or not. This area at the bottom of the relay is where the plunger can be seen and if the o-rings in the assembly are bad...vacuum will leak regardless if you have the lights on or not. For information sake...the center large vacuum hose that is connected to the relay is the vacuum supply coming from the vacuum reservoir #10 tank and is being supplied by your engine.
"DUB"
Glad to read that it is "running right"!
Depending on how much cam you have in this engine....you may want to hook up a vacuumm gauge and check...due to if this car still is going to have power brakes...you may have an issue with it or that the vacuum required to raise and lower the headlights may take longer than normal due to the vacuum the engine produces. I have had to install electric assist vacuum pumps on a very few car due to radical engines.
Last but not least...when you are tuning your engine...and you get it RIGHT...do it WITHOUT any of the vacuum that controls your inside ac/heater controls and headlights and brake booster. Just block off the vacuum fitting during tuning....THEN when you start to add these parts into the vacuum system...see if your engine reacts differently...especially when you connect the vacuum hose for the headlight system the reason being...the vacuum actuator relays that are mounted between your headlight assemblies can leak vacuum, along with the #10 tin can reservoir also that is mounted behind the front bumper. The actuator realys are real bad about leaking vacuum due to age....also MAKE SURE that the vacuum check valve that goes in the hose that comes off your intake fitting is a good check valve. It should only work in one direction (duh). They are known to also go bad along with the white plastic filter that goes between the check valve and the intake fitting. Just thought you might want to know about these issues that can occur so you are not tuning your engine with ALL of the vacuum for other systems connected to your engine at the time of tuning....it can create a "hair pulling" situation....been there....done that...now I know what to do...
To check and see if your headlight actuators relays are good or bad is easy... When looking at the relays you will see three large hoses that plug into the relay anolg with one small hose.. at the bottom of the relay you will see a squared portion of the relay that is made into the plastic. Putting a hose to your ear...while the system is all connected...and engine running....and put the other end up into the squared area...you will either hear vacuum leaking or not. This area at the bottom of the relay is where the plunger can be seen and if the o-rings in the assembly are bad...vacuum will leak regardless if you have the lights on or not. For information sake...the center large vacuum hose that is connected to the relay is the vacuum supply coming from the vacuum reservoir #10 tank and is being supplied by your engine.
"DUB"
Thread Starter
Heel & Toe
Joined: Aug 2009
Posts: 21
Likes: 0
Dub,
Methinks, sir, that you may have been hangin' around these Corvettes for a while. Yes, the only vacuum that we plumbed the other day was the brake booster and it seemed to operate the brakes just right and didn't sound like it messed with the engine. The distributor has an advance lock in it already adjusted by MAS prior to shipping and taking into account 6000 feet of elevation. Big brother has all the stat-sheet print outs and specs on the cam, timing, etc.
As always, I never thought about the vacuum operation of the lights, etc. having any impact on the engine but we will definitely check all of the items you mentioned. Big brother had been considering changing the headlight configuration to the modification where the lights are mounted stationary. He thought that maybe ACI could have those kits but we haven't checked it out yet.
I'll be talking to the drive-shaft guy tomorrow about the front yoke. I think you had mentioned that a 4-speed yoke was beefier and had a size larger securing bolts. I guess that the spline-count is the same on the 4 speed as on the TH350 and if we purchase the complete unit it will plug right in after it's re-fitted ?
Big brother is gettin' pretty excited about his hot-rod. About two more week-ends and he'll drive that critter out for a little test. And, then, probably he should take it in for an exhaust system. ( We put headers with 3 inch collectors on it after checking with MAS.) I still think he needs a case of tires. After he read your responses he is very aware of ripping out the rear-end process if he gets too crazy.
Thanks, as always, for your advice and guidance. Maybe one day I'll drive my little '39 Vette down to your part of the country and say howdy.
COPCO
Methinks, sir, that you may have been hangin' around these Corvettes for a while. Yes, the only vacuum that we plumbed the other day was the brake booster and it seemed to operate the brakes just right and didn't sound like it messed with the engine. The distributor has an advance lock in it already adjusted by MAS prior to shipping and taking into account 6000 feet of elevation. Big brother has all the stat-sheet print outs and specs on the cam, timing, etc.
As always, I never thought about the vacuum operation of the lights, etc. having any impact on the engine but we will definitely check all of the items you mentioned. Big brother had been considering changing the headlight configuration to the modification where the lights are mounted stationary. He thought that maybe ACI could have those kits but we haven't checked it out yet.
I'll be talking to the drive-shaft guy tomorrow about the front yoke. I think you had mentioned that a 4-speed yoke was beefier and had a size larger securing bolts. I guess that the spline-count is the same on the 4 speed as on the TH350 and if we purchase the complete unit it will plug right in after it's re-fitted ?
Big brother is gettin' pretty excited about his hot-rod. About two more week-ends and he'll drive that critter out for a little test. And, then, probably he should take it in for an exhaust system. ( We put headers with 3 inch collectors on it after checking with MAS.) I still think he needs a case of tires. After he read your responses he is very aware of ripping out the rear-end process if he gets too crazy.
Thanks, as always, for your advice and guidance. Maybe one day I'll drive my little '39 Vette down to your part of the country and say howdy.
COPCO
Former Vendor
Joined: Apr 2009
Posts: 766
Likes: 3
From: Charlotte North Carolina 704-394-5150
I'll be talking to the drive-shaft guy tomorrow about the front yoke. I think you had mentioned that a 4-speed yoke was beefier and had a size larger securing bolts. I guess that the spline-count is the same on the 4 speed as on the TH350 and if we purchase the complete unit it will plug right in after it's re-fitted ?
I was NOT talking about the transmission tail shaft yoke...I was talking about the side yokes that come out or each side of your rear differntial.
The manual cars used a set up that used larger diameter bolts instead of the small ones you have now due to it being an automatic....for holding the U-joints to the side yokes and the rear wheel bearing flange. I would investigate into this because with the power you are probably producing...I myself...would HAVE to install these upgraded parts to give me some sense of strength improvement. It requires that the side yokes for the differential, the inner rear bearing flanges and the half shafts be replaced. And if I were installing these parts I would HAVE to install the Spicer U-joint part number 5-799x for the half shafts.
Oddly enough, even with these upgrades, I still for the life of me can not figure out why GM didn't increase the bolt size where the u-joint bolts to the pinion flange of the differential. IT MAKES NO SENSE...and I have never seen one that has larger bolts in this area. For me...it seems like a weak link in the chain. Maybe somebody out there makes one.
I jsut do not want to hear the "snap, crackle, pop" all the way over here when you "get on it".
I just wanted to clarify.
"DUB"
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Thread Starter
Heel & Toe
Joined: Aug 2009
Posts: 21
Likes: 0
Dub,
Thank you for the additional clarifyin' ! Before big brother went off the deep end and decided to buy this engine I tried to warn him that every cotton pickin' thing from the engine back was going to be at risk of a catastrophic episode. He just kinda chuckled and I knew, then, that we were in deep trouble. He's a pretty mild guy, but that engine ain't even close to mild. Of course, he likes to aggitate me and wanted to know if we could put a turbo on it or a nitros shot. No, No, No ! "Enough is enough," says I.
I didn't get a chance to talk to the driveshaft guy today - good thing. I'm sure he would have been wondering what on earth I was talking about. At leat now I know exactly what it is that I didn't know. Saved, again, by GRANDMASTER CORVETTE.
Anyway, I truly do appreciate all of your input on this project. We'll try to get some pictures onto the forum in a couple of weeks.
COPCO
Thank you for the additional clarifyin' ! Before big brother went off the deep end and decided to buy this engine I tried to warn him that every cotton pickin' thing from the engine back was going to be at risk of a catastrophic episode. He just kinda chuckled and I knew, then, that we were in deep trouble. He's a pretty mild guy, but that engine ain't even close to mild. Of course, he likes to aggitate me and wanted to know if we could put a turbo on it or a nitros shot. No, No, No ! "Enough is enough," says I.
I didn't get a chance to talk to the driveshaft guy today - good thing. I'm sure he would have been wondering what on earth I was talking about. At leat now I know exactly what it is that I didn't know. Saved, again, by GRANDMASTER CORVETTE.
Anyway, I truly do appreciate all of your input on this project. We'll try to get some pictures onto the forum in a couple of weeks.
COPCO
Former Vendor
Joined: Apr 2009
Posts: 766
Likes: 3
From: Charlotte North Carolina 704-394-5150
COPCO,
AWWWW COME ON! Go ahead and put on a 250 hp shot of nitrous along with twin turbos. It can't be that hard...and why your at it put on an 8:71 blower. And we might as will fill in the block with concrete also. That should only take about ....an hour to do all that...like the INSTRUCTIONS say....right? Come on...be a sport. It will be fun...(just kidding)
I here the option also from time to time and many people do not consider the TIME it takes to make it RIGHT... I feel your...."fed-up-ness" Enough is enough usless THEY do the work...and we all know how long that lasts.
The best to you, (I dont' want to jinx you in any way).
"DUB"
AWWWW COME ON! Go ahead and put on a 250 hp shot of nitrous along with twin turbos. It can't be that hard...and why your at it put on an 8:71 blower. And we might as will fill in the block with concrete also. That should only take about ....an hour to do all that...like the INSTRUCTIONS say....right? Come on...be a sport. It will be fun...(just kidding)
I here the option also from time to time and many people do not consider the TIME it takes to make it RIGHT... I feel your...."fed-up-ness" Enough is enough usless THEY do the work...and we all know how long that lasts.
The best to you, (I dont' want to jinx you in any way).
"DUB"
Last edited by grandmastercorvette; Sep 9, 2009 at 05:57 PM. Reason: missing text
Thread Starter
Heel & Toe
Joined: Aug 2009
Posts: 21
Likes: 0
GRANDMASTERCORVETTE,
Exactly, my man. Anything more than what we's gots scares me to death. I'll have to get a couple of buddies to hold big brother while I give him an attitude adjustment. Actually he's never been much of a gear-head but he loves this stuff now. He's learning a lot of stuff but gets that crazed look in his eyes from time to time.
And, after all the help you've given in this thing, there's no way you could jinx it.
Thanks, as always !!
COPCO
Exactly, my man. Anything more than what we's gots scares me to death. I'll have to get a couple of buddies to hold big brother while I give him an attitude adjustment. Actually he's never been much of a gear-head but he loves this stuff now. He's learning a lot of stuff but gets that crazed look in his eyes from time to time.
And, after all the help you've given in this thing, there's no way you could jinx it.
Thanks, as always !!
COPCO
Former Vendor
Joined: Apr 2009
Posts: 766
Likes: 3
From: Charlotte North Carolina 704-394-5150
I will post you a picture of an engine I saw today at the Auto Fair here in Charlotte. It is QUITE IMPRESSIVE.
Hopefully you know that I was "just kidding" about making it is stronger engine and such. It was written to give you a "chuckle"....so to speak.
"Gremilns" are always around just waiting to be awakened. So "keywords" have to be used very carefully UNTIL the job is completed. IF these keywords are written or spoken BEFORE the job is completed...even from me..it will or possibly stir up a hornets nest of them and then all heck breaks loose. These "Gremilns" have gotten me so many times that I have respect for them and do not take anything for granted anymore.
Also when giving an "attitude adjustment" Confucius say:" Use an implement that best fits one's grasp with ease and comfort". Ummmmm......does the word "Louisville" mean anything to you? Just joking around.
The best to you and your brother....and your project.
"DUB"
Hopefully you know that I was "just kidding" about making it is stronger engine and such. It was written to give you a "chuckle"....so to speak.
"Gremilns" are always around just waiting to be awakened. So "keywords" have to be used very carefully UNTIL the job is completed. IF these keywords are written or spoken BEFORE the job is completed...even from me..it will or possibly stir up a hornets nest of them and then all heck breaks loose. These "Gremilns" have gotten me so many times that I have respect for them and do not take anything for granted anymore.
Also when giving an "attitude adjustment" Confucius say:" Use an implement that best fits one's grasp with ease and comfort". Ummmmm......does the word "Louisville" mean anything to you? Just joking around.
The best to you and your brother....and your project.
"DUB"
