Swapping out OEM distributor with HEI distributor

[TotalyHucked]

My truck the ESC went down . I put in a regular HEI I messed with it springs,weights,vacuum can initial. I never got it to run as a total package as well as it did with ESC. Same with @SirRobyn0 he chronicles all the changes he made over the coarse of a year,finally when it was all said and done,it was back as an ESC truck. He documented it all recorded gas milage etc. I can tell you mine runs better with esc. But I didn't documented anything. Working ESC is best in my truck. I suspect yours never worked right. So it's real similiar to the I took off a messed up Qjet and put on an Edelbrock and it runs great. But you never hear anybody say I compares a good Quadrajet to an Edelbrock.

Yeah, I read through that thread and think he's nuts lol. Trust me, I get what you're saying. But for the effort it takes to get it there and source the parts, especially when you're talking a lowly 305, it's not worth the hassle IMO. Better to just stab a regular distributor in, set it and go.

 

[Rustisbest]

Old doesn't mean bad, new doesn't mean good. Mine and countless others run great without it. High compression and all. We agree to disagree.

 

[boloboss]

Question:
about the 9-volt stock resistance wire going to the old distributor...since I swapped to the HEI, do I need to change that resistance wire to 12 volts? And if I don't what are the disadvantages

 

[Ricko1966]

Question:
about the 9-volt stock resistance wire going to the old distributor...since I swapped to the HEI, do I need to change that resistance wire to 12 volts? And if I don't what are the disadvantages

You don't have resistance wire,that ended like 1974.

 

[Rustisbest]

Sure it does. I can set my timing where the truck runs good on a 50 degree day with no load or 90 degree day pulling a trailer. Because timing demands change,and esc adapts.GM designed it and installed it for a reason. Yes even 350s started getting ESC 1983 ish. Small blocks didn't used to have HEI at all,but people upgrade to it. I consider knock sensor an upgrade. So did GM.

You've put it on the 75 C20 in your avatar?

 

[Ricko1966]

You've put it on the 75 C20 in your avatar?

I have several trucks,that ones getting a 6.2. Yea I know those suck too. But it suits my needs,pull trailers and get reasonable milage.

 

[Ricko1966]

Old doesn't mean bad, new doesn't mean good. Mine and countless others run great without it. High compression and all. We agree to disagree.

Yea I never said a stock HEI didn't run good I,'ve run lots of them. I even told the O.P. in post like 12 or 13 he's already changed it. It's not worth changing back. HEI and an ESC HEI are the same distributor,with the exception of the module and pigtail.Weights,springs,pickup coil,vacuum can etc. all interchange. To make a ESC distributor non esc all you have to do is splice wire a to wire c. I personally think having the ability to run more timing is an advantage. But I never said a regular HEI sucks. I also said around post 15 I don't want to argue about why I think ESC is better. But because some people wanted to know. I went there. I regret responding now.

 

[Ricko1966]

Well guys that's what I have a stock 350. So from all the info this tells me that the engine had to be swapped before I got it from a 305 because it had that type of distributor with the ESC)

8th digit of VIN will tell you what engine it had originally.Some 350s got Esc. 1984

 

[Bextreme04]

Are you sure that only the 305 came with the electronic HEI? Both my Big block truck and my 350 small block truck have those wiring harnesses hanging there doing nothing.

You are equating HEI=ESC... that is not the case. HEI came in all squarebodies from 1975 on. ESC was ONLY on LE9 engines(305). The timing control that came into the TBI, TPI, and later EFI systems is very different than the dumb knock retard only ESC that was in the LE9 used in the trucks. It is an especially terrible and unreliable system between the type of sensor used, the location it was installed, and the computer that was reading the signal.

 

[Rustisbest]

Ricko I know theyre the same distributor more or less. We bypassed it on my dad's 85 GMC and eventually stuck a regular HEI in it with all new stuff in it when it went to my nephew and set it like every other SBC prior. My thoughts were they had a real low base timing (like 6 or 8) to drive up combustion chamber temps to reduce EMISSIONS. That makes em prone to detonation.

The vacuum canister added like 20* of timing to get it back to what it should of been in the first place at cruise. I treat em all the same. 10-14 base, 20 centrifugal and 12-16 on manifold vacuum. I never said knock sensors were bad. Just that this ESC system was unnecessary. It doesnt learn or retain any info like modern EFI stuff.

 

[boloboss]

Say guys matters if we argue disagree, to disagree or whatever. I'm just glad we have this community to exchange knowledge... valuable knowledge!!!! I appreciate every last one of your comments and responses

 

[Ricko1966]

.

Ricko I know theyre the same distributor more or less. We bypassed it on my dad's 85 GMC and eventually stuck a regular HEI in it with all new stuff in it when it went to my nephew and set it like every other SBC prior. My thoughts were they had a real low base timing (like 6 or 8) to drive up combustion chamber temps to reduce EMISSIONS. That makes em prone to detonation.

The vacuum canister added like 20* of timing to get it back to what it should of been in the first place at cruise. I treat em all the same. 10-14 base, 20 centrifugal and 12-16 on manifold vacuum. I never said knock sensors were bad. Just that this ESC system was unnecessary. It doesnt learn or retain any info like modern EFI stuff.

Oh yeah GM had dozens if not 100s of combinations of weights,springs,center cams,and advance cannister. I've done more than my share of recurving GM HEIs. I don't want want to beat on this anymore,Personally I like the ESC especially if the distributors are curved the same. That or a putting a D1941 5 wire module in a 4 wire HEI, that,allows you to pull 5* on demand like going up a long hill pulling a trailer it's not fancy or complicated just does what I like. The D1941 is not the 5 wire truck ignition module.

 

[Bextreme04]

.
Oh yeah GM had dozens if not 100s of combinations of weights,springs,center cams,and advance cannister. I've done more than my share of recurving GM HEIs. I don't want want to beat on this anymore,Personally I like the ESC especially if the distributors are curved the same. That or a putting a D1941 5 wire module in a 4 wire HEI, that,allows you to pull 5* on demand like going up a long hill pulling a trailer it's not fancy or complicated just does what I like. The D1941 is not the 5 wire truck ignition module.

My whole thing with this is that he DOES NOT HAVE A 305 anymore. I'm betting that when someone swapped the engine out, they likely didn't transfer over the knock sensor either. A properly built 350 with no mechanical issues should have no issues with detonation; even hot, heavily loaded, or on pretty bad gas. My 350 got flat tops, .020" off the deck to bring the quench area in check, and a small towing cam to bring my compression up near 9.5:1 and bring the quench area into a reasonable range. I've towed a 6k lb camper through the mountains in 100 degree heat on 87 octane and had zero issues, but I also have a properly tuned quadrajet and am running 12 degrees of base timing, 22 mechanical, and ~9 vacuum. So, full throttle it is peaking around 34 degrees and cruising at highway speeds it can hit over 40 degrees.

The system on 350's was different than ESC and was used in combination with the computer controlled carburetor(CCC) that would change the high vacuum driving mixture to get better highway mileage.

 

[Ricko1966]

My whole thing with this is that he DOES NOT HAVE A 305 anymore. I'm betting that when someone swapped the engine out, they likely didn't transfer over the knock sensor either. A properly built 350 with no mechanical issues should have no issues with detonation; even hot, heavily loaded, or on pretty bad gas. My 350 got flat tops, .020" off the deck to bring the quench area in check, and a small towing cam to bring my compression up near 9.5:1 and bring the quench area into a reasonable range. I've towed a 6k lb camper through the mountains in 100 degree heat on 87 octane and had zero issues, but I also have a properly tuned quadrajet and am running 12 degrees of base timing, 22 mechanical, and ~9 vacuum. So, full throttle it is peaking around 34 degrees and cruising at highway speeds it can hit over 40 degrees.

The system on 350's was different than ESC and was used in combination with the computer controlled carburetor(CCC) that would change the high vacuum driving mixture to get better highway mileage.

So using your numbers 12+22+9 you've got 43 degrees on the highway, but you'd get better milage,even without a different carb running 50 degrees on the highway. As to whether or not 350s had Knock sensors,they did Corvettes in the early 80s,Cali. Spec trucks 83 or so,TBI trucks,Vortec trucks,I don't care how crude the system is compared to a new system,everything on these trucks is crude compared to newer stuff. A th350c is not near as good as a 4l80e,but I wouldn't pull a good th350c to put in a regular th350 with logic of the th350c is crude compared to a4l80e. I woukd replace a 350 with a th350c thou.HEI is crude compared to 87 up stuff. As to whether or not O.Ps ESC worked IDK, if I swapped in a 350 and the option of having functional ESC was there by adding 1 sensor,I'd have working ESC. A knock sensor HEI,is everything a regular HEI is with the ability to pull timing,not only pull it,but give it back when you can use it. People have no problem permanently pulling 2 degrees of initial and 4 degrees of vacuum and never getting it back. I want it back. People want to bag on @SirRobyn0 spending time and money making his ESC work (yes I know its a 305) but the couple hundred bucks he spent,made his truck more useful,more drivable and gave him more mpg. his mpg increase will pay for his repair,so it was worth doing. I have different goals for my trucks the aren't pampered,they aren't pretty,I don't care how fast they are, I do want the best mpg without hurting the vehicles intended purpose. Haul things I can't in a car ,and pull a trailer when I need too.A knock sensor HEI can be tuned and tailored EXACTLY like a regular HEI but a knock sensor HEI can do something a regular HEI can't. Pull timing if and when needed. I can have my cake and eat it too. I can pull 50 degrees on the highway,I don't need to limit my vacuum advance. IDC if the crude system was designed for a 305 it still does the intended job. If you aren't running 50 degrees on the highway,you are leaving milage on the table. I'd rather have too much,money,gasoline,tools,or timing and not use it all, than be just a little bit short.This is why I didn't want to get this ball rolling. My Chevelle will have 305 ESC on it,already gathered the pieces.

 

[Bextreme04]

So using your numbers 12+22+9 you've got 43 degrees on the highway, but you'd get better milage,even without a different carb running 50 degrees on the highway. As tobwhether or not 350s had Knock sensors,they did Corvettes did in the early 80s Cali. Spec trucks,TBI trucks,Vortec trucks,I don't care how crude the system is compared to a new system,everything on these trucks is crude compared to newer stuff. A th350c is not near as good as a 4l80e,but I wouldn't pull a good th350c to put in a regular th350 with logic of the th350c is crude compared to a4l80e. HEI is crude compared to 87 up stuff. As to whether or not O.Ps ESC worked IDK, if I swapped in a 350 and the option of having functional ESC was there by swapping adding 1 sensor,I'd have working ESC. A knock sensor HEI,is everything a regular HEI is with the ability to pull timing,not only pull it,but give it back when you can use it. People have no problem permanently pulling 2 degrees of initial and 4 degrees of vacuum and never getting it back. I want it back. People want to bag on @SirRobyn0 spending time and money making his ESC work (yes I know its a 305) but the couple hundred bucks he spent,made his truck more useful,more drivable and gave him more mpg. his mpg increase will pay for his repair,so it was worth doing. I have different goals for my trucks the aren't pampered,they aren't pretty,I don't care how fast they are, I do want the best mpg without hurting the vehicles intended purpose. Haul things I can't in a car and pull a trailer when I need too.A knock sensor HEI can be tuned and tailored EXACTLY like a regular HEI but a knock sensor HEI can do something a regular HEI can't. Pull timing if and when needed. I can have my cake and eat it too. I can pull 50 degrees on the highway,I don't need to limit my vacuum advance. IDC if the crude system was designed for a 305 it still does the intended job. If you aren't running 50 degrees on the highway,you are milage on the table. This is why I didn't want to get this ball rolling.

You are making some broad generalities there that are not necessarily true.

You would not necessarily get better mileage running 50 instead of 43. You add timing to compensate for the leaner mixture that you have tuned into the cruise cycle. A leaner mixture burns slower and therefore needs more timing to compensate. I have mine dialed in properly for the amount of lean I have tuned into my carb to not melt the pistons out of it. There is no advantage to adding more timing than the engine needs to make maximum torque. If I have my timing set up properly for maximum efficiency or power and have zero detonation... why would I want to pull timing out for detonation that isn't happening.

My comment on 350's is related to the system installed in non-EFI squarebodies. Of course corvette and camaro 350's had knock sensors. They also had multi-port fuel injection and dual sensor HEI's in them to give a crank and cam sensor signal so that the computer could tell exactly where the engine was. You are comparing apples to rice here.... they are not the same