leadfoot067
1/2 ton status
im converting to the holley commander FI...do i wanna use the small cap dist or the large cap computer dist? both will control spark curves correct?
CK5
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hei question
- Thread starter leadfoot067
- Start date
what does the system require you to use. most say what to use. and if both are usable i would say small cap tbi style as there are more of these around cheeper than the big cap ones these days.
I like the smaller ones, more overall clearance.
Both were made for CCC/TBI/TPI applications, but unless you've got some '80's parts cars around, you will more than likely end up with a small cap.
Both were made for CCC/TBI/TPI applications, but unless you've got some '80's parts cars around, you will more than likely end up with a small cap.
leadfoot067
1/2 ton status
i have one big cap(free) and access to a small cap($100)...the system i have will plug directly into the large cap dist..i would need to buy an adapter to run the small cap...can i still use my peretronix hotter coil if i run the big cap dist?
I'm sure you're aware that not all big cap HEI are the same. The early ones had a vacuum advance and mechanical advance and can't be used.
I think he said the large cap was an EFI model.
Use it! Won't run any different, we give the option when ordering some systems.
But the small cap is a better unit in my opinion. Besides more clearance which some cars require, if you look at the cap and rotor design it can not misfire to another cylinder.
Use it! Won't run any different, we give the option when ordering some systems.
But the small cap is a better unit in my opinion. Besides more clearance which some cars require, if you look at the cap and rotor design it can not misfire to another cylinder.
pauly383
Daddy383
4X4HIGH said:
The one I have like you described was for ESC ( boxed up OEM 1983 K5 I saved it ) . I do have one in my garage that looks like any other regular old HEI as well , but comes WITHOUT any advance at all , just a weatherpack connector . Whats funny is the one with no advance of any kind . Was being used by the PO of my Chevelle . It will run standalone with no computer input .
leadfoot067
1/2 ton status
upon further inspection of the hei i have it has no mechanical or vacume advance...but the harness does NOT plug in,so im guessing its a ESC dist...will it work?
I'm a bit curious as to the ESC distributors...it's said you can convert them to non-ESC operation by jumpering a couple of the wires, but that implies (and I have heard the same) that they have vac and mechanical advance, the ESC is solely for retarding the spark, and should be a 305 only item.
I don't see where ESC systems had enough data to actually control timing..no way to gauge engine load without vacuum reference, which is why the CCC applications should work...but that may be what you have, and the connectors/module just changed at some point?
Should be pretty easy to find out at acdelco.com, just see if say a 1984 305 monte carlo (ss makes it a sure thing) used the same module as a 1987 TBI truck. Any 1981+ V8 GM car application is a candidate though.
I don't see where ESC systems had enough data to actually control timing..no way to gauge engine load without vacuum reference, which is why the CCC applications should work...but that may be what you have, and the connectors/module just changed at some point?
Should be pretty easy to find out at acdelco.com, just see if say a 1984 305 monte carlo (ss makes it a sure thing) used the same module as a 1987 TBI truck. Any 1981+ V8 GM car application is a candidate though.
leadfoot067
1/2 ton status
well the dist i have came out of a 81 blazer with a 305...no vacume or mechanical advance...but the rest of the rig was so hacked i dunno if it was original
There are 2 different types of large cap HEI distributors. One has a cap that has twist lock hold downs and the other has screw on hold downs and there are 2 different wiring harnesses for them.
leadfoot067
1/2 ton status
thanks
leadfoot067
1/2 ton status
so the tech at holley tells me that the distributor i need is 81-86 gm 7 pin HEI.from a car or truck with the electronic q-jet and no advance..says the large cap HEI will just plug in and the small cap HEI will need a wiring adapter for 60 more buks...so i go to the wreckin yard today and all the large cap HEI i found with NO vacume or mech ADVANCE AND A 7 PIN MODULE none of them will plug into my harness.they were 83-86 gm distributors....aahhhgggggg this is getting irritating....
What kind of connectors are they running?
I've got the remote coil setup so it's two small connectors, but I wonder if you need the TBI large cap module, if it's different than the small cap. At best, I'd hope the distributor is the same and the module (connection) is the difference.?
I've got the remote coil setup so it's two small connectors, but I wonder if you need the TBI large cap module, if it's different than the small cap. At best, I'd hope the distributor is the same and the module (connection) is the difference.?
leadfoot067
1/2 ton status
the connecter is the 4 pin weatherpac its the big one in the pic....the plug is the same size but theres little tabs inside it that dont line up correctly with my dist...now i was lookin yesterday at a buick dist and the tab things were correct...and wires were all the same colors can i just switch the connecter?
pop the cap off and check the module out. I believe it has a description of each connector pins function cast into it. If it does, you should be able to compare that to the wiring connector you've got, and those wires' destination.
I'd be real hesitant to re-pin a connector solely because wire colors match. It may be fine, BUT if it's wrong, all sorts of additional headaches.
Napa sells the weatherpack tool that allows you to de-pin the connectors, but it's around $10. I was told you can use the ink tube in a ballpoint pen, but I tried that and they weren't the right diameter. FYI in case you do re-pin.
I'd be real hesitant to re-pin a connector solely because wire colors match. It may be fine, BUT if it's wrong, all sorts of additional headaches.
Napa sells the weatherpack tool that allows you to de-pin the connectors, but it's around $10. I was told you can use the ink tube in a ballpoint pen, but I tried that and they weren't the right diameter. FYI in case you do re-pin.
leadfoot067
1/2 ton status
WELL it runs....and it runs okay the base fuel map i loaded is on the rich side but now comes the tuning part with the laptop....
Glad to hear it, anxious to see the sort of progress you make, and how happy you are with it! 
I was going to convert my ESC dizzy to non-ESC and I think it is as easy splicing the green and the black wires together. I researched it and did it as shown in the picture below, which should be the cleanest and simplest implementation. However, I ended up going straight to full electronic control and locked everything down as shown in the second picture. So they can be converted from advance to non-advance, but I never confirmed that this ESC bypass works.
leadfoot067
1/2 ton status
well after weeks of tuning,tweaking,frustration,black smoke ,fouled plugs,and many beers it runs pretty well.i learned alot with this thing...gonna wheel it this weekend,ive been driving it around on the road and tuning it almost every day and its closer to what i think is running very well all the time.the more i drive it i find spots in the fuel curve that need adjustment,overall more than anything ALOT of patience is required with the holley system.i knew almost nothing about FI before i got this....ill report back after this weekend in the mountains....
