My 86 Regal has the original HEI ignition system and a carburetor. The original distributor GM 1103376 was set up for the emissions of the day without full spark advance until over 4000 rpm and minimal vacuum advance. Since I run much lower RPM I never get near full advance.

Summit racing sells a cheap complete replacement distributor with much better tuning. Spark advance comes in sooner and is fully advanced at 3000 RPM. Vacuum advance is adjustable up to 10 degrees. I decided to swap my system and keep the old for a modular spare.

Summit distributor # 8500001-1, wires, plugs



In the doghouse again:



Remove cap, note position of rotor and distributor body



Take off clamp bolt, remove distributor, plug hole with rag



Clean area. Note slot in oil pump drive in bottom of hole. (You may have to use a long screwdriver to turn this if the slot doesn't line up with the new distributor.)



Put a little grease on the drive gear. Drop in the new distributor, turning rotor to line up as before and engage the drive gear and oil pump.



Check alignment and clamp it down. Replace cap.



Reattach/replace the spark plug wires.



You will have to check timing with a timing light. (I use cyl 5 and look from below)




I'll report on road testing when possible.

i have herd about cyl 5 how does that work? is the mark the same?

I did the same thing on mine.

THere are 2 different timing markers on the 454. The standard one is too high and you cannot see it. THe secondary timing mark is lower and you can see it from underneath the coach but to set time on it, you have to use #5 cylinder (and I think disconnect the vacuum advance). Sure is easy that way!

Yep, what he said! The lower marks can easily be seen from below, driver's side. Only downside it is hard/impossible? to reach distributor to change timing from there. (Easy for top side assistant, though.)

Every time I do this it is so nostalgic. Few people know what timing lights are, albeit use one! I hadn't used mine in years before I bought Barth. (I got the timing light from Montgomery Wards, that's how old it is...) glad I didn't get rid of it.

Ran back from Florida to Michigan. Played with timing (advanced till started to ping, backed off a bit.) MPG on the trip down was about 6.5 and about 7.3 on the trip home. Considering the ethanol contaminated fuel we have to use, this is probably the best I'll get from a heavy 33 ft P30 rig. Doesn't sound like much improvement but it is over 10% and saved me about $100 on gas, paid for itself already. Easy to install, too!

Throttle response (such as it is!) is slightly better at stoplights and when passing. I'm happy so far.

Great info Steve! If it isn't too much trouble, could you make a note about what your idle speed spark advance setting is, and what you have at other RPMs? Also, did you go with the existing springs and weights in this Summit distributor or did you alter those at all?

thanks!
Matt

Good questions! I used the Summit distributor out of the box. The vacuum advance is adjustable to set max advance up to 10 degrees. I left it at 10. According to GM numbers, the original had only 5 degrees total. The GM had max mechanical advance at 4000, way above my operating range. The summit claims max at 3000, about right.

The factory calls for 4-6 degrees at idle but when the Thorley headers are installed, their info calls for 12 degrees which is what I had been running. No sign of knock, ever.

I installed the Summit and set it at 12 again. Road testing showed no knock so I advanced a bit. Started to ping and didn't pull as strong so I tweaked it back some. Ended up about 13-14 BTDC, more than I expected and far from the factory specs. Ran it hard and hot up the the mountains with no knocking. I could tell by feel the midrange response is slightly better, but I don't know yet what advance it has above idle.

When I get a light on it next time I'll get someone to throttle it up and check it at other RPMs. (Or I could run a throttle cable down below the engine like Bill h did) Based on the info from GM vs Summit I estimate that the Summit is giving 3-5 more degrees advance through the midrange. Total advance numbers are about the same but the GM never got there, so at cruise I'm now seeing at least 5 degrees more advance.

I'll post more when I know more. I think the mileage numbers are real since they are based on at least 1000 mile comparisons on the same route.
(Now if I could just increase compression to about 10 to 1 and get real gasoline I'd have maybe 300 hp instead of 240... ah the good old days..)

Steve, sounds like you are happy with the Summit distributor you picked out. Great research, I got on the summit website and without your knowledge I don't think I would have picked out the right one. For current model year they list pretty much a direct replacement.

I plan on removing the two emission blowers and associated hardware and tubing, clean up the engine compartment.

Did you get your plug wire set at Summit as well? I've read that you need to use high temp plug wires for motorhome application.

The distributor seems to work well. I may tinker with timing etc a little more, I'll keep you posted.

The plug wires I bought are from local auto parts store, just looked up 86 454. I have some fire sleeves over the plug boots. No heat trouble so far. (You do have a right side engine air dam installed I hope?)

Engine access is GREATLY improved after the air pumps etc are gone. I also removed engine AC and brackets, EGR valve, air pump filter canisters and exhaust injection manifolds. Vacuum lines, temp sensors also, all non functional. You can actually see most of the top side now. I'm planning some insulation work in the doghouse soon, I will have pictures then.

Okay. This thread is beginning to point me in my next project direction. Wintertime project of course.

Nice write-up with clear pics Steve!

quote:

Originally posted by Steve VW:


I also removed engine AC and brackets,

Is your PS/PB pump now driven by one or two belts?

I have two identical V-belts on the PS and one flat belt for water pump and alt.

quote:

Originally posted by Steve VW:
I have two identical V-belts on the PS and one flat belt for water pump and alt.

That's nice. My '84 would have only one belt to the pump if I removed the compressor. Alt and water pump also driven by V belts.

Steve,

You would't happen to know what size your flat belt is would ya?

I'm in the process of removing my air injection pumps and the AC compressor and brackets. One more air pump to remove and then remove the associated vacuum components. Sure is looking good. I'm excited to get back to the basics.



Is there any advantage to leaving the EGR valve operational or should I go ahead and remove it? I read somewhere that the EGR valve has a quenching effect on combustion temps reducing octane requirments which lessons the danger of detonation. I really don't know if any of that is true.

Apparently around 1986 they made em with two air pumps, and up to four belts! Mine originally had two pumps. One was mounted on pass side of engine and shared the flat belt with the crank, water pump and alternator.

85 1/2 to 89 OEM (with AIR pump): GM 14087530 (1422 mm)

Evidently the later versions did not have the air pump on that side and ran the flat belt from crank to water pump to alternator. When I removed the pump from that side, I used the "no pump" belt and it worked.

1990 OEM (no pump) GM 10085787 (1340 mm)

CarQuest crossed it to:

BVB K5256 (20mm x 1355mm) which 15 mm longer but fits perfectly.

As for EGR, nothing wrong with it, if it is working leave it alone.

As the name suggests, under certain operating conditions, the EGR system bleeds exhaust back into the intake stream to lean the mixture, to reduce peak combustion temperatures. At high peak temperatures, the amount of NOx pollutants increases. (NOx refers to several nitrogen oxide pollutant compounds... all nasty... smog... acid rain, etc)

When needed, the system applies vacuum to the EGR valve, a diaphragm valve which opens a passage between the exhaust riser in the manifold and the intake itself. This essentially partially dilutes the intake air with oxygen-poor exhaust fumes. The mixture delivered to the cylinders burns somewhat cooler, reducing emissions. Normal operation depends on engine temperature, engine load (vacuum), throttle position, and transmission gear. The amount of ignition timing advance was sometimes manipulated during EGR operation, also.

By the time we get these things, they often have vacuum leaks, defective EGR valve, plugged valve and/or ports in manifold and don't work anyway. So it was with mine. The vacuum lines were long gone, I just removed the valve and covered the holes (plugged already) with a small plate, just to get it out of the way.

Nothing like a little thread drift to keep things going!