HEI conversion

[Guest]

Yes,I need some help. I have a 1970 cutlass conv. 350/4-barrel/auto. I want to convert over to HEI distributor. Do I replace the alternator,regulator,air cleaner? Whats the best replacement year HEI for my olds? What about rewireing? Could someone give me a rundown on the conversion. Thank you much. [color:"][/color"] [color:"green"] <img src="http://www.aaca.org/ubbthreads/images/graemlins/confused.gif" alt="" />

[Sgt Art]

I may be wrong, and if I am someone jump in here, but it's a pretty simple swap. Your 350 Olds engine uses the same size distributor as HEI used in the 307, 350, 403, 455 engines. It's a drop in swap. You don't even have to pull the intake manifold. Find a HEI distributor at the salvage yard for one of the above engines and drop it in. Ok, I've assumed you've pulled a distributor and put it back in and can re-establish timing. If not, you may want to read up on that, it's not too lengthy or hard to do or get someone to help you who knows what to do. It's a good way to learn about setting timing. On an HEI distributor, all you need is a full 12 volts that is ignition controlled, by that I mean is hot when the key is on, and no power when the key is off. This connects to the distributor where it is stamped "BATT". The other connector is for the tachometer and is labled "TACH" you don't need that unless you are running a tachometer (which tells you how tacky the engine is - just kidding) or want to set idle speed etc with an external tachometer. I would buy the connector from the junk yard too, then all you have to do is splice the 12 volt wire to it. You can use your other equipment you asked about. The replacement HEI (OEM) shouldn't interfere with your air cleaner. The coil sits on top of the distributor so you can remove the old points type coil. Get the vacuuum advance type of HEI, it's easier to work with otherwise you need a computer. Also, you may have to recurve the centrifugal advance in the new distributor to suit your engine. No biggy, might just need two new springs or some weights. That's something best left to a person who knows how, but not expensive or too hard to do. Also, you'll probably need to get spark plugs that are designed for a 350 engine with HEI. Just check the parts number for whatever brand you use now against what a 1975 or newer 350 calls for. You will also be gapping your plugs considerably more with the greater spark of HEI. I think mine are set at .065 if mememory serves.

[Guest]

Hey thanks for the help. I am going to give it a try. I will get back to you if any problems.

[Guest]

The above posts are right. A few comments on what I did on my 72..

1) The air cleaner didn't have enugh clearance at first I raise the air cleaner up with spacers (like 5 bucks at local shop) and then I cut a pic of exhaust adapter to adapter the heat pipe on the snorkel. Later I caved and put in an open element stf 14" style.

2) I went to parts house and swapped alternator to a higher amp one which specs for a 1975 cutlass. Pre-1974 had external regulator and some gusy say you fry modules using the old style. It was $35 bucks. I also had ot get a wiring adapter from year one for $15 to make it wire up.

3) Get an adjustable vac. canister (crane makes them) and a recurve kit.

4) Buy an extra module and keep it in the car. If a module goes you are stuck. Always use the WHITE heat sink grease they give you with the module. It NEEDS to go betwen the module base and the housing or it'll be unable to dissapate heat and it'll fry leaving you stuck.

Have fun!

[Lou6T4GTO]

I've got a 1971 Cutlass Conv, 4 barrel Rocket 350, bone stock except for Dual exhaust and a 1975 HEI.  The 1971 engines used the 13/16" Washered spark plugs, the 1975 HEI engines (I believe) used the tapered 5/8" Plugs. will the original plugs work with the HEI ? and at what GAP?   *there is a full 12 volts going to the dist cap*

The car, (when it was brand new, yes, I've had it 47 years), ran like a Swiss watch, the engine is totally rebuilt (.030 over), Orig rebuilt and re"Bushed"Q-Jet,  original cam,  but I Can Not get it to run like it Once did.    It Doesn't run "Bad", but not as Completely Smooth as when new.  Supposed to be able to idle Smoothly at 700 RPM (In Drive).   any special "Timing Ideas" to go with the HEI conversion ???  Thanks for your help

[retiredmechanic74]

18 minutes ago, Lou6T4GTO said:

I've got a 1971 Cutlass Conv, 4 barrel Rocket 350, bone stock except for Dual exhaust and a 1975 HEI.  The 1971 engines used the 13/16" Washered spark plugs, the 1975 HEI engines (I believe) used the tapered 5/8" Plugs. will the original plugs work with the HEI ? and at what GAP?   *there is a full 12 volts going to the dist cap*

The car, (when it was brand new, yes, I've had it 47 years), ran like a Swiss watch, the engine is totally rebuilt (.030 over), Orig rebuilt and re"Bushed"Q-Jet,  original cam,  but I Can Not get it to run like it Once did.    It Doesn't run "Bad", but not as Completely Smooth as when new.  Supposed to be able to idle Smoothly at 700 RPM (In Drive).   any special "Timing Ideas" to go with the HEI conversion ???  Thanks for your help

I believe the plugs are Delco 45s the gap is 60 and they will work well with HEI also when setting the timing use a vacuum Gage along with the timing light set the initial timing and then watch the vac Gage,   move the dist. to get anywhere from 19 to 23 inches of vacuum at idle then lock it down and test drive. 19 to 23 is from a stock engine you may see something different but you want the most vacuum you can get without pre-ignition.  

[joe_padavano]

13 hours ago, Lou6T4GTO said:

I've got a 1971 Cutlass Conv, 4 barrel Rocket 350, bone stock except for Dual exhaust and a 1975 HEI.  The 1971 engines used the 13/16" Washered spark plugs, the 1975 HEI engines (I believe) used the tapered 5/8" Plugs. will the original plugs work with the HEI ? and at what GAP?   *there is a full 12 volts going to the dist cap*

The car, (when it was brand new, yes, I've had it 47 years), ran like a Swiss watch, the engine is totally rebuilt (.030 over), Orig rebuilt and re"Bushed"Q-Jet,  original cam,  but I Can Not get it to run like it Once did.    It Doesn't run "Bad", but not as Completely Smooth as when new.  Supposed to be able to idle Smoothly at 700 RPM (In Drive).   any special "Timing Ideas" to go with the HEI conversion ???  Thanks for your help

 

This is incorrect information.  NO Oldsmobile V8 from 1964-1990 ever used tapered plugs. The 1980s vintage 307s did use 5/8" hex plugs but with washers.  More to the point, use the plugs for the ENGINE, not the DISTRIBUTOR.