I am attached to my HEI and cant use the original sized ram air cleaner. Can I put a 1980 Delta 88 or similar air cleaner on without restricting my W-31 spec '68 350? Suggestions encouraged (besides going back to points or changing my hood) for forced air setup. Ideally, if the original '68 ram air cleaner was modified for HEI I would be over the moon. Maybe someone has already done this?

 

I used a MSD Billet "ready to run" distributor, part # 8529, with a MSD distributor cap, part # 8437, on a "stock appearing" Rallye 350 that I built for a customer some years ago. The cap actually has the door to adjust the points on a factory distributor and has factory type female socket wire towers.

 

I wouldn't modify a rare air cleaner like that.

Find a 75-later pan and lid, then modify that. Might have to Frankenstein it with parts from several air cleaners, but some of the later cold air emissions units have snorkels similar to the 68 OAI air cleaner.

 

I used the Spectre kit on my 66 Starfire. Clears the HEI easily.

https://classicoldsmobile.com/forums...g-cars-139103/

So do my factory ‘66 big car snorkels

Chris

 

Looking at ignitions for performance use, the best that can be said for HEI is that it is functional. The spark energy falls off quite a bit as you approach 5000 rpm; HEI was meant for grocery-getters, not high-performance cars.

You can solve clearance and performance problems by going back to the original distributor. However, you don't need to go back to points.

Here are some ways to clear the air cleaner, eliminate points, and give you high-rpm spark:

• Complete K-66 (UHV) system. This was a factory option on your car.
• K-66 distributor driving an MSD-6 CDI hidden in the passenger-side air intake cowl
• TI Specialty (tispecialty.com) points replacement module driving a stock coil directly (many use Pertronix, but it does not have the absolute reliability you want in an ignition component).

All will give a factory look.

 

I'll add a K-66 unit holding a newer HEI circuit board is another idea.

 

I have been entranced by the early factory electronics. There was a clean looking uhv in the parts section recently. I was using Pertronix before the Autozone billet aluminum hei I have now. I liked the stock look of that.

I'm going to look at tispecialty.com and distributer msd # 8529.

I could always drop a 68-69 w31 distributor, right after I win the Lotto.

Thanks for all the replies so far.

 

Or you could set up a more common distributor to W31 specs...

Go with the Pertronix or TI for the more consistent ignition, then set up your advance curves to best suit your engine. Got access to a distributor machine?

 

have reproduced the 68-69 style dual snorkel oai air cleaner assembly previously & could produce HEI compatable base dual snorkel for your application if thats what you require
...just noticed th other day that somebody thought th hood of my. 68 delmont was good place for material to produce those...

 

I have no clue if the OAI housing on my 69 is a reproduction or OEM, but it cleared the HEI distributor with room to spare.

As for HEI getting weak at high RPM, that’s a myth that won’t die. The first couple years of HEI production did have some issues with module reliability, but they got it figured out. Cheap aftermarket modules aren’t the greatest, definitely a case of getting what you pay for. Get a quality module, it will keep up with the RPM needs of probably 99% of the Olds engines.

 

I have a HEI with a twin snorkel 71 442 air cleaner and did not have any fitment issues.

 

As Scotty would regularly remind Captain Kirk, "Ye cannae change the laws of physics, Captain."

HEI circuitry is remarkable. It varies the dwell time with rpm, which prevents coil over-heating at idle and stretches the upper rpm range.

However, it is still a magnetic discharge (MDI) system, and above 5000 rpm, there is not enough time between spark events to fully charge an inductive coil. That is why the spark gets weaker.

The Olds K-66 UHV ignition overcame this drawback of MDI systems by sending a capacitive discharge (CDI) pulse to the coil. The power of this pulse did not vary with rpm. And there was no waiting time to charge the coil. The spark is so powerful that it fired plugs regardless of the condition (fuel-soaked at -30°F? Not a problem.) The only drawback is that the conversion efficiency (spark power out of the coil divided by power into the coil) is lower in CDI versus MDI.

Your choice is between an MDI system with long-duration, lower-current spark that gets weaker above 5000 rpm and a CDI system with short-duration, high-current spark that maintains its power to excessive rpm.

Olds didn't fully educate people about the advantages of their K-66 CDI. Buyers didn't understand the advantages and it dropped from the offerings within a few years. But the physics are still impeccable.

 

Is center hole offset on that 71 breather ?

 

Ever wonder how things would have panned out had Olds made CDI standard equipment in say 1967, on the heels of Toronado? Everyone else would have been forced to play catch-up, and Olds' engineering reputation would have been further cemented. As it was they let Chrysler get that glory, in 1972.

Think I'm right that only Pontiac and Chevrolet also offered it, and Chevy only on Corvette?

 

Yes, Pontiac and Chevrolet (ex Corvette) also offered the CDI system.

The Corvette Transistor Ignition (TI) system was used from 1964 to 1971. It was an MDI system that used a specific coil with thicker primary wire and greater primary secondary winding ratio. The coil had 1/3 the resistance of the standard coil to effectively use the extra amperage that the TI system put out. The higher primary voltage and current gave faster rise time. The higher turns ratio in the coil gave greater spark voltage. The system produced a good spark at elevated rpm.

 

I do not have access to a distributor curving machine. This is the motivation, to find one that is setup for w31.

 

Are any of you familiar with UHV ignition ?