Distributor springs kit

[Edward G.]

I purchased a set of distributor springs and weights from Corvette Central for my 63 360HP distributor. Comparing the springs in the kit with the ones in the distributor they look to be about 2/3 the size of the original ones. the original spring is the one is the one on the bottom of the upper group.I am hesitant to use these in the distributor. Also the kit comes with a brass sleeve for the advance limiter pin, is it best to use the brass sleeve or the nylon sleeve. Has anyone had experience with these springs

[David M.]

Re: Distributor springs kit

What are you trying to change and why?

Most often those general purpose kits provide springs which are too light. This allows to much advance too soon in the spark curve.

The secret to super tuning is to take full advantage of the curve up through the power band. You want a smooth steady advance transition up through said power band. That is where the engine will be able to take full advantage of total advance. That's a different spot for each engine combination.

The best advice I can offer is to have the distributor set up by a knowledgeable person with a Sun distributor machine. Otherwise you're going to have to play around (guess) with what the engine best responds to.

A good distributor tech will ask for your total combination specs...cam profile...hydraulic or solid lifter, intake...dual plane or single, trans, rear gear et al. Where does the power band come on in your engine? Do you have a local chassis dyno?

After establishing the Air/Fuel mixture with a vacuum gauge(to obtain the highest vac while adjusting...set the timing the same way with said vac gauge to achieve the highest reading. Verify dwell. Now get out the set-back timing light and see where it is. Record the base and vacuum degrees.

As an example only

[Duke W.]

Re: Distributor springs kit

The OE centrifugal advance is start @ 700, 24 @ 4600, which is very lazy. The best centrifugal is from the 365/375 HP 327s, same start point, 24 @ 2350.

So the first thing you should do is test with a dial back timing that the installed springs meet the OE map or are something else. Does the spring package have any info on the difference in the springs, and/or have you checked the Moroso Web site?

I'm not familiar with this spring kit, only the Mr. Gasket 928G kit.

Don't use the bushings; 24 degree centrifugal is fine, but it should come in faster.

Assuming you have an OE equivalent cam or ANY OE mechanical lifter cam you cannot get the engine to idle below 700 long enough before it stalls to set timing, plus the timing tab is not accurate with the 8" balancer. The best way to "set timing" is to set total WOT advance (VAC hose disconnected and plugged) a few hundred revs above the point of maximum centrifugal in the range of 36-40, as high in that range as the engine will tolerate without detonation.

You don't need a Sun distributor machine and even if you know of one the owner/operator likely has no knowledge of what is an optimum centrifugal curve and vacuum advance for your engine. I've been helping guys blueprint Corvette distributors with optimized spark advance maps for over 50 years. The best way for you to start is to study my tuning seminar, presented at the 2012 national convention.

Copy the following into a Web search engine including the quotes so it searches for the entire phrase:

"tuning vintage corvette engines for maximum performance and fuel economy"

In it you will learn why your high overlap cam engine needs both more aggressive centrifugal and vacuum advance curves with more total idle advance than a low overlap cam engine like the 327/250 and 300.

Duke

[Patrick H.]

Re: Distributor springs kit

The best way for you to start is to study my tuning seminar, presented at the 2012 national convention.

Copy the following into a Web search engine including the quotes so it searches for the entire phrase:

"tuning vintage corvette engines for maximum performance and fuel economy"

In it you will learn why your high overlap cam engine needs both more aggressive centrifugal and vacuum advance curves with more total idle advance than a low overlap cam engine like the 327/250 and 300.

Duke

Duke,

Your presentation is permanently affixed to the top of this forum. No searching needed.
Look under Tuning.

https://www.forums.ncrs.org/showthread.php?117966-Database-of-Restoration-Documents

[Duke W.]

Re: Distributor springs kit

Thanks... guess is should look at the "sticky" section more often.

Duke

[Edward G.]

Re: Distributor springs kit

I read all of the distributor posts until my eyes started bleeding, I was more curios about the size difference in the kit springs vs the original springs.
the kit springs seemed to be too weak. Corvette Central does not state the name of the vendor supplying the distributor kit. Maybe I need to look for a Mr. Gasket kit or are they all the same.
Sounds like no matter what spring kit I buy I will need to install plot the curve rinse and repeat until I get the advance that closely matches the recommended curve. My engine is all stock with the original cam and distributor and weights. Not looking for a hot rod just want to be assured that the distributor is functioning properly.

Ed

Ed

[Owen L.]

Re: Distributor springs kit

As I understand it, Mr. Gasket is owned by Holley.

...
Looked it up. Had no idea Holley had so many other brands under their umbrella:
Hooker Headers, Weiand, Nitrous Oxide Systems, Flowtech Exhaust, Demon Carburetion, Earl's Performance Plumbing, Diablosport, MSD, Mr. Gasket, Accel, Superchips, Edge, Racepak, Mallory, Hays, Quicktime, Lakewood, Flowmaster, Hurst, B&M, APR, Dinan

[Duke W.]

Re: Distributor springs kit

I read all of the distributor posts until my eyes started bleeding, I was more curios about the size difference in the kit springs vs the original springs.
the kit springs seemed to be too weak. Corvette Central does not state the name of the vendor supplying the distributor kit. Maybe I need to look for a Mr. Gasket kit or are they all the same.
Sounds like no matter what spring kit I buy I will need to install plot the curve rinse and repeat until I get the advance that closely matches the recommended curve. My engine is all stock with the original cam and distributor and weights. Not looking for a hot rod just want to be assured that the distributor is functioning properly.

Ed

Ed

The spring kit is Moroso, so look it up on the Moroso Web site to see if there is any data on them. Corvette Central is just a retailer. They don't know jack about many of the products they sell.

As I previously said, the best centrifugal curve for your engine is the same at the OE 365/375 HP engines, 24 max centrifugal at 2350. Pull the springs with your fingers to determine which are the lightest and install them. If they give max centrifugal at no less than 2350 and the engine doesn't detonate, you're done. If not keep experimenting.

I can tell you that the Mr. Gasket 982G kit springs are lightest to heaviest... black, silver, gold. and you don't have to use the same color for both, so you can get more than three curves.

Duke

[Edward G.]

Re: Distributor springs kit

Thank you
Ed