Mallory or HEI

[QuickCheetah]

im thinking about swapping the Mallory out with an HEI...anyone try this already? if so good or bad results? its a 455 Olds

[jetboat468]

i would not , the hei can be deadly to a olds ,if you do put a hei in check your total timing at 5,000 rpm, you have a great day :)

[CARLSON-JET]

QuickCheetah, I have used HEI's in many aplications. I currently use one on my boat now and feel it is better then a stock setup with points. What I think jetboat468 is refering to is there are a few years where G.M. added a spark retard on the HEI and above about 4500 rpms it can be bad for sustained periods. This can easily be fixed with a better module like the one accel sells and a proper curve kit. The timing curve needs to be setup for a jet. Do not buy the cheepo one on ebay for $79 as it has some non compatable chinese parts such as the mechanical advance mechanism. There are no off the shelf curve kits for them. If your budget calls for an inexpensive set-up, they work. If you are going for max performance they are not the ticket. I hope this helps. I want to add that the old wives tale about HEI's not working above 5k are false. The ones I have set up spun over 6k and never missed a beat.

[GUGS102]

Either way you go, have the dist curved for the jet application. I have run both and have been happy with both. I'm running a mallory now and just had it curved to match application. At the same time have them check bushings, clearances etc. and you'll be happy with either setup.
Gugs

[Sleek-Jet]

i would not , the hei can be deadly to a olds ,if you do put a hei in check your total timing at 5,000 rpm, you have a great day :)
Quey????
I run an HEI on my olds with no problems, as have alot of people I know. The stock HEI get's weak above 4000 rpm's or so. But that's easy enough to fix with one of the aftermarket HEI kits. I've ran both MSD's stuff and Pertronix, all with great success.
For a stock to mild performance engine, you can't go wrong with an HEI.

[kraig]

What is the jet pump application? Is it so much differnet than automotive? :)

[LynnsJet]

Go with the HEI. Mallory sensor's have a high failure rate, at least they did in a racing application. I was racing a Ford in SCCA and you souldn't hardly give a Mallory away with that crowd. I think the vibration killed them.
Just me .02 worth.
L J

[NELSON#109]

I Have Always Used Hei's With 455's... They Work Great. The Accel Hei Is A Good Distributor. As Far As Mallory, I Have Had A Lot Of Failures With Them. They All Have A Tendancy To Twist The Two Piece Shafts And Throw Off The Timing. If It Has A Photo Eye, You Better Buy A Box Of Them... The Photo Eyes Will Go Out All The Friggin Time. You Wont Run Into Too Many People That Have Much Good To Say About Mallory Distrib., Except For The Mags. Every Now And Then Yo Find A Lucky Dog Thats Been Running One Un Touched For 15+ Years, But Like They Say; The Sun Shines On A Dogs Ass Every Now & Then.... Nelson#109

[QuickCheetah]

thanks for all the advice...Mallory was working fine..then i washed the boat one weekend 3 weeks ago and since then i have been going nuts testing wires trying to figure it out...i have a few Olds 403 motors im thinking of just taking one of those and making it work...

[wet77]

I have a MSD HEI on my 540 and it works great!
It even came with a built in rev limiter!http://www.***boat.net/forums/attachment.php?attachmentid=13308&stc=1

[GUGS102]

What is the jet pump application? Is it so much differnet than automotive? :)
The difference being the total amount of timing and when it gets it. I recently threw a HEI in the dist machine and it was still trying to get full advance over 6000 RPM, the motor only turns 5500.
You also want to make sure your timing is not increasing more than you think. If you set total at 2500 RPM and leave it alone, unless you check it at higher RPM how do you know what it is doing? Some will creep into the low-mid 40* mark and you don't know it until its too late.
Worth the money.
Gugs