Re: Cranking Problem
I noticed that in another thread you said you would Kill for a Prestolite ignition 125. You can make your 90 perform almost as well if you are willing to search a bit, spend some money, and do a little work.
Background: Before 1982 your four cylinder 90 was badged as the 105. When all manufacturers changed to propshaft rating, Chrysler simply downrated the 105 to a 90. ALL four cylinder engine blocks are the same with different porting and carburetion as the only changes. Sorry, there are also two different bore sizes so in some cases pistons can not be swapped, but almost everything else can be.
NOW: To perk up your 90 and make it give an honest 90 HP, you would first look for manifolds and Big TC carbs from a Chrysler or Force 120-125-140--doesn't matter what year. Some Chrysler 120s came with small WB carbs so check before you buy if you get carbs off a Chrysler 120. Remove the manifolds with the small WB carbs from your 90 and substitute on the big manifolds and TC carbs. It is a simple swap and bolt-on. No modifications are necessary.
Secondly, search for a 2 to 1 ratio lower unit from a late Chrysler or early Force 85 HP engine. Swap this directly onto your engine and buy a prop 2 pitches higher. That is, if you are using a 13 X17 prop, swap on a 13 X 19.
With these simple changes, you will gain somewhere around 3 to 8 MPH in top speed.
If you look for engines that are not running, you should be able to buy the whole engine and get these parts relatively cheap. Then, save other parts for spares or sell on craigs or ebay.