Summit 383 Top Performer kit

[Troub]

So this was Summit’s answer if the 2086 Top Kit would fit on a 65 383 block. I’m still confused. What would it matter if the plug angle in original heads was different from 68 blocks on? The 2086 kit comes with new heads so wouldn’t be an issue. Is there ANY diffference in the 67 and earlier blocks with head to block bolt patterns?? You can see they say the 208622 kit is for earlier blocks and I assume they must have some reason to say the 2086 is for 68 blocks and up???
Mark me down as confused.

 

[Professor Fate]

Either one will physically fit your engine. The difference is in the cc's of the combustion chambers. The 20862 kit has larger combustion chambers and would result in a net drop in your compression ratio. The 208622 has smaller combustion chambers to maintain your cr. If you're rebuilding the bottom end, your piston choice would dictate which heads to use.

 

[Troub]

Thanks Professor! Why the heck doesn’t Summit just list the 20862 kit as good to fit all years 383 blocks?

 

[Professor Fate]

Because the early and late motors used different pistons. While both kits will physically "fit", the wrong combination could result in power loss, not gain. They assume a stock bottom end when spec-ing their kit.

 

[Troub]

Because the early and late motors used different pistons. While both kits will physically "fit", the wrong combination could result in power loss, not gain. They assume a stock bottom end when spec-ing their kit.

See, there you go. Now why can’t Summit say that! Much appreciated Professor. Any recommendations on pistons? Keeping the forged crank as is.
Cylinders look to be stock bore, they may be a bit over after a good honing/cleaning at the machine shop.

 

[ch1ll]

You must have talked to the wrong sales rep. They should know these answers at summit. Call back and request a mopar specialist.

 

[rumblefish360]

See, there you go. Now why can’t Summit say that! Much appreciated Professor. Any recommendations on pistons? Keeping the forged crank as is.
Cylinders look to be stock bore, they may be a bit over after a good honing/cleaning at the machine shop.

With as many different makes and years of engines, having a phone rep at Summit to answer correctly any question is amazing. With just a MoPar 383 engine, you have them made in a B & RB deck height. The various pistons used over the years as well as other small changes could be a long list. This is where you need a MoPar specialist. Not exactly a common thing.

Good thing there is FABO.

 

[440 Mike]

Either one will physically fit your engine. The difference is in the cc's of the combustion chambers. The 20862 kit has larger combustion chambers and would result in a net drop in your compression ratio. The 208622 has smaller combustion chambers to maintain your cr. If you're rebuilding the bottom end, your piston choice would dictate which heads to use.

Well............I've checked combustion chambers on some 516 heads, they poured to 84 cc's. Long way from the supposed 73.5 cc factory spec.

 

[fishmens67]

The 75cc head would be my choice for all 383's.
Good for additional .5 - 1 point compression on factory block depending on thickness of head gasket.

 

[PRH]

As far as actual “fitment” issues between the years.......

67 and earlier engines used different lifters and pushrods, so if a cam is included in the package, the lifters won’t be “correct” for both 67-earlier, and 68-later.

68-69 motor’s could have positive deck height pistons, which would require some sort of “work around” to run any closed chamber heads.

None of that is a big problem, you just need to know what you’re working with.