Evo .vs. TC -- what are the strengths/weaknesses of the Evo engine?

[Tucson_Tim]

Aside from the 80ci Evo being down in power (in stock form) from the TC88/96, what are other weaknesses of the Evo engine compared to the TC engine? (I assume it has some.) And aside from it running cooler than the TC (in stock form) what are the strengths of the Evo engine compared to the TC? Just curious . . . .

I gotta believe that a single cam makes maintenance a bit easier.

[TheBoss]

EVO are easier to work on...But the Twin Cam as you know is the new and better engine.

[Dave63]

TC Pros:

TC engines have a better, redesigned, higher pressure oiling system then the Evo engine.

Larger cubic inches from the factory. 1440, 1550 vs 1340 for Evos.

Integrated engine/trans mounting points, eliminating inner primary failures/cracks/leaks due to torque.

2 piece rocker boxes over 3 piece Evo units. Less chances of leaks.

After 2005, HD incorporated auto-chain adjusters to all the primaries. Not an "engine" item, but came during the TC era.


TC cons:

Crankbearing issues/excessive run-out depending on early model or not.

Cam chain tensioners can fail, but if checked at service intervals, no issues, especially after 2006 revamp of shoe material and chain design. (rounded edges)

If EFI, run ubber lean from the factory. Then again, Evo's with carbs barely had 1 full turn out of the a/f carb screw, but could be corrected at home and dealer's scaner wasn't needed to reflash ECU .

Harder to do a simple cam swap, and requires more tools and a press.

That's about it.........

[Tucson_Tim]

Thanks for the info.

I'm lookin' to buy an older Evo or Shovelhead sometime. Lookin' for a stock one -- very hard to find.

[Blackdog 15]

My TC runs Great, but my next scooter will be an EVO.....had a shovel, 2 Evos prior to TC.....

[badinfluence63]

None, no weaknesses in the EVO. 80ci is more then enough horses to get'er done.

I think the EVO/carbed motor may have been one of the better motors the MOCO produced. I heard that they couldn't use it to turn into a twinkie because the moco did not own the patent...don't kow how true that is?

Personally, for some reason I am not a proponent of EFI, 6 gallon gas tank, 6 speed or the 96"+ motor. I think this year or started last year, they went with the 17 inch front tire on the glides rather then the traditional 16 inch tire?

And there were those concerns of rocker box and base gasket leaks in the early models of the evo..

Aside from the 80ci Evo being down in power (in stock form) from the TC88/96, what are other weaknesses of the Evo engine compared to the TC engine? (I assume it has some.) And aside from it running cooler than the TC (in stock form) what are the strengths of the Evo engine compared to the TC? Just curious . . . .

I gotta believe that a single cam makes maintenance a bit easier.

[Crocodile56]

Good question.........................Good post Dave63........................as always!

[Dave63]

None, no weaknesses in the EVO. ..

Acutally, there were a few, John.

Post 1991 engines had the always-failing INA inner cam bearing.

Pre-1996 engines had the thin axle tappets that failed and ruined engines. Hence the "B" lifters that came out, to fix the issue.

Then there's the pre 1996 base gasket leakers......

All this stuff was remedied, but just like the TC engine, the Evo had it's share of quirks.

[badinfluence63]

Acutally, there were a few, John.

Post 1991 engines had the always-failing INA inner cam bearing.

Pre-1996 engines had the thin axle tappets that failed and ruined engines. Hence the "B" lifters that came out, to fix the issue.

Then there's the pre 1996 base gasket leakers......

All this stuff was remedied, but just like the TC engine, the Evo had it's share of quirks.

It sounds like the last 4 years of production could be considered there finest hour?

I was aware of the RB and base gasket leakage, didn't know about the other stuff.

[Dave63]

It sounds like the last 4 years of production could be considered there finest hour?.

Sure enough....but why is it that HD designs and build an engine, then once it's mastered and bug free, BAM, they change to another platform???

[Ironhead]

Sure enough....but why is it that HD designs and build an engine, then once it's mastered and bug free, BAM, they change to another platform???

good point on that issue. AMF started the ball rolling on the EVO, and once it was in production, it took many people a good while to warm up to it, then once they had a good, no great engine, they change it all over.

[Dave63]

good point on that issue. AMF started the ball rolling on the EVO, and once it was in production, it took many people a good while to warm up to it, then once they had a good, no great engine, they change it all over.

True.... It was started 7 years prior, while AMF still had the company.

The first Evo was a shovel based engine, with the Evo, non-vented heads. HD bought back the company from AMF in Feb of 1981, with it completely final (sale) in June. The Evo was released in 1984-1/2, 3 years later.

It was Harley's answer to the leaky, low quality control issues with the Shovelhead engine.

From the time line:

1984

Harley-Davidson unveils the 1340cc V²® Evolution® engine on five models including the all-new Softail®. The result of seven years of development, the Evolution engine produces more power at every speed, runs cooler, cleaner and is oil-tight.

[Ironhead]

right, and the evo set-up kept many aspects of the shovel untill , I think, 1995 when they changed alot of stuff, clutch set-up, primary design, starter location, dash and speedo style, etc

[Dave63]

right, and the evo set-up kept many aspects of the shovel untill , I think, 1995 when they changed alot of stuff, clutch set-up, primary design, starter location, dash and speedo style, etc

1992.

Inner cam bearing changed. (to the INA bearing)

Vented heads showed up with elimination of the crankcase vent hose off the crankcase/oil pump.

Clutch basket changes from the multi dpring/finger type pressure plate to the disc type.

Clutch hub went from key-way to splined. (I believe it was 1992)

Carb changed to the CV style rather then the butterfly design Keihin.

[Ironhead]

so, off topic, yet on topic sorta, why is it that untill the twin cam, it seems that any time the MoCO introduced a new engine, it always had the base or cases of the previous motor, but different heads and rockerbox design?
I may be wrong on this, but didn't the pan stat out with a knuckle bottom, and the shovel started out with a pan bottom, and the evo started out with a shovel bottom