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Cylinders as well.

tequacha said:
change flywheels to 4 1/4" stroked ones
As Mr. Tequacha says, you will need another crank. The 80's came out in late 78 (78 1/2) with the dash 78 flywheels that have 4 1/4" stroke. You can also get an Evolution crank and have it rebalanced or get a "commonized evolution crank" from your local dealer. That is an Evolution crank that has been balanced at the HD factory for the Shovelhead pistons. The main difference is that they are about 5 pounds lighter. You may view this as good or bad depending upon your outlook. I have one of these cranks in my 1982 80" Shovelhead and it works very well. S&S makes cranks for the Shovelhead too.

You will need to address the issue of cylinders as well. The 80's are stock at 3 1/2". The 74"s are 3 7/16". The 74's can be bored to 3 1/2" but I think that the height of the cylinders is slightly shorter. This could be addressed with shims or by getting a set of 80" jugs to match the 80" pistons. The pistons come in "low compression" (7.5:1) and "high compression" (8:1). I have the low compression in mine and I prefer it. There is no detonation and you could probably run it on cooking oil if need be. I would avoid raising compression higher than 8:1 on your Shovelhead since they will detonate. Some say this can be avoided with dual plugs but I'm lazy and that's a lot of extra hardware and wiring.

Original 80" Shovelhead cylinders are getting as scarce as hens' teeth. They can really only be bored to .030 over so many of them get tossed after that. At .030 oversize, they are paper thin.

Aftermarket cylinders are available in 3 1/2" and 3 5/8" from places like S&S and Custom Chrome. If you go to 3 5/8" you would have to bore the crankcases to take the extra bore. The cylinder heads are almost all the same except some have short-reach sparkplugs. The 80" version will give you a lot more grunt, especially at low speed. Another good addition is a single fire ignition. I use Spyke but there are dozens of good ones on the market. Other than that, if you have all of the parts, it's just a bolt together modification.

Good luck.

NUC
 

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You need other flywheels. Shovel cranks can be taken apart. Still, getting an EVO-Crank is a good idea. You must rebalance the crank cause EVO cranks are balanced a 50% and Shovels a 55% (surprise,surprise)

I`m a strong believer in casted pistons. KB,S&S and OEM are of very good quality.

Cylinders for 80cui shovels are 74cui shovel-cylinders. The height is the same. The MoCo did manufacture stronger cylinders (from 1982 on?) for the 80cui models but the outer dimensions are the same.
The bore of 80cu shovels was achieved by using standard 74cu cylinders and using the 6th oversize. Therefore you have 4 oversizes left only with a 80 cui Shovel. The 4th oversize of a 80cui shovel is pretty thin I agree, the 4th.
S&S cylinders is good stuff.

The compression ratio dropped to 7.5 from 1981 on till the end of production I believe (lowering of noise-emmission ?)
The FLH in 1978 came outta the gate with a 9.5 ratio
This OEM cam of the FLH is a much sought item.
A Shovel with a ratio of 9.5 or even a 9.8 is quite common overhere.
The reliability is outta question. The problem with such a high compression Shovel isn´t durability, it`s a starter, gearbox and primary-problem.
This is the reason why you see so many AM-Starters, 5 or even 6-speed gearboxes and 3" primary belts for Shovels.
High demand=big market at least in europe. Almost anywhere in Europe there is compulsary MINIMUM speed of 45 mls on highways trust me you see many stroked Shovels and Pans here.

The cylinder heads are the same except that heads from 80`s haven`t got any cooling fins on top (between the rockerbox) and all heads from 1974 on utilize long reach threads. I know cause i got one short thread 1972 motor and OF COURSE I`ve had to repair these darn threahs already grrrrrrr

Opinions on dual-plugged shovel-heads are split
Dual plugs without extensive headwork is completly useless,IMHO.
I`ve seen MANY bikes on the dyno with dualplugs and there is zero advantage. Some might argue better starting, less cough-huff innercity at red-lights. I don`t argue with that but performance wise there is no advantage without additional work

Maybe you should consider the 93cui Sidewinder-Kit from S&S. It isn`t that expensive but this beast got some punch,it`s proven and durable and very,very popular over here.
Those riders try getting an FXR-gearbox throw away the housing, get one from S&S and ready is your 5-speed Shovel doing a 100mls all day on the highway. No kidding.

Or did you play with the idea of a just using a different cam already?
I use a Crane H288-2B in my 74cui . Boy what a difference to the OEM or Andrews-A hahaha !
ray
 

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Discussion Starter · #5 ·
Newultraclassic and Shovelbolle......THANX MUCH

shovelbolle said:
You need other flywheels. Shovel cranks can be taken apart. Still, getting an EVO-Crank is a good idea. You must rebalance the crank cause EVO cranks are balanced a 50% and Shovels a 55% (surprise,surprise)

I`m a strong believer in casted pistons. KB,S&S and OEM are of very good quality.

Cylinders for 80cui shovels are 74cui shovel-cylinders. The height is the same. The MoCo did manufacture stronger cylinders (from 1982 on?) for the 80cui models but the outer dimensions are the same.
The bore of 80cu shovels was achieved by using standard 74cu cylinders and using the 6th oversize. Therefore you have 4 oversizes left only with a 80 cui Shovel. The 4th oversize of a 80cui shovel is pretty thin I agree, the 4th.
S&S cylinders is good stuff.

The compression ratio dropped to 7.5 from 1981 on till the end of production I believe (lowering of noise-emmission ?)
The FLH in 1978 came outta the gate with a 9.5 ratio
This OEM cam of the FLH is a much sought item.
A Shovel with a ratio of 9.5 or even a 9.8 is quite common overhere.
The reliability is outta question. The problem with such a high compression Shovel isn´t durability, it`s a starter, gearbox and primary-problem.
This is the reason why you see so many AM-Starters, 5 or even 6-speed gearboxes and 3" primary belts for Shovels.
High demand=big market at least in europe. Almost anywhere in Europe there is compulsary MINIMUM speed of 45 mls on highways trust me you see many stroked Shovels and Pans here.

The cylinder heads are the same except that heads from 80`s haven`t got any cooling fins on top (between the rockerbox) and all heads from 1974 on utilize long reach threads. I know cause i got one short thread 1972 motor and OF COURSE I`ve had to repair these darn threahs already grrrrrrr

Opinions on dual-plugged shovel-heads are split
Dual plugs without extensive headwork is completly useless,IMHO.
I`ve seen MANY bikes on the dyno with dualplugs and there is zero advantage. Some might argue better starting, less cough-huff innercity at red-lights. I don`t argue with that but performance wise there is no advantage without additional work

Maybe you should consider the 93cui Sidewinder-Kit from S&S. It isn`t that expensive but this beast got some punch,it`s proven and durable and very,very popular over here.
Those riders try getting an FXR-gearbox throw away the housing, get one from S&S and ready is your 5-speed Shovel doing a 100mls all day on the highway. No kidding.

Or did you play with the idea of a just using a different cam already?
I use a Crane H288-2B in my 74cui . Boy what a difference to the OEM or Andrews-A hahaha !
ray
You guys are a treasure of info! All the details and insights are great. Sure helps me know what to look for at swap meets and so on. I'm still debating on whether to buy the bike for 5 grand. Sure would make a great winter project.
Thanks for taking the time to post such lengthy reports
DigiTerry
 

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Highly Seasoned Rider!
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Right.

shovelbolle said:
You need other flywheels. Shovel cranks can be taken apart. Still, getting an EVO-Crank is a good idea. You must rebalance the crank cause EVO cranks are balanced a 50% and Shovels a 55% (surprise,surprise)

I`m a strong believer in casted pistons. KB,S&S and OEM are of very good quality.

Cylinders for 80cui shovels are 74cui shovel-cylinders. The height is the same. The MoCo did manufacture stronger cylinders (from 1982 on?) for the 80cui models but the outer dimensions are the same.
The bore of 80cu shovels was achieved by using standard 74cu cylinders and using the 6th oversize. Therefore you have 4 oversizes left only with a 80 cui Shovel. The 4th oversize of a 80cui shovel is pretty thin I agree, the 4th.
S&S cylinders is good stuff.

The compression ratio dropped to 7.5 from 1981 on till the end of production I believe (lowering of noise-emmission ?)
The FLH in 1978 came outta the gate with a 9.5 ratio
This OEM cam of the FLH is a much sought item.
A Shovel with a ratio of 9.5 or even a 9.8 is quite common overhere.
The reliability is outta question. The problem with such a high compression Shovel isn´t durability, it`s a starter, gearbox and primary-problem.
This is the reason why you see so many AM-Starters, 5 or even 6-speed gearboxes and 3" primary belts for Shovels.
High demand=big market at least in europe. Almost anywhere in Europe there is compulsary MINIMUM speed of 45 mls on highways trust me you see many stroked Shovels and Pans here.

The cylinder heads are the same except that heads from 80`s haven`t got any cooling fins on top (between the rockerbox) and all heads from 1974 on utilize long reach threads. I know cause i got one short thread 1972 motor and OF COURSE I`ve had to repair these darn threahs already grrrrrrr

Opinions on dual-plugged shovel-heads are split
Dual plugs without extensive headwork is completly useless,IMHO.
I`ve seen MANY bikes on the dyno with dualplugs and there is zero advantage. Some might argue better starting, less cough-huff innercity at red-lights. I don`t argue with that but performance wise there is no advantage without additional work

Maybe you should consider the 93cui Sidewinder-Kit from S&S. It isn`t that expensive but this beast got some punch,it`s proven and durable and very,very popular over here.
Those riders try getting an FXR-gearbox throw away the housing, get one from S&S and ready is your 5-speed Shovel doing a 100mls all day on the highway. No kidding.

Or did you play with the idea of a just using a different cam already?
I use a Crane H288-2B in my 74cui . Boy what a difference to the OEM or Andrews-A hahaha !
ray
==================================
All good info from Mr. Shovelbolle save for the cylinders: The 80 cu. in. OEM cylinders have 9 fins and the 74 cu. inchers have 10 fins. The 74's can be bored to 3 1/2" but there's not much left. They also have different part numbers: Late 74's are 16485-74A (front) and 16492-74A (rear). 80's are 16494-78 (front) and 16495. Those are basic P/N's. There are other P/N's in my book for FXWG's which are different for some reason. He may be correct about the height of the cylinders but remember, the stroke on the 74 is 3- 31/32 and that on the 80 is 4 1/4 so you need to check this carefully. I really am not certain about the height of the cylinders since I've never owned a 74 Shovelhead.

The 1982's also have a drain hole with a tube that drained pushrod tube return oil into the cylinders. A nice fix for a non-existant problem. Most people drilled the tappet blocks and plugged the cylinder holes. I did.

When you go to swap meets, you will see 74 Cylinders all over the place but the 80's are really scarce in OEM.

Good luck,

NUC
 

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shovelbolle said:
You need other flywheels. Shovel cranks can be taken apart. Still, getting an EVO-Crank is a good idea. You must rebalance the crank cause EVO cranks are balanced a 50% and Shovels a 55% (surprise,surprise)

I`m a strong believer in casted pistons. KB,S&S and OEM are of very good quality.

Cylinders for 80cui shovels are 74cui shovel-cylinders. The height is the same. The MoCo did manufacture stronger cylinders (from 1982 on?) for the 80cui models but the outer dimensions are the same.
The bore of 80cu shovels was achieved by using standard 74cu cylinders and using the 6th oversize. Therefore you have 4 oversizes left only with a 80 cui Shovel. The 4th oversize of a 80cui shovel is pretty thin I agree, the 4th.
S&S cylinders is good stuff.

The compression ratio dropped to 7.5 from 1981 on till the end of production I believe (lowering of noise-emmission ?)
The FLH in 1978 came outta the gate with a 9.5 ratio
This OEM cam of the FLH is a much sought item.
A Shovel with a ratio of 9.5 or even a 9.8 is quite common overhere.
The reliability is outta question. The problem with such a high compression Shovel isn´t durability, it`s a starter, gearbox and primary-problem.
This is the reason why you see so many AM-Starters, 5 or even 6-speed gearboxes and 3" primary belts for Shovels.
High demand=big market at least in europe. Almost anywhere in Europe there is compulsary MINIMUM speed of 45 mls on highways trust me you see many stroked Shovels and Pans here.

The cylinder heads are the same except that heads from 80`s haven`t got any cooling fins on top (between the rockerbox) and all heads from 1974 on utilize long reach threads. I know cause i got one short thread 1972 motor and OF COURSE I`ve had to repair these darn threahs already grrrrrrr

Opinions on dual-plugged shovel-heads are split
Dual plugs without extensive headwork is completly useless,IMHO.
I`ve seen MANY bikes on the dyno with dualplugs and there is zero advantage. Some might argue better starting, less cough-huff innercity at red-lights. I don`t argue with that but performance wise there is no advantage without additional work

Maybe you should consider the 93cui Sidewinder-Kit from S&S. It isn`t that expensive but this beast got some punch,it`s proven and durable and very,very popular over here.
Those riders try getting an FXR-gearbox throw away the housing, get one from S&S and ready is your 5-speed Shovel doing a 100mls all day on the highway. No kidding.

Or did you play with the idea of a just using a different cam already?
I use a Crane H288-2B in my 74cui . Boy what a difference to the OEM or Andrews-A hahaha !
ray
Shovelbolle....good information and it seems to me you know your shovel heads....but....the evo and shovel flywheels are ballanced at a 60% factor not 50% or 55%. The Twin Cam is 50%
 

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Back in the 70's when HD first went to an 80" motor I purchased all the necessary parts to convert my 74 incher. I don't remember what I expected from the change but if memory serves me, I was disappointed. I don't really recall gaining much from the conversion other than being able to say I had an 80 incher (back then 80 inches was still considered to be a "big" motor). It was assembled with all OEM parts so nothing high performance at all.
 
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