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SelfAfflicted
01-19-2005, 01:25 AM
Hiya's, I've got a delema & need some advice. I'm building this Shovelhead see & the motor at present is a 103" stroaker built for the drag's. I need to tame this beast a bit for the road. I'm gona have the 13.1 pistons milled but not sure if I should go 10. or 9.5 . Then the cam to use,currently 575. The valve springs are a bit heavier as you'd expect & I realy dont want to have to change them. Thank's for lookin... Any adivice??

junior
01-19-2005, 01:41 AM
couple thoughts....

if this bike is truly a drag bike, forget about using the top end in any form for a street bike. the heads are likely set to flow at unusable steet settings, and simply cutting pistons is not really a good choice.

if it were me, i'd take it down and look at what's there. if the spigots have been oversized and the bore is now where custom heads are required, i'd shelf the whole thing and look for a street engine. if the spigots will take say a 93 inch kit, i'd simply bolt up an s&s sidewinder kit.

maybe soretail has a different take since he's a machinist...

j

Wide
01-19-2005, 07:50 AM
Hi SelfAfflicted

Like junior says, has a lot to do with what the heads had done.

Let me ask you this, are you driving it on the street now & how is it running?

I'm trying to get feel for you engine combo, you may be able to get away with a cam with the right specs, hopefully :D

rwpatton
01-19-2005, 05:44 PM
As Junior and wide have said as long as the heads are not augered out it can be made streetable.

There are a couple of ways to come up with a 103 but the most common set up is 3 5/8 bore with a 5" stroke. I would suggest replacing the pistons with some forged 9.6:1. Compare piston wieghts to check for flywheel balance issues.

Running a cam with around 560 lift and 255 duration will give you good power while being streetable, S&S 560s is a good choice. Its a little fast ramped and noisey but runs great.

Dont know what carb your running. The super E might be considered to small for this size motor but it sure keeps intake velocity up and make'em behave on the street.

Let us know how she goes. And we should hear from Soretail soon.

RW

Soretailcat
01-20-2005, 02:36 AM
SelfAfflicted,
Wow, what a name!
All the posts gave some great info. Like RWPatton said the usual route to 103" in a shovel is 3.625" cylinders and a 5" stroke. The engines have a tough time fitting in most stock frames. Even if the pistons are advertised as 13 to 1, the mods necessary to clear .575" cams will greatly increase the combustion chamber size, on stock type heads that have not been welded, that you may be down to 10 to 1 or less. The only way to tell for sure is to cc the head and cylinder with the piston in it. There are a couple of ways to do this and both are a pain in the posterior with a hemi head, but it must be done to know for sure. The cam you select will depend on the static compression ratio you determine from cc ing the head and cylinder. YOU CANNOT just cc the head and learn anything on a hemi head.
On the street, running a cam with lift more than .485" will shorten guide life.....sometimes a lot. This does not apply to the evo or tc88. The guides in a shovel, pan, or iron head are too short to begin with and do not meet engineering standards for length to get good life. If the heads have been clearanced properly....notice I stated properly, for .575" cams, the rocker arm geometry will be incorrect for something shorter. New valve seats will probably be necessary to correct the geometry. Inspection and measuring will determine what you have and what you need.
Shovels have ports much too large for the valve they use. Any hogging of the port reduces the vacuum signal at the carb even more. If the heads are true drag race heads, they will not perform at their best on the street.
A shorter cam may help the situation since it will have less TDC lift and the piston will have a chance to pull a little more vacuum.
I don't think I have been very much help. It is much easier to build a race engine than it is to detune one.
Soretailcat
BTW - For those of you out there, both of you, that want to know how to figure correct valve guide length, here 'tis:
(Valve Stem Diameter) X ( 7) = minimum correct valve guide length.
An evo head does not last longer than a shovel because of superior engineering.....the valve guides are the right length.
STC

junior
01-20-2005, 03:14 AM
soretail....

i value your opinon a lot, so i wanted to kinda put a "what-if" twist on this....

as far as i know, the balance factor used for most h/d's with a relativley stock stroke is about 60% or so. however, as i understand it as the stroke in creases, the balalnce factor gets closer to 50%

if this is a properly built drag motor, wouldn't that be a consideration to a certain degree?

i'm just wondering if in the long run it would be esaier to put an s&s sidewinder kit with some std heads? (i'm a cheap bastard at heart i guess....)...lol

j

Soretailcat
01-20-2005, 04:39 AM
soretail....
as far as i know, the balance factor used for most h/d's with a relativley stock stroke is about 60% or so. however, as i understand it as the stroke in creases, the balalnce factor gets closer to 50%

if this is a properly built drag motor, wouldn't that be a consideration to a certain degree?

i'm just wondering if in the long run it would be esaier to put an s&s sidewinder kit with some std heads? (i'm a cheap bastard at heart i guess....)...lol

j

Junior,
Being that the HD is a 45 degree twin, it can only be in "balance" in a very narrow rpm range. In other words, the balance factor does not just determine the smoothness of the engine, it determines WHERE the smoothest point will be. I never purchase balanced flywheels because I prefer to use the weights of the components that are to be run.
The early knucks, pans, and early shovels were balanced at 50%. As the gearing changed to become taller ( lower numerically) the balance factor was increased to lower the rpm where the smoothest running would be. I use 60 to 62% regardless of stroke in a street engine big twin or sportster running at normal speeds with stock gearing. If you told me you only run the interstate and cruise at 3500 rpm I would probably balance the crank at 55% in order to raise the rpm where the smoothest running would be. If it was a drag motor, probably 50%. I have never seen the need to change the balance factor because of stroke length. The balance factor is determined using the reciprocating weight (small end of rods, pistons, rings, wristpins, and locks or buttons) which is independent of stroke length and not in the equation.
To answer your question, Yes, balance factor would be a consideration if it was really low and your gearing tall.
I like long arm engines....if this one was mine I would keep the 5" stroke, drop the compression to 9 to 1 or so, use S&S heads, and an Andrews "B" grind cam and sleeve the cylinders to get rid of the oil holes, and drain the oil straight through the cases as well as put outside oil drains in the heads to keep the top end nice and dry.
Unless STD has started putting steel inserts in their heads for the head bolts, I don't care for them.....the bolts screw directly into the aluminum and when the heads get hot they unscrew themselves. I quit using them over a decade ago.
Soretailcat

junior
01-20-2005, 07:45 AM
soretail-

gotta tell ya bud- i really enjoy reading your take on stuff as i learn quite a bit-

thanks for the response...

j

Wide
01-20-2005, 03:58 PM
soretail-

gotta tell ya bud- i really enjoy reading your take on stuff as i learn quite a bit-

thanks for the response...

j

^^^^Ditto^^^^

What can I say, I feel like I'm in school again

1beer

rwpatton
01-20-2005, 03:58 PM
very nice piece Soretail. B)

RW

junior
01-20-2005, 07:10 PM
What can I say, I feel like I'm in school again

1beer

true, but at least we ain't going to the pricipals office every other day...

lol

j

TexasFatBoy
01-20-2005, 07:48 PM
What can I say, I feel like I'm in school again

1beer

true, but at least we ain't going to the pricipals office every other day...

lol

j

Every other day? How'd you manage to get a day off?

Soretailcat, man, you are one knowledgeable SOB and a real asset to the forums. Thanks for sharing your experience with the less mechanically inclined! 1beer

Soretailcat
01-20-2005, 10:25 PM
Thanks Gang, glad you were interested.
Soretailcat

SelfAfflicted
01-21-2005, 01:13 AM
Thank you all for your response's. It's nice to get input & advice from people who know their shit & you guy's sure do. I'm trying to get the spec's on the head's to see what's been done to 'em. I'm the 3rd owner of this motor @ my uncle know's most of the history on it. It was built by the Mec for Ring Racing here in Dayton years ago & has been started only 3 times since. It's never been run on the street or track. But I swear by the gravel in my hip I will have this bike on the road by May.. there's before pic's of the bike the day I got it, in the gallery if you's is wantin to take a look. No after pic's till May. Thank's again for your intrest & I'll get back with more info shortly.

rwpatton
01-21-2005, 06:36 AM
Hey selfafflicted

Since our motor guru (Soretail,with all my respect)) does not like my cam choice. :D

I just happen to have a brand new ( less than a 600 miles) B grind cam.

You, or anybody else can have it for $65 plus shipping.
Also have an A and a stock H same price.

Got shovel rocker boxes,front 80" cylinder, 74" crank assy.TC 88 complete topend,heads.cyl's ect. and a pile of other crap.

Maybe should post in the for sale section. Just sing out. Man this shit is all over my garage. What y'all need?

RW :)