ironhead cams

7686 Views 51 Replies 12 Participants Last post by Hillsidecycleco, Jan 28, 2015

Fireplug

Discussion Starter · Dec 5, 2014

Ok so I just found out that the Ironhead project im picking up tomorrow doesnt have any cams. When looking for a set, what type of cams should I look for and what type of considerations do I take to get to that decision? Not used to having options in cam selection....... Also I have no carb for it, any suggestions? My ultimate goal is just a nice little bar hoppin chop that looks as scary as it sounds! Ill post pics of the whole shebang tomorrow when Ive gone through the boxes and organized everything.

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Breeze3at

· #2 · Dec 6, 2014

For an Ironhead, Ebay is a good place to get reasonable prices for parts. I never had an Ironhead, so I can't recommend cams. You should do a lot of reading to get compatible parts. Nothing worse than parts that don't work together.

Thunder~Struck

· #3 · Dec 6, 2014

Won`t suggest a particular manufacturer.
But for bar hopping\stop light to stop light you will want something that comes in just off of idle and makes power through to the midrange.
Something with fast ramps will give you a very crisp throttle sound and response.
Your lift and timing, set my the lobe spread which is what creates the lope, will depend if you want the cams to be bolt on or if you plan other engine work.
If you are staying reasonably stock then an OEM carb properly jetted should be plenty.

98DARKHORSE

· #4 · Dec 6, 2014

Thunder~Struck said:
Won`t suggest a particular manufacturer.
But for bar hopping\stop light to stop light you will want something that comes in just off of idle and makes power through to the midrange.
Something with fast ramps will give you a very crisp throttle sound and response.
Your lift and timing, set my the lobe spread which is what creates the lope, will depend if you want the cams to be bolt on or if you plan other engine work.
If you are staying reasonably stock then an OEM carb properly jetted should be plenty.

Lobe separation is part of the lope sound. ..but mostly the overlap, as u can have two cams both with the same lsa..say example of 108 degrees...but one cam might have 55 degrees of overlap where as the other may only have 32 degrees of overlap

Cams are "lopes" of fun

The crisp throttle response will come from good jetting and a good cylinder psi...id stick to 190-195 psi on an older motor with possible high domes and bad combustion chamber designs along with head flow

Fireplug

Discussion Starter · #5 · Dec 6, 2014

Ok thanks guys. Guess I have some studying to do! What other kind of engine work you talking about Thunder? Would cam changes cause the need to machine parts? Not sure what the pistons are yet but ill get them in my grubby little hands tomorrow and ill see what they are stamped with. Would be good to know!

Thunder~Struck

· #6 · Dec 6, 2014

98DARKHORSE is correct. A properly jetted and tuned carb is most responsible for good throttle response.
But the right or wrong cam, as well as the rest of the set-up, will make or break what the engine does with the gas that the carb is feeding it.

The first thing that comes to mind regarding other engine mods\machining would be desired compression. Whether you mill the heads, or go with domed pistons, or.....
And do the cylinders need bored? Will just a clean up hone and restoring the crosshatch do the trick. Or do they need, or do you want them bored out?

Since you are rebuilding a basket case there is a chance the heads may need milled to bring the mating surfaces flat again. As well as decking the heads and the already mentioned honing or boring.
You will lose height, reduce valve to piston clearance and increase compression doing the heads.
While enlarging the cylinder bore will decrease the compression.
How much? Depends how much metal is removed. A small fraction can be made up with the head gasket.
The compression lost by boring can be made up with piston dome choice.

Depending on which way you go. Milled heads and\or high compression pistons, you may need either a cam with less lift or pistons with valve reliefs.
Also, higher compression needs higher octane.
From the factory HD recommends Premium gas.
You have a little leeway in modifications\gas used by the timing adjustment.
But would think for convenience you would want to be able to stay with pump gas. 90+ depending on what is readily available in your area.

There is a real science to building a modified engine. Everything is related to everything else.
Building a solid performance engine, mild or wild, is`t always about throwing big $$$ at it. Just using a combination of the proper parts, all designed to work together and set up properly.

There are some real good Wrenches\Builders on this site.
I have only scratched the surface. And honestly am a babe in the woods when it comes to the real in`s and out`s of properly setting up an engine.
Hopefully they will chime in.

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SCHMIDTY

· #7 · Dec 6, 2014

Stock Ironheads always worked well upgraded with "PB" cams.
A CV carb would top the list IMO.

98DARKHORSE

· #8 · Dec 6, 2014

Compression is bled off by the cam...the intake closing point is what will bleed off the compression...i have 11:1 pistons in my evo with the .030 gasket giving 11.25:1 however i can run pump fuel...this is due to proper tuning and the cam bleeding off the compression

Also boring cylinders is said to increase compression..not decrease...you are removing material from the cylinder yes but you are increasing volume...so that volume has to be compressed back into the original combustion chamber volume...now unless you are doing a huge overbore i wouldnt sweat the typical .010-.040 overbore...also i dont know how good piston company's r at factoring that into there design vs the 70s ...this is why some companys show you compression differences based on what head you are using

For a low end street cam go high 230 degrees duration mid 30s overlap ...intake closing in the mid upper 30s and lsa of 108-110

For a solid all around power go mid 240s duration. .overlap in the lower mid 40s..intake closing in the mid 40s and lsa of 107-110

Then keep cranking compression around 190-195

This will give good performance

As far as lift...use as much as ypur valve train can handle

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Fireplug

Discussion Starter · #9 · Dec 6, 2014

Ok so I picked up the motor today and im pretty sure that cams are the least of my troubles. Looks like Ill need a new set of jugs and probably a whole transmission. This motor was not complete at all! I did pick up a set of cyclinders that I was told were used for racing. They had all the fins shaved off. I have included an attatchment of them. So my next question is, where do I find a decent manual with good pics of this motor? Im just glad it only cost me a set of CB750 carbs and not cold hard cash!!

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Fireplug

Discussion Starter · #10 · Dec 6, 2014 (Edited)

And one interesting note, one piston is marked as being 050 and the other is 040. What would that do, having two different sized cylinders? Weird........ I also got a gasket kit for a 77 ironhead NIB with billet valve guide covers. Some extra stuff is always nice!

98DARKHORSE

· #11 · Dec 7, 2014

There is no real advantage to having different size bore unless racing rules only allowed a certain cc size and the guy wanted to be fair and have as close as he could get get to the limitations perhaps two .050 over pistons were technically too large...there are many reasons we could conclude...i would be concerned with the added weight be off balanced on the crank at that point

SCHMIDTY

· #12 · Dec 7, 2014

That engine looks to be a perfect candidate for a Shovester conversion.

Fireplug

Discussion Starter · #13 · Dec 8, 2014

So where should I start? Tomorrow Im taking the cases to the maintenance shop at work for a bath in varisol, I just cant stand to see them so dirty. I know Im missing allot of parts so whats my best bet for a parts list or maybe some kind of engine manual? I like to have a good reference with decent pictures to avoid any confusion!

MADMACK

· #14 · Dec 8, 2014

You are more ambitious than I. I hope you get it done as that's a cool engine. Good luck.

Hillsidecycleco

· #15 · Dec 8, 2014

We've built/re-built more of those than I can even remember.
They'll give good service once completed, if operated as intended, but it may be a bit of a financial endeavor.
Scott

SCHMIDTY

· #16 · Dec 8, 2014

I like that "financial endeavor" ... to say the least !

Badbet1

· #17 · Dec 8, 2014

I've got a couple sets of Andrews cams. Have to find them and post what they are. Think they have a good lift and duration. Have always heard the pb+ were the best for a stock to mild build. Just a note. Don't replace the cam bearings unless you find someone who can ream them. Special reamer that goes thru the case to line ream them. Having replaced mine, then trying to finding the tool was a problem. And when I did it was pretty worn out. Ended up using old cam and lapping compound to make make it fit right.

Sent from Motorcycle.com Free App

SCHMIDTY

· #18 · Dec 8, 2014

Bill's Custom Cycles is a good place to find those old obsolete hard to find Sportster parts.

Breeze3at

· #19 · Dec 8, 2014

Your engine number shows it to be a 1976, 1000cc.
Below link has a OEM parts list for the model. I find the exploded parts photos to be one of the best tools when working on my bikes.

OEM Parts Finder Granite State Harley-Davidson Lebanon, NH (603) 448-4664

Hillsidecycleco

· #20 · Dec 8, 2014

SCHMIDTYS said:
Bill's Custom Cycles is a good place to find those old obsolete hard to find Sportster parts.

Yes, Bill's.
In Bloomsburg, PA.

He has a museum that has more in it than 1 man should be allowed to legally own........haha.

Been there a couple times, but if one does not mind using imported parts(and what isn't these days?) Tedd's is a good source for that.
Drag does have some in their "Old Book".

Tolerances on those cast-iron engines are looser that today's aluminum engines, as the heat that is held via the cast iron, head and cylinder.
Scott

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