Adjustible cam gear Options

[lmcchesney]

This is regarding my 96x78 rebuild project. We will be using adjusted 2.0L D-jet FI system and gave up trying to find the ultimate cam. I went with the Web Cam 73 grind and lifters. My mechanic, Denny @Autocraft Engines, said he cannot obtain the best cam advancement with the stock cam gear and suggests to go with an adjustable stright cut cam gear. The costs approx. $260.
Question:
1. When I use the timming on my simulator for a 73 grind I am using 0.05 lift and 224° duration and intake centerline of 103° and lobe center angle of 108° with +5° advance. Are these correct?

2. Are all adjustable cam gears stright cut?

3. Who is the best source to obtain the cam gear from?

4. If you use a stright cut cam gear, do you not need a stright cut crankshaft gear?

Thanks,

L. McChesney

[Bleyseng]

Straight cams are loud too, do you want that buzzing noise?
Just use the stock cam gear with the Web73 install new bolts and spotface them.

Geoff

[machina]

I have heard (read) that these straight cut gears are garbage, not made well.

And I don't think they really free up any power.

Maybe Jake will weigh in.

dr

[Brad Roberts]

Your having the guy's from AutoCraft help you build your engine ?? The flat 4 alcohol guy's ???

There used to be a company called "Dial-A-Cam" back in the late 80's early 90's that had exactly what they are asking for. I also bought two straight cut cam gears with adjustable shims from a place in Oregon.. then found out who made them for them.

B

[Bleyseng]

I remember Dial-A-cams.

[Aaron Cox]

brad were they MSHS gears?

[415PB]

Straight cams are loud too, do you want that buzzing noise?
Just use the stock cam gear with the Web73 install new bolts and spotface them.

Geoff

I agree with Geoff. I did this last year. I pressed the rivets out of my stock cam gear and re-used it on my 73 cam. When I mocked up the cam and oil pump, the bolts were hitting the oil pump. I had to spot grind all bolts, but it worked out just fine.

[Jake Raby]

Dial in cams became logic cam in the 90s..... They made the gears for MSHP.

I have seen so many sets of elliptical cam gears that I absolutely quit using them.

Alot of them are not round, and its hard to measure them to see if they are. The only way I have been able to do it is by putting a smal bit of lapping compound on them and running them together in my lapping fixture. Then take it apart and clean them up and start looking for consistency of the lapped areas.. If its not consistant, they are not round.

I have seen a single engine snap off three cams before the owner finally listened and threw his away.

I'd like to know what autocraft is looking for with the cam timing.... I still don't think that the 73 with timing change or not is the correct cam for what you are building.

[lmcchesney]

Thanks Guys,

I agree Geoff. I do not wish to use straight cut gears. I would not look forward to the high pitch whine and they do not last as long. Why could the standard gear that came with the Web Cam be altered to make the advancement?

Brad, there are two AutoCraft groups it seems. There is the Mike Seymour group in Marlboro, Mass. And another in Toledo ran by Denny McNutt. Denny has been building T1/T4 racing engines for many years and known locally.

Jake, I find no listing for logic or MSHS camshafts.
I realize that you do not believe that the 73 cam will not be the best cam. Geoff relates good success with the 73 in his 2056 T4. I tried to work with John of Eagle cam without success. I would like to find a cam with a 260-265°duration split with a prolonged exhaust duration or lift. I believe that combination would work.
Denny said he needed more advancement to hold on to the low end torque.

Thanks,
L. McChesney

[Jake Raby]

You need split duration... I have a 73 based split duration cam that works well, but still has alot of cylinder pressure... Less than a straight 73 but more than I like for efficiency.

Geoffs engine is a 2056, not a 2270... That extra 6mm of stroke changes everything, including the dwell time at TDC and BDC with the longer stroke. With the stock length rod the piston speed increases with the added stroke.

You have many things against you in this endeavor.

MSHP used to be Mark stephens High Performance- they have been out of biz for 4 years now or so.

[Bleyseng]

Touch or buy nothing that came from MarkStephens!

[Brett W]

Guys I gotta weigh in on this. I am running striaght cut cam gears in my street motor. They are loud, they sound cool as hell, they get old on a road trip. I got my gears from FAT back in the day and they are made by Pauter Machine. The gears are cut from billet and are extrememly well made. I have never had a problem with them I will probably run them in a 1911 I am kicking around.

AS Far as MSHP goes, I had them do a set of heads and they were Alright I ran them for 17k miles and they now need guides, but other wise they seem ok. I will probably fix them and run them again. as they have good port work, (did that myself).

I talked with Bob at Logicam a couple of times and he was nuts. Said something about building some sort of Pikes Peak record 914-4. I think I still have the info he faxed me. His info request sheet is awesome, two pages of info about your setup to pick the right cam.

[Bleyseng]

I don't have anything against the straight cut cam gears other than the noise. If you don't mind it ok. 914's are loud enough in IMHO.

I do think at one time MS did okay work but lots of people got ripped by him and I do know a few.

Geoff

[lmcchesney]

Thanks Guys,

Jake, is the split duration cam available to purchase from you? I would much rather go with a split duration cam to prolong exhaust duration/lift. I have not seen one on the aircooled site. Would you give us some guidance here?

Thanks,
L.McChesney
lamcchesney@netzero.net

[lmcchesney]

Some threads relate to adjustable cam gear failure. Thus far, my understanding is the following regarding adjustable cam gears:
Stright cut adjustable gears can be made of steel or Al.
Stright cut adjustable gears produce a high pitched sound at higher RPM's.
Helical cut adjustable gears do not make the high pitched sound.
Helical cut adjustable gears are made of Al.
Al. gears have reports of breaking under load.
Steel gears do not seem to break.
Does anyone not agree?
Adjustable cam gear vs stock non adjustable cam gear:
56 teeth/360° gear = 6.4°/tooth.
Five bolt patern = 11.2 teeth per 72° sector.
Since you cannot have 11.2 teeth the teeth do not align on the same degree spot on each sector and thus each sector is 0.2 x 6.4° = 1.28° diffenerce in the teeth arranged on each sector.
Thus, to obtain 1.3° adjustments, you use different sectors to mount the cam gear.
Thoughts/Comments?
Thanks,
L. McChesney

[Mark Henry]

IMHO I don't think an adjustable cam gear will do anything for you with your engine spec.

I've never had a stock modified german Al gear fail on me, but I have seen old cams with loose rivets.

[ChrisFoley]

The 5 bolts that hold a cam gear on are not evenly spaced. Therefore it is not possible to move the gear to another position on the cam in order to alter the timing.

[kdfoust]

The 5 bolts that hold a cam gear on are not evenly spaced. Therefore it is not possible to move the gear to another position on the cam in order to alter the timing.

I'll be damned, you're right!

I'd send the cam and gear to a machine shop (assembled) and have a 1.9" or 2.0" BC with 5 holes drilled on a even pattern. It'll probably cost no more than the straight cut gear and be a heck of a lot more civilized to listen to.

[lmcchesney]

Guys,
If we redrill the mounting holes to equal sectors, will that excessively weaken the cam/cam gear interface?
L. McChesney