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high ratio rocker arms plain bushed...

Posted by dukeodray

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high ratio rocker arms plain bushed... #1
dukeodray david reynaud fargo, nd, USA	Posted: April 12, 2012 02:09PM Registered: 1 year ago Posts: 14

Hi,

Anyone know a source for 1.6: 1 rocker arms without the neddle rollers? I've read many places, including P.Burgess' book, that shaft rollers wear out fast, but that the high ratio rockers with plain shaft bushes hold up well.

Thanks,
Dave

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Re: high ratio rocker arms plain bushed... #2
the omega man phil wilkins staffordshire, United Kingdom 1973 MG MGB GT	Posted: April 12, 2012 04:21PM Registered: 2 years ago Posts: 1,697

Hello David,I do not know a source for the arms.But I was interested to know what gains you would get with high ratio arms over a set of standard arms.

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Re: high ratio rocker arms plain bushed... #3
Steve64B Steve Opitz Phoenix, AZ, USA 1966 MG MGB	Posted: April 12, 2012 05:11PM Registered: 6 years ago Posts: 8,347

David... who's rockers do you have?

First place I'd look would be the manufacturer.

I know in Phoenix there's a speciality shop that does noting but bearings... it might be a little tougher in Fargo, but Chicago must have something!

You could start by going to the Oilite site, or at McMaster/Carr which is a master distributor, but my guess is knowing a good machinist will be very helpful.

Edited 1 time(s). Last edit at 04/12/2012 05:45PM by Steve64B.

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Re: high ratio rocker arms plain bushed... #4
dukeodray david reynaud fargo, nd, USA	Posted: April 12, 2012 07:19PM Registered: 1 year ago Posts: 14

Hi Phil,

I've read in Peter Burgess' book, How to Power Tune MGB 4 Cylinder Engines that the gain can be as high as 10%.
In his Power Recepies chapter, Burgess cites one car in particular, that had a 9 BHP gain, using high ratio rockers. They come in 2 types, a simpler, much less expensive,( several hundred dollars), configuration, that does strain the valve train components, because of the geometries that it posesses. The other much more costly type,($1200-$1700), that has far better geometries, which put much less strain on the valve train. This better type relocates the rocker shaft further away from the valve tip, about .070" and keeps the pushrod closer to the original more vertical angle; this puts less side load on the lifters and valve stems. On this better version, the contact half of the arm is longer, causing less wear on the stems.

So why spend so much on HRRs to get more lift, lift that can be achieved with a performance cam, that costs far less? The answer is, that a higher lift cam gives more lift, at the expense of increased duration, which is not always desirable in a street engine. More duration, along with high lift reduces cylinder pressure at lower rpm, where a street car tends to operate. With a higher lift cam, power increases occur mostly at higher rpms. HRRs increase lift without significantly increasing duration. This gives the engine higher torque, and more power througout the entire rpm range, not just the upper end.

I haven't purchased a HRR set, but just wondered if anyone knew of a source for bushed, not roller bearing HRRs.

Thanks for your interest Phil,
Dave

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Re: high ratio rocker arms plain bushed... #5
pinkyponk Adrian Page Nova Scotia Canada, Canada 1971 MG MGB GT 1973 MG MGB MkIII	Posted: April 13, 2012 07:46AM Registered: 2 years ago Posts: 2,737

Harland Sharp make HHRs with plain bushings. I also found someone who offer modified stock rocker arms with offset bushings to increase the ratio. I'll see if I can find them again.

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Re: high ratio rocker arms plain bushed... #6
MG David David Witham Warwick, United Kingdom	Posted: April 13, 2012 08:23AM Registered: 1 year ago Posts: 118

If you use offset bushes in the rockers and bore the pedistals to take the same rotated 180 degrees you will maintain the push rod angle and hammer position over the stem.

I am not sure how easy it is to buy offset bushes though. You might have to get a machine shop to make them for you.

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Re: high ratio rocker arms plain bushed... #7
Speedracer Hap Waldrop Greenville, SC, USA 1967 MG MGB "The Biscuit"	Posted: April 13, 2012 09:01AM Registered: 7 years ago Posts: 20,334

On my MGB race engine I have Titan 1.625 roller rocker arms, Fred got them from Brown nad Gammon in the UK, $530 delivered to his door, a year ago, they are bushed on the shaft, and this drasticly reduce the cost of the Titan RR arms, Titan makes bushed version of their roller rocker arms for Mini Spares for the A series engine, and Brown and Gammon for the B series engine, a needle bearing on the shaft of the regular Titans, make the price alot higher as I mentioined, but there's no reall good real reason to have a needle bearing here to begin with. Now I will tell you this, we had to wait about 3 months to get the 1.625 ratio Titan set up from B&G, but it was worth the wait, it is a complete assembly even has lovely aluminum solid sapcer on it, and nice correct ratio pedestals, it been on the race engine for over a year now, and performing flawlessly.

Hap Waldrop
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Re: high ratio rocker arms plain bushed... #8
BumbleB74 William Milholen Tidewater VA, USA	Posted: April 13, 2012 09:09AM Registered: 7 years ago Posts: 4,645

Hap....any real benefit on a stock type street engine?

1974-1/2 Roadster, "Bumble Bee", Corvette Yellow - in shambles, wire wheels
1976 Roadster, un-named, Sandglow - "driver" condition (stock + 32/36 Weber DGEV, cast iron header, 25D distributor), bolt on wheels

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Re: high ratio rocker arms plain bushed... #9
Winston Shift Right David Crosby Lone Tree, Colorado, USA 1953 MG TD "Martha Ann" 1980 MG MGB	Posted: April 13, 2012 09:20AM Registered: 4 years ago Posts: 426

I got mine here...
http://www.aptfast.com/ShowItem/100077%20Offset%20%20Rocker%20Bush%20-%20%27B%27%20Series.aspx

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Re: high ratio rocker arms plain bushed... #10
pinkyponk Adrian Page Nova Scotia Canada, Canada 1971 MG MGB GT 1973 MG MGB MkIII	Posted: April 13, 2012 09:48AM Registered: 2 years ago Posts: 2,737

In reply to # 2038985 by Winston Shift Right I got mine here...
http://www.aptfast.com/ShowItem/100077%20Offset%20%20Rocker%20Bush%20-%20%27B%27%20Series.aspx

Hey... nice find. Any report on what difference they make?

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Re: high ratio rocker arms plain bushed... #11
Winston Shift Right David Crosby Lone Tree, Colorado, USA 1953 MG TD "Martha Ann" 1980 MG MGB	Posted: April 13, 2012 10:09AM Registered: 4 years ago Posts: 426

In reply to # 2039019 by pinkyponk

In reply to # 2038985 by Winston Shift Right I got mine here...
http://www.aptfast.com/ShowItem/100077%20Offset%20%20Rocker%20Bush%20-%20%27B%27%20Series.aspx

Hey... nice find. Any report on what difference they make?

Holy Crap! I step on the accelerator and I am slamed back in my seat eye popping smiley

OK... Really I might be able to sense something weather it is just a placebo or not. It has to do something to give that engine some more HP like Peter says smiling bouncing smiley

. It sure won't take HP away.
You have to ream the bushings or have them reamed once you press them in and then there is the discussion as to weather the oiling holes should be drilled or not confused smiley

.
And why did the engineers design a little resivoir in the original bushings? To keep a little oil in the bushing for start up before pressure builds up confused smiley

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Re: high ratio rocker arms plain bushed... #12
spikemichael Michael Caputo Athol, MA, USA 1973 MG MGB 1973 MG MGB "Freebie" 1976 MG MGB "B-4" 1979 MG MGB "MegaBeanie" 1989 Suzuki Intruder 800 → more	Posted: April 13, 2012 10:27AM Registered: 4 years ago Posts: 6,790

I would trade 10 HP for 10 lbs of torque any day.

Saw the offset Rocker Shaft Bushes, not exactly sure why they have to be offset like that rather than just thicker walled.
How I do you make them line up perfectly.
Interesting idea though.

How much lift do you gain?

Michael J. Caputo
'79 RBB and '73 CBB owner with extensive experience in 12v Audio System design and installation.
Vendor of Regalia and Promotional Products. Forum Member with a warped sense of humor.

Edited 2 time(s). Last edit at 04/13/2012 10:38AM by spikemichael.

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Re: high ratio rocker arms plain bushed... #13
pinkyponk Adrian Page Nova Scotia Canada, Canada 1971 MG MGB GT 1973 MG MGB MkIII	Posted: April 13, 2012 10:39AM Registered: 2 years ago Posts: 2,737

Here's a link to the ones I found. http://www.crateparts.com/rockers.html

They seem to claim about 3 hp increase from what looks to be about a 35 thou offset.(just me guestimating)

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Re: high ratio rocker arms plain bushed... #14
dukeodray david reynaud fargo, nd, USA	Posted: April 13, 2012 03:06PM Registered: 1 year ago Posts: 14

Hi Hap,

Thanks for your reply. Are you saying that Brown and Gammons sell the Titan RRs bushed, not fitted with roller-bearings, and with off-set shafts, complete with pedestals? smileys with beer

Thanks,
Dave

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Re: high ratio rocker arms plain bushed... #15
Winston Shift Right David Crosby Lone Tree, Colorado, USA 1953 MG TD "Martha Ann" 1980 MG MGB	Posted: April 13, 2012 05:27PM Registered: 4 years ago Posts: 426

In reply to # 2039063 by spikemichael I would trade 10 HP for 10 lbs of torque any day.

Saw the offset Rocker Shaft Bushes, not exactly sure why they have to be offset like that rather than just thicker walled.
How I do you make them line up perfectly.
Interesting idea though.

How much lift do you gain?

When I bought them from APT I asked Dave how to line them up and he said,"It's not critical". But I measured and marked them before I pressed them in so they would all be lined up the same as close as I culd get them.

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