MG Midget Forum
Crank pulley
Posted by wakeskate10
Crank pulley
#1
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wakeskate10
Joe N
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Topic Creator (OP)
Mar 1, 2015 11:21 AM
Joined 13 years ago
114 Posts
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See the attached picture, I was having a small engine leak somewhere on the front end of my motor. I was going to replace th timing cover gasket and upon removing the crank pulley I discovered a crack on the side that is inside the timing cover. Surprisingly the oil seal, is still in good condition. I am guessing that was where my oil was leaking out of? I already ordered a new crank Pulley.
Edited 1 time(s). Last edit at 2015-03-01 11:22 AM by wakeskate10.
Edited 1 time(s). Last edit at 2015-03-01 11:22 AM by wakeskate10.
tomshobby
Tom Smith
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Mar 1, 2015 12:16 PM
Joined 14 years ago
1,881 Posts
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Mar 1, 2015 05:09 PM
Joined 13 years ago
5,849 Posts
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A 1974 should have a harmonic balancer. Thats a special crank pully thats got a cast iron outer ring thats isolated from the center piece with rubber. Its designed to reduce the vibrations and smooth out the engine (thereby reducing stresses). Basically, when a cylinder fires, the engine speeds up, but the compression and intake strokes slow the piston down. As the engine turns it gets a boost every 1/2 rotation, and somwhere between tdc and bcd it slows down. The harmonic balancer acts as a sort of shock absorber.
Seth Jones
1971 MG Midget
www.SpridgetGuru.com
Seth Jones
1971 MG Midget
www.SpridgetGuru.com
omahawg
Dallas Tipton
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Mar 1, 2015 05:59 PM
Joined 11 years ago
555 Posts
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Mar 1, 2015 07:10 PM
Top Contributor
Joined 15 years ago
4,501 Posts
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Seth, I assume you do realize that pulley, with the crack in it, is the correct, original-type harmonic balancer? My first call, for a replacement, would be to Scott Harper of Team Triumph British Automotive, in Warren, OH. Scott will have a good, used one on hand for a lot less money than a new one.
Dallas, yes, there are light-weight pulleys available, but the factory put that chunk of iron (harmonic balancer) on there for good reason. Not worth the cost & effort to replace it with some lightweight pulley that will have no effect on engine performance, but which may lead to other "issues" as the miles build up.
Before changing to any lightweight pulley, I'd check with someone like Hap Waldrop and get his input on the subject. Hap will have plenty of actual experience with such modifications and can tell you the pros & cons of them in relation to your particular engine and driving style.
Joe, you will want to replace that seal, as well, even if it "is in good condition" when viewed with the naked eye. That fracture, on the crank pulley hub, will have done some damage to the seal, in all probability.
Dallas, yes, there are light-weight pulleys available, but the factory put that chunk of iron (harmonic balancer) on there for good reason. Not worth the cost & effort to replace it with some lightweight pulley that will have no effect on engine performance, but which may lead to other "issues" as the miles build up.
Before changing to any lightweight pulley, I'd check with someone like Hap Waldrop and get his input on the subject. Hap will have plenty of actual experience with such modifications and can tell you the pros & cons of them in relation to your particular engine and driving style.
Joe, you will want to replace that seal, as well, even if it "is in good condition" when viewed with the naked eye. That fracture, on the crank pulley hub, will have done some damage to the seal, in all probability.
tomshobby
Tom Smith
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Mar 1, 2015 07:39 PM
Joined 14 years ago
1,881 Posts
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To get some understanding of what a damper does this is a good start.
Damper white papers
I had the damper for my Midget rebuilt. Not all that expensive and I feel it is very much worth the cost, especially with all the time and money we pour into these cars to get them to run correctly..
Tom Smith
1974 Midget
1976 TR6
Damper white papers
I had the damper for my Midget rebuilt. Not all that expensive and I feel it is very much worth the cost, especially with all the time and money we pour into these cars to get them to run correctly..
Tom Smith
1974 Midget
1976 TR6
Mar 1, 2015 09:24 PM
Top Contributor
Joined 15 years ago
4,501 Posts
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Good stuff, Tom!
Speaking of harmonic dampers/balancers, the addition of one, on the Freddy Baker-driven Jaguar E-Type that beat all the Corvettes for the B-Production Nat'l Championship (or was it: beat all the Datsuns for the C-Production......) around '82-'84, was the difference between a reliable, high-reving, big horsepower engine and an also-ran. Yeah, they couldn't get the engine to rev high enough to produce the horsepower they needed until they found the right harmonic balancer to keep the crankshaft under control.
I used to watch that car run at Nelson Ledges and it was truly impressive. Nothing in it's class could come close to it.
BTW, Tom, where did you have your Midget's harmonic balancer rebuilt?
Speaking of harmonic dampers/balancers, the addition of one, on the Freddy Baker-driven Jaguar E-Type that beat all the Corvettes for the B-Production Nat'l Championship (or was it: beat all the Datsuns for the C-Production......) around '82-'84, was the difference between a reliable, high-reving, big horsepower engine and an also-ran. Yeah, they couldn't get the engine to rev high enough to produce the horsepower they needed until they found the right harmonic balancer to keep the crankshaft under control.
I used to watch that car run at Nelson Ledges and it was truly impressive. Nothing in it's class could come close to it.
BTW, Tom, where did you have your Midget's harmonic balancer rebuilt?
tomshobby
Tom Smith
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Mar 1, 2015 11:11 PM
Joined 14 years ago
1,881 Posts
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Mar 2, 2015 04:34 AM
Joined 13 years ago
5,849 Posts
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In reply to # 2930649 by omahawg
I've wondered but never really put any research time in. Is there a light weight pulley available for the a series?
Yes. The 948 and 1098 just had a pulley, the vibrations got bad enough on the 1275 that they switched to a harmonic balancer.
In reply to # 2930707 by purpleGT
Seth, I assume you do realize that pulley, with the crack in it, is the correct, original-type harmonic balancer?
yeah I saw that, but op said pulley.
Seth Jones
1971 MG Midget
www.SpridgetGuru.com
Edited 1 time(s). Last edit at 2015-03-02 04:34 AM by AmishIndy.
Re: Crank pulley
#10
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Speedracer
Hap Waldrop
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Mar 2, 2015 05:58 AM
Top Contributor
Joined 17 years ago
43,606 Posts
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In reply to # 2930649 by omahawg
I've wondered but never really put any research time in. Is there a light weight pulley available for the a series?
Yeah Romac, made in Australia, You can get a all alloy unit, Seven Enterprises in the US may carry it in stock, expect to pay around $300 for it. BWR (Brian Waters Racing) make some harmonic balancers too, knowing Brian, probably the trickiest balancer for A series on earth and probably pricey as well. You can get any trick part you can dream up for A series engine, just pricey.
Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com
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