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Spitfire Spitfire pushrod drop? Lifter/ Cam??

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freespitfire

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Hello all, I'm new here, first triumph. I've got a 72 spitfire that's real stock(1300). It sat for 5 years but rebuilt the carb/pump etc and it ran pretty good. Maybe 20 miles later I started hearing a miss in the motor. Checked points and plugs but no, after pulling the valvecover a pushrod was out. Still straight not bent but not under the rocker. I bolted it back in place and turned the motor over by hand and the pushrod "pushed out" again. Am I looking at a collapsed lifter or flat cam or something? Anybody have something like this happen to them to advise me? Can I pull a lifter out with a magnet? Any ideas??
thanks all for your help
shawn
 
No experience with Spits, but I'm thinking more along the lines of broken valve spring.

Lifters are solid so can't 'collapse' like hydraulic ones can; and I don't see why a flat cam lobe would pop the pushrod off the adjuster ball.

If just turning the engine by hand will pop it off, try turning it slowly enough to see what happens when it pops off.

I'll be surprised if you can pull the lifter out without removing the head; but Andy is usually right and knows Spits much better than I do.

BTW, Welcome to the forum, Shawn.
 
Thanks for the help. I did check all the valve clearances and they all seemed fine. I should run through this whole process again tonight and see where the pushrod goes. The spring and rocker arm sure looked okay like all the others. Anything else I should look for?
thanks again
shawn
 
TR3driver said:
I'll be surprised if you can pull the lifter out without removing the head; but Andy is usually right and knows Spits much better than I do.
Click to expand...
Maybe I do, Randall...and maybe I don't. I do know that, in rereading my post, I realize I might have given that impression. My apologies.

According to the Triumph Spitfire [MkIV]Repair Operations Manual, it's very simple:

Removing

1. Remove the cylinder head 12.29.10
2. Lift out the eight cam followers and identify for reassembly.

Refitting

3. Reverse instructions 1 and 2....
 
Before you go pulling the engine apart, I think you should take a real good look at those springs. Chances are they are original. On my Herald when I took the head apart I was able to remove all 8 springs by hand. Not good. 30+ years is really more than a reasonable lifespan for a spring.

You can easily find out what the condition of the cam is without pulling the head off. Just get a dial indicator and see how much the lift (difference in height between lowest point [fully closed] vs. Highest point [fully open]) is and compare it to the other cylinders. They should all be very close. If not, pull the head, and start taking things apart.

I would be less than shocked if the springs were so weak that the valve started floating. Also, I would check the rod very carefully. If it is popping out, it probably is damaged to some extent.

If it were my car, I would 1. check the cam / lifter with an indicator. 2. replace springs and probably the rods.
 
Sounds like a good idea about the springs. I'll check them out tonite. What's the best way to test a spring and where should I get a new set?
thanks
shawn
 
Before pulling the head, I would remove the rocker-arm assembly and check it over carefully. You'll want to pull the rockers anyway if you need to pull the cylinder head.

With the rocker assembly off, see if you can pull the pushrod out. I think you should be able to. Check the end of the pushrod where it engages the rocker arm to make sure it is still cupped properly. Likewise check the ball-adjuster on the rocker arm and the rocker arm itself to make it is not bent.

Disassembling the rocker shaft is pretty straightforward. It may be worth pulling it apart to check the springs that hold the rockers in place and also to check the rockers and the rocker shaft itself. I have heard of a bent shaft causing a variety of valve adjustment problems.

With the rocker assembly off you can get a good look at the valve springs also.

Remember to make note of where each pushrod, rocker, etc. came from so you can get them back in the same order.
 
freespitfire said:
What's the best way to test a spring
Click to expand...
Usually the most basic test is to check the free length. Value should be in the book, or compare to a new spring.

A better test is to compress them to installed length and see if the force required matches the installed pressure (which should also be in the book), but that generally takes some special tools. A drill press, ruler & bathroom scale will work, if you've got a good, accurate scale. Or I believe most machine shops will do the test for cheap (maybe even free if they think you'll bring them some paid work).

Don't know the best place to buy springs, but I see TRF has a set for the Spit Mk 1-4 for $20.
https://the-roadster-factory.com/
 
My money's on a damaged pushrod, either bent or the "cup" on the end is damaged
 
This kind of sounds familiar.

My 77 Spit 1500 was making a noise last year that sounded like a rod perhaps. A quiet knock that increased with rpm. The crank bearings had been changed several months before.

After taking the motor out of the car we found that the crank was a little worn, but what was expected in a 1500. The interesting thing was the cam was badly worn. At the #8 location it was almost flat.

We had a good machine shop do a three axis valve job and inspect everything. The head appeared very good. Springs were good.

Oddly enough the #8 pushrod was bent...

I would have liked to know what caused this in order to fix it. The motor was rebuilt and now runs very well with higher compression and dual HS4’s.

I am still curious though and $2500 poorer.

Larry
 
My recommendation for valve spring purchase is Ken Gillanders at British Frame and Engine.
 
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