Well......I goofed. I set my valve lash on my solid lifter cam based on memory....memory of the wrong spec. It is suppposed to be 0.016 Intake and 0.018 Exhaust when hot. This should more or less equal 0.018 and 0.020 when cold. However, I set all valves to 0.025" cold.

Now normally I would think this can't effect performance very much, just valvetrain component longevity, however......

Reading up on all this, I find that a loose lash effectively makes the cam look smaller to the engine and that would tend to improve low-end torque at the expense of high end Hp.

BUT, a long time ago I bought a used MGB. An owner ran the engine dry of oil and the guy I bought it from re-did the engine by installing a Marina short-block. Odd thing was, I could squeal the tires from idle, but it would hardly go over 30 mph. Turned out the guy had adjusted the valves for zero lash. I put it back to British-Leyland valve lash specs and everything was fiine. Engine would rev, and of course it would no longer squeal the tires at all.

Now that MGB story goes completely against what I've read about changing valve lash. Can anybody enlighten me a bit about it?

ps: and "yes", I will be setting to proper specs soon....just curious at this point....

 

Aww your not the first to do that or be the last...LOL.. John you can actually palt with the lash at the track whenever you go and see what runs best that way...It changes the timing a tad... You can get a little more out of the big end..or a little more Tq down low..Of course we know you dont need anymore Tq..LOL

 

That does sound backwards. I myself have done Triumph TR7's in the past, quite a few of them, three or four of them for myself, and a few for others. What a pain, removing the cam to set the valve lash on an OHC motor.

Anyway, if you increase the valve lash, say .005", you are reducing the maximum valve lift by .005" multiplied by whatever the rocker-arm ratio is. For the FE, that's 1.6:1 I think? So, .005" more valve lash means .008" less valve lift at max lift.

It also means you are ramping up on a later part of the cam ramp, which may or may not be a good thing for longevity. Also, it might mean the lifters may not rotate as much, as the initial ramp on the cam initially turns the lifter. (Again, not sure how much that matters in reality, or how much the initial ramp does versus the tip of the lobe).

Back to that MGB, I suspect something else was going on there. If you advance a cam, you get more bottom end. So, reducing the valve lash not only makes the valve duration longer, but it also advances the valve opening. Depending on what it's cam specs were, that little bit of advance might have done more for low-end torque than it took away by extending the valve duration.

 

I think you've nailed it there. It could increase or decrease low end torque a bit dependant on cam profile. Guess I'll find out, though at such a small adjsutment, I doubt I'll notice anything.

Tomorrow it rains, so good day to do it, then wait overnight for the gasket shellac to dry on the valve cover gaskets.

ps: and it was quite a goof. 0.025 was the spec for Ford cams, not Crane, plus it was a "hot" spec and I used it cold. Poor ole Crane.....back in business I see, but only time will tell if they open production to their entire previous product line.

 

OK, set my lash yesterday, and put in new plugs while I was at it. Installed valve covers and let gasket shellac dry overnight.

Now, the performance test today. Well.....darn, I can't tell for sure if there was an improvement or not BECAUSE when I removed the plugs, I found a badly fouled one. More on this below (sidenote). However I am sure the plug did fire under light load, so I can say (without 100% confidence):

1/ With the tighter lash (Crane correct lash), the idle dropped. I had to turn both carb idle stop screws in a little over 1/4 turn. Best guess for this was tightening lash increased valve overlap.

2/ Low rpm power seemed snappier, but this could also have been from changing plugs. But I do believe it helped as the cam should appear more "advanced" with a tighter lash.

3/ It seems a little bit quieter (as one would expect) but hard to tell over the exhaust, even while cruising.

4/ high rpm was always great and I admit to never taking advantage of all the power available, so no difference there that I can see, but that's due to my driving style.

Sidenote:

Seeing that 1 bad plug was worriesome. I knew the engine doesn't smoke, so that was in my favour. I did a compression test and a leak-down test, and compared it to another cylinder. Identical readings. Compression test was wacky (as in very high)....after I rebuilt this engine in the spring, I got 195 psi. Now I am getting 220 psi. Must be due to rings wearing in, although I can't remember for sure if I held the throttle open during the first compression test last spring. I also checked valve rise and fall and found everyting OK in that regard.

I had an internal carb leak on the rear carb, which I recently fixed. Before I fixed it,. back four cylinders were running richer than the front four as indicated by reading the plugs. So it's possible this plug fouled due to the carb leak, and couldn't clean itself after I fixed the carb, while the others did.

But, even though I say I checked them, the truth is I never did check #4 cylinder as the plug is a bit tricky to remove/install due to the close proximity of the battery. Actually, it's getting the plug wire back on securely that's the difficulty....dont' laugh until you try it! So, the plug could have been damaged by the crossfire I was having during the humid part of summer, although I can't see a crack in the porcelin. I did test the plug on my ancient AC Delco SparkPlug checker/cleaner and it failed miserably.

This plug was one of a set of RF11YCs I installed as no RF9YCs were in stock. I did acquire 8 RF9YCs the other day, but NAPA said there was none at the warehouse so manged to get me NOS from two of there other stores.

By the way, I think Champion quality is going down hill. Check these pics:



One of those two is not like the other......top one is constructed properly



Hard to see, but threads are deformed at bottom. Note how threads converge near side electrode. Came that way. I didn't notice until I tried to install it. I guarentee I didn't cross-thread it myself, as I always use my fingers to start plugs. Of course, maybe I had Wheaties for breakfast that day.....LOL.

 

Good report Argess

 

You wouldn't factor in rocker ratio in the lift, you're already at the end of the system, at the valve- .005 is .005. If you were making a change at the cam end, then factor ratio in. Rocker ration for adjustable FE's is 1.76:1- 1.6 is the ratio for Windsor small-blocks. It will affect actual running duration- very slightly
You can play with running the lash up and down a bit, usually a tool to tell if the cam is properly sized- if it runs a bit better one way or the other, a slightly different cam would help- but the differences are minor, and more racing related where it matters more. In this case, it's going to run & behave better because it's now set up correctly, whereas before it was far enough out of spec to make it a bit unhappy

 

Gene, you are correct. I was thinking OHC for some reason where you measure the lash at the cam.

I had 1.76:1 in my head as the rocker arm ratio, but for some reason did a Google and came up with 1.6. Fooey.

 

Put either Motorcraft or Autolites in it. Chumpians are the bottom of my list.

 

A while ago here we were comparing the new Autolite 45's made over "yonder". And how crappy they are compared to the older "Made in the USA" plugs. Quite a difference. When I changed the plugs in my 390 they were older USA Autolites and still in nice shape. They looked so much better than the new plugs so they got cleaned up, gap checked and back in they went. It's just sad to see such a decline in quality across the board. I've been scrounging for old Motorcraft BF-32's without much luck. Not a fan of the Champions here either. Although I do use one in my lawnmower. LOL. I have a couple of oddball Denso plugs from Japan in my parts bin and those actually look very good quality wise. Wish I had stocked up on the 32's years ago. I could get them cheap back then.

 

Glad to hear John you got R done....As we spoke about..I use Autolites in my FE also.. I was lucky about 20 years back at a car swap meet...I bought 3 sets of 45's for $15 new in the box...and have only used 1 set all these years ..but the truck doesnt see many miles either.. I have a few sets of Chanpions down stairs..and they come in handy for weights for deep sea fishing when you run out of sinkers !!

 

AND they are more environmentally friendly than lead sinkers!

I used to use Champions in everything. Gotta check with my brother-in-law who wholesales them to the marine industry to see what his take on quality is.

Who knows, maybe there's two grades these days...

 

Got a little more road time in today. The engine is definately "snottier" with the new (and correct) lash adjustment, even taking into consideration the bad plug I had. And there's a definate "thumpiness" at idle, although it isn't much different, just noticeable.

On the Champion plugs, the NOS I just bought had "Made in Canada" printed on the little boxes. The one in the pic above with the bad threads, came in a blister type package from Canadian Tire. I can't remember when I bought the other two in the pic together, but it wasn't more than a few years ago.

I had posted the plug pics in another forum, and there was some definate thoughts on Champions being made in China these days.