Adjusting valves

[Rex T.]

What is the best and least messy method for adjusting the valves on a 427-390 hydraulic flat tappet camshaft? The engine was "supposedly" pre-adjusted when I got it and once it was started, it ran very poorly. Can the rocker arm nuts be adjusted an additional 1/2 turn once the slack is removed from the rocker arms for adequate adjustment? They were all loose when I removed the valve cover and checked. As always, thanks in advance for your help. Rex

[Clem Z.]

Re: Adjusting valves

What is the best and least messy method for adjusting the valves on a 427-390 hydraulic flat tappet camshaft? The engine was "supposedly" pre-adjusted when I got it and once it was started, it ran very poorly. Can the rocker arm nuts be adjusted an additional 1/2 turn once the slack is removed from the rocker arms for adequate adjustment? They were all loose when I removed the valve cover and checked. As always, thanks in advance for your help. Rex

use the the system in the chevy shop manual that does it in 2 steps using the TDC location

[Martin N.]

Re: Adjusting valves

REX-
I would second Clem's suggestion. I just finished my 74 valve adjustment this weekend as per the shop manual and it sounds and runs just great with no mess.

Marty

[Rex T.]

Re: Adjusting valves

Of course..............the old faithful Chevy Shop Manual. I failed to look there. Got it!! Thanks guys ....................... have a great day and an even better tomorrow. Rex

[Rex T.]

Re: Adjusting valves

Wellllllllllllllllllllllllllllllllllllllllllllllll lll............I'm obviously doing something wrong. I've been adjusting and moving the distributor all afternoon, all to no avail. I've adjsuted the valves per the Chevy Shop manual, removed the distributor and rotated it 180 degrees, adjusted valves, removed distributor and rotated 180 degrees...................still no luck. This is a new engine and supposedly the engine was pre-adjusted to just fire right up. Well, when I finally did get it fired about a month ago, it ran, but very poorly. I ran it about 20 minutes to break in the new cam. At that time, I just thought the valves needed a final adjustment and I would get to that a little later. Well, a little later is now and now I'm beginning to wonder how the engine started at all a month ago, and if I may have damaged the cam.

I'm open to suggestions. Thanks, Rex

[Martin N.]

Re: Adjusting valves

REX-
You do not rotate the distibutor 180 degrees, you rotate the engine 180 degrees. You'll need to get #1 piston @ TDC on the compression / firing stroke, re-install your dist. to #1 firing position and start over from the manual. If you have a fax machine I could fax you my pages from the service manual, maybe they changed in ease of explanation over the years.

Marty

[Tom H.]

Re: Adjusting valves

Hopefully you didn't flatten a cam lobe during break in. Don't ask me how I know this !

What kind of oil was in the engine when it was test run ??

[Duke W.]

Re: Adjusting valves

As a first step I suggest spending some quality time with your CSM and COM.

The first thing to look at is distributor installation, then verify that the spark plug wiring is correct in the distibutor cap. The one thing the books won't tell you is that the dist. drive gear dimple should be pointed the same direction as the rotor tip. I'm not absolutely sure if this is the case with big blocks, but it's definately the case with small blocks.

Also, the CSM will probably say to index the engine at #1 TDC for distributor installation. I use the initial timing setting rather than TDC. Once the distributor is properly installed, turn it until the points just begin to open. You can use an ohmmeter for best accuracy, and the initial timing should be within a degree of spec, which will facilitate rapid startup.

Too many guys just start throwing things together, and this includes some "professional engine builders". Then if there's a problem they start changing things helter skelter. That's the "bubba way". Go back to GO and start over using the GM published procedures in the books.

The best time to adjust hydraulic lifters is before they are full of oil. Just install them with some oil on the lifter surfaces and lifter bores.

Without oil inside, the lifters will easily compress the plunger spring to whatever preload you choose. Then you can "preoil" the engine by turning the oil pump while rotating the engine, which will fill up the lifters.

Duke

[Rex T.]

Re: Adjusting valves

Thanks Duke and everyone else who chimed in. Here is the story.......a friend of mine brought this car to me to get the engine running. It's a 67 427-400, already installed in the car. He told me "everything is ready to fire up, engine is freshly rebuilt by a competent rebuilder, all you have to do is set the timing and it should fire right up".

First problem..........it's a little difficult to set the timing when there is NO timing tab on the front cover. Second problem, he says "I am CERTAIN that the rebuilder installed a flat tappet hydraulic version of the L-88 cam". Hmmmmmmmmmm, the plot thickens.

So, I am finally able to get the engine started and it runs very poorly. I adjusted the timing so the engine would start and not diesel when shut off, but it still ran poorly and the valves were clattering. At this point I asked the DB members about adjusting hyd valves. Upon making the adjustments per the Chevy Shop manual, the enigne would not start at all and sounded very unusual when cranking over. I did this several times over a 2 day period and finally I decided to just back the valve adjustment off to about .020 clearance. The engine sounded much better when cranking over, but still would not start. Yep, it's getting plenty of fuel and spark at the plugs. So it should fire....right?

Since I know nothing about the internals of the engine and if the timing gears are set correctly and I don't know exactly what type cam is in it, I am back to you guys for suggestions. Sorry to be a pain in the ankle, but I am somewhat perplexed, to say the least. If it's truly a hydraulic cam, the rockers should have no valve lash.

Anyone..........everyone.............suggestions (other than telling this guy to take the engine back to his rebuilder)? Thanks in advance for your help. Rex

[Timothy B.]

Re: Adjusting valves

Rex,
I would think the distributor is not correctly installed. Pull #1 plug and bump the engine until compression is felt with your thumb then bring crankshaft to align balance marh with timing mark TDC. Install the distributor per the shop manual (rotor pointing to #1 on cap and indexed so the tach drive cable will install properly). If there is no timing mark on the timing cover then you need to find exact TDC and mark this then measure balancer and time total timing at 36* (info in archives)

[Duke W.]

Re: Adjusting valves

Thanks Duke and everyone else who chimed in. Here is the story.......a friend of mine brought this car to me to get the engine running. It's a 67 427-400, already installed in the car. He told me "everything is ready to fire up, engine is freshly rebuilt by a competent rebuilder, all you have to do is set the timing and it should fire right up".

First problem..........it's a little difficult to set the timing when there is NO timing tab on the front cover. Second problem, he says "I am CERTAIN that the rebuilder installed a flat tappet hydraulic version of the L-88 cam". Hmmmmmmmmmm, the plot thickens.

So, I am finally able to get the engine started and it runs very poorly. I adjusted the timing so the engine would start and not diesel when shut off, but it still ran poorly and the valves were clattering. At this point I asked the DB members about adjusting hyd valves. Upon making the adjustments per the Chevy Shop manual, the enigne would not start at all and sounded very unusual when cranking over. I did this several times over a 2 day period and finally I decided to just back the valve adjustment off to about .020 clearance. The engine sounded much better when cranking over, but still would not start. Yep, it's getting plenty of fuel and spark at the plugs. So it should fire....right?

Since I know nothing about the internals of the engine and if the timing gears are set correctly and I don't know exactly what type cam is in it, I am back to you guys for suggestions. Sorry to be a pain in the ankle, but I am somewhat perplexed, to say the least. If it's truly a hydraulic cam, the rockers should have no valve lash.

Anyone..........everyone.............suggestions (other than telling this guy to take the engine back to his rebuilder)? Thanks in advance for your help. Rex

Yeah, every "engine builder" is "competent", and everyone who has an engine rebuilt claims the guy who did it is "competent". A vast body of evidence proves otherwise. In this case the lack of a timing tab is exhibit #1.

The L-88 cam, other than being completely unsuitable for a road engine (exhibit #2), is a mechanical lifter type. So the first thing you need to do is verify what cam is installed. Review all the paperwork and talk to the "engine builder".

Unfortunately you've gotten yourself involved in a typical "engine rebuild" kluge. It sounds like a disaster in progress. If it were me, I would offer some suggestions to the owner, but avoid any direct involvement. Been there, done that. It's a black hole.

Duke

[Floyd B.]

Re: Adjusting valves

I have to agree with Duke. It sounds like you can't know what was done by this "competent" engine re-builder. The only way to know is to open it back up and see what's under the covers. Ugh!