Engine idles rough in "Drive" but fine in neutral or park...

[xgecko]

The intake is only $600 or so, what's the big deal? That said, I do strongly suggest that it is worth the money if you are going to redo the motor anyway. Save for bit longer if need be; you will not regret it. Of course, most of my basis for my claim is the sheer coolness of it as well as the option for port fuel injection and the integrated square/spread bore flange. It also eliminates the dreaded heat crossover that inevitably cooks your oil.

As for the heads, they come ready to burn unleaded. Have your heads been modified or do you simply add lead substitute when you fill it up? If you have the money I personally think it is well worth it when you consider the cost of a full head workover.

Disclaimer: I make no warranty with respect to my own personal sanity, esp. when it comes to these cars...

[Twilight Fenrir]

The intake is only $600 or so, what's the big deal? That said, I do strongly suggest that it is worth the money if you are going to redo the motor anyway. Save for bit longer if need be; you will not regret it. Of course, most of my basis for my claim is the sheer coolness of it as well as the option for port fuel injection and the integrated square/spread bore flange. It also eliminates the dreaded heat crossover that inevitably cooks your oil.

As for the heads, they come ready to burn unleaded. Have your heads been modified or do you simply add lead substitute when you fill it up? If you have the money I personally think it is well worth it when you consider the cost of a full head workover.

Disclaimer: I make no warranty with respect to my own personal sanity, esp. when it comes to these cars...

I doubt very highly my valve seats have been hardened, beyond potential work-hardening. Jusy a valve job would be a pittamce, but the hardened seats bump me up. I was hesitant to buy them when I thought that the $800 pricetag was for a pair! So i'm not too thrilled to shell out double that. I dunno, i'll see what's actually wrong first, and go from there.

It could still be a bad carb mounting gasket I used the same one after I rebuilt my carb. O'reily's kept pushing back the arival, so I just said to hell with it.

Or, maybe just adjusting lash out of the valves... I'll find out tomorrow, or sunday.

[xgecko]

Might indeed be the carb gasket were it not for the particulars of your vacuum signal. Carb gasket is easy to deal with so should be verified, but the particular signal you have implies a valve problem.

Got a question for you... How do you plan to adjust the lash in a non-adjustable hydraulic lifter?

I found that prices ranged from possiblyl as low as $600 to as much as $1,000 or more to do a proper head workover. I decided that given the amount of work involved and the length of time I hope to have the car it was well worth the investment, but as always my value system is unique to me so your choices may differ and for very good reasons.

Good luck tracking down your issue; I am in the middle of my own fight with the opposite end of things; I am installing the newly machined exhaust manifold and crossing my fingers to hope it does not leak like it was...

[Twilight Fenrir]

Might indeed be the carb gasket were it not for the particulars of your vacuum signal. Carb gasket is easy to deal with so should be verified, but the particular signal you have implies a valve problem.

Got a question for you... How do you plan to adjust the lash in a non-adjustable hydraulic lifter?

I found that prices ranged from possiblyl as low as $600 to as much as $1,000 or more to do a proper head workover. I decided that given the amount of work involved and the length of time I hope to have the car it was well worth the investment, but as always my value system is unique to me so your choices may differ and for very good reasons.

Good luck tracking down your issue; I am in the middle of my own fight with the opposite end of things; I am installing the newly machined exhaust manifold and crossing my fingers to hope it does not leak like it was...

Sorry, I meant on the rocker arms, not the valves themselves With any luck, there's a loose rocker that's making the valve stick. Otherwise, I'll remove the intake and change out the hydraulic lifters since I know one of them was sticking. If that doesn't work, I'll turn on the cyl head.

[xgecko]

Hmm... I meant the same thing either way as the valvetrain is non adjustable...

You might want to check as to the viability of replacing a single lifter... not sure it is a viable option. I never really looked into it and I suspect that the cam and lifter need to break in together or you risk flattening either the cam or the lifter. If your bottom end is solid it might be much better to replace the cam and lifters as a set; I can strongly recommend the Mondello JM 18-20 cam as being just right if you are not willing to deal with a more agressive cam; I know from experience as well as the 112 degree lobe seperation that this cam is very strong while supporting vacuum power brakes just fine. Of course, as you know, I much prefer the hydroboost now so for me this is a non-issue.

Good luck with it either way!

[Twilight Fenrir]

I would replace all the lifters if I did so... I really don't want to fidget witht the cam if I don't have to. I cant tell you how much i'd like not to have to remove the engine... I have everything I need to do it, but still...

How are they non-adjustable? There's a nut that holds the rocker in, which can be too loose, isn't that what gives you lash? I know alot about engine theory, but i'm a bit shy on specifics...

[xgecko]

If you replace the lifters you have to replace the cam at the same time as you will end up replacing it anyway a few hundred miles later when it is flat... Flat Tappet (non-roller) cams and lifters must break in together; they produce unique matched wear patterns in the first twenty to thirty minutes of runtime. With flat tappets you have to add a ZDDP additive to modern oils to make sure this happens properly and run the engine for 20-30 mins at 2,000 to 3,000 rpm with a steady variation in the engine speed between these limits. There are many articles on the subject but this one is a good read:

http://www.carcraft.com/howto/ccrp_0702_break_in_new_cam/index.html

The valvetrain is non-adjustable because the rocker arms are mounted on a fixed pedestal that you torqe the rocker arm bracket to. No adjustability whatsoever. Look at the shot first below to see the rocker arm hold-downs which bottom out on the pedestal when you torque them down. Where the rocker arm brackets have bolts, the bolts simply bottom the brackets out on the pedestal. Either they are fully tightened down properly or they are loose which is not a good thing at all.

When I bought the new Edelbrock heads and the accompanying roller tip rockers (final image) it is clear what the difference is. The new heads have a stud where the pedestal pad (see second to last image below) is and you have to adjust each rocker arm by making sure the lifter is on the root of the cam when you tighten the bolt to the point where there is no more lash and then you turn it one additional half turn. Very different procedure.

[Twilight Fenrir]

Would bad valves smooth out when the RPM's went up? I mean, after it gets out of idle, and the car gets moving a little bit, the engine runs just beautifully. When at cruising speed, I really have to listen hard to hear the engine running at all, and the entire car runs smoother than any vehicle I've ever owned. I realize there's almost no load on an engine cruising though, so it probably doesn't help me optimistic for too long... but still, a valid question

[Twilight Fenrir]

I just looked up what causes sticking valves, and apparently it's mostly junk building up. Which, actually makes kinda good sense. I had thrown full synthetic oil shortly before I started having the problems. All the detergents int he oil could have swirled some gunk that was stuck up there around the valves before it had a chance to go through the filter.

I could still get lucky and have an easy fix yet! Pry up the valve covers, pour some Seafoam over the valves and let 'em soak Just as long as there hasn't been any damage... And there's been no strange noises... so I might be lucky there... a broken valve I suspect would make some racket.

[xgecko]

That is a good approach; as long as you are careful you should not hurt the engine in any way. If nothing else, you will have proven to yourself that you really do need to do more, or if you are lucky the sticky valve opens up.

I think I figured out why I cannot get a good seal on the drivers side of my exhaust... It looks like the pipes are contacting the frame and when I hit the gas the twisting of the engine puts pressure on them and opens up the joints. I will be investigating later today and hope to move things around a bit.