First off I want to say a special thanks to Bleyseng, SGB, LvSteveH, Kwales, JK76.914 and of course the Cap'n for helping me understand hydraulic lifters. The good news is that I have progressed from beginner to novice when it comes to these damn things. The bad news is I need to be an expert. Here's the current situation... (All measurments are being done from the carb velocity stacks using a syncrometer with the carb wired open at full throttle. This is because I do not have a compression meter. Yes, the fuel pump is turned off. I am using a remote starter switch to simply turn the motor over). OK, here's the confusing part...I seem to be able to adjust the intake velocity psi simply by adjusting the lash on the lifters.? For example; 1/4 to 1/2 turn past contact and I get very little intake psi. If I go to 1 1/4 to 1 1/2 I get a significant increase in the intke psi. I have also measured this with the motor running (about 2500 rpm) and it seems to remain the same. In fact, If I set cyls 1&2 at 1/4 lash and 3&4 at 1 1/2 there is a significant difference in intake PSI between the two sides of the engine. Should lash on hydraulic lifters effect intake PSI like this?

Yep.. The hydro lifters are effecting the valve timing events, therfore impacting chamber filling.. Yes they can impact the engine's vacuum signal severely...

I gave up on them 10 years ago and have refused to work with them every since.. there is NOTHING good about them in a TIV engine!

only two posts and already a good thread : )

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Yeah, I'm finding that out Jake but they'll have to do for now. (One of these days when I have the capitol I want to rebuild the engine with the cool Jake parts). So since they effect the intake vacuum would it not make sense to use the syncrometer like I am and set them all at the highest vacuum value (intake obviously) then do a leakdown test to make sure I have not compromised compression due to a leaking valve?

Your hydros have no impact on a leakdown test. Assuming you don't have a tight valve.

And yes... Like Jake said. they impact vacuum immedietly after any adjustment.

I can't seem to figure out why you just don't set em to spec and run em?

Are they not pumping up evenly at idle? Or do you have to run em up in RPM to get them to quiet down?

Me thinks I am missing something here.......... (nuthin new)

C

There are a dozen opinions out there about what they should be set (spec) at; everything from 1/4 turn after contact to 2 turns. I am trying to find a way to figure the best for my engine since I am not sure what type these are and I am getting differeing results with the different lash settings. The engine has about 20k miles on it and has changed a bit. I'm just trying to find the magic combination for this engine.

I don't wanna piss anyone off... If you want to read my thoughts on the hydros do a search here, on the STF and on the samba...

Hydros create a compromise, promote neglect, effect tuning and most of all they crush efficiency...

People think that hydro lifters extend maintenance intervals, only thing is that **most** of those people **THINK** they need a valve adjustment every 3K with solid and do not relize that hydros still require adjustment unless you want to kill the engine..

Hydros run quieter, but you pay very dearly for that one benefit...

I'll be doing a Radio show dedicated to the subject in February. It'll be the most intense show we have ever done, filled with facts, fiction and stories of experiences these lifters create based from first hand experience... Some will like it, others will hate it but it'll all be the truth and I won't be caring if feelings get hurt, not at all!

Agreed on all points - BUT: the first two discuss owner practices, not engine behaviour
The third is what I think is being realized here, but mostly in a R & D sense.

The fourth is just true. Thats the price of quiet.

I could talk about this for year, but won't do it here.. If someone wants to learn more go make a post on my forums and I'll take it from there!!