[Duntov]

Originally Posted by wadedog

I took my car into the shop again and they checked the cam index. and it turned out to be correct .
They think I should be making 50 to 80 more hp than now and that maybe it's through the drivetrain and it might be because of my B&M holeshot 3000 converter and they recommended i try and find a good 3500 to borrow and test with.
They think maybe my converter is too tight and thats why the chassis dyno is showing low numbers and maybe it's not my engine at all.

Does this sound like a good possiblity ?

It doesn't sound right to me but I have seen a lot of aftermarket converter problems in the past, so I don't know.
This might be worth re-posting from this angle in the transmission/differential forum. Several real sharp guys hang out there.

[ericnova72]

I don't know,.... but my experience is that the chassis dyno is more accurate with a tighter converter, it is the loose race converters that give them problems getting good consistent readings.

Not to say that there isn't something either wrong with the B&M converter, or that it is too ineffecient due to the style of parts used to make it(the 'you get what you pay for' syndrome).

[wadedog]

At the time I bought the B&M I thought I was gettign a good converter but now maybe I should have bought another. I didn't have the conections with the internet I do now to ask advice.

They did manage to boost 50hp more from the dyno tuning from when it first drove in ,so maybe next year at the track will show the results.

[ericnova72]

That was my other thought, before you get too crazy hung up on dyno #'s....get it to track and get some #'s to see where you are at. Chassis dyno is a tuning tool for making improvements, not a definative measure of track ability.

Finding 50hp to the tires is exactly the tuning use of a chassis dyno, thats a roughly 65 hp engine improvement, it will make a difference

[cobalt327]

I think that if it were the TC, there'd be a big difference between the RPM and tire speed- something that should show up on a chassis dyno. Not to mention a LOT of excess heat- enough so that it, too, should be evident.

Back to the recent dyno readout- what were the readings for torque and HP @ exactly 5250 RPM (or as close to that RPM as possible)?

Everyone else- shhh until he can answer, OK?

I recall ericnova72 mentioning in another thread how Lunati Cams' recommended spring rates were screwy. After reading what he had to say about this, it makes sense.

But to now hear that nothing more than re lashing the valves 'cured' the problem, I'm not sure WHAT to think...

I was still going along w/him and Duntov and you other guys who had gotten on board w/there being a spring-related issue w/this engine. I'm still going to be surprised if it doesn't still somehow relate to the springs in some way.

If you were to zero lash the valvetrain, this would take lifter pump-up out of the equation. I don't think that was ever the problem, but if you wanted to check it out, you can.

I had also given some thought to it being carb related, but after seeing the A/F was in the 13-something range at peak power, I'm now doubting it- presuming the reading is correct.

Something I wanted to add: I'm glad you didn't attempt to swap out the original lifters for another set of new lifters, be they anti pump-up or otherwise. Using new lifters on a broken in cam or using a new cam w/broken in lifters is a recipe for disaster that all too often results in at least one failed cam lobe and lifter.

[wadedog]

you want to know the STPPwr CHp right?

at 5200 its 287.0 and at 5300 it's 288.0

[oldschool hero]

FLOATING VALVES ....

[cobalt327]

Originally Posted by wadedog

you want to know the STPPwr CHp right?

at 5200 its 287.0 and at 5300 it's 288.0

I wanted to know:

what were the readings for torque and HP @ exactly 5250 RPM (or as close to that RPM as possible)?

At 5250RPM, the lines should intersect. If they don't for some reason, the dyno printout is munged somehow.

But those numbers are too low, any way you want to look at them.

[wadedog]

thats as close to 5250 i have.

the STPTrq is 289.8 at 5200 and 285.4 at 5300
CHp

[cobalt327]

OK, I see. That's as close to intersecting as need be.

[wadedog]

Ok I got my scanner working and can post the dyno sheet for any use it is.

Its still winter and I haven't had a chance to drive it at the track and see how it runs but I think the springs need changed and i'm not sure if it's worth testing right now really, maybe not .

I'm not sure what springs I need but I guess around 135 or so ?

anyone know what springs I need in that range, part numbers ?

[ericnova72]

What is the current spring and retainer diameter now in use?? Do you know the current installed height??

Do you want to stay at the current spring diameter, or willing to go to a new larger diameter retainer and spring package if it would fit?? Any idea of the spring seat diameter in the head??

[wadedog]

sorry don't know your answers , my builder isn't saying what springs he used and I haven't measured them or have the tools to do so.

I don't think I have a problem with bigger diameter springs.
I don't know what my heads will accept,sorry.

[sqzbox]

I'm kind of getting in on the tail end of this but what kind of plug cables are you using? and what heat range plugs?

[cobalt327]

Originally Posted by wadedog

sorry don't know your answers , my builder isn't saying what springs he used and I haven't measured them or have the tools to do so.

I don't think I have a problem with bigger diameter springs.
I don't know what my heads will accept,sorry.

What do you mean, "my builder isn't saying what springs he used"? Are you saying you asked and he refuses to tell you??

A short primer on dealing w/service providers:

YOU are the "boss", in that you are paying the freight. This doesn't mean you can boss anyone around or be an a-hole, however it DOES sure as hell mean you have the right to expect an honest answer to any reasonable question!

Be polite yet firm. If you feel that you're being lied to or are getting the runaround, either decide to take your business elsewhere, or be content paying him to be his beech. I would strongly suggest the former rather than the latter.

If the dynamics are such that you cannot or will not be able to face up to this guy, it may well be too late for you to step up now, but let this be a lesson in how to proceed when dealing w/the next shop- the shop I hope you take the work to next.

If these are RHS aluminum heads, they will surely accept a larger spring than the stock 1-1/4" diameter springs, so that part should not be an issue.

Measure the width of a retainer- that'll tell you what size the springs are unless they're "beehive" or conical. In that case, the sides of the springs will not be parallel- which will be readily apparent by just looking at them. A beehive spring will be fatter in the middle, a conical spring will have a bigger retainer than the spring seat or sometimes vice versa (spring w/a larger seat end than the retainer end).

I wouldn't take the engine back to high RPM until the spring issue- if one exists- is resolved. The risk is dropping a valve, which will be a very costly bit of bad luck. If this machine shop is refusing to tell you what springs are being used- it is for a reason. And the reason is NOT to hide the fact they installed a good, high quality spring- of that I can assure you.

All that's required to test a spring for pressure is to remove one and hie it off to a machine shop that has a spring pressure tester. Some shops may have the tool for testing spring pressure on an assembled head, so ask what they're set up for.

Give them the installed height- that will give you the seat pressure. Then, subtract the valve lift of the cam from the installed height. That will give you the open spring height where the open pressure can then be measured.

The spring can also be measured for coil bind height, and the spring rate in pounds per inch can be determined as well. This should be routine stuff for any half way decent and/or 'performance' shop.