Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, please

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

Wow - appreciate all of the advice, and the tech. Some good info being discussed, and I appreciate the debate.

However, I am nowhere closer to making a decision. Just have more pros and cons to weigh... ou:

Just to go over the basics, as this is a unique application, and atypical for most that build these 350 motors for higher end, street/strip performance:

Engine will be installed in a Jeepster Commando, and operated idle to 3500 rpm. (That's almost 80 mph in my 1969 Jeep, people. I DO have Saginaw power steering and 4-wheel disc brakes, all new ball joints and HD steering components, BUT, and I mean this seriously - I don't have any business going that fast with 32 x 9.5 Bias Ply tires!!!)

Use is currently (and projected) 50/50 highway and offroad. Looking for economy on road, and low end torque offroad.

I WILL use the 350-4V and Quadrajet. I am going to use regular 87 if I can get away with it.

1972 or 1973 heads, on a 1972 or 1973 block (Yes, I know all heads will fit on the '73 block, but only '72 heads will fit on '72 block).

Mild cam (Crower I), Crower hydraulic flat tappet lifters, TA grooved cam bearings, Melling double roller timing chain, and TA adjustable OP regulator and restrictor plate.

I will use the stronger '73 con rods (thanks for that tidbit!), and Polish the best looking crank.

Hone and re-ring on the best looking block, and basic valve job (with EXISTING VALVES) on the best set of matching heads.

The machinist ("Stump") offered to put in hardened exhaust seats for $64. He has a very high reputation for good work, but I don't know his experience with Buicks, and I seriously doubt he has the knowledge and experience expressed above.

Enthusiasts sometimes spend the time to do the research, so in the engineer vs. enthusiast camp, there can be advantages to the latter. Engineers don't always design the best item - they design the best item within the constricts of money and time, and possibly lawsuits. And engineering is sometimes used to fix the design of an existing item for a new application (unleaded gas), which some consider to be "band-aid" fixes. Also, engineers move on to other projects, egines and heads. Enthusiasts become subject matter experts on one component or one package of components. Sometimes, enthusiasts grab onto a piece of internet lore, and count it as truth. This all weighs into the equation. And we are surmising a lot, as these heads are about 40 years old, and the engineering used back then is a little different than now...

SOOOOOOO, to reiterate the question: Should I just get the basic valve job, or have "Stump" go the extra step and put in hardened seats for $64?

I am seeing two distinct camps here:

1) Hardened exhaust seats may help, but may hurt (weaken crack-prone area) and is ultimately not necessary due to higher nickel content of the heads

2) Cheap fix to make exhaust valves work with unleaded gas.

Full admission here: I have a Jeep allowance set by my wife for "that damned Jeep." So, I am "one and done" for this engine rebuild - I do NOT plan on pulling it two years down the road to put in aluminum heads.

However, since I have it broken down to this level, I want to do it cheaply, but also "right." $64 is nothing at this stage, but I don't want to regret the decision, either way. I am leaning toward 2, but now you all have me worried that my cheap-a$$ rebuild might create head crack issues down the road.

Does that make sense?

You are free to continue the discourse (I'm learning a LOT ), but keep in mind the application, and please give me your recommendation for (1 or (2 above.

Thanks!

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

One of the reasons for burned valves is from heat expansion/stretch of the valves which can lead to the valve not closing properly. Buick addressed this with sodium filled exhaust valves. The higher nickel content of Buick blocks and heads not only increases strength and reduces weight but also changes the thermal conductivety thus creating less chance of valve recession even when using lead free gas. Also why the valve guides don't wear like they do in Chevy heads. Alas...bygone are the days when the different marques had control over their engines and we didn't have corporate engines. That is if your a Buick fan! )
David

---------- Post added at 07:13 PM ---------- Previous post was at 07:07 PM ----------

My 2 cents; if you have no valve resession at this point nothing more than a slight touch of a stone to dress the seat and leave it alone!
David

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

If the seats look ok, just clean them up and go with it. I wouldn't mess with steel inserts, especially when you're going with very mild parts.


Gary

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

I agree with David here,with the level of build you are doing,low compression and low RPM,as long as the heads you're using are still in good shape on the seats,no need to spend the $64.

There is a thread in the 455 street/strip section that Jim Weise said that it takes around 3-4 valve jobs before the induction harding is ground off.(I'll try to look for that thread,I don't want to mis-quote Jim)

Derek

---------- Post added at 02:35 PM ---------- Previous post was at 02:30 PM ----------

Here it is;

http://www.v8buick.com/showthread.php?272748-Fuel-Requirements&highlight=hardened+valve+seats

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

Not wanting to pat myself on the back too hard here, but I think I'm pretty close to being right. Others here are right too though. This information and discussion is important to get some myths (or misconceptions) out in the open and hashed out.

I don't care if I'm right or wrong, I just want the truth to be known, whether from or by me or others, and let everyone's knowledge grow as a result.


Gary

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

I learn something new every day. I'd have never suspected this.

I knew that Ford used sodium-filled exhaust valves, but only in the highest-performance engines of the '60s.

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

They looked at using helium but they got valve float- BA- DUM - CHING!!! Thank you, thank you, I'm here all week, tip your bartenders....

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

Thanks. Makes sense.

I have three sets of heads to choose from - I'll keep them matched sets, and choose the ones that look the best.

I've read some about removing the inner springs for the 20-minute break in of the cam, and running it at 2000 rpm for those 20 minutes.

Doesn't sound complicated, but since they're used springs, will it matter?

Also - do I label the springs from each lifter and put back in same location, or does it matter? I'm thinking of cleaning parts with an untrasonic cleaner and some simplegreen - would really like to put them in as a batch instead of one at a time...

---------- Post added at 06:59 PM ---------- Previous post was at 06:36 PM ----------

And another question... with .0015 to .002 optimum for the crank, would it be better to grind it .010 or just polish an existing crank?

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

Your head won't have inner springs from the factory.

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

^^^ what he said.
Stock springs aren't stiff enough to worry about removing the "inner" spring, which if it exists at all, is more accurately considered a "damper".

The springs don't need to be kept in order, but if you wanted to, you could string them together with a piece of wire, just remember which end of the wire is the front.

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

Zactly... if there is a spring looking thing inside that is made from a flat winding, that is a damper not a spring. It's intended purpose would be to reduce harmonics in the spring.
DavidR

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

As for the crank question,that depends what it measures and what the surface finish looks like. The machine shop should be able to look up what the crank tolerance is from the factory to know if it should ground or if it can get away with just a polish.


Derek

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

some guys don't have the luxury of installing hardened seats due to their casting being very thin(from what I've read)
don't recall which motor but it was ford based BBF to be exact cause youre likely to hit water
but to me just sounds like a machinest error as its been done to every engine..and if they fall out..same deal...install error

hell some people don't believe the zinc and calcium debate effecting camlobe and lifter wear..had this discussion over at the maverick.to site
but thats not saying much when they let a guy run 10w40 in an engine that calls for 10w30 when he asks for best weight to run for winter :spank:

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

Crower Stage I cam ($41!!!) and lifters, and Melling timing delivered by Brown.

Found out the current 350-4v block I'm working on has a "P0" code, which means that it is originally a '68 350-2V. It has the HEI mod and the pushrods all had holes in them. Don't know what year heads they are. This is the "supposed" rebuild motor that looks like someone just put new bearings and maybe a re-ring in. other than that, the timing chain was loose, etc.

If I'm not mistaken, this block should have 9.0 to 1 compression pistons. If I can get away with a hone and re-ring, these pistons will be used.

Will use the '73 rods, these pistons, and the best block/crank combo.

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

If you can,try to use one complete rotating assembly from one engine so you know it will probably be balanced to each other. Or have the mixed and matched peices rebalanced together? GL


Derek

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

The "PO" code is from 1968 and corresponds to the 2v engine, yes. It has the deeper dish pistons and is probably closer to an actual 8.2-8.4:1 SCR, which should suit your needs just fine. Hopefully your bores, pistons, and the rest of the rotating assembly looks good enough that you can just re-ring and re-bearing it with a hone on the cylinder walls.

Though as Derek said, best to use the same rotating assembly to ensure it is all balanced together.

What's the .006 numbers on that Crower level 1 cam again? 250* on intake? With an 8.2:1 SCR and 250* @.006 intake installed @4* advance and 112* LSA, your DCR would be 7.12:1, which is probably too high for regular grade gas, though mid grade would be ok.

You might be able to get away with regular, as long as you twiddled with the timing.

Though before jumping to conclusions, the SCR may be even less and you could always install the cam a bit different (less advance on IVC install) to adjust it.


Gary

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

since 68-69 engines used steel shim head gaskets you can guess that the 9.0 pistons are about the same as 71 8.5 pistons. so you didnt really gain anything.as for crank you might be able to find .001 over bearings . then you could polish crank.

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

Thanks, Gary.

Crower level 1 cam has the following specs: 250 HDP grind with a 112 lobe center, 250 intake duration and 258 exhaust (advertised), and 192 intake, 196 exhaust at .050. Gross lift: .411 intake, .419 exhaust.

(I believe the 112 lobe center means it has 4 degrees advance built in, right?) On the cam install with a three-way adjustable gear for the crank (-4, 0, +4), should I go for 0, or +4 ???

How do you figure those compression ratio numbers? Sorry, I'm a little new to the scene with figuring SCRs and DCRs - I don't even know the terminology. What are the rules that go with the numbers? What is best SCR for regular pump gas, and how do you figure it? A primer or a thread reference would help...

Last question: I have a gram scale that I used to "zero balance" my pistons, rods, caps and bolts on a hi-po 2276 VW motor. I know a dynamic balance is the gold standard, but would a static balance be OK if I mix and match these pistons?

 

Re: Well, "Rebuilt" was only half the story. The other word was "Needs"... Advice, pl

Ok so I remembered correctly: 250 'advertised' (.006) duration for intake.

112 'lobe center' is the Lobe Separation Angle (LSA), measured in camshaft degrees, from lobe tip to lobe tip on intake and exhaust (this is the easy way to explain, though LSA can actually change depending on lift and lobe symmetry--Crower's are symmetrical I believe). This means the intake and exhaust lobes are 112* apart from each other. If the cam is installed 'straight up' it means zero degrees advance or retard, in which case the cam would sit at 112* intake center line (ICL) and 112* exhaust center line (ECL).

When one advances a cam, it is twisted so the ICL reads a lower number than the ECL, and vice-versa for retard. The Crower cams are designed (last I checked) to be installed at 4* advance, so your ICL would be sitting at 108* while your ECL would then sit at 116*. It moves 4 degrees in one direction, subtracting 4* from intake and adding it to exhaust.

This alters where your valve timing events occur, and will occur sooner when advanced, and later when retarded. This also corresponds with the power band (moves power band lower, or higher in relation to advance or retard).

It also changes the clearances between valves and pistons, though you won't have to worry about that with your combination.

It also changes where the Intake Valve Closes @.006 (advertised) which affects dynamic compression and stroke (and thereby dynamic CID, which isn't really discussed much I've noticed on the forums...I may need to remedy that).

For purposes of this duscussion, IVC will focus on where your dynamic compression ends up, which will affect the octane requirement for your engine (if it's borderline with Static Compression Ratio (the '9:1' pistons)).

SCR: static compression ratio, is total volume divided by static volume, where total volume = swept volume + static volume.
Swept volume is the distance in the bore the piston moves from bottom dead center (BDC) to top dead center (TDC) --and is incidentally the means manufacturers used to determine the engine's 'displacement'.
Static volume (the volume that never changes) is head volume (combustion head chamber cc) + head gasket volume + deck volume + dish volume.

EDIT: for calculating the CID on anything cylindrical, take .7854 x bore (diameter) x bore (diameter) x stroke (length) for CID. To translate this CID into cc's, multiply by 16.387. There's another way where you take R (radius) * Pi (3.14~)^2 (Pi squared) instead of using the .7854, though either way works.

Basically you take the entire volume and divide it by the volume that never changes (I call it the 'static' volume; others refer to it as 'TDC' volume). You can use an online calculator to figure this out here:

http://www.summitracing.com/popup/calcsandtools/compression-calculator

DCR: dynamic compression ratio, is calculated the same way as SCR, except the stroke is different (always lower) because of the effective, or 'dynamic' stroke that is determined by when the Intake Valve Closes (IVC), which shortens the stroke since it always closes ABDC (after bottom dead center). This also affects dynamic or effective Cubic Inch Displacement, obviously, as mentioned previously.

Remember this: SCR means jack. What matters is your DCR. SCR is incidental.

Rule of thumb is 7.5-7.75:1 DCR is your best bet with an otherwise untouched combustion chamber and premium pump fuel (up to 8:1 for combustion chambers smoothed and polished to reduce detonation risk), and somewhere around 6.5:1 for regular. This is based on research of many different sources.


Again, an online calculator that figures DCR can be found here: http://www.wallaceracing.com/dynamic-cr.php

Here is an example:

[TABLE]
<tbody>[TR="bgcolor: #B0C4DE"]
[TD="align: right"]Number of Cylinders : [/TD]
[TD]<input name="cyl" size="5" type="text">[/TD]
[/TR]
[TR="bgcolor: #B0C4DE"]
[TD="align: right"]Bore in Inches : [/TD]
[TD]<input name="bore" size="20" type="text">[/TD]
[/TR]
[TR="bgcolor: #B0C4DE"]
[TD="align: right"]Stroke in Inches : [/TD]
[TD]<input name="stroke" size="20" type="text">[/TD]
[/TR]
[TR="bgcolor: #B0C4DE"]
[TD="align: right"]Rod Length in Inches : [/TD]
[TD]<input name="rod" size="20" type="text">[/TD]
[/TR]
[TR="bgcolor: #B0C4DE"]
[TD="align: right"]Static Compression Ratio : [/TD]
[TD]<input name="cr" size="20" type="text">1)[/TD]
[/TR]
[TR="bgcolor: #B0C4DE"]
[TD="align: right"]Inlet Valve Closes ABDC : [/TD]
[TD]<input name="abdc" size="20" type="text"> [/TD]
[/TR]
[TR="bgcolor: #B0C4DE"]
[TD="align: right"] Boost Pressure in PSI : [/TD]
[TD]<input name="boost" size="10" type="text">[/TD]
[/TR]
[TR="bgcolor: #B0C4DE"]
[TD="align: right"]Target Altitude : [/TD]
[TD]<input name="alt" size="10" type="text"> (Feet)[/TD]
[/TR]
</tbody>[/TABLE]

The numbers inside the boxes didn't want to transfer, so just enter in the info you know. Inlet Valve Closes ABDC is 53* for your Crower level 1 cam, boost pressure and target altitude set to 0, rod length 6.387.

I can't really answer your last question with certainty, though I would think any sort of balancing is better than no balancing, even if dynamic balancing yields different results based on other factors besides piston weight. So that's my 2c on that. Others here would probably be better qualified to answer that question for you.

Also, a sticky in the big block forums can help you with your camshaft degreeing:

http://www.v8buick.com/showthread.php?220945-Camshaft-degreeing-101

Hope this helps.


Gary