Valve Installation Question

[old28]

If I am installing new modern stainless valves in a model A block, can I lap in the exhaust valves that are the same size as the originals or do I have to do a complete 3 angle valve job? What about the installation of the bigger 1.700" intake valves? Block has good seat area and do not want to install hard seats.

[l. bacon]

If the exhaust seats are in good shape and have been recently ground, you could probably get by with lapping them in, but if the seats are too wide or of questionable condition , probably not. The oversize intake seats will have to be ground to fit the larger valves.Your three angle valve job should get you there.

[Jim Brierley]

You're going to have to have the intake seats ground so might as well do the exhaust too, and not lap either.

[H. L. Chauvin]

Hi old 28,

Imagine you are expecting more HP with larger intakes, and ...........

If you would like, you could call Mr. Ron Kelly, (advertised in The Restorer), where you can learn from his dynamometer Model A engine testing experiences where he found the most effortless and most inexpensive method for increasing Model A engine horsepower by his directions on performing mild engine "porting".

For example, using a Dremmel tool grinder to smooth out sharp corners in the intake & exhaust ports; rounding and removing the sharp metal lip on bottoms of valves & slightly rounding 90 degree tops of valves; smoothing sharp corners on bottoms of valve seats; smoothing sharp corners in intake manifold; etc., etc.

[old28]

H L Chauvin -- Jim Brierley -- l. Bacon -- Thanks for the help. I think I will install the new one piece valve guides and have a fresh 3 angle valve job done on both the intake and exhaust. Better to get it right the first time. I have already cleaned up the Int & Exh ports a little.

[Patrick L.]

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I use pencil to check face to seat fit. You could do that just to see what you have and that'll lead to an answer. I think you'll find that a good valve job will be needed. A man that knows what he is doing will be able to fit the seat to the face correctly.

[old28]

In preparation for installing new double lock lifters along with V8 springs would it be a good idea to have the machine shop lower tops of the lifter guide tower in the block to make for a little more clearance for adjusting the lock nuts? I have read a couple of articles on this, all good, comments? Not looking at doing more machine work than I need too.

[Tom Wesenberg]

I wouldn't lower the guides. The more support the better. I can spend a few extra minutes adjusting.

[CarlG]

Originally Posted by H. L. Chauvin

Hi old 28,

Imagine you are expecting more HP with larger intakes, and ...........

If you would like, you could call Mr. Ron Kelly, (advertised in The Restorer), where you can learn from his dynamometer Model A engine testing experiences where he found the most effortless and most inexpensive method for increasing Model A engine horsepower by his directions on performing mild engine "porting".

For example, using a Dremmel tool grinder to smooth out sharp corners in the intake & exhaust ports; rounding and removing the sharp metal lip on bottoms of valves & slightly rounding 90 degree tops of valves; smoothing sharp corners on bottoms of valve seats; smoothing sharp corners in intake manifold; etc., etc.

I visited Ron Kelley's shop last week and witnessed first hand what H.L. is describing. That guy is ablolutely a pure artist when it comes to "all things Model A".

[George Miller]

Originally Posted by old28

In preparation for installing new double lock lifters along with V8 springs would it be a good idea to have the machine shop lower tops of the lifter guide tower in the block to make for a little more clearance for adjusting the lock nuts? I have read a couple of articles on this, all good, comments? Not looking at doing more machine work than I need too.

No I would not do it. I took a old camshaft nut and welded a little crank to it. Then you can turn the cam real easy, then adjusting the lifters is no problem. You just have to do it before you put the cam gear on.

[old28]

Tom Wesenberg -- CarlG -- George Miller -- Thanks to all for the input. I will leave them as they are and save some machine cost. It may take me a little longer to adjust the lifters, but being retired I have lots of time to get it right.

[Dodge]

Don't use the double lock lifters, use the single lock.

[bnchief]

X2 on what dodge said they are a lot less painless to adjust.

[jhowes]

Patrick L, Can you explain the pencil way of checking valve contact to seat? Jack

[100IH]

One of the best ways to check contact of valve seats is with an EXPO marker. These markers are used on the white, dry erase boards. Mark the valve face, install & twist the valve while lightly pushing down. Then mark the seat in 3 even quadrants. This is easy to see, almost no dry time and wipes away clean.

[Patrick L.]

Originally Posted by jhowes

Patrick L, Can you explain the pencil way of checking valve contact to seat? Jack

Easy. Basically its as 100IH mentioned.

I just mark the valve face in 3 places across the face [ 120º apart], insert valve into guide and twist. The seat will wipe away the graphite showing how wide and where the seat sets on the face.

The valve seat width should be .070-.080" for intakes and .080-.090" for exhaust. The graphite should be rubbed off near the middle of the valve face [or slightly toward the stem] for correct placement for normal every day engines.

The location of the contact is changed if needed by regrinding the seat which is the reason that a minimum of 3 angles is needed.

Once seat contact is correct the lash is changed by grinding the end of the valve stem [ original style lifters] and using the micrometer thingy on the valve facer machine.


I still use pencil since I've been doing this long before magic markers were discovered.

[H. L. Chauvin]

Just One Old Vintage Valve Lapping Verification Method:

If one looks carefully after lapping a single valve, and after wiping off the valve grinding compound, one should be able to clearly see if one has a new and distinct, "full" 360 degree by approximately 3/32" wide abraded band on the surface of both the valve and valve seat.

If this distinctly marked metal band is at least approximately 3/32" wide and fully continuous for 360 degrees, this valve is good to go.

[Jim Brierley]

I wouldn't cut the block down either, I like the full support. I adjust the valves with only the crank and cam installed, no springs or pistons. George Miller's idea sounds good too. I turn the crank to the position wanted to adjust each valve, using your thumb to hold the valve closed, measure the clearance. Then you can push the lifter up from below to adjust it, prevents the need to keep turning the engine. This will get you surprisingly close, if not spot-on. Re-check the clearance after installing springs. I use the rule of 9's to position them for adjustment. Everyone does things differently, choose the method you like.

[old28]

Dodge -- bnchief -- Thanks, I will order up the single lock lifters.

100IH -- Patrick L. -- H. L. Chauvin -- Thanks for the information on lapping.

Jim Brierley -- I will use your method, it is all new to me with this A motor.

Well the top of the valve area hold a spacer on top of the V8 spring without machining? May need to use a .060" spacer to get my 2.0'" @ 85# seat pressure.

[Patrick L.]

1/16" = .062
5/64" = .078
3/32" = .093

I do not lap. Haven't for decades. If one feels the need to lap then do it after the valve is fitted to the seat. If lapping compound is used to check how the face relates to the seat the stain marks left can not be removed to check placement if a change in seat placement is needed. Lap only after you're happy with what the pencil tells you.