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Opinions of guides in import heads

General engine tech -- Drag Racing to Circle Track

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cgarb
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Re: Opinions of guides in import heads

Post by cgarb » Wed Oct 09, 2019 4:18 pm

Yes, if you want to check for roundness, taper and clearance the correct way. If your checking to see if they are worn out you can do that with the heads on the motor, but you need tools to be able to take the spring off on the motor.

ProPower engines
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Re: Opinions of guides in import heads

Post by ProPower engines » Wed Oct 09, 2019 5:31 pm

Belgian1979 wrote:
Wed Oct 09, 2019 3:26 pm
BillK wrote:
Wed Oct 09, 2019 3:04 pm
Belgian1979 wrote:
Wed Oct 09, 2019 2:54 pm
How do you spot a knock of Dart sbc head from an original ?
Personally I have not seen an actual counterfeit but would not be surprised if they are out there. A dart head will say Dart on it and have a Dart part number. The others will have their own part number or no part number at all.
Belgian1979 wrote:
Wed Oct 09, 2019 2:54 pm
And second question : with the valves in the head, doing a wiggle test : how much wiggle is acceptable and what is not ...
The wiggle test is really not an accurate test. Someone who has done hundreds of heads can use it for quick check but a bore gauge is the correct way to do it. The wiggle test has too many variables. How far you pull it out of the guide and the length of the guide will both affect it considerably.

That being said . . . . VW actually specifies the wiggle test in their service manuals on several engines. But they tell you exactly how far to pull the head out of the guide to measure it.
So if you want to check the valve guides, pulling the heads is the only option #-o
THE OFF SHORE HEADS I have seen all have a large amount of clearance. Much more then what I consider acceptable.
.0015 for an exhaust is the absolute max with perfect valve train .0008-.00012 for an intake.
These sizes are for a honed guide. This is also with stems with less then .0005 run out most quality valves ar .0002-.0003 for run out and when honing guides you will very quickly see what the stem quality is.
Say you measure the stems at .3413-.3417 and are fitting each valve based on size.
If there is run out the valve will be stiff to push in the guide and will not fall in with the seats facing up.

Now you have to decide whether or not to get more valves but it seems that guys will just increase the guide iD and go with it creating oil consumption issues soon as the seal wears a bit from the loose guide.

But yes a properly fitted stem to guide will have almost no movement or wiggle.
Real Race Cars Don't Have Doors

cv67
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Re: Opinions of guides in import heads

Post by cv67 » Wed Oct 09, 2019 9:38 pm

How is Darts quality far as guides these days?Had issues with a Conquest head many yrs ago, wasnt a geometry issue.
If they are the slightest bit better than the offshore piece they look promising..didnt take much to get a strong # from them.

Anyways keep the good stuff coming.

GM seems to still use a lot of iron guides, how come the aftermarket doesnt? One better than the other-

Belgian1979
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Re: Opinions of guides in import heads

Post by Belgian1979 » Thu Oct 10, 2019 11:30 am

Well I have Darts and on some valve I can wiggle it. Not huge but definately a noticeable amount with the valves about half lift.

I was contemplating taking them off since I still have some amount on smoking on decels.

I’m pretty sure this is how they came out of the box but no numbers on actual clearance. They do carry a Dart name and partnumber in the casting.

Hate this type of thing. Had something similar happen too many times before. More than I care to count actually. Seems nobody is interested in customer satisfaction anymore. A shame.

ProPower engines
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Re: Opinions of guides in import heads

Post by ProPower engines » Thu Oct 10, 2019 4:31 pm

cv67 wrote:
Wed Oct 09, 2019 9:38 pm
How is Darts quality far as guides these days?Had issues with a Conquest head many yrs ago, wasnt a geometry issue.
If they are the slightest bit better than the offshore piece they look promising..didnt take much to get a strong # from them.

Anyways keep the good stuff coming.

GM seems to still use a lot of iron guides, how come the aftermarket doesnt? One better than the other-
Because any stock vale is hard chromed on the stems. not a bad idea for stem life but stainless valves will gall an iron guide.
Or wear it very quickly. I see lots of iron heads sold with stainless valves and the guides never seem to last long.
Real Race Cars Don't Have Doors

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