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I agree, using chevy valves is a no problem. I ran them when running the Windsor JR heads. I think they were 1.94/160s. They lasted, they sealed, they did what they are supposed to do. The Vid does a nice job of detailing P/R geo. Also, ask your builder to fill in the details for you. The worst situation is not knowing your build needs this attention and it's not performed.
 

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Why would you take the opinion of SGOTI over your machinist who's done this before? I'd listen to someone who could tell me, "Hey, I did this same thing, and here's the problem I encountered". But the guy who just says, "Oh, no, that won't work" without anything to back it up... not so much.

It's interesting, though, that the topic came up. I was just reading -- literally yesterday afternoon -- an article on Ford smallblock heads. The author says that using larger Chevy valves was a common practice. According to the article, the only potential issue was that cutting the seat larger would get you out of the induction hardened area of the head, leaving non-hardened cast iron. Not a problem (according to him) for a street engine. Ah, here's the link: Modifying Small Block Ford Cylinder Heads

Now, is this guy more credible than someone else? I have no idea, but a quick Google search will bring up quite a number of references detailing pretty much the exact same thing.
I had 1.94" intake, 1.6" exhaust valves put in my C4OE 289 heads and haven't experienced any problems This was done in 2010. I could be wrong but the hardened valve seats absorb the impact of the valves closing.
 

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The whole 'valve erosion' thing is a bit overblown, really. With better understanding of WHY valve seats would erode, the problem is mostly gone for well-planned engines now. In fact, the biggest reason they went to Tetraethyl Lead in gasoline was to prevent this 'valve erosion' problem. It was believed that the additive helped lubricate the valves, and kept them from sticking to the seats. The added detonation resistance was also seen as a good thing. Modern research has shown that it was the octane improvement that helped, not any 'lubrication effect'. In fact, TEL was really hard on exhaust systems, with the lead salts being very poisonous to boot.

What few people realized was that engine technology of the time - cam, combustion chamber, ignition, and carburetion, combined with cheap gas, often led to conditions favorable for detonation. If it happened during cruise, (which is common due to lean mix for economy) power levels were low enough that the quiet pinging could go unnoticed. Meanwhile, the exhaust valves would get so hot they'd try to weld themselves to the head every time they closed. If the condition was allowed to persist for long enough, it resulted in serious damage to the heads.

So, they went to TEL to raise octane, which helped. And later, hardened valve seats. With modern sensors to help sort out real-time fuel/air ratios, not to mention electronic fuel injection, leaded gas wouldn't help the average modern car, even without considerations for the environment and catalytic converters. Gas quality is a lot more standardized now, despite alcohol and other additives. Thanks to modern technology, the old 'hardened valve seats' thing is usually not a big deal for cast iron heads - although I'm sure for some high performance applications, it can come in handy! It probably falls into the same category of "Well, do I need hypereutectics, or forged?" It just adds safety margin.


The camshaft's closing ramp is a lot more responsible for limiting impact of the valve on the seat than anything else.
 

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Thanks to modern technology, the old 'hardened valve seats' thing is usually not a big deal for cast iron heads.
Are you actually saying that the fact I didn't have my valve seats hardened in my 66 GT may not be a problem?

Stunned...and from a recent post I now know that I should add...'sarc off'.

Allen
 

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Discussion Starter #26
Comp Cams has a good, short video on pushrod length and geometry. Helps if you pull the spark plugs when rotating the engine.

https://youtu.be/Cqx8Cs6O6Vo
Are you suggesting I get an adjustable pushrod and follow their procedure?

And yeah, I figured that out :grin2:
 

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Discussion Starter #27
I just went back to look at the other thread again and saw the new info that was added this morning. LSG pretty well gave the OP all the info he needs. Now it's time to start checking geometry to see if those new pushrods are the correct length.

Alex, I also want to point out that you never responded about if you have rail type rockers. You don't want to use those with shorter valves as the rails can contact and wear on the locks and retainers.

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Sounds like I'm getting an adjustable rocker arm and following the procedure posted in the video earlier in this thread.
I have conventional rockers. Not rail type!

I think those valve sizes are pretty good for a SBF head, really. 2.02's (and anything larger, though I don't know how you'd fit it!) will have problems with shrouding because the edge is so close to the cylinder wall. I think your machinist is making good choices. Good heads really make a tremendous difference on any engine, and the SBF is no exception. Like @Dan Babb said, your engine doesn't care that they are "bow tie valves", so long as they fit I'd like to know more about the rest of the engine choices he's making!
Thanks for the reassurance. Pro Machine is the shop (Murray, UT) in case you wanna talk to him. His name is Yates.

If the size of the valves you posted 1.84I/1.5E is what’s installed, you will be just fine. You actually could have gone slightly larger in the intakes. When you mentioned Chevy valves did you disclose the sizes? If not, everyone probably assumed 2.02/1.94.

You will want to make sure to do some port work on the exhaust side of the heads to take advantage of the larger valves. Make sure the intake sides are just cleaned up.
The exhaust ports were ported, that much I know!

Guys, did anybody look at the other thread? It wasn't the size of the valves LSG commented on, it was the length. Chevy valves are shorter in length than Ford valves potentially causing rocker arm geometry issues. The pushrods will potentially be too long now and the contact pattern between the rocker arms and the stems of the valves may be less than optimal.

The OP needs to verify his geometry and make adjustments as necessary to ensure a good contact pattern on the valvestem. If he does that he'll be fine. If not then wear issues may show up down the road from side loading the valves. The problem comes when guys just slap it all back together without checking and then wonder why the valves and guides prematurely wore out on the heads they paid good money to completely reccondition.

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This is valuable information. I think it's pretty certain now that I'll be doing a geometry check now.

Valves just go up & down, so as long as the dimensions are right and they seal in the heads, why would the fact that they were used on a chevy motor too matter?

I had a 354 Chrysler Industrial Hemi rebuilt by a local shop (in business forever with a good reputation) and the valves use on that were the same size as some ford big block motor, so that's what he used during the rebuild. They were dimensionally the same.
Good info, thanks.

The whole 'valve erosion' thing is a bit overblown, really. With better understanding of WHY valve seats would erode, the problem is mostly gone for well-planned engines now. In fact, the biggest reason they went to Tetraethyl Lead in gasoline was to prevent this 'valve erosion' problem. It was believed that the additive helped lubricate the valves, and kept them from sticking to the seats. The added detonation resistance was also seen as a good thing. Modern research has shown that it was the octane improvement that helped, not any 'lubrication effect'. In fact, TEL was really hard on exhaust systems, with the lead salts being very poisonous to boot.

What few people realized was that engine technology of the time - cam, combustion chamber, ignition, and carburetion, combined with cheap gas, often led to conditions favorable for detonation. If it happened during cruise, (which is common due to lean mix for economy) power levels were low enough that the quiet pinging could go unnoticed. Meanwhile, the exhaust valves would get so hot they'd try to weld themselves to the head every time they closed. If the condition was allowed to persist for long enough, it resulted in serious damage to the heads.

So, they went to TEL to raise octane, which helped. And later, hardened valve seats. With modern sensors to help sort out real-time fuel/air ratios, not to mention electronic fuel injection, leaded gas wouldn't help the average modern car, even without considerations for the environment and catalytic converters. Gas quality is a lot more standardized now, despite alcohol and other additives. Thanks to modern technology, the old 'hardened valve seats' thing is usually not a big deal for cast iron heads - although I'm sure for some high performance applications, it can come in handy! It probably falls into the same category of "Well, do I need hypereutectics, or forged?" It just adds safety margin.


The camshaft's closing ramp is a lot more responsible for limiting impact of the valve on the seat than anything else.
Lots of information here that I think is above me. Definitely something to research in my free time. Thanks for the detailed info.
 

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Are you suggesting I get an adjustable pushrod and follow their procedure?

And yeah, I figured that out :grin2:
Check it with what you have first. It may be good. If not, then get the tool. You can probably borrow one from the machine shop....
 

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An experienced machinist can do exactly what was done. Installed height, open and closed spring pressure can be checked in house and manipulated. You can change installed height through seat work, keepers, or retainers. You can also increase and decrease spring pressure through the same methods (within reason). Spring seat work/ shims can also be another method to attain optimal results. This happens all the time. For that matter most (practically all) SBF aftermarket heads work off a standard performance installed height of 1.800" which is also shared with SBC 350 aftermarket heads (generally speaking).

I'm betting this is the valve ( or equivalent) you are running(intake) S.B. International e-Catalog

If you compare the installed heights of the two in stock form you will find they are very similar. Look at the associated springs to see pressures and what installed heights they are designed for and you will find they are very close. To ease your worries, I have been running 2.02 1.600's on a EFI 351 Windsor that uses Chevy valves in an aftermarket aluminum head. They are set up at 1.800" and have about 50k miles on them.

You did well by supporting a local trusted machinist that backs his work. Looking at your build sheet I see he used an Engine Pro double roller timing set with an upgraded Rolon chain. That's a quality set and chain and coincidentally is what I am using on the same 351 Windsor.

FYI, by the way, early Chevy 350's with a 4.00" bore share the same exact piston ring as 289/302/351's and are sold as such, as well, in the aftermarket.
 

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I have conventional rockers. Not rail type!
This is meant with absolutely no intent to slight or disrespect you in any way whatsoever, but do you know what rail type rockers are? Rail type rockers ARE conventional rockers. They have ears to help keep the rocker arm centered on the valve when guideplates are not used.

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In the 1970's me and many others put 1.94 and 1.6 chebby valves in our 289-351W heads. Never had a problem. Never. Not even with pop up pistons. valve to piston clearence was always checked. too many stupid idiots out there that think they know it all. I always liked racing them for money because they were easy to beat.
 

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Guys, did anybody look at the other thread? It wasn't the size of the valves LSG commented on, it was the length. Chevy valves are shorter in length than Ford valves potentially causing rocker arm geometry issues. The pushrods will potentially be too long now and the contact pattern between the rocker arms and the stems of the valves may be less than optimal.

The OP needs to verify his geometry and make adjustments as necessary to ensure a good contact pattern on the valvestem. If he does that he'll be fine. If not then wear issues may show up down the road from side loading the valves. The problem comes when guys just slap it all back together without checking and then wonder why the valves and guides prematurely wore out on the heads they paid good money to completely reccondition.

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not a problem. use the springs you need and pushrod length you need. We used screw in studs. Its been so long since i done chebby valves in 289-351W heads i dont remember if anything else is needed but they will work great.
 

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Agreed. With the proper pushrod length and if everything else checks out fine it will be ok.

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How much shorter are chevy valves compared to Ford. Does that also have an effect on springs binding as they are already compressed more??

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So this is somewhat of an over simplification. If the Ford valves are 5.03's(not the only size around) and you get some 4.91 length valves(not the only size around) which are neither Ford or Chevy or actually they are Ford and Chevy for certain heads like AFR's then you are .12 short.



If you have the same cam and it wants the taller valve spring installed height, the biggest problem that causes is compressing the valve spring .12 more on the seat which increases the spring pressure and it reduces your total lift capability. Whether you get coil bind depends on how much lift your cam has. Regardless, it may work but it is technically wrong unless the valve spring installed height and the push rod length are corrected.



Depending on the heads, a shop might cut the valve pockets down to get the extra spring installed height but it would be best to get the right length valve for the specific heads and not have to cut on the heads. If you have a relatively high lift cam you might need a longer than stock valve to provide for the taller total lift. Regardless of which valve or what you are doing if any machine work has been done or you have swapped cams the push rod length needs to be checked and most likely it will be different that what it used to be.



Another valve dimension that could be different and something that has to be watched for is the valve stem width. AFR's for example seems to like 8mm valve stems for Ford or Chevy heads and in fact, advertise the exact same valves for their Ford and Chevy heads. However, Ford seemed to like 11/32nds(.3438) and so did Chevy for "the old stuff" but then there are some other valve stem widths also.



I'm glad I don't have to work on this stuff in a machine shop and I may have just made the water more muddy writing this. If so, my appologies. There are probably books just on valve train geometry, issues and solutions for all this.
 

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Discussion Starter #36
This is meant with absolutely no intent to slight or disrespect you in any way whatsoever, but do you know what rail type rockers are? Rail type rockers ARE conventional rockers. They have ears to help keep the rocker arm centered on the valve when guideplates are not used.

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No disrespect taken.

Doesn't rail rockers mean that the rockers have a channel to ride on the stem? If so, I do not. There is no channel. Let me know if I'm missing something-- thanks.
 

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Discussion Starter #37
Agreed. With the proper pushrod length and if everything else checks out fine it will be ok.

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Seems to be the general consensus. Thanks.

So this is somewhat of an over simplification. If the Ford valves are 5.03's(not the only size around) and you get some 4.91 length valves(not the only size around) which are neither Ford or Chevy or actually they are Ford and Chevy for certain heads like AFR's then you are .12 short.



If you have the same cam and it wants the taller valve spring installed height, the biggest problem that causes is compressing the valve spring .12 more on the seat which increases the spring pressure and it reduces your total lift capability. Whether you get coil bind depends on how much lift your cam has. Regardless, it may work but it is technically wrong unless the valve spring installed height and the push rod length are corrected.



Depending on the heads, a shop might cut the valve pockets down to get the extra spring installed height but it would be best to get the right length valve for the specific heads and not have to cut on the heads. If you have a relatively high lift cam you might need a longer than stock valve to provide for the taller total lift. Regardless of which valve or what you are doing if any machine work has been done or you have swapped cams the push rod length needs to be checked and most likely it will be different that what it used to be.



Another valve dimension that could be different and something that has to be watched for is the valve stem width. AFR's for example seems to like 8mm valve stems for Ford or Chevy heads and in fact, advertise the exact same valves for their Ford and Chevy heads. However, Ford seemed to like 11/32nds(.3438) and so did Chevy for "the old stuff" but then there are some other valve stem widths also.



I'm glad I don't have to work on this stuff in a machine shop and I may have just made the water more muddy writing this. If so, my appologies. There are probably books just on valve train geometry, issues and solutions for all this.
This is good information for me and it helped me better understand where my problems might be coming from. Thank you!
 

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No disrespect taken.

Doesn't rail rockers mean that the rockers have a channel to ride on the stem? If so, I do not. There is no channel. Let me know if I'm missing something-- thanks.
Maybe I missed something in the thread and maybe you already know this but you need some way to keep the rocker centered on the valve stem. My original ford iron heads had rail rockers with the "guides" on the rocker itself. My new alum heads have guide plates and the rockers are roller tip with no rails.
 

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I have no interest in reading through this thread, but if you trust your machinist, why are you here asking for advice?

What’s the advantage to using the mismatched parts?
 

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How much shorter are chevy valves compared to Ford. Does that also have an effect on springs binding as they are already compressed more??

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as with any spring install you have to measure how much distance between valve seat and retainer. Pick a spring with the pressure and installed height needed. < this is what an engine shop does but you can do it if you know what you need and have the measuring tools. There are deep cup retainers and the heads can be cut and you can also install lash caps to make the valve stem a little longer. Any performance engine shop can do this. In the early 1990's i had 429 CJ valves put in 1973 small port 460 heads for a powerful low rpm street engine. the CJ valves were taller than the 460 valves and thick shims and universal valve springs had to be used. Lots of measuring was done and I needed longer pushrods. The mild 460 made 550HP on the engine dyno with 100 amp alternator installed at 5700 rpm. I was in my 66 wagon in the foto.

PS. Its not called "Hotrodding" for nothing. Hotrodding is taking and engine and modifying it with non stock parts. MT put Chtysler Hemi heads on a 427 ford. http://macsmotorcitygarage.com/mickey-thompsons-427-ford-hemi-v8-and-its-fascinating-secret/ The 302 boss came about when a ford engineer decided to put 351C 4V heads on a 302. A friend modified a 460 ford aluminum intake to fit a cadillac engine.
 
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