pop23235

What was the original part number and ID for the 327 SpHP engines in 64? I'm getting confusing information on something I though I knew.

vettsplit 63

ID?? Who knows The OD is the same as every other small block spring that will fit in the original uncut seat. Something like 1.250. If you use later Z28 or LT1,tThey are stiffer tham stock . I used beehive H-11 tool steel springs on my 30-30 Comp Cams flat tappet camshaft. Will rev freely to 6500

MikeM

I can't give the the original part # but I remember the springs on the SHP engines ID'd with a blue paint stripe and they had some kind of special heat treat. Same tension though as base engine springs.

Maybe if Critter sees this thread he can comment. His memory is better than mine.

Critter1

I think valve springs for a 365 HP 327 are the very same as those used for all V8 engines of the era. I'll look to make sure.

Edit: I looked up the spring. Same 3735381 spring was shown for all V8 engines from 55 to at least 66. (I looked in a 1966 printing of the GM parts book) I think a slightly different spring and different part number was used for 67 and later.

Several different ID stripe colors are listed.

I don't have ID or OD specs though.

pop23235

By ID, I actually meant color of stripes. Didn't think of inside dia. as ID. Appreciate the responses. I purchased 20 of these back in early 70. Thought they had a blue or purple stripe, but no. it's white and bluish color. Can't find the spares that are still in the box. That will confirm, if I can locate. I was seeing the same as you Critter, but in a 72 P&A.

At least no one hinted that it was the same as the Z28/302.

MikeM

I am not sure if the '66 P&A book shows the OEM SHP valve spring part number. The older I get, the less I am sure of.

Still think the originals had the blue stripe.

Critter1

Same 3735781 spring as a 283", Mike. Same all the way from 55 to 66, all small block engines.

For 67, the spring and part number changed but it was still used for all small blocks for several years after that. It was even used in LT-1 and Z28. Same spring, no difference for HP engines.

The 3735781 spring is shown with many different color strips. I only remember seeing one or two different colors though. Yellow and blue comes to mind.

TCracingCA

I am pretty sure they are right close to .870! But I have seen some vary to about .876.

Also you would be better off running the 3927142 single springs or HD off road which are 1.273 dia OD or a comparable aftermarket unit, just for that little bit more insurance, and slightly higher ability to rev!

Critter1

I wasn't 100% sure on the valve springs used with LT-1 engines so I dug out a later (1974 printing) parts book. As I suspected, the LT-1 engine used the very same spring as all other small block passenger and Corvette engines. I don't have a Camaro parts book handy but I'm sure the Z28's also used the same spring. These springs were nothing special.

I don't remember exactly what the change was for the new 67 and later spring but I do remember that it was very close in lbs/in to the previous spring for 55-66.

So......

55 to 66 all small blocks............... 3735381

66 to 74 all small blocks exc. 73-74 W/O Sp. H/Per..........3911068

73-74 W/O Sp. H/Per...............6263796 (used with rotators for exhaust only)

The HD 3927142 valve spring was never installed on a production engine. It was to be used with the 3927140 "off road"cam. Originally designed for Trans-Am racing in Camaros. As TC mentioned, it also worked well with the original 346 30-30 Z28 cam. That was one of the very first things I installed in my new 68 Z28.

TCracingCA

People see the 140 race cam recommended and get all worried, but this was a highly recommended upgrade on any of the solid lifter cams! The 142 I have pushed 6800 rpms! The 585 duals to 7200 rpms and the mushroom springs to 7800 rpms!

And on both of my 140 cam engines, I on one run the 330585 duals and not with the aluminum retainers but a Tool steel 7 degree lock! (1.379 off memory) and on the other I have the 1.525 OD mushroom lifter GM Performance Valve springs with the titanium retainers!

I have virgin spares NOS replacements for all of this stuff (virgin 140 cam, virgin 30-30s, virgin LT-1 cam and more of these valve springs and such) for future rebuild! The stuff is getting unobtainable!

TCracingCA

PS because valve springs are not marked, it is always best to measure them, so you know for sure what you have to size your retainers and bottom cups if you run such!

Dr L-88

Correct again Mike !!!!

This is from my original Chevy P&A book dated October 1, 1965. Just rotate your head, OR your eyeballs, whichever is easiest for you, 90 degrees to the left.

Rex

Critter1

Thanks Rex. I rotated my computer 90° right. LOL

MikeM

That sounds right. The question is, why did they color code with two different paint colors. That blue swatch of paint on other parts of the SHP shortblock indicated that that was exactly what it was. As I remember, the yellow springs went in the lower horsepower engines.

The service replacement part number could very well be the same part vs a difference in the OEM assembly parts as you well know.

Here is a photo, compliments of you that shows the blue paint.

MikeM

You have never told us what you thought you knew?

Critter1

I don't know why the various colors are shown in the parts book or on the springs. There are several, probably six, or more. I suppose it's possible that the colors could indicate a source/manufacturer? I doubt there were more than one spring for all 55-66 engines. If there were, I think a few different numbers would have been listed in the P&A for service for different applications.

It's also possible that each spring passed some test in manufacture?

I don't know the answer.

I wonder how many small block valve springs were made every year? How many small block engines, times 16. That's a bunch! LOL

Did I post that short block picture here or was that over at the NCRS? Can't remember. The big S on the side stands for service. For production, that would have been an engine assembly code, like RF for 63-64 with FI.

Critter1

The 140 cam was not good on the street if the exhaust ran through mufflers. The high RPM power band was very narrow and the low end was about as powerful as a 283" with a dead cylinder. I learned this 1st hand against advice from two guys from Chev engineering but at that age, I thought I knew all there was to know about everything.

MikeM

VH's I think.

pop23235

Mike, at my age, I'm not sure of anything any more. I'm trying to locate in my storage of parts the spare springs in parts boxes I purchased in about 1974 for the CE short block I now am "refreshing" for it's maiden start. I decided to use new springs on the old heads, bought about 20 of them, culled one or two for being out of spec., saved the good ones and installed the 16. A friend who has done nothing but head work for over 40 years asked if they had the blue paint. That is what started this. They have white and blue. Pushrods have blue. Now if I can just locate my spares.......I'll know what part number I bought. I do recall the spring seat pressure was good, in spec. and about 18 of them were very close. When I checked my 72 P&A book, I didn't see a listing for SpHP springs in 64. I'm thinking I agree with everyone that there were no special springs for the 30/30 cam, but my "expert" says there were, and had blue paint.

Critter1

A blue ring/stripe around one end of a new pushrod indicates that end is to be positioned up.