1987 231 n/a valve guide diameter?

[nicad]

I am getting ready to swap out the springs in a 1987 normally-aspirated 231 (stock iron heads). I ordered some Comp #26981-12 Beehive springs, as well as the # 4693 spring locators. I understand you either have to machine down the valve guides for these locators to fit, or bore out the ID of the locators to fit over the stock guide. I plan to bore out the locators since it seems much easier. But I do not know the OD of the valve guides, and the car is currently in another city.

Can someone please tell me the diameter of the valve guides? And possibly, since I have seen others machine out the ID of these locators before, the diameter they bored them out to for a good close fit over the stock guides?

Thanks much!

 

[thessman]

measure the installed height of the beehive retainers before you start machining. the locators are .060 thick and may give you trouble when you go to install the new springs (not enough installed height with the locators.)
Even with +.050 locks you may be short. hope this helps you. Keech

 

[nicad]

Thanks for the heads up. I have been doing a bit of reading on installing these and have seen mention about lowering the spring seat depth.

According to the listing for the stock springs, they have a coil bind height of 1.15", whereas these 981 Beehive springs have a bind height of 1.115", giving 0.035" lower bind height.

If I am not mistaken, don't the stock spring "cups" have some shim height with them as well, so when those are replaced with these spring locators with the 0.06" shim height, the stock cups would have to be less than 0.025" shim height for these Beehive to result in a taller bind height?


Anyone know the outside diameter of the stock valve guides?

Thanks!

 

[turbodave231]

I just measured a 8445 head and came up with .775-.780"

Here is a similar setup I did on a ported stock head engine. I opened up the ID of the spring seats on a lathe. Worked out very nice.

Dave

 

[TurboBob]

With iron heads and stock rockers, would those springs be ok at .520 lift?

I was thinking that the smaller retainer (lighter) would help the valvetrain stay stable at "higher" RPMs without a ton of seat pressure.

Bob

 

[nicad]

TurboDave- The spring locators I have here are Comp #4693, which have a shoulder of 0.8" OD and 0.57" ID. The 981 Beehive (not the 918) springs are specd to have a base ID of 0.825". They are on back order so I do not have them in-hand yet. According to Summit-

Comp Cams 26981-12 Flat tappet hydraulic
Installed Height (in) 1.700 in.
Seat Pressure (lbs) 110 lbs.
Open Height (in) 1.175 in.
Open Pressure (lbs) 292 lbs.
Coil Bind Height (in) 1.115 in.

If I machine the ID these locators out to 0.78" to fit over the valve guides, there will only be a 0.01" wall remaining!? I am wondering if I even need locators if the guide OD is that close to the spring ID already? Is it OK to run the spring directly on the cast iron head.. or will the spring chew it up?

TurboBob- What retainers should be used? Comp # 774-12?
I was planning to re-use my stock retainers and locks, and maybe machine them to a smaller OD since they do not need to be as big for the beehive. Is this a good idea or should I get the #774-12 and use them with my stock locks? What part # would I need for those +.050 locks that have been mentioned?

Lastly, these 981 springs are listed for use with flat tappet hydraulic cams, which is what I am running, but 110# seat pressure (at the stock 1.70" installed height?) still seems a bit excessive...? Any input?

Thanks again for all the input-

 

[nicad]

I got the 981 springs in today. Nice looking little things.
I will be working on it this weekend. I am anticipating having to machine some on the spring locators, and maybe even turn down the OD of the stock retainers, since the top of the beehives are smaller OD.

I hope to report back next week with positive results!

 

[nicad]

After looking at what all extra parts and modifications will be needed, I decided it was probably going to be too much trouble to try to make the Beehive springs work.

So, I ordered a set of Comp 980 and some shims and will just simply drop those in next time I work on it.

 

[nicad]

I measured one of the stock valve springs that are currently in it. Including the inner damper coil, I was getting around 65# seat pressure at 1.73" installed height. I am running 1.65 aluminum roller rockers and an old Lunati flat hyd cam that I have no specs on... "medium street" is all I was told, which is pretty much useless info I know. :redface:
Is 65# substantially low? Next weekend I plan to install the Comp 980's and find out if that makes any difference in the top end..

 

[nicad]

Well, I put the Comp 980 springs in, and it didn't seem to help anything. Still running out of steam around 5200-5500 rpm. I am starting to wonder if it needs more timing now... 2.5 more weeks till I can work on it again! bleh.