Probably Beating a Dead Horse, but... Cams?

Aftermarket sbc retainers might be different than stock, AFAIR.
Just checked a stock 250 head having a valve tip to spring length of 2.040" with a 3250/3251 type 7* retainer.
I get an installed height of 1.875".
Plenty of spring options at that height.
 
Correct.

Since you are measuring spring-less, let the retainer and valve fall onto the guide, and peck the top of valve gently to seat retainer and locks.

Post with the info and we can move forward on spring choice.

Use Stock or stock height aftermarket sb chev retainer and stock caddy locks. 4.3 will also be same

Dave

EDIT: f85, what is a 3250/3251 retainer? Do you have any stock sb retainers to compare?

Please post your spring choices. Are you ok with my 90-110 seat and 250-270 open?
 
Last edited:
That may not have been a stock retainer, I just assumed it was - pulled it off of a 283 that sits in the shop for the introductory Engines class to learn on.

dave brode said:
Correct.

Since you are measuring spring-less, let the retainer and valve fall onto the guide, and peck the top of valve gently to seat retainer and locks.

Post with the info and we can move forward on spring choice.

Use Stock or stock height aftermarket sb chev retainer and stock caddy locks. 4.3 will also be same

Dave

EDIT: f85, what is a 3250/3251 retainer? Do you have any stock sb retainers to compare?

Please post your spring choices. Are you ok with my 90-110 seat and 250-270 open?
Click to expand...

Not entirely sure if you're talking to me or f85, lol :confused:

15 thou. isn't terrible far off from what f85 came up with - maybe it was an aftermarket, different style retainer?
 
Hello. I would change springs, but only put in stock replacement springs, the stock rockers will not hold up with any thing bigger
 
>Not entirely sure if you're talking to me or f85, lol :confused:

> 15 thou. isn't terrible far off from what f85 came up with - maybe it was an aftermarket, different style retainer?

The text following EDIT was for him.

You have a stock caddy retainer that you can use to see what the difference in spring room there is with sbc vs caddy retainer? And while you're at it, gently squeeze a stock spring to solid in a vice and measure it.
Dave
 
Last edited:
Outlaw,
Many guys here have run moderate cams with stock rocker w/o issue. Imo, with moderate spring pressure, it is feasible. Have you seen failures? If so, what cam and what was the open and closed pressure?
Dave
 
what is a 3250/3251 retainer? Do you have any stock sb retainers to compare?
Click to expand...

Those retainers are the $1 ea. sbc Z-28 std performance type, as seen in the competition products catalog or elsewhere.
If I run into any factory retainers I'll check, but I don't re-use those.
I think the .015" difference might just be the metal shield, but that's why I listed the stem height.
The inexpensive 10* locks and retainers give a fair amount of extra height for the spring, if needed.
Different brands are not universal, some just sit different.
I keep some of these items and the +- locks around because I often ignore factory seat heights or do what's necessary to make something work. The goal being 'no shimming' if practical.

90-110 seat and 250-270 open
Click to expand...

Perfect for this type of build if it doesn't rev too high.
I won't get much catalog time until later this week, but there's quite a few candidates in just the comp prod catalog with a list of matching retainers.
For the most part, there's 1.7x and 1.8x height springs of various types. The inexpensive ones seem to hold up for our local circle track racers for a few seasons of full rpm.
For a low rpm Caddy with a 2" valve, just choose what fits with the least hassle.
 
dave brode said:
http://www.rockauto.com/en/partsearch/?partnum=VS485

Only .062" left at .490" lift installed as per stock height.

http://www.rockauto.com/en/moreinfo.php?pk=217493&jsn=257
Click to expand...

I might be able to machine the tops of the valve guides, if I have to - we do have a mill and some other precision equipment in the school lab.

dave brode said:
>You have a stock caddy retainer that you can use to see what the difference in spring room there is with sbc vs caddy retainer? And while you're at it, gently squeeze a stock spring to solid in a vice and measure it.
Dave
Click to expand...

I'll measure those tomorrow morning.
 
8ad-f85 said:
Perfect for this type of build if it doesn't rev too high.
I won't get much catalog time until later this week, but there's quite a few candidates in just the comp prod catalog with a list of matching retainers.
For the most part, there's 1.7x and 1.8x height springs of various types. The inexpensive ones seem to hold up for our local circle track racers for a few seasons of full rpm.
For a low rpm Caddy with a 2" valve, just choose what fits with the least hassle.
Click to expand...

What's too high of rpm? over 4500? Or a little better?

It'll probably never actually see those rpm aside from maybe revving it sitting still - most likely never get it that high on the road. Though, I ~might~ have to take it down to the strip in Wichita, just to see what it'll run... Once. ;)
 
This will be, for the most part, a daily driver and show queen, with the occasional stoplight drag race, lol.

I did a sketch of the look we're shooting for - put what was in my head, on paper.
 

Attachments

  • IMG_2544.webp
    IMG_2544.webp
    81.9 KB · Views: 30
So, I went back to the engines lab and measured again. One thing I noticed... On the 283 head I pulled the retainer from, there were three different styles... o_O Took a photo of it, dunno how well you can see them.

Anywho; two were very similar, and basically the same spring seat height - I had measured one of those before. I tried the different one today - see the pics - and came up with 1.880" closed. The stock Caddy retainer was at 1.925".

Also, Caddy spring fully compressed was 1.400".
 
Great pictures!! They can really help tell the story - or show the problem.

Interesting how many different 'styles' of the same part can show up in an old engine. It lets you know for certain that somebody has been there before.

Keep at it. I love to see this process unfold, knowing that in the end major fun will be had!

Best,,

d
 
Cutting the guides [which may need done] does nothing to allow the stock springs to work. They are solid at 1.400". Add the lift [.490"] = 1.890". There is not enough travel left. Using the stock spec of 1.946", there is .056" left. Using your number of 1.925", there is.035" left. not enough.

Btw - please re-check the height w/a stock cad retainer. Make sure the locks are seated. Btw, It is hard to believe a college does not have a valve spring height mic!

Please also measure from the spring seat on the head to the valve tip, with valve closed. Stock spec is normally 2.040" -2.060".

It looks to me that the 1943 elgin spring is the best bet. Anyone see a better option , please say.

125# @1.750", 325# @1.200" [363 lbs/inch]

Let's say that you end up with 1.900" of room with the stock chev retainer after a valve job. Reduce that by .060" with a minus lock = 1.840".

So, .090" taller than the spring's closed spec. 363 x .090" = 32.67# change.

125 - 33 = 92 lbs seat. Add .490" lift = 178# for 270 open.

http://www.northernautoparts.com/part/ei-rv1943xs

The other 1.75" and 1.800" springs are all 400 lb/in or more. There are 1.700" tall springs that would be ok, but
I know of no easy way to reduce the height, w/o shims, which I hate.

A sbc beehive looks better and better. They normally go in at 1.800"
 
dave brode said:
Cutting the guides [which may need done] does nothing to allow the stock springs to work. They are solid at 1.400". Add the lift [.490"] = 1.890". There is not enough travel left. Using the stock spec of 1.946", there is .056" left. Using your number of 1.925", there is.035" left. not enough.

Btw - please re-check the height w/a stock cad retainer. Make sure the locks are seated. Btw, It is hard to believe a college does not have a valve spring height mic!

Please also measure from the spring seat on the head to the valve tip, with valve closed. Stock spec is normally 2.040" -2.060".

It looks to me that the 1943 elgin spring is the best bet. Anyone see a better option , please say.

125# @1.750", 325# @1.200" [363 lbs/inch]

Let's say that you end up with 1.900" of room with the stock chev retainer after a valve job. Reduce that by .060" with a minus lock = 1.840".

So, .090" taller than the spring's closed spec. 363 x .090" = 32.67# change.

125 - 33 = 92 lbs seat. Add .490" lift = 178# for 270 open.

http://www.northernautoparts.com/part/ei-rv1943xs

The other 1.75" and 1.800" springs are all 400 lb/in or more. There are 1.700" tall springs that would be ok, but
I know of no easy way to reduce the height, w/o shims, which I hate.

A sbc beehive looks better and better. They normally go in at 1.800"
Click to expand...

I took a few more measurements after class this evening. We ground the valve tips and faces today, so that took a couple thousands off, and I imagine we'll take another thou or two when we grind valve seats.

As far as spring pad to valve tip, I came up with 2.040". After firmly seating the locks with a ball-peen, I got apx 1.928".
 
Back
Top