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  #16 (permalink)  
Old 07-05-2012, 03:58 PM
lt1silverhawk's Avatar
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Quote:
Originally Posted by Silver Surfer View Post
New flat tappet cam = new lifters, always, no matter what, no exception. Ever.
Got it. Thanks!

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  #17 (permalink)  
Old 07-09-2012, 05:07 PM
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A few updates. Summit finally got back to me today asking me to call and speak to a tech. Considering the horror stories shared, I think I'll pass.


Presently, I am leaning towards the 252H as it seems to be the one with good low-end operating range and might be safest for all stock components (discussion welcome). I am not sure how much lift the stock springs can handle.


Lastly, I have a couple of questions:

-For break-in, do I use the break-in oil additive, the break-in oil, or both?

- What exactly are Z28 springs?


Thanks
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  #18 (permalink)  
Old 07-11-2012, 12:33 PM
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Got a few valve spring questions.


- How much lift can the stock springs on a stock iron from a Goodwrench 350 head handle?


- Can these heads use LS1 beehive springs (mild cam upgrade)?


- What exactly are Z28 springs? All I've found are these: Z28 VALVE SPRINGS


Thanks!
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  #19 (permalink)  
Old 07-11-2012, 02:35 PM
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Quote:
Originally Posted by lt1silverhawk View Post
Got a few valve spring questions.


- How much lift can the stock springs on a stock iron from a Goodwrench 350 head handle?
Put it this way: they can allow more lift before coil bind (CB) than they can handle, tension-wise. In other words, you might get 0.460 or so lift w/o CB, but the seat and open pressures will not control a SBC valve train at that lift at any kind of RPM.


Quote:
- Can these heads use LS1 beehive springs (mild cam upgrade)?
In a word, yes- providing the right retainers are also used. Check the posts by member Spin. He has used them, or similar OEM beehive springs on his engine and seems to like them.


Quote:
- What exactly are Z28 springs? All I've found are these: Z28 VALVE SPRINGS
They are stock diameter replacement springs that give more seat and open pressure than the stock springs. Often they will be rated for more lift than these, but unless they are a different spring altogether (which would usually mean more cost), they shouldn't be used where the lift will be much more than 0.500" as they advertise.

With the Z-28 type springs, the stock retainers can be used unless you have exhaust rotators (which you do have) so you'd need to get 8 more intake retainers along w/a new set of split locks (cheap insurance). Stock retainers from a stock SBC engine don't get a lot of wear so using used retainers if in good condition would be fine.

Howards and others sells a GM spring (p/n 98214 @ Competition Products) that advertise 0.510" max lift, 120 lbs @ 1.7 installed height and 300 lbs at 0.500" lift, coil bind at 1.160". They cost about $30/set. These I have used w/o any problems. Not saying you need them but I just have no experience w/the springs you linked to- but I have no reason to believe they would give any problems either.

On a related note, I know you're thinking about swapping the cam in the truck. Unless there's a good reason (reduced lift due to wear, or there was other related work being done like a timing set change, etc.), I wouldn't. You can make more power w/a different cam, but as you know already, any increase in the mid/top end comes at the expense of the bottom end. You might find yourself needing a gear ratio change and/or a torque converter stall speed change to take advantage of a new cam's powerband. And if you choose a cam that works fine w/the stock gearing and TC, then you've really not changed the cam specs all that much unless you were to go w/one of the ultra-fast ramped cams like the Comp XE or Lunati Voodoo series, but even then the lift and duration would need to stay relatively mild. A stock cam is a compromise but it's biases towards a daily driven vehicle capable of working in a wide verity of situations. Given the weight and use for the truck, I just don't see much of a return on the money and labor invested.

I would put a free flowing dual exhaust system on it, including headers. That needs to be done if you want to get the full potential of a cam swap anyway, so I would have to say to start there and see where it leads you.

Last edited by cobalt327; 07-11-2012 at 02:49 PM.
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  #20 (permalink)  
Old 07-11-2012, 05:41 PM
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Hey cobalt,


Thanks for the info on the Z-28 and LS1 springs. I also contacted the seller and he responded very quickly, saying that even the stock springs should be fine on such a mild cam (the Comp 252h). He also offered a set of Z-28 springs with retainers and locks for $79.50 if I wanted to upgrade.


As to the cam swap itself, it is something I am considering doing off and on. I am planning on redoing the intake manifold gaskets for a peace of mind, and thought it might be a good time to learn to do a basic cam swap just to learn how to do it and see if I can get a bit more performance out of it. Having never done one of these before, it is hard for me to get a feel for what the numbers I read really mean in the real world. But of course, as you correctly pointed out, the amount of labor and the money spent has to be taken into consideration as well. And if the performance really isn't worth the cam that fits the bill, then I will focus my attention and money to everything else that needs doing.


I have been thinking about buying a set of headers but I need to find some that won't give me any issues come smog time. I've been looking on Summit and, while some of them do offer AIR injection manifold option, none mention CARB compliance (example: Flowtech 11500FLT - Flowtech Headers- SummitRacing.com). As to the exhaust, haven't really looked into it much but I would even consider this combo: SUM-CBJJ102 - Summit Racing® Dual Exhaust Systems.


In the end, this may just be nothing more than a brain exercise lol!


Thanks for the straight talk.
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Old 07-12-2012, 04:45 AM
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Another consideration for headers is that you want them to hold up to the relatively rough ride of a truck. I have been looking at Hedman Elite headers, since they use thicker flanges and thicker pipes than most others. However, I don't know what emissions certification they have.

The other alternative I am considering is Corvette ram's horn manifolds with 2 1/2" outlets. They are still available from Dorman as a standard replacement part, and they are supposed to be one of the best flowing OEM manifold options. I would like to have a more free flowing exhaust manifold, but not have to worry about everything loosening up because of the truck's rough suspension.

Bruce
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  #22 (permalink)  
Old 07-12-2012, 07:57 AM
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Hey Bruce,

Quote:
Originally Posted by 75gmck25 View Post
Another consideration for headers is that you want them to hold up to the relatively rough ride of a truck. I have been looking at Hedman Elite headers, since they use thicker flanges and thicker pipes than most others. However, I don't know what emissions certification they have.
I went to Hedman's website and their online Flip Catalog catalog has a section on emissions legal headers. The cheapest I found for my '77 4x4 with AIR are the Standard Duty Uncoated #69231, going for $369.95 on Summit.




Quote:
Originally Posted by 75gmck25 View Post
The other alternative I am considering is Corvette ram's horn manifolds with 2 1/2" outlets. They are still available from Dorman as a standard replacement part, and they are supposed to be one of the best flowing OEM manifold options. I would like to have a more free flowing exhaust manifold, but not have to worry about everything loosening up because of the truck's rough suspension.

Bruce
Interesting. What year Corvettes would they be off of?
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  #23 (permalink)  
Old 07-12-2012, 10:31 PM
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@Bruce: I was going to ask you what mods you had done to your truck aside from the cam and newer Quadrajet, but I coincidentally found your thread on Google: Camshaft/exhaust selection for '75 GMC K25.




Just for kicks, I was checking out CamQuest tonight and was surprised to see that Comp Cams offers a stock replacement of the same cam in my truck's engine (929H). So I decided to see what data the dyno would provide. I went with the more optimistic 8.0:1 compression ration (recent CarCraft issue showed it being well below that for a stock Goodwrench 350). Below is what I got.






Taking this with a grain of salt, I never realized that everything was peaking at such a higher end. I don't think I've ever pushed this truck past 2,500 while driving, but definitely up to 4,000 while revving it.
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  #24 (permalink)  
Old 07-13-2012, 04:37 AM
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These are the Dorman manifolds I mentioned. Dorman 2.5 Inch Corvette Style Exhaust Manifolds - Speedway Motors, America's Oldest Speed Shop This listing is from Speedway, but almost any car parts place can order from the Dorman catalog.

I'm not sure how well the 2 1/2" manifolds fit in the truck around the large frame rail, but it looks like there should be enough room. The OEM rams horn truck manifolds were only 2" outlets, and the outlet turned and pointed to the back.

Bruce
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