Spider vs. retrofit roller

73 Mike

73 Mike

I'll drive it someday
Joined
Mar 30, 2008
Messages
713
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Boston, MA
I may be missing something obvious like the lifters being different diameter or height, but other than fitting the spider, is there any reason that you couldn't use stock roller lifters in a pre-1986 block? They are MUCH cheaper.
 
I would ditch the block and go with a later '88 up block.....I have a '89 truck factory 4 bolt block in mine...all the improved rear seal, and the block is already machined for factory rollers...

the top of the lifter bores is cut flat for the dawgbone to fit over, that keeps the lifters from twisting of course, and the spider has to be a custom/aftermarket to fit the newly machined bosses in the early blocks....

IMO, I would NEVER use any toggle type lifters, I have heard too many stories over the years about them letting go in street/wear use....race only item apparently....

I suspect the GM engine folks knew a trick or two....never heard of a factory lifter failing due to twisting in the bore........

either way, with the block swap, or cutting your present block, you out some machine work...if you want rollers in there....

:surrender::thumbs:

Oh, edit, factory rollers are taller, so the pushrods are shorter too....don't forget that.....
 
The lifter bores are machined flat on the upper side and there's a bar that holds the lifters from turning. Early blocks don't have the flat face or the bosses in the center of the valley for the spider. Short of some machine work, the retro rollers with a link bar are the best bet. I'd bet that by the time you had the necessary machine work done to an earlier block to install the late factory type rollers, you could have bought the link bar style.

The one piece seal is not a bad thing, but GM did it because of emissions requirements- not oil leaks. Properly installed, there's no more chance of a leak from two piece seal than a one piece.
After 30+ years of the two piece seal, GM wouldn't have done all the re-tooling needed for the one piece seal unless they were driven to it by emissions requirements.
 
73 Mike said:
I may be missing something obvious like the lifters being different diameter or height, but other than fitting the spider, is there any reason that you couldn't use stock roller lifters in a pre-1986 block? They are MUCH cheaper.
Click to expand...

I had a fellow racer and very experience engine builder suggest I do what you suggest with the spider. He suggested fitting it myself and drilling and tapping the holes myself with hand tools. This was seriously considered by me, but in the end I did what Tim suggests and went with the attached rollers. The racer/builder I mention claims he sold a motor built as he suggested and that is still running fine. I dunno, I'm just throwing it out there as what I was told, but never saw the result.
 
It WILL work, just have to use a different lifter, namely the one from a 60deg. v6. They are shorter. The later 1pc roller blocks have taller lifter bores. Use the 90deg V8/V6 lifter and the oil groove will pop out of the bore. The V6 lifter is about the same length as the flat tappet one in there now. It's the same bore too. The only thing you have to watch for is that you don't run too small a base circle on the cam and not too much lift, I'd say it would be OK to right around .5 or a little more. You can drill the block for the retainer plate and massage the bores carefully so the dog bones will sit. Don't break through the water jackets. The front can be drilled for a retainer plate but it's a little tricky. A good old cam button would be easier.

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So would the taller 90 degree V8/V6 lifter work with a small base circle cam or would you simply have to measure and find out?

For me, I think this is becoming an academic discussion as my Motown block doesn't have a center ridge at all and I think the spider would interfere with some of the cam lubing drain holes that they added in the center. Thanks for the input guys and the pics TT. Now I know.
 
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No, the problem w/ the small base circle is that the oil slot pops out on the bottom. Same issue w/ the taller lifter.
 
It's been a while and I have given up on finding a good (cheap) set of lifters with the link bar.
Couple of months ago I bought the roller cam mod papers on ebay for like $20.
Fairly detailed instructions.
So I plan on going the roller cam way with the V6 lifters.
Figure I can do everything myself before I send the block out for a 030 overbore.
If I mess it up at least I will not have the machining cost.
First I have to clean out my shed since I can't find anything anymore.
 
Imo Apita said:
Couple of months ago I bought the roller cam mod papers on ebay for like $20.
Fairly detailed instructions.

.
Click to expand...

That auction was what prompted me to ask the question in the first place. I was curious for a while about this but I couldn't really see what machining you could do with a die grinder that would allow he use of stock type lifters.
 
all you need to do is rework the dogbones a little, clean up the lifter bore tops and grind in the corner where it meets the coolant wall so the dog bones can sit flush on the lifter bores

I remember that paper, douche_bag was giving that info away on CF for free.
 
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