Cam advice

[gregs78cam]

I have had a buddy's '92 1/2T 5spd sitting here for a while that originally needed just a clutch problem fixed, but last summer when we went to start it, #8 cylinder was blowing back through the TB. So we tore it out, and found some bad news. Any way it has been sitting here since, and today we just went a picked up another shortblock, in really good condition, for $100. Well the guy who had it tossed the lifters when he took it out, so now I am trying to decide what to do with it. It supposedly has a cam that is one step above stock, which is kind of what I would like to have in it anyways. Now, I have never used a new set of lifters with an old cam, and I don't think I want to try now. Here is what I see as my options.
1. Pull the cam/lifters out of the original engine and see if they are usable (which may be a possibility), and re-use them. $ = Free
2. Buy new 'stock' cam/lifters and put them in. = ~$100
3. Buy new 'RV' cam/lifters = ~$150
4. Pull-N-Save a set of roller lifters, retainers, spider, then get OEM/RV roller cam. I don't know what the cost of this will be but I am sure most of it will the cam. Does anyone have any advice as to what cam I should look at. And does anyone know of any good deals on GM cams that might work well, for a reasonable price. If I could get a roller cam, even a factory stock one, for around $100 that would be great. If I were to find a Vortec V8 in PnS, would that cam/lifters/retainers/spider work in this engine?

Thanks guys.

[jim_in_dorris]

If the block you got has the setup for a roller cam, then a set of roller lifters, retainers and spider from pull-n-save might be the way to go. I wouldn't, because a new set is just good insurance. The spider and retainer on the other hand are not wear parts, I would reuse them. An LT4 hot cam can be picked up lightly used for as little as $75 with a little internet digging. Easy to install and will put a grin on your face without putting a dent in your wallet.

[EagleMark]

If it can roller lifter look for an LT1 cam pull, there were lots of them in $75 range awhile back...

If not I vote #1...

[gregs78cam]

If it can roller lifter ...

Oh I know, not only does it have the bosses in the valley, they are already threaded.

I was looking at those but I think the LT1 and LT4 might be too much lift to try to get away with on factory truck valve springs. I was thinking more along the lines of the 87 350ci Corvette and IROC-Z Camaro with 202/206 @.050, and .403"/.415" and a very TBI friendly 115 LSA. I guess I will head over to TGO tomorrow, err....today and see whats out there. Thanks.

[dave w]

Roller camshaft conversion from a Vortec L31 5.7 liter engine is what I'd personally do, if the block is able to be converted to roller camshaft. If the block has a fuel pump block off plate bolted in, then the block is likely a good canidate for a roller cam conversion. If the fuel pump mounting is cast completely closed, (no hole for a fuel pump push rod) forget the roller cam option.

If I couldn't do a roller cam conversion, I'd go for option #3. I would use a re-ground camshaft to save a few $$. I get my re-ground performance cams from Oregon Cams http://www.oregoncamshaft.com/ I can usually get flat tappet cam, lifters, and timing chain with gears set for about $110.

dave w

[gregs78cam]

So it looks like I may have scored a used LT1 cam and lifters, along with some other 'goodies' thrown in for $50+shipping. Now what I need to know is, has anyone used the factory LT1 cam with stock TBI heads, i.e. the valves spings will work fine right? I mean we are only talking about 0.050" more lift.

[gregs78cam]

Dave, what exactly makes the blocks with a closed off fuel pump mounts not able to be converted? This block has the spider bosses tapped, the tops of the lifter bores machined, and no hole for fuel pump pushrod. The only thing I don't know for sure about the cam retainer plate mounting holes. But I am pretty sure I can drill/tap those holes in it if they are not.

[dave w]

Dave, what exactly makes the blocks with a closed off fuel pump mounts not able to be converted? This block has the spider bosses tapped, the tops of the lifter bores machined, and no hole for fuel pump pushrod. The only thing I don't know for sure about the cam retainer plate mounting holes. But I am pretty sure I can drill/tap those holes in it if they are not.

I've only worked on a dozen or so TBI engines, so my limited sampling of TBI engine blocks of what can be converted to roller camshaft might not be comprehensive. What I've seen as the best candidate TBI block to convert to roller block will have a fuel pump block off plate bolted to the block. Once the fuel pump block off plate is removed, the holes for the fuel pump push rod should be drilled and the oil drain back hole is drilled. When I've seen the fuel pump push rod hole cast over the spider bosses were absent. I've seen one block where the spider bosses were present, but not drilled and tapped when the fuel pump push rod hole was cast over. The same block that did not have the spider bosses drilled and tapped had some clearances not machined for the lifter dog-bones, which caused the lifter dog-bones not to lay flat onto the block. So when I'm shopping / looking for a roller one piece rear main seal block in the junk yard pile of rebuildable cores, the best candidate to purchase (IMHO) is the block with a fuel pump block off plate bolted to it. Then remove the fuel pump block off plate and verify the fuel pump push rod hole and oil drain back hole are drilled and machined. If you find a light chocolate color looking oil after removing the fuel pump block off plate, it's time to look for another engine block.

dave w

[gregs78cam]

Thanks for the clarification Dave. I think this one is good to go roller.

[jim_in_dorris]

Dave, I have a roller block core with the fuel pump block off plate (which was missing). I have never heard of the push rod hole and oil drain back hole modification. Can you enlighten me please. It is going to eventually end up in my 4x4

[1project2many]

Greg, I have stripped several LT1 / L99 engines here and have several cams and lifter sets around. I also have a ZZ4 and an LT4 cam although both are mid range rather than low end camshafts. A very good bang for the buck cam is the HT383 roller cam. It's inexpensive, provides a boost to low and mid range power, and on L31 heads it will work with 1.6 rockers and stock valve guides (probably no issues with TBI heads).

[dave w]

Dave, I have a roller block core with the fuel pump block off plate (which was missing). I have never heard of the push rod hole and oil drain back hole modification. Can you enlighten me please. It is going to eventually end up in my 4x4

Based on the dozen or so TBI engines (1987 ~ 1995) I've worked with, not all of them would accept the old mechanical fuel pumps. The TBI engines that would accept the mechanical fuel pump, would also accept all the roller cam parts without modification.

It seems to me, depending on the year of the TBI engine, GM saved a few production $$ by either:
Not machining the TBI engine blocks for a mechanical fuel pump. (No fuel pump push rod hole, no oil drain back hole, no threaded holes for mounting a mechanical fuel pump)
Not machining the TBI engine blocks for the spider hold down with threaded bosses.
Not machining the TBI engine blocks for proper clearances for the lifter dog bones.
Using old blocks (most likely from 1986) that did not have the spider hold down bosses castings.

dave w

[jim_in_dorris]

Okay, I don't intend to use a mechanical fuel pump, so I guess that it is not an issue. Thanks

[dave w]

Okay, I don't intend to use a mechanical fuel pump, so I guess that it is not an issue. Thanks

I guess all I was saying is;
If the TBI engine has the fuel pump push rod area completely cast over like my second picture, based on my limited experience, it's going to be a block that Will Not accept all the parts needed to convert to a factory roller camshaft. Based on my limited experience, if the TBI engine can be set up to run a mechanical fuel pump, it Will accept all the parts needed to convert to a factory roller camshaft. This GM production stuff is never 100% accurate. There are always exceptions to the generally accepted rules of the SBC. The SBC was in production for more than 45 years, and there were many changes during that time. Kind of reminds me of how to identify a 4 bolt main SBC block, easy if the oil pan is removed. The easy way to know for sure if a TBI engine block can be converted to roller camshaft is try installing all the roller camshaft parts. Another easy way to get a roller SBC block is get a L31 Vortec block, which has a factory roller camshaft already.

dave w

[jim_in_dorris]

This one had a flat tappet cam, but is drilled and tapped.