Cam options

[L31MaxExpress]

Yup. I screwed the pooch on my truck 'cause I failed to drill the "vertical" hole.

I keep telling myself that when I get enough electricity to run the welder, I'm going to build a drilling fixture for that hole. But getting electricity is proving to be a challenge. Or rather, getting electricity into an enclosed area that protects the shielding gas from being blown-away by the wind, is a challenge. And all my circuit-breaker panels are maxed-out.

Just went through having a whole new 250a service panel installed when our 7.2KW solar grid went in. House was down to 1 spare 20a breaker on the antiquated 150a panel.

 

[VIKING_MECHANIC]

So I checked my two blocks and the one that was in the truck when I got it has the coolant bypass and the provisions for a roller cam. The one that I'm going to build doesn't have them.

So educate me. What's the purpose of the bypass and will be detrimental to my build?

Side note: I'm a dumba** and just realized the block at my house is a 638 casting 4 bolt and the one I'm building is a 880 2 bolt. Any major issues I'll run into?

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[Erik the Awful]

If you drill the bypass hole you can run the TBI water pump. Without the bypass hole you need to run the Vortec water pump with the heater hoses routed to the pump - which doesn't fit well with the TBI accessory bracket. Supposedly you can drill a hole in the thermostat and still run the TBI pump, but I'd drill the bypass hole to make sure. Don't forget to make sure the heads have the corresponding hole.

 

[VIKING_MECHANIC]

If you drill the bypass hole you can run the TBI water pump. Without the bypass hole you need to run the Vortec water pump with the heater hoses routed to the pump - which doesn't fit well with the TBI accessory bracket. Supposedly you can drill a hole in the thermostat and still run the TBI pump, but I'd drill the bypass hole to make sure. Don't forget to make sure the heads have the corresponding hole.

I'd rather run the vortec pump and not have to deal with drilling in the block. I'll find a way to route the hoses. Would I need to do anything with the coolant passage on the TBI head?

Can I run the TBI fan/clutch on the vortec pump?

 

[Supercharged111]

I'd rather run the vortec pump and not have to deal with drilling in the block. I'll find a way to route the hoses. Would I need to do anything with the coolant passage on the TBI head?

Can I run the TBI fan/clutch on the vortec pump?

Vortec pump has a spin on clutch, unless there was an early and a late.

 

[Schurkey]

So I checked my two blocks and the one that was in the truck when I got it has the coolant bypass and the provisions for a roller cam. The one that I'm going to build doesn't have them... ...the block at my house is a 638 casting 4 bolt and the one I'm building is a 880 2 bolt. Any major issues I'll run into?

I think you're building on the wrong block.

Kinda surprised that an 880 block doesn't have provision for a roller-cam 'n' lifters. Are you sure?

I don't know about the 638 casting. Fairly sure the 880 uses larger oil-gallery core plugs beside the cam bearing in front, with one or two of them VENTED with a tiny hole. Be sure to buy the correct soft-plug kit with the larger core plugs for that gallery, and it'd be worth your time to drill 'em with a 0.032 (tiny) drill bit.

Or pay the insane price for vented plugs. I forget which size is correct. MPC-54V, I think...maybe.
www.summitracing.com/search/department/engines-components?N=part-type%3Aengine-expansion-plugs%2Bbrand%3Amelling&SortBy=BestKeywordMatch&SortOrder=Ascending&keyword=vented

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So educate me. What's the purpose of the bypass and will be detrimental to my build?

Allows coolant circulation before the thermostat opens. Reduces hot-spots, reduces water pump "stall" where the impeller spins but doesn't do anything useful--just churns the coolant.

Side note: I'm a dumba** and just realized

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You would not have to do anything with the TBI heads and their bypass holes. They're sealed with the head gasket. No leakage, but no functional bypass either.

Whether you want to locate, drill, and tap the front of the block for the missing front cover bolt-holes is up to you. I did. 1/4-20 tap, 13/16 13/64 tap drill.
www.amazon.com/IRWIN-HANSON-Tap-Drill-80230/dp/B00004YOAS/ref=sr_1_5?crid=1ZVMT9SBZ76W0

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Depending on which front cover you use, you may want to pop a couple of locating dowels into the dowel-holes on the block. If you don't use dowels or a Vortec front cover you MUST be careful to leave the cover slightly loose, install the torsional damper far enough so that the front cover centers it's seal on the damper hub, and THEN tighten the front cover.
www.summitracing.com/parts/pio-839059

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One example of stuff that came on random core engines I acquired:

Threaded fan clutch, (Vortec) vs. bolt-on (TBI); and different pulley spacing. They may not all be the same.

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You could use the TBI pump on the Vortec block, there's no leakage but there's also no functional bypass. The heater-core on stock cooling systems should be a bypass, and/or a hole drilled in the thermostat will bypass, but it'll also slow warm-up. I do not recommend drilling thermostats UNLESS there's an issue with the OEM bypass--as there is here.

 

[Erik the Awful]

If I were to do it again, I'd drill the block.

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[Supercharged111]

Not a cheap option, but did the Vortec/TBI intake use the Vortec thermostat? That is part of the bypass system on the Vortec, would that be a bolt on no drill way to get a functioning bypass?

 

[sntrym]

Vortec pump has a spin on clutch, unless there was an early and a late.

Correct. Vortecs only used spin on clutches. You can swap fan blades between clutches if you want plastic on the TBI pump. I went with electric fans

 

[sntrym]

Not a cheap option, but did the Vortec/TBI intake use the Vortec thermostat? That is part of the bypass system on the Vortec, would that be a bolt on no drill way to get a functioning bypass?

The Vortec to TBI intake uses the TBI tstat.