383 Vortec/TBI Build Thread

[4WDKC]

I have a few Proto tools that are 40+ years old. No doubt made in the USA back then.

Read on a auto mechanics forum that the Blue Point tools are very nice. Also, a guy I used to do part time work for has been buying Blue Point and even Tekton and GearWrench. He's got a gazillion Snap-On and MAC tools from 30+ years as a mechanic, but says the prices are killing him.

Personally, I've never had any problems with Craftsman tools, but I'm just a hobbyist. I do like Snap-On's semi-deep well sockets, but see where SK Tool and others also sell them.

Just want to add that the Taiwanese tools are light years better than the Harbor Freight low Chinese bidder tools. Maybe they're getting better, but back in the 1990s their sockets were total junk, and could round off a bolt head in nothing flat. Still remember using a friend's 1-5/16" socket that was closer to to 1-11/32". Not good when trying to break loose suspension bolts that had been torqued to over 100 lb/ft.

Just a heads up Sears sold the Craftsman brand to Stanley so keep an eye on the new tools you buy.

back to topic at hand with vortecs, am working on a similar swap possible LT1 cam swap, still need the TBI to carb adapter which did you use? I ordered 2 of the AC Delco EP241 pumps that supplied fuel for the TPI cars and are supposed to be able to supply enough for a stock LS swap at 60 PSI. What are you doing for headers?

 

[Daveo91Burb]

I have a few Proto tools that are 40+ years old. No doubt made in the USA back then.

The Proto/Stanley socket came today, very impressed, made in the good ol' US of A! And it fits inside the Comp rocker with room to spare.

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[MikeB]

The Proto/Stanley socket came today, very impressed, made in the good ol' US of A! And it fits inside the Comp rocker with room to spare.

Good to hear!

 

[MikeB]

back to topic at hand with vortecs.....What are you doing for headers?

On my 82 C10 with Vortec heads, I used Patriot H8048 headers and Mr. Gasket #5907 gaskets with steel cores and 1.5" round holes. Had to slightly open up gasket holes and header ports at 10 and 2 o'clock.

However, there was a problem with the headers, where the #2 tube hit the three hard lines running down the frame rail and under the motor mount bracket. I had to remove and re-bend the fuel line and "hand bend" the brake line and fuel vent line in place, and then strapped all three closer to the frame. I blame Patriot for saying these fit 73-87 trucks. That said, the hard lines might be routed differently on your K10.

I chose these headers because they tuck up well, almost too well! Had to modify Hedman s-bend extensions to go up and over (and down and under) the stock crossmember. Again, this may be different on a K10.

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I don't have an "after" picture, but the lines ended up approx 1.5" closer to the frame.

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Notice below where the Vortec ports are raised relative to the bolt holes, so header and gasket selection is important. That's because you don't want to cover the top of the port where gas flow is the greatest.

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[4WDKC]

On my 82 C10 with Vortec heads, I used Patriot H8048 headers and Mr. Gasket #5907 gaskets with steel cores and 1.5" round holes. Had to slightly open up gasket holes and header ports at 10 and 2 o'clock.

However, there was a problem with the headers, where the #2 tube hit the three hard lines running down the frame rail and under the motor mount bracket. I had to remove and re-bend the fuel line and "hand bend" the brake line and fuel vent line in place, and then strapped all three closer to the frame. I blame Patriot for saying these fit 73-87 trucks. That said, the hard lines might be routed differently on your K10.

I chose these headers because they tuck up well, almost too well! Had to modify Hedman s-bend extensions to go up and over (and down and under) the stock crossmember. Again, this may be different on a K10.

You must be registered for see images

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I don't have an "after" picture, but the lines ended up approx 1.5" closer to the frame.

You must be registered for see images

Notice below where the Vortec ports are raised relative to the bolt holes, so header and gasket selection is important. That's because you don't want to cover the top of the port where gas flow is the greatest.

You must be registered for see images

I picked up a set of used 87-92 Camaro shorty headers I am hoping to use, to run duals on a K series you have to route the exhaust around the t case between the case and frame. I am hoping to have enough room with the shorties to route the ps back to ds.

 

[Daveo91Burb]

Bummer about the Patriots - they look nice. I had some exhaust issues with the Vortecs on my Vette too. I used the original rams horn manifolds, but those manifolds have weird casting bumps that interfere with the valve cover placement on vortecs. I had to grind off the bumps to get the valve covers to go on. That and making sure the manifolds and gaskets mate properly to the exhaust ports - as you did. I'm probably going to stick with the original TBI manifolds on the burb (I'm just not a header guy especially for a 3/4 ton 4x4) so I don't expect to have too many problems. I also have a set of stock manifolds that came with the vortec donor engine, not sure if there's any advantage to using them or not? Disadvantage is I think the outlet is in a different location, though. I currently have a 3" single exhaust with a magnaflow muffler. (No cat, I bought it that way and it passed WAs sniff test!) Factory y-pipe. I think the only change I'll make at this point is get a better y-pipe or have one made at a local shop.

 

[MikeB]

Bummer about the Patriots - they look nice.

Yes, they are nice otherwise. Tons of spark plug clearance, great ground clearance, and exact same bends as Doug's, but 16 gauge tubes instead of 14 gauge, and 5/16" flanges instead of 3/8". Both hecho en Mexico in the same Pertronix factory.

Seems like just about every brand has some kind of issue. If I had it to over again, I'd try some 3/4-length late 60s Camaro headers. Don't know it they would fit my Square, but that's what I used on my 69 C10.

 

[Daveo91Burb]

Progress on my 383 build has been less than stellar. I had a lot of problems with my machinist - he had the block for more than two months and I ended up taking it back before it was done. (Long story, but final straw was he texted me the night before I was supposed to pick it up for the final time, told me he was out of town for a cousin's funeral, but then I drove by the next day and he was there. Took it back on the spot). Anyway, here's where he left it:

- Purchased Eagle cast 383 crank, speed pro pistons, all bearings, and rings.
- prepped block
- bored block
- clearanced for 383
- rebuilt and resized original rods

but here's what needs to be done:

- cam bearings installed
- balance rotating assembly
- assemble short block (I think I'll do this)
- other misc odds and ends

My biggest problem:

- He bought -12cc pistons. By my calcs, this could get me a CR of almost 10:1, way too high for TBI, stock vortec roller cam. I have to decide if I want to try to get deeper dished pistons or use a really thick head gasket. Opinions????? I think I understand why he got -12cc - anything for a 383 with deeper dish seems to be really hard to find, at least in hypereutectic style. Not sure Speed Pro/Sealed Power even has anything with -18cc or more for a 383 with 5.7 rods?

 

[4WDKC]

If you are using 6" rods you might not be able to use any deeper dish. Remember the vortec heads are more efficient and use less timing than others. As far as why you think compression affects TBI not sure? My concern in the vortec cam its a tiny cam originally used in the Caprice and Impala LT1s with the extra cubes you will be lowering power band of that cam.

 

[Daveo91Burb]

I'm using OEM 5.7 rods. My concern with the TBI is it's my understanding it doesn't do well with much overlap. But with the higher compression you really need a pretty good LSA or compression is really high at low speeds and you get detonation or retarded timing with the knock sensor. Stock Vortec cam has LSA of 111 compared to 117 for stock TBI so doing pretty well there. But seems like that's still not going to work well with 10:1 CR, especially if I want to be able to tow, which I do.

Talked to a new machinist today, comes recommended to me by multiple people. He told me I can get Keith Black hypereutectic pistons at -18cc, just found them online. I plugged numbers into my CR spreadsheet and I think I can get it down to 9.5:1 if I use a .04 or so head gasket. Still seems high, but the CR on the stock vortec is 9.4:1 so maybe I'm not doing too bad.

My other plan for this cam that may seem too small is I have Comp 1.6:1 roller tip rockers for it. Doesn't help with duration, but does give a little more lift. Also note that I'm limited to about 320 HP by the throttle body (46mm) I'm using.

 

[4WDKC]

I'm using OEM 5.7 rods. My concern with the TBI is it's my understanding it doesn't do well with much overlap. But with the higher compression you really need a pretty good LSA or compression is really high at low speeds and you get detonation or retarded timing with the knock sensor. Stock Vortec cam has LSA of 111 compared to 117 for stock TBI so doing pretty well there. But seems like that's still not going to work well with 10:1 CR, especially if I want to be able to tow, which I do.

Talked to a new machinist today, comes recommended to me by multiple people. He told me I can get Keith Black hypereutectic pistons at -18cc, just found them online. I plugged numbers into my CR spreadsheet and I think I can get it down to 9.5:1 if I use a .04 or so head gasket. Still seems high, but the CR on the stock vortec is 9.4:1 so maybe I'm not doing too bad.

My other plan for this cam that may seem too small is I have Comp 1.6:1 roller tip rockers for it. Doesn't help with duration, but does give a little more lift. Also note that I'm limited to about 320 HP by the throttle body (46mm) I'm using.

I have much of the same plans with my TBI but mine is staying 5.7 and I picked up a LT1 fbody cam, it has more duration than the vortec and the lt1 fbody cars were 10:1 (IIRC)

 

[Daveo91Burb]

Yeah duration and lift look pretty good, but LSA is 116? Seems like that is a high number for 10:1 CR. Seem like there were a lot of iterations of that cam and lots of disagreement on specs on the 'net. Do you have the specs for the cam you actually have?

I think the 383 will be cool when it's all done, but the $$ keep adding up. Recently found out I need a new balancer for externally balanced that is basically what was used on the 70s 400s. Factory roller cam stuff is adding up too - need a new timing set and of course those for the late model roller cam motors are about double what they cost for the older versions.

 

[4WDKC]

Yeah duration and lift look pretty good, but LSA is 116? Seems like that is a high number for 10:1 CR. Seem like there were a lot of iterations of that cam and lots of disagreement on specs on the 'net. Do you have the specs for the cam you actually have?

I think the 383 will be cool when it's all done, but the $$ keep adding up. Recently found out I need a new balancer for externally balanced that is basically what was used on the 70s 400s. Factory roller cam stuff is adding up too - need a new timing set and of course those for the late model roller cam motors are about double what they cost for the older versions.

It is supposedly from a 95 which was supposed to be second best only to the 92 Vette cam. Everything I have found says 112+ or the TBI goes crazy trying to operate even when tuned. Seems high for installing an aftermarket cam but look at the specs of the LT1,even the LS engines use LSAs like that without problems. I think the issue you are comparing it to is when it has low duration numbers placing the power band at idle creating a lot of pressure at low rpm and causing spark knock with a load on the engine.

One of the things I kept reading about TBIs 350 & 454 was towing up hills couldnt be done at low rpm, so the tranny had to down shift, then it was at the top of the power band and couldnt pull anymore and couldnt upshift causing all the problems. So I started looking at why, the 454 tbi has a cam with the same duration as the lt1 and more lift. The extra 100 cubes move the power band down 1000 RPM so the engine starts making power under the stall rating of the convertor leaving a 2500 ish rpm range that can be used. Seems all off topic right? All this is relevant as i understand because the LSA also affects how broad or "peaky" you power band is. A low duration cam with a 116 LSA will cause problems like the TBI cams, a higher duration cam with the same LSA moves the power band and high pressures up in rpm giving a more useable RPM band and way to avoid low speed, high load, high detonation problem. There's alot more science to it and its way over my head but the above is what makes sense to me. In this image borrowed from hot rod you see the lower LSA starts and makes power longer than the tight but it makes les peak all from the same duration cams.

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heres the article if you want to read it. http://www.hotrod.com/articles/camshaft-shootout-lobe-separation-angle-tested-explained/

 

[MikeB]

I think I can get it down to 9.5:1 if I use a .04 or so head gasket. Still seems high, but the CR on the stock vortec is 9.4:1 so maybe I'm not doing too bad.

Vortecs are typically fine with 9.5:1, at least with cams that close the intake valve a little later than stock. I wonder if the GM RamJet/HT383 cam would work for you? It's obviously used by GM with EFI. It does have a 109 LSA, but don't let that fool you because duration is pretty short at 196/206, meaning overlap is not too bad. In my truck's 355 that cam makes around 19" vacuum at idle.

Another question: What will your quench height be with the decked block and new pistons? As I recall K-B hypers have stock compression height. If you can end up with something around .040"-.045", that will go a long way to fight detonation.

 

[Daveo91Burb]

Thanks for the comments guys. Regarding cam, Yeah, this stuff is really tricky. I've looked at this a lot over the past year or even two, and I keep second guessing myself, but bottom line is the tuner I'm going to use (Old School EFI, Vancouver, WA) has told me point blank that the stock L31 roller cam is the way to go for my build. So I think I'm going to trust him. (Plus it's the one I have!!!) LSA on the L31 is 111, and I have also read that 112 is about as low as you want to go with TBI, but at least some of the articles I read said that was with stock tune. My tuner seems to think no problem with that cam. What do you guys think about my plan to use the 1.6 rockers to get more lift?

Mike B, not sure about quench height - how do you calculate? Compression height is 1.433 (speed pros were 1.425) and my new machinist measured deck height today and I'm at 9.015. I'm coming up with about 9.5:1 in my compression calculator, assuming .04 head gasket compressed.

Thanks!