Spec Carbureted Engines

[64GunPilot]

6.12 & 6.13 Allows the spec carbureted engines. I don't see any posts with folks using these, or asking about them. What kind of power do they put down and is anyone competitive with these setups? I have more than a few vortec 5.7 laying around from 96-99 chevy trucks, tahoes, ect. Just curious if they could be used as spare engines. Update/Backdate rules should not apply in this instance as the rule states the spec as a 5.7 liter with those specific components. Curious about their power numbers. My first tech question of many.

[Supercharged111]

What exactly did that car come with for a motor? I believe Bob Denton over in the Great Lakes region has a 3rd gen running a carb'd setup. Matter of fact we have a guy here who hasn't run in a couple years. His wasn't spec but the Dyno came out good with no cheater curve.

[64GunPilot]

What exactly did that car come with for a motor? I believe Bob Denton over in the Great Lakes region has a 3rd gen running a carb'd setup. Matter of fact we have a guy here who hasn't run in a couple years. His wasn't spec but the Dyno came out good with no cheater curve.

Plum's car (soon to be my car) is a 305 TPI, L31 heads, 255/307 and 3000lbs without driver. Engine is fresh. I guess those numbers, I may not be as competitive. But Im sure it'll be awhile before my driving is good enough to need 11hp to stay with the pack.

Its legal for me to use any 350 block for a spec carb engine right? I'd just need stock manifolds instead of shorty headers....I think.

[Supercharged111]

255/307 is doing really good for a TPI. They tend to make so much more torque than hp that you end up backing timing off to keep from going over on torque. 255hp is plenty, I think the Jordan-mobile makes about that much and they hang out up front. I'd take it to a Dyno myself first and verify what it makes, maybe play with the timing some and see if there isn't a little more in there.

[Storm Trooper]

255/307 is doing really good for a TPI. They tend to make so much more torque than hp that you end up backing timing off to keep from going over on torque. 255hp is plenty, I think the Jordan-mobile makes about that much and they hang out up front. I'd take it to a Dyno myself first and verify what it makes, maybe play with the timing some and see if there isn't a little more in there.

Since when is playing with the timing legal?

[BADVENM]

You can do whatever you want with the timing, just have to specify what it is on the dyno sheet.

7.6.2 Timing tolerance shall be +/- 1 degree.

[64GunPilot]

Going back to original object of the thread....is is legal for me to put a carb'd spec 350 in a 3rd Gen? I've read in other places on this forum through searches, that no 350 is allowed in 3rd gens and I quote "period" but they were talking about 350 TPI and I think those threads were at least 10 years old.

[Fbody383]

You'll hear this a lot... look at the rules.

Section 6.13 in part:
5.7 liter (350ci)
1. Holley carburetor 600cfm-4bbl #4776
2. Edelbrock Performer intake manifold #2101, #2104, #2116, #7116, #7516
3. GM Camshaft #24502476
4. GM L31 #12558060 or L30 #12552520/12558059 heads
5. GM OEM H.E.I. distributor (non-computer controlled)

And just keep asking questions...

[michaelmosty]

If you are putting down 255/307 numbers then I would not spend another penny on the motor. The extra 5hp will equate to maybe a tenth of a second and will cost tons of money and time to get.

If you go the carb route on the 305, Bob Denton ran that motor very successfully in previous years in the Great Lakes region.

[64GunPilot]

If you are putting down 255/307 numbers then I would not spend another penny on the motor. The extra 5hp will equate to maybe a tenth of a second and will cost tons of money and time to get.

If you go the carb route on the 305, Bob Denton ran that motor very successfully in previous years in the Great Lakes region.

Yea I was thinking more of a fresh spare engine. I've been passed Bob Denton's contact info. But Im sure that money is better spent on tires/brakes.

Speaking of tires....did the previous rules limit the tires to 255 size RA1s? This car hasnt been raced in a few years, and he has like 16 wheels/tires all 255/40/16. Everyone is now running 275 RR? Probably a question for a separate thread. Regardless, Im sure the 255s will be great for DE.

[64GunPilot]

You'll hear this a lot... look at the rules.

Section 6.13 in part:
5.7 liter (350ci)
1. Holley carburetor 600cfm-4bbl #4776
2. Edelbrock Performer intake manifold #2101, #2104, #2116, #7116, #7516
3. GM Camshaft #24502476
4. GM L31 #12558060 or L30 #12552520/12558059 heads
5. GM OEM H.E.I. distributor (non-computer controlled)

And just keep asking questions...

I guess I had that coming.

[Fbody383]

I guess I had that coming. Just part of the learning process.

I think you also had a question about tires - yes 17" usually the way to go now... up to 275. I might need to check the rules... (see what i did there???)

But you're welcome to BBQ...

[marshall_mosty]

If you have 255’s, burn them up.. learn Racecraft. Seat time... seat time... seat time...

[Den34]

We have 3 third gens in our region running carbed 350s. They all make good numbers and are stupid simple. The 350 with a LT1 T56 makes a pretty solid setup. Bryan White has been running this setup for several years and it has been very reliable. The downside is that some are actually on the high side of torque so you have to be careful of your exhaust configuration so as not to build too much torque. The other downside they are iron head iron block. Still waiting for someone to submit a RCR to allow the 80s corvette aluminum heads.
Bob

[64GunPilot]

We have 3 third gens in our region running carbed 350s. They all make good numbers and are stupid simple. The 350 with a LT1 T56 makes a pretty solid setup. Bryan White has been running this setup for several years and it has been very reliable. The downside is that some are actually on the high side of torque so you have to be careful of your exhaust configuration so as not to build too much torque. The other downside they are iron head iron block. Still waiting for someone to submit a RCR to allow the 80s corvette aluminum heads.
Bob

Hey, Thanks for chiming in. Been told you have good experience with them. The 305 TPI I got is fresh, so I'll probably keep it in the car as long as it is healthy. But, possibly in the distant future, I'll roll with the carb'd spec engine. I like EFI, but I enjoy simplicity too. Thanks for the info.

[39PitCrew]

Hey, Thanks for chiming in. Been told you have good experience with them. The 305 TPI I got is fresh, so I'll probably keep it in the car as long as it is healthy. But, possibly in the distant future, I'll roll with the carb'd spec engine. I like EFI, but I enjoy simplicity too. Thanks for the info.

Which intake are you running? If I recall, the 305 runs out of air at about 4500-5000 RPM.
You might talk to Sean (Storm Trooper #15) about his experience with his 3rd Gen.
Sean did the 5.3 LS conversion on his car last year. Big change was that the LS uses about
1/2 to 2/3rds the fuel as the 305 and the torque is better across the RPM range.
Trying to recall if he changed diff gears too, he can tell you.

[64GunPilot]

Which intake are you running? If I recall, the 305 runs out of air at about 4500-5000 RPM.
You might talk to Sean (Storm Trooper #15) about his experience with his 3rd Gen.
Sean did the 5.3 LS conversion on his car last year. Big change was that the LS uses about
1/2 to 2/3rds the fuel as the 305 and the torque is better across the RPM range.
Trying to recall if he changed diff gears too, he can tell you.

A couple months late on this answer, but as far as the intake, its the Vortec to TPI intake thats on the car now. I've been looking at the 5.3 LS engines out there. Trying to figure out how much going the LS conversion route costs in total. T56s are not cheap, and I'd have to buy all the LS1 accessories, intake, and exhaust manifolds per the rules.

I have a spare Vortec 350. I think I am going to build it per the spec carb rulebook, and then maybe use it in another non-daily driver project and dyno tune it (more emphasis on the tuning than hp/tq numbers). But then, if my 305 starts to have troubles, I can just pull that Vortec as my backup engine since it'll be spec. Thats the thought right now anyways. I just wish the spec engines could run roller cams since thats what I already have.

[Supercharged111]

Sean's 3rd gen still runs (ran?) a T5 at least as far as Hallett.

[39PitCrew]

A couple months late on this answer, but as far as the intake, its the Vortec to TPI intake thats on the car now. I've been looking at the 5.3 LS engines out there. Trying to figure out how much going the LS conversion route costs in total. T56s are not cheap, and I'd have to buy all the LS1 accessories, intake, and exhaust manifolds per the rules.

Talk to Sean, he can tell you costs. And probably give you some ideas on
where to get stuff on a tight budget. I think he actually used the truck block
(LM4?) and accessories brackets because they are readily available at
the pick-a-part yards. And they make more power than you can use.
He runs a tail pipe restrictor to get the HP/TQ numbers down to avoid
penalty weight.

[64GunPilot]

I found this $800 for turn key with accessories, harness, ect. Would need accessories, intake, and exhaust from LS1. So maybe $1250 for all of it. Then getting the trans to bolt up probably needs a bellhousing and crossmember. Yea. Ill definitely get with someone who has done this before. My career in HPDE pre CMC license, will definitely be running the 305 vortec TPI. As long as it lasts, im gonna run it.

https://dallas.craigslist.org/ftw/pts/d/fort-worth-2002-silverado-53-liter/6791509649.html

Looking at the spec carb route, the intake, carb, cam, ect is gonna be over $1000 and that doesnt even include the rebuild. But the engine would be fresh vs 150,000 miles on the 5.3 LS.

[Supercharged111]

Screw an iron block at that price. Run what you have until it holds you up. In the meantime find a real deal on an LM4 aluminum block 5.3. If you're savvy you can convert a truck harness yourself to save a buck. We also passed an RCR to allow cheap aftermarket accessory mounts instead of the ripoff prices CL fiends are demanding. I found myself a $225 LM4 at the pull and pay some time back, hoping to find a spare without a hole in the block at some point. I've hunted down the LS1 rack, k member, steering shaft, plastic tank, etc but just know the swap process, at least on a 4th gen, is fairly involved. The early early LS1s had return lines, so hunting down those rails will be a necessity for that 3rd gen. Not an overwhelming asspain, just something to consider. It's more than a motor and mounts to get that thing in there.

[64GunPilot]

Ive read that the L33 is the best 5.3. Its aluminum and heads are pretty much the same as the LS1 castings.

[Pranav]

Ive read that the L33 is the best 5.3. Its aluminum and heads are pretty much the same as the LS1 castings.

The L33 is a great motor, but you'r spending more money for a hotter motor that will be hard to restrict down to the 260/310 level

Stock 5.3s are easily getting 260hp and just under 310 torque (mine is a weirdo at 262/305), while in most cases LS1s with their better flowing heads and hotter cams are restricting at 260hp and are ending in the 290s on torque.

Stick with an LM4 or LM7, cheaper and a better fit for the class, plus with a stock cam your valvetrain is under less stress.