The Dilemma:
In 2014 we were going to have the engine in our '76 rebuilt to go along with her TH350 Automatic to TK500 Manual conversion. I took the advice of some friends to have engine rebuilt into a 383 for more power since they claimed "it should cost just about the same". The custom shop doing the rebuild said "sure, no problem". After I took delivery I took it on over to the DEQ to get tested and renew the registration (it had expired during the time the shop had her, and '76 or newer cars need the certificate to be registered in our county). The DEQ sniffer reported 11x over the required hydrocarbon limit at idle, instant fail. As part of our "warranty period" with the shop, both the builder and another shop they work with tried for a detune and pass but couldn't get one. Our regular mechanic then tried his hand at a detune again with no luck, and now that their Five Gas has died no more attempts with them. After their turn our regular shop's opinion was "this engine was never built to pass emissions". And so here we are.

Advice I'm not interested in hearing repeated again:

• Registering outside of the emissions control area

Advice I am Interested in:

• Is there any chance of salvaging the existing build for a lower performance, but street legal result?
• If a crate engine is a better route, and are there any 350 SB options that are C.A.R.B. qualified? I see plenty that say pre-emissions applications only…
• We had hoped the 383 would let us have fun while saving for an LS Swap in five or so years, mainly due to how involved other LS Swap threads here have seemed to be. But given the situation, would that ultimately be a better long-term solution, even with all of the changes to other systems (fuel, electrical, etc) that it would require?

The Details of the Build:
Components Used and Part Numbers

• Original 350 block, was 0.030, now 0.040, magnifluxed
• Edelbrock performer air gap intake 7501
  http://www.edelbrock.com/automotive/...r-gap-sb.shtml
• Edelbrock E-Street 5073/5089 202 heads
  http://www.edelbrock.com/automotive/...treet-sb.shtml
• Comp Cams cam 12-234-2, Grind #: CS XE256H-10
  http://www.compcams.com/Company/CC/c...x?csid=84&sb=2
• Comp Cams Timing Chain (#2100, #3100, or #3200)
• JEGS Headers (30049 Ceramic , or 300106 Coated)
• B & M StarTek Starter 77104 or 77105
• MSD Digital HEI Kit P/N 850 1
• Eagle 383 Kit including:
  • Eagle Cast Steel Crankshafts 10350375057I
  • Pistons
• Dynaflow carb (1x per side of true dual exhaust) - don’t have model numbers.
• Magniflow mufflers

The engine started with a Holley Street Avenger 670CFM carb, but after the first few attempts to get the HCs down it was swapped with an Edelbrock Performer Series 600 cfm, Square-Flange, Electric Choke Carburetor (non-EGR). On the last of their attempts, the builder added a fuel flow regulator and 195 degree thermostat, then tried the ½ tank of premium and alcohol strategy. The car blew the worst result yet on that try, even after a 30 minute warm-up drive to get the cats nice and hot.

And so here we are. Life got in the way and she's been hibernating in her Winter clothes since the last attempt in August, but I'd like to start plans for her rescue and need some honest advice on if it's a top-end issue (I noticed plenty of "Not 50-state legal!" on Edelbrock's site for the E-Street and Performer Air Gap, after the fact) or if it's time to move on and go with a crate or LS swap.

Thanks all.

Edit 2016-01-30:
There's been requests for some additional information, so I'll add it here to try to keep things all together. Sorry I didn't put it in the first time around, but "life got in the way" includes a toddler who consumes most of our free time these days.

The test is just a quick visual (cats, cap, and EGR present) then a tailpipe sniffer (in our case, one per tailpipe). They do an idle, then post high-RPM sniff, have to have good numbers for both sniffs to pass. None of the tests progressed past the first idle sniff (failed right off the bat).

Portland, OR Emissions Standard Maximums:
HC: 220
CO: 1
CO2: 6

Results of emissions tests
Attempt HC CO CO2 RPM Notes
1 534 9.942 8.1 N/A Initial pickup
2 99 1.4796 13.7 N/A Detuned by mechanic
3 932 11.69 7.1 N/A w/ 600CFM Fuel flow limiter, 195⁰ thermostat, no detune

So far, the mileage on the engine after the rebuild's been at most a few hundred miles. I'll try to check where the vacuum advance is pulling from when I have an hour to spend in the garage, might take a few days for that to happen though. As for the cats, no idea what their parameters are, I'll look around for a part number on them to make an educated guess. Two of the plug wires had burned on the headers before the attempt #1, since then fiberglass sleeves and better routing have been used with the replacements. I'll have to check the gap if I can get the plugs out, the clearance with the headers isn't great and they used full-sized plugs instead of stubbies...

 

That cam, while a bit tight on lobe separation isn't really that aggressive and should be able to pass the tail pipe test with some skilled tuning. Before you do anything drastic like changing parts you need to find someone who knows what they're doing to do some tuning to try to get the numbers lower. I'm gonna assume you have the vacuum advance hooked up, is it running off manifold vacuum or ported vacuum? Reason I ask is that reducing initial timing by using ported vacuum will make a huge difference on idle HC readings.

 

Are they high flow cats? If so I've seen CA fail with those because they don't do a very good job.

Assuming EGR is gone. Thats going to hurt as well.

I feel your pain being in California.

Here in CA you can take a LS say from a 2004 GTO and swap everything over. The states then tags it as a 2004 GTO for testing.

GM also have a CARB legal conversion called the EROD. Not cheap though but all new.

Look up what Shark_Racer build. He passes CA tail pipe emissions.

 

What are the laws in Oregon? Is it a tailpipe only test or is it a visual also? Do they do a functional test(check timing, EGR operation etc.)?

 

x2 on their visual inpection requirements. With EGR that car should pass without much of a problem thats a tiny cam passes in Ca.

wonder what the co/hc requirements are in comparison

 

Sucks when states stick on a year like 1976 vs the old way of rolling 25 yr exemption. I bet you could find a shop to give you a pass on it somewhere anyways. I did when I was in NY, there are car enthusiasts everywhere, and its easy for the shop to claim you changed it after testing if you did get caught.

I wont say register it outside the emissions area, I will go further - MOVE. You are implicitly supporting such regulation and paying for it with your taxes. I love the fact that we have no testing or inspections here in OK, and I will venture to guess that our air here is still cleaner than California. Well, unless you believe that crap about cow poo causing pollution, we do have cows here.

Personally, I would not want a detuned engine like that, defeats the whole point of building a 383.

I voted LS in your poll because its the easy way and will probably make more power than your 383 anyways, but hate to see the government force you to rip the heart out of a vintage piece of Americana.

 

With an exhaust heated iron intake manifold and QuadraJet you would likely pass the sniffer test.

 

You don't need an iron intake, not sure whether or not you need a Q-Jet to pass but I passed with more cam and 10.24:1 compression.

There are a couple major deltas between your engine and mine:
1. Intake manifold: I ran a low rise dual plane which allowed me to use the stock emissions components; most importantly EGR.
2. EGR: this allows you to run a leaner burn without increasing NOx emissions, but not really your problem.
3. A Q-Jet. The smaller primaries could help w/ more precise metering and preventing unburnt fuel.

Typically, high HCs are caused by incomplete combustion. If CO is low, then you pretty much have to look at either a too-lean idle mixture or a fault in the ignition system (burnt plug wire, failing spark plug, both of which would be more likely to "burn through" at higher RPM).

I'd start with checking the ignition system. Make sure your plug gap is correct (0.045) and that timing is up-to-snuff. This car was designed with manifold vacuum to the vacuum advance from the factory, no need to mess with it it should pass.

With the cam you have in there right now, idle should be very smooth, by the way. It should be capable of idling very smoothly at 700RPM, if not lower. If it's rough at all, idle calibration or ignition would also be suspect.

 

it would be helpful to know what the initial timing is and if the vacuum advance is hooked to ported or manifold vacuum plus I would like to see the CO and HC readings at idle and 2500 rpm. a high HC reading can be caused by a too rich or too lean air/fuel mixture or too much spark advance (or too little) plus it could be caused by an air leak causing a misfire problem. Is the high HC reading the same in both sides of the exhaust? perform a cylinder balance test to be sure all the cylinders are doing their job at idle. a air leak from a PCV valve that is flowing too much air at idle or a bad power brake could also cause high HC problems.

I would also suggest getting exhaust gas reading in front of the cat convertors to be sure they are actually working, the readings should be a lot higher before the cat then after the cat. a good starting CO reading would be 1 to 2% CO at idle and cruise and it should be well below 1% after the CAT if it actually doing its job. a HC reading of under 500 ppm at idle and under 150 ppm is what I would hope to see with a mild cam engine.

I hope this helps Henry @ oles carb

 

It clearly states on the Edelbrock site that the intake, 7501, is for pre-pollution controlled vehicles. It has no EGR and no heated crossover. Look at the 3701 manifold which has EGR and heated crossover. Install it to pass and then put the 7501 back on. Make sure your initial timing is low, 6 to 8 degrees at most with no vacuum advance at idle, ported vacuum. Make sure the idle mixture screws actually can do a lean drop.

 

The OEM iron intake manifolds had cross-over exhaust heat to heat the runners and the fuel in the carburetor. With their smaller runner cross sections and the heat the velocity at idle is high and the heat helps to vaporize the fuel. The Air Gaps on the other hand are "cold" manifolds with much larger runner cross sections so the fuel doesn't get heated and the velocity is slow; causing failed emission tests.

 

To get my hot rodded, single plane intake, long tube headers without cats.

No egr... no stupid exhaust cross over.... Heads and manifold didn't even have the cross over passages anyway.

First of all how many miles do you have on this new engine? Fresh rebuilds will test high on hydrocarbons until the motor is broke in.

Shark Racer has good advice. I pulled my Vette into a sniffer shop and we put the sniffer in the tail pipe. Then we messed with the idle mix screws and adjusted the timing while watching the sniffer. Turning up the idle speed will also reduce high hydrocarbons. timing generally changes to CO emissions

You can pull off the PVC if you suspect excessive oil mist blow by. But cap the carb side because it creates a large vacuum leak lean condition.

Years later my new 427ci 11.7 c/r with over 250@.050 duration solid roller with .685/.714 lift tall single plane............ anyway it had high hydrocarbons. I kind of blame the 1/16 inch racing rings. So anyway i ran the gas tank down to nearly empty like a gallon or so. I changed the oil to light weight full synthetic. I drove to my buddies race shop and we put in 5 gallons of noncorrosive treated racing methanol. It would simulate something like ethanol based E-85 that they don't sell here. Using e-85 might also lower hydrocarbons. I put in 4 jet sizes bigger on the primary and secondary and drove like I stole it 5 miles over to the emission test station. Alcohol has no hydrocarbons and it passed with flying colors. Now I have plates requiring no emission testing

 

 

FYI, Alcohol and ethanol are hydrocarbon based fuels, if you are in doubt place the sniffer from an exhaust gas analyzer above a glass of vodka and watch the HC readings. Alcohol burns at a much lower temperature than pure gasoline so most engines will have a lower HC reading because it is easier to light off (vaporizes at about 140 degrees) than what is sold for gasoline today (which may not fully vaporize until the temp reaches 400 degree range).


Henry @ oles carb

 

I know that I worded it wrong. I was mainly saying that it was an alternative way I thought up to pass emission testing. Very simplistic comparison of methanol to the long carbon chains of modern gasoline blends. I was a petrol chemical major as a young lad. Methanol = CH3OH Gasoline = 2 C8H18 + 25 O2

This is one of the simpler explanations of modern gasoline

The bulk of a typical gasoline consists of hydrocarbons with between 4 and 12 carbon atoms per molecule (commonly referred to as C4-C12).[5] It is a mixture of paraffins (alkanes), cycloalkanes (naphthenes), and olefins (alkenes), where the usage of the terms paraffin and olefin is particular to the oil industry. The actual ratio depends on:

1. the oil refinery that makes the gasoline, as not all refineries have the same set of processing units;
2. the crude oil feed used by the refinery;
3. the grade of gasoline, in particular, the octane rating.

The various refinery streams blended to make gasoline have different characteristics. Some important streams are:

straight-run gasoline, usually also called naphtha is distilled directly from crude oil. Once the leading source of fuel, its low octane rating required lead additives. It is low in aromatics (depending on the grade of crude oil), containing some cycloalkanes (naphthenes) and no olefins (alkenes). Between 0 and 20% of this stream is pooled into the finished gasoline, because the supply of this fraction is insufficient[clarification needed] and its RON is too low.[citation needed]. The chemical properties (namely octane and RVP) of the straight-run gasoline can be improved through reforming and isomerisation. However, before feeding those units, the naphtha needs to be split in light and heavy naphtha. Straight-run gasoline can be also used as a feedstock into steam-crackers to produce olefins.

reformate, produced in a catalytic reformer has a high octane rating with high aromatic content, and relatively low olefins (alkenes). Most of the benzene, toluene, and xylene (the so-called BTX) are more valuable as chemical feedstocks and are thus removed to some extent.

catalytic cracked gasoline or catalytic cracked naphtha, produced from a catalytic cracker, with a moderate octane rating, high olefins (alkene) content, and moderate aromatics level.

hydrocrackate (heavy, mid, and light) produced from a hydrocracker, with medium to low octane rating and moderate aromatic levels.

alkylate is produced in an alkylation unit, using as feedstocks isobutane and alkenes. Alkylate contains no aromatics and alkenes and has high MON.

isomerate is obtained by isomerizing low octane straight run gasoline to iso-paraffins (non-chain alkanes, like isooctane). Isomerate has medium RON and MON, but nil aromatics and olefins.

butane is usually blended in the gasoline pool, although the quantity of this stream is limited by the RVP specification.

 

I would think the Edelbrock Air Gap is your biggest problem because they have very large diameter runners which slows the velocity down a LOT and the fact its a "cold" manifold really hurts the sniffer testing because the fuel easily sticks to the sides of the cold runners. I would try using a stock cast iron exhaust heated intake and heat riser valve before trying anything else and make sure you run it for at least an hour before the sniffer test.

 

I still passed smog with an aluminum intake. The 3701 Edelbrock Performer mentioned previously has worked well for me, as well as the 10185063 ZZ4 manifold. They are both low-rise dual planes very similar in form to the stock and include heated crossover passages.

Given the cam and relatively small port heads you have I honestly don't think you'd be giving up much by going to a low-rise anyway.

 

Can you post up the numbers it actually blew? I did ca. smog for 27 years, and could get that car to pass. The biggest factor is ignition timing, idle mixture adjustment, and idle speed for HC. was any other number high like the Co #s?

 

Shark racer, Tobroke is some kind of a lost in the 60's or 70's bubba or shade tree mechanic. It is the the only way to describe his posts. It is like he is in the special Olympics of mechanics. No forward progression

I still work on old vettes and when you take off a cross over intake manifold the baked on tar and carbon build up is horrible. The cross over exhaust blocking spring is so rusted that you always have some hot flow.

Any hot rodder from the 60's got rid of that junk and put intake gaskets plugging the cross flow exhaust gas.

 

Thanks everyone for your suggestions. I updated the first post with the numbers, and will need to get back to you on the rest of the items (vacuum source, EGR/no EGR, etc). Ran out of time during the kid's nap time to step out to the garage...