[68HellCo]

Originally Posted by Silver Surfer

I wonder what the horsepower per dollar is on that Shelby GT500 versus what you got and what it could/should be.

Considering I've dropped in 3 different motors, two transmissions and lots of other crap into this ELCo, plus two years of my sorry *** life, let's see ... I've probably got $20k invested by now and I missed two years of work (at $90k a year ... ) That makes this a $200k "project" or 4x the cost of that Shelby but with half the horses. Waaah. Now you get my drift?

[curtis73]

I've been there.... and I didn't mean to sound so apocalyptic in my last post.

I put $4000 into a Caddy 500 build only to be disappointed with my choices and I ended up selling it for $500. So far I've put $19k into a 66 Bonneville and its just now coming out of the body shop. I have another $10k to go at least.

But that is why this forum was invented

I think you have a great engine, but the heads are holding you back. Spend a little money up top on heads and you'll be very happy.

[68HellCo]

Youch, i know the feeling -- the money never comes back. That '66 will be worth it eventually. Thanks on the heads vote, that was my sense that it's a good build candidate for a lobotomy!! At least the motor won' t have to come out again. ... I'm losing hair, patience and knuckles. But at least I'm not alone!!!

[American Muscle]

Why does everybody worry about hp numbers. If he built the engine right and it puts out 290hp and you like it then ride on. I have a mousey 305 with bolt ons and its a blast to drive and reliable and sounds baby monstrous too. Numbers mean nothing. Build it right, build it to last, and ride. I think im more interested in longetivity now more than hp numbers. Im more worried about keeping the truck in running condition until my 7 yr old is 16 cause he said its his. lol

[454C10]

With a 350cid, stock stall, and 3.08 gear. The engine should be limited to around 350hp.

A 400-450hp 350cid would need around a 3000-3500 rpm stall and a 3.73-4.11 gear

A 450-500hp 350 will need a 3500-4000 stall and a 4.11-4.56 gear.

Needless to say, big cams, high rpms stalls, and high numeric gears will not make a nice street car. and not good for durability or mpg.

A 3.08 gear with a stock stall makes a nice driver but needs low rpm torque to go fast. keep the cam mild, add more cids, good heads, free flowing exhaust, dual plane intake, and a good carb.

In this case, change the heads, add 2-1/2 exhaust, use a dual plane intake, get a holley 3310 carb. And consider a little 150hp shot of NO2 to make the 500hp goal. N02 also increases torque about the same as the hp increase.

Also, your current ignition timing is not high enough. Try 17 or 18 degrees at idle, and use the vacuum advance in the manifold source (vacuum at idle). Get an adjustable vacuum advance canister (summit racing) and add 10 more from the vacuum advance. so the engine should be idling at 17 + 10 =27 degrees. This set up will help the engine's throttle response.

Hotrodding is a way of life. If you start to add up money then it isn't fun anymore. However, there are cheaper ways of getting the same results which takes time to figure out.

[twistedaxle]

Originally Posted by 68HellCo

Thanks Dogwater for the quick fix on the exhaust. And thanks Bogie for the the in-depth info. I know the machinist zero decked the block and built it with some particular pistons for that. As well, rolling rockers of 1.6 and drilled studs and plates. The cam had these specs:
http://www.enginepro.com/downloads/EPCatalogCams.pdf
MC1730 HYD 2 204 214 278 288 .420 .433 107 117 1500-4000 SMOOTH 817 B
His partner redid the 2.02 heads to match what he was up to. I wanted to make the best of the heads I had rather than fork out for some others. I suppose I'm doomed and should just go out and buy a brand new 500HP car and skip all this nonsense going into my 68 ElCo. Sometimes I wonder why I keep at this. Thanks for the advice, wisdom.

The 350/350hp engine was the L46. The problem is, that cam isn't a performance upgrade. The L46 cam was p/n 3896962. It's duration at .050" was 222/222. Lift was .450/.460 intake and exhaust. You've got 1.6:1 ratio rockers. You'll have about the same lift as the L46 cam had with the 1.5 rockers, but less duration.

A Holley Street Dominator can be a good manifold. Depending on which one you have. There was one that was basically a knock-off of the LT-1 high rise dual plane. That's p/n 300-36. There was another one, p/n 300-38 (both were previously sold under the name "Contender") that was basically just an aluminum low rise Q-jet manifold. If you've got the high rise manifold it will have a square bore carb flange. If you've got the low rise Q-jet copy it will have a spread bore flange.

Which could also cause you problems. An Edelbrock carb has both bolt patterns, so it will bolt on. But there could be interference with the linkage or the butterflies that will keep the carb from doing everything you want a carb to do for you.

You should check to see which manifold you have, definitely. Unfortunately the part numbers are stamped under the manifold. You should be able to determine which manifold you have by the flange. You may very well have the low rise manifold because that's what the original L46 had to prevent hood interference issues. But then, it also had a 750cfm Rochester Q-jet, and you have a 600cfm Edelbrock.

So, you have a bit less cam than an L46, and less carb (which may not be working optimally as it's best not to mix square bore carbs with spreadbore manifolds & vice versa). You undoubtedly have less compression as well; did your mechanic build you an 11:1 small block? That's how the L46 was built.

You basically have less of just about everything that matters when it comes to making power that the factory had to put into them back when Chevy was optimistically rating them at 350 horses. That may go for the heads as well, depending on what your engine builder did to them when he reworked them. Frankly, I don't see how he could have possibly believed you'd get anywhere close to 400 horses when he was building you what's essentially a lower-performance version of the L46.

[68HellCo]

Originally Posted by twistedaxle

The 350/350hp engine was the L46. The problem is, that cam isn't a performance upgrade. The L46 cam was p/n 3896962. It's duration at .050" was 222/222. Lift was .450/.460 intake and exhaust. You've got 1.6:1 ratio rockers. You'll have about the same lift as the L46 cam had with the 1.5 rockers, but less duration.

A Holley Street Dominator can be a good manifold. Depending on which one you have. There was one that was basically a knock-off of the LT-1 high rise dual plane. That's p/n 300-36. There was another one, p/n 300-38 (both were previously sold under the name "Contender") that was basically just an aluminum low rise Q-jet manifold. If you've got the high rise manifold it will have a square bore carb flange. If you've got the low rise Q-jet copy it will have a spread bore flange.

Which could also cause you problems. An Edelbrock carb has both bolt patterns, so it will bolt on. But there could be interference with the linkage or the butterflies that will keep the carb from doing everything you want a carb to do for you.

You should check to see which manifold you have, definitely. Unfortunately the part numbers are stamped under the manifold. You should be able to determine which manifold you have by the flange. You may very well have the low rise manifold because that's what the original L46 had to prevent hood interference issues. But then, it also had a 750cfm Rochester Q-jet, and you have a 600cfm Edelbrock.

So, you have a bit less cam than an L46, and less carb (which may not be working optimally as it's best not to mix square bore carbs with spreadbore manifolds & vice versa). You undoubtedly have less compression as well; did your mechanic build you an 11:1 small block? That's how the L46 was built.

You basically have less of just about everything that matters when it comes to making power that the factory had to put into them back when Chevy was optimistically rating them at 350 horses. That may go for the heads as well, depending on what your engine builder did to them when he reworked them. Frankly, I don't see how he could have possibly believed you'd get anywhere close to 400 horses when he was building you what's essentially a lower-performance version of the L46.

Twistedaxle,
VERY helpful. I think i have the square bore open manifold. It seems to be higher than a stock Qjet manifold. Is this good? I wasn't certain from what you said. I suppose I could check for butterflies interfering, seeing if they don't open completely, i presume. Yikes. That would suck. I think he zero-decked it and did something special with the heads guy he works with and ordered appropriate pistons for the setup, with standard compression ratios for pump gas. That's all I remember. The receipt and parts list looks like Chinese to me in some parts (just cause I can't figure some of it out). The pistons look like forged L-2256 .30 over.

Sounds like I need new heads but need to know if the manifold is interfering.

Any recommendations on heads? My old ones are 2.02s with guide plates, ARP studs and those mentioned rollers. ... thanks a lot for advice.

[twistedaxle]

Originally Posted by 68HellCo

Twistedaxle,
VERY helpful. I think i have the square bore open manifold. It seems to be higher than a stock Qjet manifold. Is this good? I wasn't certain from what you said. I suppose I could check for butterflies interfering, seeing if they don't open completely, i presume. Yikes. That would suck. I think he zero-decked it and did something special with the heads guy he works with and ordered appropriate pistons for the setup, with standard compression ratios for pump gas. That's all I remember. The receipt and parts list looks like Chinese to me in some parts (just cause I can't figure some of it out). The pistons look like forged L-2256 .30 over.

Sounds like I need new heads but need to know if the manifold is interfering.

Any recommendations on heads? My old ones are 2.02s with guide plates, ARP studs and those mentioned rollers. ... thanks a lot for advice.

Yes, the square bore high rise is considered the good one. It's about equal to an Edelbrock Performer RPM. Not the air gap version, though. That's not just my opinion, either:

http://www.crankshaftcoalition.com/wiki/Intake_manifold

It looks like these are your pistons.

http://www.summitracing.com/parts/SLP-L2256F30/

They should give you about 9.5:1 compression with the 64cc combustion chamber (that is what your heads will have if they are off an L46 vette) and a .039 gasket.

Basically, what your engine builder put together sounds more like the L82. It was rated at 250hp net when it came out in 1973. So I don't think its underperforming for the build. It just underperforms compared to what your builder told you it would produce in terms of horsepower numbers.

I don't really care to recommend heads; I like AFR though. Just about any aftermarket head will breath better and has a better combustion chamber than the heads you currently have.

[68HellCo]

Originally Posted by twistedaxle

Yes, the square bore high rise is considered the good one. It's about equal to an Edelbrock Performer RPM. Not the air gap version, though. That's not just my opinion, either:

http://www.crankshaftcoalition.com/wiki/Intake_manifold

It looks like these are your pistons.

http://www.summitracing.com/parts/SLP-L2256F30/

They should give you about 9.5:1 compression with the 64cc combustion chamber (that is what your heads will have if they are off an L46 vette) and a .039 gasket.

Basically, what your engine builder put together sounds more like the L82. It was rated at 250hp net when it came out in 1973. So I don't think its underperforming for the build. It just underperforms compared to what your builder told you it would produce in terms of horsepower numbers.

I don't really care to recommend heads; I like AFR though. Just about any aftermarket head will breath better and has a better combustion chamber than the heads you currently have.

OK, sounds like I'm good on the manifold; yikes, close one. On the heads on this, I'm using some later year 2.02 heads on this, rebuilt, drilled, guide plates, ported, polished, yada, yada. So I imagine it does better than that. What's the best power boost possible non aluminum heads? I want those. Thanks again.

[twistedaxle]

Originally Posted by 68HellCo

OK, sounds like I'm good on the manifold; yikes, close one. On the heads on this, I'm using some later year 2.02 heads on this, rebuilt, drilled, guide plates, ported, polished, yada, yada. So I imagine it does better than that. What's the best power boost possible non aluminum heads? I want those. Thanks again.

Yes, if you have the Contender/Street Dominator p/n 300-36 you've got a good manifold. Still check to make sure there's no binding of the linkage, and that it's adjusted so the primary and secondary butterflies open all the way, that your choke is opening all the way, etc. It's not always the case.

When you say you're using some later year 2.02 heads, you may well have open chamber 76cc heads. The closed chambered heads were only used for a few more years after that '69 vette came out although Chevy did sell versions of them as service replacement parts. The close chamber heads aren't any great shakes by today standards. These open chamber heads were worse, and aren't performance heads by any stretch of the imagination even if Chevy shoved some big valves into them.

I think just about any good aftermarket aluminum head would make a night and day difference on that engine. Just don't go crazy and get something with huge ports. Something with 180cc intake ports would work well and definitely nothing bigger than 200.