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Discussion Starter #1
Jut opened up my valve covers last night to find out what heads I have.
462624
L137
NAWIAT
Thanks to Larry(larryh56) for the decode.

462624 76-87 1.94/1.50 & 2.02/1.60 valves
HP - Not listed
76 CC Chambers
These are crack prone! according to http://www.thedirtforum.com/castings.htm

What would be recomended for my supercharged sbc.
Cast Iron or Aluminum? and some numbers please. Thanks
 

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I have never heard of this. This is what Mortec says about your heads:
462624.....75-86...350/400......76cc chamber, 1.72/1.5, 1.94/1.5 or 2.02/1.6 valves


I would recommend aftermarket aluminum heads for your supercharger like Dart's or AFR's.

I assume you have this engine already running with the supercharger on now right? If so just keep an eye out on everything and run them.
 

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Discussion Starter #5
here is a pic of the heads.

I have been driving the car since i got in January. No issues and runs strong.
No track time and no Dyno yet. Want to learn and test the car first before i blow anything up.
It has a GM stamping inside and TAIWAN stamped backwards on the edge. Whats up with that?
Now i want to take the engine apart to see what else is in there.
I do not know the compression or what this engine is capable of.
Smog 305 Head? what about them.
So, i should get rid of these heads.
What aluminum heads are cheap and would work with my combo?
 

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What is your combo ? Is it the 383 in your signature ? If it is, Those are not very good heads for that. The Smog 305 heads were known for cracking. You do want some larger chamber heads with that blower and some heads that will flow good. Look at the RHS Pro Action heads that are priced reasonable and flow great.

http://www.racingheadservice.com/Cyl.../Aluminum.aspx
 

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Discussion Starter #7
Hey Tom,
For the waiend 144 supercharger, its recommended 8.0 to 1
no more than 8.5 to 1 compression. Other than cracking, what would be the damage to the engine on the long run. I will not be racing the car till i get good headers and better exhaust. It mostly a cruiser for now.
All i know about the engine is that its a 350 sbc stroked to 383.
 

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I ran those heads for a long time on a mild 350. They are Ok to run. They are a thinner, casting and are less forgiving if you overheat the motor. Otherwise they are fine to run. Performance wise they are not very good. Non of the factory small block heads are very good for performance.....aftermarket is the way to go if you are looking for a performance head. But if you want to run them....budget perposes becasue you already have them on the motor then they will work. Just do not overheat them.
 

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Discussion Starter #9
I heard Hydraulic Roller Assemblies are better than Flat tappet for blown engines. I this true?
As far as intake runner size and combustions size, what would work better for my combo?
Thanks for the help guys.
 

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If you want stock heads, I think the 882's would work better for you.

How about these ?

http://cgi.ebay.com/ebaymotors/PERF...ptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

Starting with the 1975 model (fall of 74) Chevrolet began cutting corners on the SB heads, such as the 462624 head. They were lighter, thinner castings, had an additional exhaust crossover passage (more heat) in the center of the head. Consequently, they are MUCH more prone to developing cracks, or developing them sooner, than the 1974-earlier heads. ANY 1975-later (with a date code of around Aug 74-later) PRODUCTION SB head is a lesser desireable head. I'M ONLY REFERRING TO PRODUCTION HEADS, NOT CHEVY'S OVER THE COUNTER PERFORMANCE HEADS, SUCH AS BOWTIE HEADS!
I hate to be the bearer of bad news, but you asked. If you choose to use these heads, BE SURE TO HAVE YOUR MACHINE SHOP THOROUGHLY MAGNAFLUX THEM! If they have no cracks at this time, do not be disappointed if cracks develop soon after you put them into use.

Your Date code is L137 or December 13th of 1977.
 

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Here are some flow numbers comparing the 882's and fastburns and Vortec's. I have not found numbers for the 624's.

Please note That this is one time, you want big chamber heads, to keep your compression down, for a blower.



 

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Discussion Starter #12
Thanks Tom,
Since i have no idea where Im at as far as compression ratio, and Waiend recommends 8:1 to 8.5:1 CR, what should i look for in heads. Would heads alone bring the CR that low?
 

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Yes

I would run something like this:
http://www.summitracing.com/parts/DRT-10421111P/?image=large

with that engine, but before making that recommendation it would help to know something about the cam and compression. Using factory 882's would also improve performance over what you have now, but the cost would be similar and you'd be leaving performance on the table using the factory castings.
 

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Until you know what pistons are in the engine it will be near impossible to know what heads you need. You can run the small blower with more than 8.5:1 compression, but I wouldn't go over 9:1.

Are you wanting the blower to make power or just for looks? If you want to make power you might want to look at The Blower Shops 194ci blower, it will ake a lot more power than the 142ci and is a better built unit.

Where are you getting your blower advice? Where did you hear a hyd roller is better than a flat tappet cam for a blown application? Ask whoever told you that , Why? For serious blown stuff a solid cam is prefered, for milder engine a hyd cam is fine either flat tappet or roller. The blower doesn't know if the cam is a roller or not. The only difference is boost creates more resistance for the valve to open against, this is why is higher boost applications a solid cam is a better choice. Hyd lifters can bleed down. As far as roller vs. flat it's no different than a naturally aspirated engine.

About cylinder heads, I would pull the heads you have off check out the pistons and go from there. Since you don't know if they are forged or not that will be another issue and will determine what boost level your engine can handle.

If I were in your shoes I would think about leaving the engine you have alone and trying to sell it complete. Build or buy an engine that is better suited for a blower. You are going to want to run more boost and make more power, it's addictive. Now if you know for sure you aren't going to want to run over 4-6psi of boost then, just slap the 142 on the engine as it sits and chances are you will be fine, read the plugs and limit the timing, should run just fine.
 

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Discussion Starter #16
Thanks for schooling me guys.
I do not know the internals of my engine, thats why im trying to pick at it one at a time. The car runs very strong, looks good and i am enjoying it while i can till summer is gone. I want to make sure Im destroying the engine over time. I cant afford to pull the engine and rebuild it, or go crazy with a bigger supercharger. The car is a cruiser right now and i want to work with what i have right now. I wonder how much of difference would the heads make as far as power.
You guys are not kidding when you say it is addictive..hehe.
I have spent a lot of $, and Im so far from race ready.
 

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If you don;t want to spend the money twice, do it right the first time. If you do it on the cheap once and then have to do it right the second time, how much money did you save in the end?

First thing you need to figure out is how fast you want to go or how much power you want to make. Look at the parts you have on hand. If you already have the 142 blower, then run it, if not look at the 192, it is still a single carb mini blower.

Sounds like you are not quite sure what you want. Here is the easiest fix for it all. Just install the 142 on your engine and add an alcohol injection kit. That way even if your compression is 10:1 you will be fine. There are several places you can get alky injection kits. The only thing after that that will be limiting your boost is your pistons, I would assume they are cast and error on the side of safety. Where did this engine come from? Can you get ahold of the previous owner? Does he know who built it? With the 142 on a 383 you are not going to make much more than 8lbs of boost anyway. Limit it to 6lbs add water/alcohol injection and go have fun. Leave the heads you have on the engine, they will not be your limiting factor at this point.
 

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Discussion Starter #18
If you don;t want to spend the money twice, do it right the first time. If you do it on the cheap once and then have to do it right the second time, how much money did you save in the end?

First thing you need to figure out is how fast you want to go or how much power you want to make. Look at the parts you have on hand. If you already have the 142 blower, then run it, if not look at the 192, it is still a single carb mini blower.

Sounds like you are not quite sure what you want. Here is the easiest fix for it all. Just install the 142 on your engine and add an alcohol injection kit. That way even if your compression is 10:1 you will be fine. There are several places you can get alky injection kits. The only thing after that that will be limiting your boost is your pistons, I would assume they are cast and error on the side of safety. Where did this engine come from? Can you get ahold of the previous owner? Does he know who built it? With the 142 on a 383 you are not going to make much more than 8lbs of boost anyway. Limit it to 6lbs add water/alcohol injection and go have fun. Leave the heads you have on the engine, they will not be your limiting factor at this point.
The supercharger was on the car when i bought the car. The guy i bought the car off of had it for about 9 monthes with the same engine.It was at the body shop for most of the time.He said he only put about 200 miles on it.He had to get rid of it because he did not have room for it next to his bad a$$ road runner.
The guy he bought it off of was a speed freek and had to sell the Camaro because of bike accident. He lost contact with him.
Anyways, I think to find out what is in this engine i have to take it apart.
Royce, this SC is a waiend 144 and get 4-8 psi boost.
I heard others mention about the water injection system but have not really looked into it. I have a basic knowledge of how it works, but is there anything else i should know. Pros, cons, maintanece, tuning, and other issues. Stage 1, 2 or 3? Is it controlled manualy, or is it auto?
Cruising on the freeway at 3500 rpm my Boost gage shows press 20 and goes down to 15 at idle. Is that normal?
Here is a pic of my setup.
 

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Ok that changes things a bit. This combo is already together and running. Have you looked at your plugs? Do you know how much boost it's making? (can only find out at WOT with a load on the engine). If the car is running and not giving you any problems, I would leave it alone. I was under the impression you wanted to add a blower to an engine you already had.

The reading you see when at idle, cruising or on the highway is not boost it's vacuum. That is perfectly normal. It is possible to drive around all day and never see any boost. That doesn't mean the blower is not making power it just means the engine is using all the air flow or even more than the blower is producing at that time. With the throttle only partially opened there is not much air for the blower to pull in.

As far as water injection, it's probably not needed, but wouldn't hurt and will actually help make a little moe power. The systems are automatic, you just set what boost level you want the system to activate, keep the tank full and not worry about it. In most cases you just run windshield wiper fluid. There really are no cons other than having to deal with another fluid and the cost of the kit. No real maintenance other than keeping the tank supplied.

I wouldn;t suggest you go out and buy a kit just yet. I would drive the car and smash the pedal a few times and see if it rattles (detonates), pings. If so, then you need to check your tune-up. Do you know where your timing is set? (total and initial).

Do you feel the car was built fairly well? If so, you could probably assume the engine was built right. The 76cc heads are a good hint that they were trying to keep compression down. I doubt you are over 9:1.
 

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Discussion Starter #20
Time to time i open it up on the freeway and the boost gage seems to always stay on the vac side. After rebuild and tuned my carb, i pulled the plugs and noticed fould plugs but not as bas as before.
The car does rattle, vibrate at high speed but that could be because i do not have it dynamatted, stock suspension up front except the after market spring and koni shocks. No sway bars and no sub frame connectors. Muli leafs with konis in the back, no traction bars.
How would i know if it detonates at high speed?
I do not know the timing.
I do feel the car was built well, but on a budget..lol
I have changed a lot of the accessories in the engine department. It was messy and cheep looking.
It is hard to find higher octane around here and very expensive. I use 91 with
a bottle of octane boost. Seems like waist of money to me.
Im trying to comprehend the idea of adding a water injection system will boost my octane as high as 120. Is this true? Is it water alone or a mixture of water and Methanol?
Seems like a smart thing to do and save the money for better things.

Thanks Royce for your time and help.
 
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