993 heads info?

Brian79

Frequent Racer
Aug 21, 2008
383
0
0
Wataga, IL
I am looking at getting a set of these from a member. 993 heads They have 2.02/1.6 valves and some port work done. (fully ported intake runners and gasket matched). I was wondering if they would improve my set up. Looking to drop my E.T. I run 12.50's now looking to improve 3-4 tenths. I am running 305 heads now that have real small chambers. I think something like 58cc or smaller. I built the motor for 11.1 w/64cc. so I figure my CR now is 12 something. I know my CR will drop but I will gain flow on the big end.

355
.530 lift cam
Weiand Team G intake
750 DP race series carb
Super Comp headers 1 3/4"
TH 350 w/3800 stall
4:10
Car is gutted, lexan frt and back windows, glass hood,glass frt bumper w/LW brackets. Should weigh less than 3000. Give me your opinion if these will improve my ET.
 

DOUG213XRJ

MalibuRacing Junkie
Sep 18, 2006
4,671
1
38
West, MI
Hey, Not sure if this helps.
3998993
1968-79
307-350
HP 115 -175
CFM in 150.8
CFM ex 91.1
CC 75.5
 

bowtie81

Moderator
Mar 28, 2008
5,008
0
36
sarnia, ontario canada
I had a set of those before and ran into the 12's and could have gone quicker with a few things. Mine weren't fully ported either. You will do better than those 305 heads.
 

Brian79

Frequent Racer
Thread starter
Aug 21, 2008
383
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0
Wataga, IL
Thanks for the info. I knew there would be someone out there that has run these heads in the 12's. I am looking to run in the low 12's with these.
 

monzaz

Dragway Regular
Aug 10, 2005
704
0
0
Richfield, Oh
www.jdrace.com
That would be NO - You will not have enough track to notice the difference. KEEP the compression as Most small block chevy heads are good to 6000 rpm easy.

You need the low end torque to get the car out of the hole to bring down the ET.

Unless they are cheap. Save money and buy NEWER heads. It is NOT the valve size that determines ALL the flow. The amount of compression loss will well over come the gain you will get from the porting that someone could have done to that head. 993 is a VERY common 70's head.

993 heads are like 76-80 cc combustion chambers. as far down as you can afford to go is 64cc. 041 heads converted to 2.02 would work well. The problem here is the amount you would spend to get this machining done ...you might as well by aftermarket heads.

AGAIN your choice and you can try BUt I can pretty much guarantee slower ETs Jim

P.S. IF YOU WERE SUPER CHARGING OR TURBO CHARGING WE MIGHT BE TALKING A DIFFERENT OUT COME.
 

bowtie81

Moderator
Mar 28, 2008
5,008
0
36
sarnia, ontario canada
monzaz said:
That would be NO - You will not have enough track to notice the difference. KEEP the compression as Most small block chevy heads are good to 6000 rpm easy.

You need the low end torque to get the car out of the hole to bring down the ET.

Unless they are cheap. Save money and buy NEWER heads. It is NOT the valve size that determines ALL the flow. The amount of compression loss will well over come the gain you will get from the porting that someone could have done to that head. 993 is a VERY common 70's head.

993 heads are like 76-80 cc combustion chambers. as far down as you can afford to go is 64cc. 041 heads converted to 2.02 would work well. The problem here is the amount you would spend to get this machining done ...you might as well by aftermarket heads.

AGAIN your choice and you can try BUt I can pretty much guarantee slower ETs Jim

P.S. IF YOU WERE SUPER CHARGING OR TURBO CHARGING WE MIGHT BE TALKING A DIFFERENT OUT COME.
These 993 heads are a 76 chamber head, and no way they cannot be taken down to 64cc head. I had mine shaved .045 and that brought it to about 70-71cc. My heads were only pocket ported and had no tuning done when i took it to the track. (hockey pucks for slicks) and i still ran a 12.80's. So with a full port job and better tuning with the right combo theose heads will get into the mid to low 12's.
 

Brian79

Frequent Racer
Thread starter
Aug 21, 2008
383
0
0
Wataga, IL
Ok here is another question. I am selling my Bu as a roller. I was going to put those heads on my 355 to lower the CR so it would be streetable. I was wondering if these would be good on a street motor or would it run like a dog due to the same fact as stated before. I would be happy if these heads made the motor run the same; that way it would be a kinda hot running car for some one. I was thinking about putting it in a S 10 or 80's Camaro and sell it to a young kid. As stated before I built the motor 11to1 CR w/64cc heads so the 993's should lower it enough to run pump gas. If this isn't going to work then it isn't going to work and I will come up with something else. Thanks for your time and effort guys.
 

bowtie81

Moderator
Mar 28, 2008
5,008
0
36
sarnia, ontario canada
If i had to guess i'd say you'd be around the 9.5-1 comp, which you can still make that 355 turn pretty good. If you want to keep a bit more compression get thinner head gaskets. I droppeed my compression down when i put a blower on and it still ran great with the blower belt off and it still ran strong and even stronger with the belt back on.
Do you already have these heads and how much?
 

monzaz

Dragway Regular
Aug 10, 2005
704
0
0
Richfield, Oh
www.jdrace.com
[quote/]
These 993 heads are a 76 chamber head, and no way they cannot be taken down to 64cc head. I had mine shaved .045 and that brought it to about 70-71cc. My heads were only pocket ported and had no tuning done when i took it to the track. (hockey pucks for slicks) and i still ran a 12.80's. So with a full port job and better tuning with the right combo theose heads will get into the mid to low 12's.[/quote]

I think you read my reply wrong. I did not say to cut your heads...I said that he should not go under 64cc head to purchase if he was going to keep his ET relatively unchanged.

I do not doubt what you are say on YOUR car. But he wants to know about his car and combo. IT ALL depends on the short block combo with the heads.

QUOTED) Ok here is another question. I am selling my Bu as a roller. I was going to put those heads on my 355 to lower the CR so it would be streetable. I was wondering if these would be good on a street motor or would it run like a dog due to the same fact as stated before. I would be happy if these heads made the motor run the same; that way it would be a kinda hot running car for some one. I was thinking about putting it in a S 10 or 80's Camaro and sell it to a young kid. As stated before I built the motor 11to1 CR w/64cc heads so the 993's should lower it enough to run pump gas. If this isn't going to work then it isn't going to work and I will come up with something else. Thanks for your time and effort guys.

The heads will bring the compression down enough to run High test gas, But even on a HOT day you might have some detonation issues.

You can not expect to take out compression and have the same running and feeling motor. Period.

The car with out the high stall will run pretty doggy until the cam gets into its power band. You have a all or slug set-up It is a drag race car. Right?

AGAIN I do not have duration of the cam either. BUT with a .530 lift I am sure you are in the 240 and up range unless you are using a ROLLER cam. Solid lift cam? Hydraulic?? roller cam???

What are your shift points when you race this car? What is your trap rpm and speed/ mph?

What also is your 60 foot time ?

Remember to if the car is sold to someone that has NO idea how fast the car went and has never had a faster car this is all a moot point to the buyer. It maybe doggy to you but to the buyer it may be the fastest, torquey machine that they have even been in...???

Hopefully you an offer more engine info to hash out a lot of gray areas
 

Brian79

Frequent Racer
Thread starter
Aug 21, 2008
383
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0
Wataga, IL
The cam is a hydraulic. .510 intake .533 exhaust duration @.050 244/254 lobe centers 107int/117exh it is choppy
I don't have a killer stall in it. 3800 and it kicks in before that. Shift points 5800, I have tried higher but with the 305 heads it doesn't help.
60ft- 1.72-1.75 alot of 1.73-.74
Trap speed: 105-107

I kind of figured that lowering the CR would hurt it some. Just kinda hoping it wouldn't kill it. If it ran 12.90-13.10 with these heads in a street car then I think that is respectable. Will the 3800 be to much on the street? I had a B&M 3000 holeshot convertor in the car before and it fell on its face. Not sure what the power band is but I know it is over 3000 for all out hammering it.

After looking at my cam card it looks like I will hopefuly find someone looking for a good drag motor(cheap). I know it has alot more in it if it had better heads, those 305's are killing it. I am just moving on to something else so if this street car thing don't work out then on the stand it goes.

Yes the heads are cheap. $200 That is bolt on. They have been cleaned and new springs,locks,guides,studs ect... It has rockers on it but I would put my roller rockers on. I figured I would put on a thick gasket on to get the CR down some. I agree if I take out all the CR then it will hurt the motor.
 

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