Go Back   Corvette Forum > C3 Corvettes, 1968 - 1982 > C3 Tech/Performance
Sign in using an external account
Register Forgot Password?
Register Search Today's Posts Mark Forums Read FAQ Vendor Directory
Search
C3 Tech/Performance
V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette Sponsored by
VBP

Welcome to Corvetteforum.com!
Welcome to Corvetteforum.com.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join Corvetteforum.com today!


Corvette Store
 
 
C7 Parts & Accessories
C6 Parts & Accessories
C5 Parts & Accessories
C4 Parts & Accessories
C3 Parts & Accessories
C2 Parts & Accessories
C1 Parts & Accessories
Wheels & Tires
Sponsored Ads
 
 
Vendor Directory
  
Reply
 
 
 
 
Thread Tools Search this Thread
Old 09-04-2010, 10:04 PM   #1
arcticcatmatt
CF Senior Member
 
arcticcatmatt's Avatar
 
Member Since: Apr 2002
Default What intake manifold gasket do I need? LT-1 heads on 350

Hey guys, I already ordered up the wrong gaskets and wasted 40 bucks.

I have a 350 small block with 71-72 LT-1 75cc heads casting number is 3973487. Here is a picture
Click the image to open in full size.
I just got these gaskets in
Click the image to open in full size.
http://www.summitracing.com/parts/FP...n/?prefilter=1
There is no center hole which I think is exhaust for EGR function if I wanted to use it. And its too tall, can't get valve covers on.
and they do not fit even though they say they are for a small block chevy. Now I see in the text that it won't fit an LT-1 setup so I am having a hell of a time figuring out what I need.

Help please! THANKS

Last edited by arcticcatmatt; 09-04-2010 at 10:55 PM.
arcticcatmatt is offline   Reply With Quote
Old 09-05-2010, 12:08 AM   #2
Little Mouse
CF Senior Member
 
Member Since: Apr 2006
Default

Quote:
Originally Posted by arcticcatmatt View Post
Hey guys, I already ordered up the wrong gaskets and wasted 40 bucks.

I have a 350 small block with 71-72 LT-1 75cc heads casting number is 3973487. Here is a picture
Click the image to open in full size.
I just got these gaskets in
Click the image to open in full size.
http://www.summitracing.com/parts/FP...n/?prefilter=1
There is no center hole which I think is exhaust for EGR function if I wanted to use it. And its too tall, can't get valve covers on.
and they do not fit even though they say they are for a small block chevy. Now I see in the text that it won't fit an LT-1 setup so I am having a hell of a time figuring out what I need.

Help please! THANKS
Stock gasket with the open heat crossover you want fel pro FPP1256 if you want the stock size gasket with a blocked heat crossover you want FPP1204. both gaskets have the same 123 x 199 runner size. The gaskets you bought if there from summit simply send them back. If your in a hurry most auto parts stores will have fel pro gaskets.

Last edited by Little Mouse; 09-05-2010 at 12:38 AM.
Little Mouse is offline   Reply With Quote
Old 09-05-2010, 08:06 AM   #3
mar
CF Senior Member
Support Corvetteforum!
 
Member Since: Dec 2007
Default

Since the LT1 engine has a 'reverse' flow cooling system, can that setup use a typical intake manifold for a carb versus the injection system the LT1 came with ???
mar is offline   Reply With Quote
Old 09-05-2010, 04:01 PM   #4
Little Mouse
CF Senior Member
 
Member Since: Apr 2006
Default

71/72, LT1 heads pictured did not have reverse flow, fuel injection.

Last edited by Little Mouse; 09-05-2010 at 04:09 PM.
Little Mouse is offline   Reply With Quote
Old 09-05-2010, 04:54 PM   #5
hdpete98
CF Senior Member
 
hdpete98's Avatar
 
Member Since: Feb 2002
Location: Carlsbad CA
Send a message via AIM to hdpete98
Default

Quote:
Originally Posted by mar View Post
Since the LT1 engine has a 'reverse' flow cooling system, can that setup use a typical intake manifold for a carb versus the injection system the LT1 came with ???
71-72 did not offer fuel injection or reverse flow cooling.
hdpete98 is offline   Reply With Quote
Old 09-05-2010, 06:47 PM   #6
mar
CF Senior Member
Support Corvetteforum!
 
Member Since: Dec 2007
Default

My 'bad' - I had my wife's '95 SS Impala on the brain. The engine is called 'LT1' and it features reverse flow cooling to run a little more advance with the computer.

Quote:
Originally Posted by hdpete98 View Post
71-72 did not offer fuel injection or reverse flow cooling.
mar is offline   Reply With Quote
Old 09-05-2010, 08:57 PM   #7
arcticcatmatt
CF Senior Member
 
arcticcatmatt's Avatar
 
Member Since: Apr 2002
Default

Thanks little mouse. I will check that out. It appears the center is not cut out though?
Click the image to open in full size.
This is for a supercharged engine so I am told I need the metal center gaskets.

I am confused what you others said. These heads were designed for fuel injection? What is reverse flow?

I looked up the casting number 3973487 and the internet told me 71-72 LT-1 heads, thats all I know. This was a drag car I am converting to be more streetable. I took the dual carbs and NOS off.. it is keeping the blower and the new holley blower carb and hilborn scoope are going on as soon as this stupid intake is figured out

Last edited by arcticcatmatt; 09-05-2010 at 10:00 PM.
arcticcatmatt is offline   Reply With Quote
Old 09-05-2010, 10:40 PM   #8
mar
CF Senior Member
Support Corvetteforum!
 
Member Since: Dec 2007
Default

Coolant flow was reversed thru early-mid-90's 5.7L 'LT1' engine and 9C1 engine. The additional cooling facilitated more advance through the systems computer and the result was a fine running engine that would rev really fast. I believe the Corvette LT1 in that era had aluminum heads and/or aluminum block, but don;t quote me. The SS Impala and 9C1 was all iron. All this on 89 octane. You could 'tune' the engine to run even better by tricking it into using 93 octane, installing cooler t-stat, freer flowing air intake, headers + 2.5" exhaust, etc. It was a sleeper of a big car. We had two SS Impala's and one 9C1 - they are truly neat cars.

Quote:
Originally Posted by arcticcatmatt View Post
Thanks little mouse. I will check that out. It appears the center is not cut out though?
Click the image to open in full size.
This is for a supercharged engine so I am told I need the metal center gaskets.

I am confused what you others said. These heads were designed for fuel injection? What is reverse flow?

I looked up the casting number 3973487 and the internet told me 71-72 LT-1 heads, thats all I know. This was a drag car I am converting to be more streetable. I took the dual carbs and NOS off.. it is keeping the blower and the new holley blower carb and hilborn scoope are going on as soon as this stupid intake is figured out
mar is offline   Reply With Quote
Old 09-06-2010, 07:00 PM   #9
arcticcatmatt
CF Senior Member
 
arcticcatmatt's Avatar
 
Member Since: Apr 2002
Default

Measured a the ports tonight with my dials. 1.19 x 2.10. The gaskets little mouse said I need are 1.23 x 1.99 according to the website. Sounds like he is correct. I am hesitant to order them because the center port square isn't knocked out in that picture.
arcticcatmatt is offline   Reply With Quote
Old 09-06-2010, 07:12 PM   #10
TimAT
CF Senior Member
 
TimAT's Avatar
 
Member Since: Oct 2006
Location: Gladstone MO
Default

Many of the intake gaskets have that small hole in the center exhaust crossover or come with a little 2 piece stainless plate to install and restrict the amount of exhaust that flows thru there. My usual thing is to get gaskets that are 100% blocked or cut a thin piece of stainless and put that in there. But I'm trying to keep all the heat I can out of the intake.
TimAT is offline   Reply With Quote
Old 09-07-2010, 08:29 AM   #11
arcticcatmatt
CF Senior Member
 
arcticcatmatt's Avatar
 
Member Since: Apr 2002
Default

^ Gotcha. I may do the same, considering I don't drive in winter and this is a supercharged car I have enough heat to deal with.

Here is a picture of the gasket that came out of it. These fit no problem with those valve covers. So I need a set of these whatever they are.
[IMG]Click the image to open in full size.[/IMG]

Last edited by arcticcatmatt; 09-07-2010 at 08:35 AM.
arcticcatmatt is offline   Reply With Quote
Old 09-07-2010, 11:57 AM   #12
arcticcatmatt
CF Senior Member
 
arcticcatmatt's Avatar
 
Member Since: Apr 2002
Default

Just ordered these http://www.summitracing.com/parts/FPP-1604/
arcticcatmatt is offline   Reply With Quote
Old 09-07-2010, 03:00 PM   #13
mar
CF Senior Member
Support Corvetteforum!
 
Member Since: Dec 2007
Default

They look like the Felpro gasket you'll get when you go to NAPA. (If you look very closely, you should see: "This Side Up" on on side of the gasket. Did yours not have the metal restrictor in the center cutout?

Quote:
Originally Posted by arcticcatmatt View Post
^ Gotcha. I may do the same, considering I don't drive in winter and this is a supercharged car I have enough heat to deal with.

Here is a picture of the gasket that came out of it. These fit no problem with those valve covers. So I need a set of these whatever they are.
[IMG]Click the image to open in full size.[/IMG]
mar is offline   Reply With Quote
Old 09-07-2010, 06:57 PM   #14
Little Mouse
CF Senior Member
 
Member Since: Apr 2006
Default

Quote:
Originally Posted by arcticcatmatt View Post
Measured a the ports tonight with my dials. 1.19 x 2.10. The gaskets little mouse said I need are 1.23 x 1.99 according to the website. Sounds like he is correct. I am hesitant to order them because the center port square isn't knocked out in that picture.
If you have an accurate top to bottom measurement on the head. FPP1205 is 128 X 209. without looking it up doubt it has the heat crossover.
Little Mouse is offline   Reply With Quote
Old 09-07-2010, 07:25 PM   #15
jackson
CF Senior Member
 
Member Since: Sep 2001
Location: Timmonsville SC
Default

As TimAT wrote ... cut your own Xover block from thin shim stock ... you can add that to an OE replacement-grade intake gasket & go racing; No problem. Glue shim to heads w/ silicone ... then install gasket as usual. Do NOT use aluminum shim; Al Will burn thru sooner than later.

-add-
above is commonly used in restricted circletrack motors where both OE iron heads 487 etc & EB performer 2101 intakes are mandated. Cheap replacement grade gasket w/ a homemade shim is fine ... I run some rtv around the coolant & aircharge ports too.

Last edited by jackson; 09-07-2010 at 07:34 PM.
jackson is offline   Reply With Quote
Old 09-07-2010, 07:25 PM
 
Go Back   Corvette Forum > C3 Corvettes, 1968 - 1982 > C3 Tech/Performance
Reload this Page What intake manifold gasket do I need? LT-1 heads on 350
 
 
 
Reply

Tags
350, blocking, burn, center, chevy, crossover, engine, gasket, head, heads, heat, intake, lt, manifold, port, restricted, solid, stock


Thread Tools Search this Thread
Search this Thread:

Click for Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump


All times are GMT -4. The time now is 09:44 PM.


Emails & Password Backup

Search Engine Friendly URLs by vBSEO 3.5.2