Fel Pro intake manifold gaskets - Pics - Intake re-work

I've been tracking down an off idle, part throttle miss. I did a number of things before I pulled intake. So I ended up doing the intake manifold gaskets assuming I had a vacuum leak in the lifter valley - under the intake manifold.

Here's what I found upon removal:







Visually I don't know what this shows, but I expected better from Fel-Pro. I did read about a bad product run from Fel-Pro IDK the exact years but 2004-2005 IIRC. Here's how in the intake manifold looked:















Looked like several vacuum leak suspects to me, but IDK.

I went with Edelbrock gaskets due to suspect Fel-Pro quality.

I used hi tack gasket set, first time. I liked the product. I intend to use it on all paper-ish gaskets (non-rubber/silicone/exhaust gaskets). Here's a progress picture:





I used right stuff on the front and rear water jackets, intake side as per Edelbrock instructions. I also made some studs out of all thread to help when setting the intake manifold. IDK how much it helped, but all thread is cheap, and throwing sparks with the grinder is cool.

End Result

With a 600 cfm edelbrock 1406 the surging was gone, but the off idle, part throttle miss still existed, better, but not 100%. So I switched over to a 500 cfm carter I had just bought. Now I'm happy, no part throttle miss, great response from bottom on up. Of course some loss of top end, but totally acceptable for the improvement in bottom end repsonse. We'll see about mileage.

DA

Here's some carter info. 125-150 is the going rate for 500 cfm carter, much better then the edelbrock equivelant 1403/1404, also a rebuilt carter may come with spring loaded needle and seats which was OEM for a carter, un upgrade to an Edelbrock.

To determine Carter AFB carb flow, measure the butterfly bores and use the table below:



CFM Venturi Diameter Bore Diameter
primary secondary primary secondary
--------------------------------------------------------
400 1 1/8 1 1/4 1 7/16 1 7/16
500 1 3/16 1 1/4 1 7/16 1 11/16
575 1 1/4 1 9/16 1 9/16 1 11/16
625 1 3/16 1 9/16 1 7/16 1 11/16
750 1 7/16 1 9/16 1 11/16 1 11/16


9000 Series AFB Code Deciphering

Base part number is 9000 and the last three digits refer to flow rating. For example, 9625 is a 625 CFM AFB carb. Adding 0, 9625 means it was set up for a Chevy style linkage, adding 1, 9626, means it is a 625 for a Chrysler, adding 2, 9627, means it is for Ford; adding 10, 9635, means provision for EGR.

If the carb is an aftermarket version, it will have a 9xxx cast in the front near where the mounting stud goes through.

​

Pretty common issue with Felpro 1250 gaskets. I've yet to have a issue with mine but I think many issues come from the different expansion rates between iron heads and the aluminum manifold. I'm running aluminum heads so maybe thats why I have had issues. They supposedly have different ones that are better something like 1250-2 or something like that.
So where are you getting 500 cfm carters for 125-150?

Those look like photos of my failed FelPro 1250s. Look at your photos and you will see most of the damaged seals are on the the ports next to the exhaust heat riser insert. I found the inserts are both harder and thicker than the rest of the gasket. I believe that keeps the gasket fromcompressing properly. I now use FelPro 1250S3. It has no heat riser port at all and has a thin steel sheet laminated in it to keep the gasket from splitting.

same thing happened to me thought it could have been from not re-torking them so i replaced with the same thing then found out that they do have issues seems to be working fine but did not solve all my problems keep us posted on how the edlebrocks are holding up I have aluminum heads so i dont think the expanding theory works for me wish i could say that but since i didnt re-tork them it was probably all me;D.KC

I'd block the exhuast riser if it were simple, and if I had the option of running coolant through the bottom of the intake.

I don't imagine that a gasket alone will seal the exhuast port. I've been wrong before, but I just wouldn't trust it to that alone.

I have found in other cars that heat at the bottom of an intake manifold helps to atomize fuel.

Just an opinion though.

-------------------------------------------------------------------------

500 cfm carter for 125-150: craigslist + meta program or website which searches all the US lists = 2 carter 500's on first search. I just bought the better looking one.

You'd be suprised how many people on CL will ship CONUS with either paypal or a USPS money order.

When I found out I had torqued the manifold with the taller heat riser insert, I checked the manifold with a straight edge. Yes I had distorted it. I had to have it resurfaced to get it straight again. I should have sent the bill to Fel-Pro>

I've always used the teflon blue coated gaskits are they no longer available? Those gaskits were metal reinforced.