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> Carb manifold sealing, use phenolic spacer or not
North Coast Jim
post May 22 2020, 04:12 PM
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Engine is out and I'm doing some investigations. Bought a set of Redline 40 IDFs for the engine build. They've run OK but not great. Couldn't keep lean idle set properly. drivability an issue, pops and backfires at times. Jetting changes made no difference. Suspected gasket air leaks. Should have done the starting fluid check but didn't.

While the engine is out took the manifolds off from the heads. The gasket as supplied from Redline is a thick phenolic (?) spacer with paper adhered to both sides. Found a defect in each one at both ports. Near the top of each port the phenolic has a defect - a void. The paper on each side covers the defect but does not seal the intake. Found evidence of a leak path at this area

Question - do I need the phenolic spacers ?? Can't find them on line as single replacement parts. Read of a need to keep the carbs from heat soaking but the manifolds are aluminum and are 5" tall. Don't see a need for them. Am I correct in this analysis ??

Was thinking of using .060" gaskets with Permatex red (min film deposit ) at this interface instead. What wisdom can you all impart.

Thanks for any and all input
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Al Meredith
post May 23 2020, 11:31 AM
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I have had problems like yours, Found the manifolds (probably made in China or Mexico ) are not flat on the head side. If you have access to a belt sander , level the manifolds that should allow them to use a thin gasket if you want. AL
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HAM Inc
post May 24 2020, 07:59 AM
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QUOTE(Al Meredith @ May 23 2020, 10:31 AM) *

I have had problems like yours, Found the manifolds (probably made in China or Mexico ) are not flat on the head side. If you have access to a belt sander , level the manifolds that should allow them to use a thin gasket if you want. AL

Al, this issue with poorly finished manifolds has been a problem for the past few years.

CB manifolds used to be very nicely finished. No more. The castings stink and the machine work looks like it was done with a hatchet. They flow good, but that's about all I can say good about them.

There are only two manufactures currently making high quality T4 manifolds that I'm aware of. Both perform great on the flowbench.

Pierce makes some damn fine manifolds, and on the flow bench they have superior swirl characteristics to the CB.

I am not a paid spokesman and I am not friends or even know anyone at either company.

https://www.piercemanifolds.com/product_p/99004.822.html

https://www.csp-shop.com/en/brand-shops/int...0k3-21127b.html
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porschetub
post May 24 2020, 03:50 PM
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QUOTE(HAM Inc @ May 25 2020, 01:59 AM) *

QUOTE(Al Meredith @ May 23 2020, 10:31 AM) *

I have had problems like yours, Found the manifolds (probably made in China or Mexico ) are not flat on the head side. If you have access to a belt sander , level the manifolds that should allow them to use a thin gasket if you want. AL

Al, this issue with poorly finished manifolds has been a problem for the past few years.

CB manifolds used to be very nicely finished. No more. The castings stink and the machine work looks like it was done with a hatchet. They flow good, but that's about all I can say good about them.

There are only two manufactures currently making high quality T4 manifolds that I'm aware of. Both perform great on the flowbench.

Pierce makes some damn fine manifolds, and on the flow bench they have superior swirl characteristics to the CB.

I am not a paid spokesman and I am not friends or even know anyone at either company.

https://www.piercemanifolds.com/product_p/99004.822.html

https://www.csp-shop.com/en/brand-shops/int...0k3-21127b.html


(IMG:style_emoticons/default/agree.gif) I have a new set of Empi ones and the casting are truly horrible,very poor runner/port alignment and would require some time to clean up the casting flash's...it's like they were never really finished.
I fitted the short ones (like CSP ) to a motor recently and they required very little work.
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