no luck with gt-40 upper and lower

rockyracoon

10 Year Member
Nov 23, 2005
671
7
29
margate NJ
#1
Tried 3 times (3sets of gaskets) and car still wont even stay running. have to keep on the throttle for it to stay running and it seems like it is running really bad.

used guide studs for both upper and lower, no rtv under rubber rails. dabs at corners where heads, manifold and block conjoin. used a smear of blue rtv around coolant ports.

upper and lower were from a 97 mountaineer, purchased a trick-flow elbow, made sure all vacuum lines were connected but still no luck. im in the process of putting stock manni back on.
Gaskets used were for a 97 mountaineer. seemed to me that there was a major vacuum leak. did have the dizzy in 180* off at first but reconciled that. any ideas greatly appreciated.

Car ran great after I installed 4.10 gears but just wanted more power.
 
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Feb 18, 2001
29,753
6,327
224
Massachusetts
#2
Before you rip it all apart, I would build a smoke machine and do a smoke test.

https://www.stangnet.com/mustang-forums/threads/smoke-machine-for-vacuum-leak.907314/

Usually when ive done lower intakes, I've used stud guides, use the china wall gaskets but lay a think strip of RTV down amd gobs in the corner, and then a small rtv circle around the water ports. Then I set it down and tighten.

If you suspect a vac leak, i'd smoke test to determine where your vac leak is as it can help you pay more attention to the end seals if they are the culpits.