711KMD
Recruit
- Joined
- Jun 7, 2014
- Messages
- 5
Hi. 1992 Merc 454 7.4L Carb 0D804171. Self taught, barely backyard mech status, for the love of the game. I have a rough/high idle issue. Just not running right. Idling at 800, sounds/feels like what used to be 680ish when she ran right. Idle screw down to 680 and she dies out, also wants to stall when coming off a high rev. Summary. Carb just rebuilt by pro, I installed and had high/rough idle, found vacuum leak around carb base with carb cleaner, fixed that. That brought rpms down a little bit. If I spray around the intake manifold I'm still getting a change in rpm. Something is sucking air on both sides. Could it be the valve covers? The pressure is outward on those and oil would be leaking, correct? It would be a leak in the intake, right? I'm getting some slight surging/chasing when at idle, she never did that. I ruled out bad gas by running off a secondary source and a fresh filter. I've been all over the map with idle mixture screws with no change. The "pro" sent it back with them 5 turns out, I'm at just under 2 now. Rochester 4bbl, what's the screw on the left under the choke levers? I did crudely lift the motor two seasons ago to get at manifolds and probably stressed the intake more than I should have. Assuming I need to reseal the intake, would it be smart to do it all and do the head gaskets also if I'm going that far or just leave alone? To do it I'll need head gaskets and intake gaskets. Can I/should I get automotive for either? A quick search and the intake gaskets are 130 a piece, I'd pay someone if I could afford that.. Is there any chance it could just be loose valve covers? (I can't get out to tighten and test, just gotta ask) Thank you
