Vacuum gauge will clearly indicate valve issues with a rhythmic drop in vacuum upon actuation of a bad valve. Your compression is fine. 170 is what I make on my built Pontiac. You need a tune. And, yes you could have been bleeding off cylinder pressure with a loose plug. I.5 turns on the idle screw looked good. Give it more timing. It maybe a clogged Idle air passage in the carb? If no vacuum leak is detected I’d swap a “known good “ carb onto it a see what it does. All this predicated on the distributor receiving 12v not 8v (you’d be surprised, seen many an HEI on an 8v resistor line to a point ignition or other accessory) and of being sound structure and set at ballpark decent initial timing.
Plug off all vacuum ports on the carb (remove the hoses first) start engine then spray around the carb base and manifold mount areas with carb cleaner. If engine rpm increases that's where the leak is. If that is a fairly stock cam you should read at least 14 to 18 inches of vacuum. More radical cam will have less vacuum naturally.
It’s a bit rowdier than a stock cam. But I need to check out PCV and brake booster for leaks. Already sprayed the intake and carb base to no effect. Thanks for watching!
I know how that is. My middle name is stubborn. lol I always seem to learn things the hard way. My Dad has a 1966 SS Chevelle that he has been having numerous problems with and he has a Holly. I keep telling him to put a Quadrajet on it and it will run for ever. He is a stubborn 81 year old. lol @@Rustrevivalgarage
Yeah I know how it is, stubborn is my middle name. lol My Dad has a 1966 SS Chevelle that he keeps having problems with and it has a Holly. I told him to throw a Quadrajet on it and it will run forever. Well he is a stubborn 82 year old. I get it honestly. lol@@Rustrevivalgarage
Vacuum gauge will clearly indicate valve issues with a rhythmic drop in vacuum upon actuation of a bad valve. Your compression is fine. 170 is what I make on my built Pontiac. You need a tune. And, yes you could have been bleeding off cylinder pressure with a loose plug. I.5 turns on the idle screw looked good. Give it more timing. It maybe a clogged Idle air passage in the carb? If no vacuum leak is detected I’d swap a “known good “ carb onto it a see what it does. All this predicated on the distributor receiving 12v not 8v (you’d be surprised, seen many an HEI on an 8v resistor line to a point ignition or other accessory) and of being sound structure and set at ballpark decent initial timing.
4 months is the motivation you need to get the Pontiac ready. LET'S GO!
I don’t know. I need to rewire it, replace shocks and springs, upgrade brakes, and hope the trans is good. Might be a bit much.
Plug off all vacuum ports on the carb (remove the hoses first) start engine then spray around the carb base and manifold mount areas with carb cleaner. If engine rpm increases that's where the leak is. If that is a fairly stock cam you should read at least 14 to 18 inches of vacuum. More radical cam will have less vacuum naturally.
It’s a bit rowdier than a stock cam. But I need to check out PCV and brake booster for leaks. Already sprayed the intake and carb base to no effect. Thanks for watching!
Holly Carbs can be very problematic. If you happen to have another carb around that you could stick on there, it might be worth trying.
I still plan to block off every port - PCV & Brake Booster - next and check it, just to eliminate those possibilities. I'm a bit stubborn :)
I know how that is. My middle name is stubborn. lol I always seem to learn things the hard way. My Dad has a 1966 SS Chevelle that he has been having numerous problems with and he has a Holly. I keep telling him to put a Quadrajet on it and it will run for ever. He is a stubborn 81 year old. lol @@Rustrevivalgarage
Yeah I know how it is, stubborn is my middle name. lol My Dad has a 1966 SS Chevelle that he keeps having problems with and it has a Holly. I told him to throw a Quadrajet on it and it will run forever. Well he is a stubborn 82 year old. I get it honestly. lol@@Rustrevivalgarage
Check your brake booster. I've had them cause vacuum isses. Just a thought
That is next. PCV and brake booster are the only things left. It’s driving me crazy…