I have a fresh rebuilt flathead and I am having little power and feels like its "BOGGY" as hell when accelerating. stock flathead rebuild 2 new Stromberg 97s Harrell Heads Eddie Meyer High Rise intake Stromberg E fire Distributor, flame thrower 1.5 ohm coil and e fire spark plug wires new electric fuel pump with fuel pressure gauge showing 3 pounds. Here is what I have done. I first changed the jets to .43 and power valves to #69s and thought I possibly damaged accelerator pumps when installing power valves so I replaced those just to be safe. I had a helmet style distributor prior and tried getting another rebuilt one but had the same issue. Someone mentioned maybe because I wasn't running a vacuum line from the new eddie meyer manifold to the helmet distributor that was causing an issues. I decided to change it to Stromberg E fire and after installation same issue. I did a new fuel pump with pressure gauge....same issue. I tried tuning the carbs, messing with timing, changing spark plugs, triple checking everything and its always the same issue. I am wondering if the high-rise manifold needs and special jetting or power valves because the fuel is traveling further? I don't know it was just a thought. I have literally tried everything and because I have gone through the entire ignition system several times replacing everything I am now leaning towards a fuel issue. Like I mentioned everything is brand new and the care fires up no problem, no smoke etc but the second I go to drive it, it feels like its running on 3 cylinders. Any ideas?
Yes where did you buy the carbs. Are you running straight linkage? Did you use a synchronizer? Have you check for a vacuum leak? Run a unlit propane torch along all carb and intake joints. Increased rpms will be the the tell.
Restrictive air cleaners...restricted exhaust...low voltage to ign. circuit (grounds)...squished spark plug electrodes...vacuum leak...retarded cam...float level...
So I have checked for vacuum leaks with propane and had none. Float levels seemed right after removing the top of the carbs and then turning on electric fuel pump to let them fill up. Grounds are good but that was an issue before not allowing car to start but they all got switched out and that fixed that issue. Issue happens with airecleaners off or on so restrictive is not an issue. I did use a carb synchronizer and that's not the issue. I also adjusted the fuel mixture using propane and adjusted them until the propane stopped the rpm from changing. Spark plug gaps are all good and new. I bought the strombergs from cw moss brand new. I bought the stromberg straight linkage. The throttle linkage is weird Z shape because it's a high-rise manifold but a shop made that and not sure if that's an issue? Here are some pics
Not familiar with the carbs made by CW Moss….I’m at a loss here. I can tell you I’m running a high rise Thickstun on my 8ba and didn’t have to change any carb setups. That engine and car is a beauty. I know you don’t want to do this but I’m going to repeat something told by Bruce Lancaster. If all else fails, install a single manifold and carb and see what results can steer you in the right direction.
They are stromberg 97s from stromberg in England but purchased through cw moss haha. Sorry. Thank you!
You are in it but let's step out of it for a moment. These are some other possibilities. Mechanical... 1. Brakes Are the brakes too tight. Are the brakes slowly applying? A bad or out of adjustment pedal linkage can cause the brakes to drag. If the master cylinder does not have a clear internal by-pass port, it can pressurize the system. A sure sign is the brake lights coming on, on a car with a pressure brake switch. Untitled by Travis Brown, on Flickr A brake problem can make the car sluggish. 2. Wheel Bearings... If too tight these too can impede performance. With both of these you'll usually see lots of heat. It pretty simple to check. 3. Clutch and driveline... Is the clutch slipping? A well-oiled clutch is a slipping clutch. Is the rear gear set too tight. If it's set up too tight, this can impede performance. Speaking of the rear gear. What is the ratio? The car may not have the right gear ratio that matches the powerband of the intake and camshaft combination. This may be an issue if you have a Highway Gear. Above are things not related to the engine that are fairly simple to check. 4. Engine... Do a compression check. This will tell a lot. Are the engine bearings too tight? Is the engine hard to turn? Related to the rear gear, what is the power RPM band of the camshaft? 5. Fuel System... You have been doing a lot of checks here. I recall that the Stromberg's (great carburetors by the way) are real sensitive to fuel pressure. If I remember right, they like less than 3 pounds of pressure. I recall that some Strombergs were dribbling fuel into the engine after shutdown. This may have been specific to the Big 97. The remedies were... running a fitting at the carburetor to run a tiny line/line (oil gauge size) back to the fuel pump to relieve or bleed the pressure. Lowering the fuel pressure. Related to the cam and rear gear, does the intake match or compliment the "combo"? Pete mentioning Bruce Lancaster's test of a single manifold with a single carburetor. This is great diagnostic test! 6. Ignition... I know the Stromberg unit gets mixed reviews. Since it done the same with the stock units I would say it's OK. I would not rule it completely out though.... eventually you may have to come back to it and check it out. Keep at it.
Yes if all else fails, F1 may be right. It could be mechanical. A temporary single carb and manifold may have to happen. Also, try adjusting your initial timing by vacuum, the old school way. I’d drop fuel pressure to 2 lbs. Check your spark strength at a higher rpm. I’ve been embarrassed myself on this. (Installed the plug wires in the wrong rotation at the distributor) Finally…. When laying in bed trying to figure it out, grab the keys, go out to the shop with the lights off and fire it up. You may have a dead short hiding. An errant spark with all that chrome ought to look like the 4th of July in there.
Yes, LOVE THE CAR & MILL !!! What cam are you running? Too much fuel for a stock cam ??? Petejoe has a GR8 idea with the single carb to see what happens.
I had a similar issue with my 292 c.i. build, Potvin 3/8ths cam, full race porting, Edlebrock Slingshot. I also had .043 jets and .067 PV. When accelerating hard in 2nd, the car would stumble (fall flat) and then catch up soon after. In my case, I wouldn't say it was bogging. Went up to .046 jets and keep power valves the same. Too rich. Went down to .045 and it now runs perfect. Check the plugs under a hard acceleration (WOT) in 2nd, pull over immediately and turn it off. Pull the plugs and take a look. If white or white-ish, it's too lean. It helped that my headers run/exit right behind the door and I could hear it pop like it was lean with .043's.
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