I'm new to the hotrod scene (at 71). My wife told me I needed something to do. So I bought a 30 Ford roadster. I bought it from a guy who new nothing about it. He was the 3rd owner. I did talk to the 2nd owner, who shed some light about the build. But he is a cl***ic car dealer and can't remember the name of the original owner. So I'm stuck with the info on the build he told me about. It has a very early 327 block, double hump heads, a Duntov cam with solid lifters and roller rockers. Topped with an Edlebrock 1406 600 cfm carb. Its mated to a TH350 ****** with a shift kit. I purchased a timing light and vacuum gauge and reaquainted myself with their use. Its been over 50 years since I turned wrenches on a set up like this. The car was running way too rich with black sooty tailpipes and the exhaust smelled of gas. I checked the timing. It was set at 11 degrees btdc. At idle of 800 rpm it was pulling 0 vacuum. I checked all the vacuum lines and gaskets. No leaks. Set the timing while watching the vacuum gauge. I got it to 10 lbs vacuum at 14 btdc. I left it there and adjusted the idle mixture screws which seemed to help the richness and it bumped up the idle to about 900 rpm. Still pulling 10 lbs vac. I lowered the idle to 750 rpm and the vacuum dropped to about 7 or 8 lbs. It seems to run fine and seems more responsive. But it has a power booster and the pedal is very hard when stopping and starting at lower speeds and rpm. Good pedal at highway speeds. So I'm thinking of installing a vacuum canister to see if that will help the brakes. Any ideas would be great. Sorry for my first post here to be so long. Thanks.
Cam , Stock sounding or Lumpy ? Spec's? Cam & Converter will determine Idle speed .... If lumpy , cam more likely low Vac , Find True Tdc , or experiment with adding 2 degs @ a time , & a drive . Stockish 10-15 ish degs, Btdc Lumpy will be 15- as much as 22 ish. Btdc. Then move possibly to vac can , What's the brake set up Drum or Disc / both ? With 327 stock or around 2,200 stall / torqe converter ? 327's finicky on converter size , A Stock Vega works well Unless you want to have one Made to order , Will need cam & other Spec's if you go that route . Lumpy cam , Carb adjustments more likely beside just Enrichment screws & a distributor cure adjusted . Some times will need to play with the Th350 Gov or Trans module
Welcome to the HAMB from Illinois . Let me see if I understand: The power brake pedal doesn't have a good feel, when stopping at around town speeds. Tell us what you can about the brakes. Pedal ratio? Front: disc or drum? Rear: disc or drum? Describe the brake booster unit, size, location. Do you really need power brakes in a light weight car? This may help get the discussion.
The cam is lumpy. I don't have any specs other than it's supposed to be a Duntov cam which would be the 097 with .395"/.401" lift and 228/230 duration. Seems to be a factory converter. It has disk front., drum rear.
Disk front, drum rear. The booster and master are under the car, not sure on size but it doesn't appear very big. I didn't build the car and I can't find out who did. I think it might have been So Cal Northwest in Oregon, which is no longer in business. The ch***is is a TCI, so the brakes were probably installed by them, but I don't know what they were using back in 2013 when I think the car was built. No I don't really have to have power brakes, but if it has them, I might as well try to get them to work properly. My wife does drive it too.
That's pretty weak vacuum. Before you put a band aid on it, be sure the engine is sound. A compression test is in order, and I wonder if the valve adjustment is wrong, i.e. over tight or loose? ensure firing order, all cylinders firing.
I fixed the same problem on my Chevelle by losing the brake booster as questioned by Phil above. It stopped way better with manual disc front/drum rear than it ever did with low vacuum because of the cam. A Model A weighs almost nothing and should be pretty easy to stop with manual brakes. I get trying to make it work as it is, but that could be the easiest fix.
welcome not saying that this is your problem but.... having a similar engine in a '31 A Roadster, I had low vacuum when I got the car one of the findings was intake gaskets that had disintegrated on the valley side and was drawing crankcase air instead of engine compartment air...the clue was header pipes on those cylinders were lean hotter than the others.... then came the fun of getting intake gaskets to cover the port match properly between the intake manifolds and the heads..... good luck and just keep picking away at it side note...my '31 has drum drum...no booster
Given this seems to be more of a brake thread than a vacuum leak thread, I've attached a link to a thread I put together a couple years back regarding my "new car built by someone else" brake investigation and repair. ***uming your avatar is your model A roadster, once you get it sorted, it will be a cool and fun car. https://www.jalopyjournal.com/forum...e-thread-a-story-with-a-happy-ending.1289583/
Take the line off of the booster and plug it. See if the vacuum reading goes higher, if so the booster has a leak large enough to cause your issue but small enough to still provide some ***ist, especially when the throttle is closed and the engine is decelerating the car which is when vacuum is at the highest. I am in the ditching the booster on a Model A camp, it is really not needed. Also do inspect the condition of the line going to the booster, they can start deteriorating and allow air through, but the simplest check to do first is to plug it. Make sure your gauge is connected straight to the intake manifold for the vacuum source to get the most accurate readings. Even with a big lumpy cam I would expect something well over 10 inches of mercury for a vac reading, an OT El Camino I worked on had a more extreme cam than yours and pulled 13 at idle requiring a vac pump to help the brakes, which is why I am suspect of your booster.
Welcome to HAMB! Sounds like you dove in and got stuff better. A lot of guidance already to keep you going. I would do a major tuneup on the car, to set a baseline. Change the oil & filter, it's probably got a lot of fuel in it due to being at a used car place. Lots of cold starts without coming up to temp, plus the way it was adjusted before. Change the plugs for the same reasons. Set points, if equipped, then recheck timing. Run the valves. Most people don't do it correctly or enough. While under the valve covers, give everything a good look for uneven wear or strange stuff. If you feel comfortable at that point, I'd also swap intake gaskets. This requires draining coolant, which would probably be a good thing to change also given the history is murky. At this point, you know that it's none of the basic stuff holding it back. Run the engine up to temp a few times, checking vacuum and adjusting the carb. You should be more comfortable with the engine and how it responds. You can then follow the brake troubleshooting laid out by others. Normally it's smart to get brakes sorted first, but in this case, they rely on vacuum so that and diving back into cars it makes sense to start at the engine. I would again do an inspection, grease bearings, bleed or replace the fluid and build that confidence in yourself and the car. Probably a good idea to start a notebook on each service date, part numbers as you find them and other stats. Think how much easier all this would have been if they previous owner had done this for you.
I checked the vacuum at the carb where the brake hose is attached. It was extremely low at idle. Bumping the timing up 3 degrees jumped vacuum from almost none to 10. I've only been told what the cam is and I'm guessing it's a Duntov 079. My timing is at 14 degrees btdc right now. Starts great, no pinging. I'm thinking of bumping it more to see if that helps vacuum at idle. At 1600 rpm I have good vacuum around 22.
The car only has 2500 miles on it. I don't know if the engine was built at the same time, but the quality of the build tells me it probably was. The guy i bought it from knows nothing about cars. He only put about 800 miles on it in 5 years of ownership. He did have it tuned by someone who didn't do a very good job. I've only put about 80 miles on it since I bought it right after this past Christmas. That included driving it home 40 miles. The oil looks like it came out of the can ten minutes ago. I know this is an extremely low mileage car as I found the auction company ad from 2018 that said it had 1700 miles on it. I replaced a burned out high beam headlight dated 2012. I checked the tires date code and they were made in December 2012. They look like new and still have the blue protectant on the raised white letters that have been turned inside. That's why i think it was built in 2013. All this leads me to believe the engine should be in good shape. I intend on a plug change and probably an oil change. Thanks for your reply
You're welcome. Very low mileage over 12+ years and barely broken in will be more of a 'recommissioning' or awakening than a refresh, so perhaps the oil and intake gaskets will be fine for now. Sniff test should confirm. Sounds like it was perhaps done by a shop or a quick builder with lots of parts purchased all at the same time. If you want help with tracking the history, pictures of the car and a location might help. Hope you are having fun!
A lumpy cam coupled with a poor tune up can cause a vacuum issue at an idle. I suspect the low vacuum is the cause of the brake issue. Were I in your shoes, I would change the oil and filter, simply because is could be really old oil that may have enough contaminates in it to cause future damage to the motor. I would also change the plugs, because if the timing was retarded and the exhaust was sooty, the plugs may be partially fouled out. Since you have said you can drive the car with the brakes as they are, I would probably pull the hose to the booster off at its vacuum source and plug the source. As is the power effect of the booster on the brakes is likely very inconsistent. Plugging the vacuum source will at least make the brake pedal effort consistent. Then I would drive the car. After a few hundred miles have been added, the vacuum to the booster can probably be tested again, to determine which direction to go with the brakes. I believe making the car function as good as it can, then add on some quick miles to get everything moving and functioning, may improve a lot of things. At least that would be the direction I would lean towards.
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