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05-10-2022, 01:10 PM | #1 |
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Join Date: May 2010
Location: Yucaipa, CA
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Carb Jetting and other engine advice needed
Hello everybody,
I inherited dad's '32 roadster and it has a stuck valve from sitting for so long. Since I need to pull the two-carb intake to get to the valve unstuck I'm going replace it with a three-carb Edelbrock intake wall hanger I have. While I'm at it I might as well remove the heads and swap out the Isky Max 1 cam for a more aggressive Isky 400 jr, Clay Smith 272 or a Potvin Super 3/8 I have. If I do this what would be a good jet size to start out with? I'm going to weld in a wideband O2 sensor bung into the exhaust and do the final tuning with a air fuel ratio gauge. I have no idea what jet size to start out with? its an 8BA, I assume its a stock crank but I'll check the stroke when i have the heads off. I'll use one of those cams above, three Stromberg 97s, Mallory duel pint distributor, headers, It has Edelbrock thick (race style heads designed for relieved blocks. I don't know if the block was relived or not until I yank the heads. Whoever polished the heads polished off the stamped compression ratio. I bought a "CC beaker to CC the heads. Is there a chart that shows the CC volume to compression ratio? If I have them surfaced what was the valve to head clearance I remember you guys talking about for better performance? I'll clay the valves with the used already compressed gaskets. Port dividers or no port dividers with a high duration cam? Is the exhaust restriction worth the divided port? I think I'll plug the block heat risers, what do you guys use for plugs.? An old-timer dry lakes racer said he used the 1943 "steel" Wartime pennies. I have a penny collection from when I was a kid I could rob. I could use the 1943 "S" pennies Maybe the "S" can stand for more speed and not the San Francisco mint. I need to get rid of those stupid radiator flex hoses, I hate those hoses on anything! Get rid of the alternator they do not belong an a period correct hot rods and clean up the spark plug wire routing... This is exactly how it was the day my bad bought it 20-25 years ago. In all that time he only drove it maybe 100 miles The last 15 years it sat and was started. When I started it on new gas it ran so bad and had a noisy lifter that I'm 99% sure it has a stuck valve. Just for fun and because I will never have another reason to use this wall hanger/garage art. I have one of those KR Wilson tools that replaces the intake so you can run the engine and watch the valves to see if they go up and down and how much. You could spot a worn cam lobe, dished lifter... I'll bolt it to dad's engine with a vacuum gauge and make a video for you guys. That way we can watch down in there and watch the stuck valve and watch how the needle fluctuates on the vacuum gauge. Its kind of a useless tool, you can see all that stuff by just rotating the engine. Maybe if you had an intermittent sticking valve it would be useful. I can fix engines easier than I can post a video. I don't know what the correct format is to post a video on YouTube. I'm not into modern technology "at all". Now I have reason to learn. Last edited by Flathead Fever; 05-10-2022 at 01:18 PM. |
05-10-2022, 04:03 PM | #2 |
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Join Date: Jan 2011
Location: Central Ohio
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Re: Carb Jetting and other engine advice needed
Question: I don't believe that intake has heat risers anyway . . . correct? So, there is probably nothing to plug. What are the cubic inches of the engine- any idea? If it was mine, I'd just start with stock 97 jets - '45's and then tune it once you get all the changes made and go from there. I've found that in order to have the correct AFR at higher RPMs, that 97's tend to run a bit rich down lower - like a 12/1 type of ratio. Keep us posted on what you find on yours during tuning.
Also, depending on the cubic inches, you might be better off with a 2-pot manifold anyway. Just something to think about. |
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05-10-2022, 04:22 PM | #3 |
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Join Date: Jul 2011
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Re: Carb Jetting and other engine advice needed
The hi rise video will be very interesting to see if you indeed have a stuck valve, even more so if it's intermittent. Another interesting bit will be to see if there is a noticeable lag in response time to punching the throttle. that's going to be a popular video!
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Alan |
05-11-2022, 11:15 AM | #4 | |
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Re: Carb Jetting and other engine advice needed
Quote:
Edelbrock 3 pot came both ways; heated and non-heated. |
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05-11-2022, 11:18 AM | #5 | |
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Join Date: May 2010
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Re: Carb Jetting and other engine advice needed
Quote:
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05-11-2022, 12:53 PM | #6 |
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Join Date: Jul 2019
Location: Southern Oregon
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Re: Carb Jetting and other engine advice needed
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Here is a comprehensive compression chart.
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Frank '35 Ford Model 51 '48 Ford F3 '54 Ford Tudor Mainline |
05-11-2022, 05:15 PM | #7 |
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Location: Central Ohio
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Re: Carb Jetting and other engine advice needed
I have a couple Edelbrock 3 and 4 carb manifolds, Navarro 3 carbs, Weiand 4 carbs, etc. - don't believe that any of them have heat risers. The Edelbrock 'Super' duals do not either. The SlingShot does.
The Eddie Meyer does - and it is a good thing (especially with those carbs way up in the cold air). |
05-12-2022, 07:31 AM | #8 | |
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Re: Carb Jetting and other engine advice needed
Quote:
Dale, Original Edelbrock Supers did have heat. I have one hanging on my wall and can take a pict of it if you'd like. I recently sold my Edlebrock 3 pot that also had heat. Like I mentioned yesterday, the Edelbrock 3X2's came both ways. I'll pull out an old Edelbrock catalog to see if they list them both ways. I don't buy them if it they don't. The repop Super without the gen mount does not have heat. Unsure why. I've never seen a 4X2 with heat |
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05-12-2022, 07:39 AM | #9 |
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Join Date: Jan 2011
Location: Central Ohio
Posts: 5,064
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Re: Carb Jetting and other engine advice needed
Thanks Tim - I don't have any Edelbrock's with heat - other than the Slingshot (which is a great street manifold - one of the best).
I'm with you on the 4x2 manifolds - they were pretty much used by the racing crowd, who never wanted/needed any heat in their applications. |
05-12-2022, 10:22 AM | #10 |
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Re: Carb Jetting and other engine advice needed
I plugged my heat riser with cupped core plugs. Running dual 97s on Edelbrock Regular, 45 main jets and 71 power valves. Engine would bog with 65 pvs.
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