please enlighten me.Nope.
please enlighten me.Nope.
What carb is it? If it’s a Holley call BLP or maybe ProForm is still making parts and get a billet plate.
please enlighten me.
That reminds me BLP offer slabbed throttle shafts for increased air flow: 4150 Pri Shaft Thinned/ Coated Thinned shaft [102264-BX1] - $42.99 : BLP, Xtreme Performance Made In USA
That's a model 4150 with 1 9/16 primary and secondary throttles4776-4
74 with a 72 340. electronic ignition, will throw a timing light on it tonight and get back to you on that but ive gone up and down. Sound gets worse when i advance it. there is a vacuume advance and it is operating. 91 octane fuel.
No idea what you mean by 'reads good'.i was thinking that too, vacuume gauge reads good on manifold and ported. but since spraying the base of the carb and getting the reaction I did ill try the gasket next.
People have run much more than that and there are other factors involved than just cylinder pressure.
240 psi on pump is possible when you know what you're doing.
I am certain you are correct, but we are trying to help figure out an unknown build. 180 psi and up on an unknown combo is at least enough to consider as a possible issue.
I agree but again there is more to detonation than just cylinder pressure. Are you suggesting he pull the engine apart and change the compression so as he can now safely say that he is what other people consider safe territory for cylinder pressure?
I haven't seen any mention of initial timing or what his advance curve is like from the OP? Where is it detonating? is it detonating in the lower rpms or higher rpms?
Maybe, maybe not. I can tell you about mine. "All of a sudden" it started spark knocking again a while back. Not "as bad" as before I tuned it out. Guess what it ended up being? The carburetor had loosened up on the mounting gasket. To my stupidity, it was an old one I reused, so I got a new thick one and tightened it down good. Problem gone. So that tells you how "close" the tune is on mine. I just bet I could remove one of the plugs from an unused port on the base plate of the carburetor and it would start rattling again. It doesn't take much sometimes.It’s not lean.
There's a guy over on The Hamb running an old school 392 Hemi. He has a measured 13.5:1 with iron heads and a mild solid lifter cam. He runs on pump gas. No spark knock. So yes, it can be done.You can do it. You just have to have a purpose going in.
And that’s one reason why cranking compression isn’t a very good predictor of detonation.
Just get a quick fuel 450. That's the base plate they have.That's a model 4150 with 1 9/16 primary and secondary throttles
From an older numberical list, the Throttle body and shaft assembly is (was) p/n 12R11086A
Don't think its available new. Could check for new old stock on ebay or look for a cheap used one, or carb with one.
I don't recommend paying stupid money for a new carb unless you're racing. Find an old one at reasonable price. If you can find another baseplate for your 600 double pumper, it should be easy to get a nice crisp throttle response. Yes it may be down a few mph in the quarter mile compared to a well tuned larger carb, especially with headers and gearing. Doesn't seem like thats your focus right now.
It may be easier to find another 4776, or a 4777 to get you going for now.
I agree but again there is more to detonation than just cylinder pressure. Are you suggesting he pull the engine apart and change the compression so as he can now safely say that he is what other people consider safe territory for cylinder pressure?
I haven't seen any mention of initial timing or what his advance curve is like from the OP? Where is it detonating? is it detonating in the lower rpms or higher rpms?
You haven't read through all the posts as they address exactly your questions including what my suggestions at this point are.
Question is do you care to add anything helpful to the discussion?
If the intake manifold doesn't have the bolt pattern and openings for the Thermoquad, then it becomes a hassle and IMO not is not usually a good match for the intake.
So assuming the intake is for a Holley squarebore with not adapters, then find a used Holley and switch over the throttle extension from the old one. New is not always better, its just new. That said, if you want something new more like an T-quad but fits a square bore intake, then the "Street Demon' is worth looking at.
I don’t get offended, I am asking for help and appreciate the advice. I had a ton of Experience way back in the late 80’s early 90’s with thermoquads ( I used to call them thermo bogs ) but damn when those secondary’s kick in. It’s just been a while. I have zero experience with holleys but have learned a lot over the last few weeks. Just really want something that will be an easy use. Not looking to run 1/4 mile times or get every horse out of the motor.I do not mean this insulting in any way shape form or fashion, so please take it in the intent it is given. If you do not have good and I mean GOOD carburetor tuning skills, don't get a thermoquad. They are great carburetors, but the learning curve is pretty steep if they are new to you. Also, if you run a square bore carburetor on that intake, you will need the thin plate from Edelbrock to assure you have no vacuum leak around the secondaries. This is all you need. Most O'Reilly stores stock it.
Edelbrock 2732 Edelbrock Carburetor Adapters | Summit Racing
If you want something easy peasy, I suggest looking at the Quick Fuel carburetors. They have so much MORE adjustability than the old Holleys, it's pitiful. I have a 450 on a slant six and it runs fantastic.I don’t get offended, I am asking for help and appreciate the advice. I had a ton of Experience way back in the late 80’s early 90’s with thermoquads ( I used to call them thermo bogs ) but damn when those secondary’s kick in. It’s just been a while. I have zero experience with holleys but have learned a lot over the last few weeks. Just really want something that will be an easy use. Not looking to run 1/4 mile times or get every horse out of the motor.
anyone have any experience with the quick fuel 600 series?
Quick Fuel SL-600-VS Quick Fuel Slayer Series Carburetors | Summit Racing
I have 180-190 CCP in my street 340 with ported X heads. Run 91 octane no ethanol fuel all day crz'n - no issues180 psi is too high for 91 octane with LA iron heads.
Get another carb and go back to post #10