Does my 451 have to small of a cam?

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daredevil said:
All right flame away. If it doesnt have any top end it isnt the converter as mentioned and it isnt the cam as you said your six pack cam was smaller so what is it?I run 750,s on small blocks. That 451 has a rod ratio that needs to breathe is all I was saying. (stolen from Diamondback))>> Get the proper carb for your vehicle- undersized carbs, while great for response will be dead at the top end, run richer as a rule (excess velocity causes main circuits to come in wrong) and usually get worse mileage. Oversize carbs (especially vacuum / air secondary type) will have an untunable low end bog, lazy acceleration and nearly impossible idle problems. Somewhere in between is what we are looking for. A simple equation to get you close : ((Max rpm X CID) / 3456 )X V1. V1 is a variable representing the efficiency of your engine . Use .85 for a normal street engine, 1.00 for a fairly stout street engine ( we're talking close to strip car here) 1.2 for a highly modified strip only vehicle. (Yes< I know these are not the same numbers as some books show, but they work for these carbs) BE HONEST (you don't have to tell anybody) -along those lines do not use 7600 for the rpm on your hydraulic cam 8.5:1 street engine.

EXAMPLE: 440, hydraulic street , 5800 max rpm. ((5800 X 440)/3456) X .85 or ((2552000)/ 3456) X .85 or 738 X .85=627 or a 625 440, 620 lift mechanical, 6800 rpm max ((6800X440)/3456) X 1.00 or ((2992000)/3456) X1.00 or 865 X 1.00=865 or 800 (biggest) or 2 X 500
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Your talk is fancy but your missing the whole point, He has ALOT more issues going on & to think a carb change will be his miracle cure is nuts, he needs to fix his main problems 1st., Its not always the "size" of the carb that makes it shine, its in the metering, I've run the 451 low deck for a long time with basic parts, it reacted better ET & MPH wize with the smaller carb, with his smaller cam he won't be seeing alot of RPM, so he doesn't need a bigger carb, If he wants to throw his money away, have at it, but its money down the toilet. I'm not flaming you, don't take it personal, i'm just speaking from exsperience, & i'm not the only one that realizes bigger isn't always better when it comes to carbs, that theory still stands true today as it did back in the day & for his MPH to be so low at 101, theres alot more to be fixed then a carb change.
 
JoeDust451 said:
Your talk is fancy but your missing the whole point, He has ALOT more issues going on & to think a carb change will be his miracle cure is nuts, he needs to fix his main problems 1st...

...his MPH to be so low at 101, theres alot more to be fixed then a carb change.
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This was why I suggested the pressure readings. Also bear in mind that that was a quote from another source. I also don't agree with the quoted material but that's another thing all together. I think there are other issues besides the carb/stall/cam bit.
 
Like I said,iam really going to dig into the motor SAT.,but I did a quick PSI check after work on #1and#2cyl...#1was 180,#2 was 178.6..#1 plug was clean, #2 was slightly oily.
 
I will butt out. You guys are professional mechanics and i,m just a plumber who turns wrenches in his own garage who has no choice but to believe what he reads till the author steers him wrong. Never said a carb was a cure all but do know that in a lot of cases a soft top end will benefit from a bigger carb. Please listen to the pro,s and disregard what I posted. I,d hate to steer you wrong. Maybe the problem is nothing more than a low float setting but its hard to repair things theoretically.Wish you luck. Theres a lot of white papers that explain the theory of how things work where I quoted the carb sizing from. Its at Diamondback Racing Engines. Check it out. DD
 
Dare, I wasn't meaning to belittle your ideas or step on toes. Everybody's input here has value. The carb may well be a problem too but I happen to think theres something more to it and I've read some from the Diamondback guys and don't subscribe to what they say "in general".
 
Welcome fellow Iowa looks like you are getting some good help. When you bought this did you verify any of the builders statements? Did you drive it first at all? Have you done a compression test at all?
 
Hey ScampTramp! Yes I drove it , he didn't let me heat the tires up!lol.But it ran fine around town. I did get some paper work,but the builder was killed 8mons. Ago.It is my firs project car so I'm learning the hard way,but with all you guys help it will be a lot easier!
 
Roger Price said:
Hey ScampTramp! Yes I drove it , he didn't let me heat the tires up!lol.But it ran fine around town. I did get some paper work,but the builder was killed 8mons. Ago.It is my firs project car so I'm learning the hard way,but with all you guys help it will be a lot easier!
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Roger, did you run this car on street tires at the track? Also, what kind of fuel system do you have?
 
Get it all tuned in if its not. Easiest thing to do for the carb is borrow one if you can for a run and see if that seems to change things up. I would guess that converter is a stock non hp converter i heard they stall around 1800 rpm. You could borrow a converter for that matter too but I would suspect you need more stall.

Also mentioned whats your suspensions set up? You can have all the power in the world but if you cant get it to the ground it dont matter. Did they guy you bought it from ever run it at the strip what were his times and what was it in? I didnt see if you bought just the motor or purchased the whole car and all. The kickdown is hooked up and adjusted properly?
 
JoeDust asked about fuel/tires. FuelSystem is a 10gal. Fuel cell with 1/2"steel line. The pump is an elec. High vol. With an ajustable regulator at the carb. The prev. Owner has it set at 6psi. The tires are street tires 265/50/15.....ScampTramp,He never took it to the track and the nimrod sold it to buy a 86 trans am. The rear susp. Is some kind of ajustable,I haven't figured it out yet? There is also something mounted up front for the fuel line called a "COOLCAN"?
 
Roger Price said:
JoeDust asked about fuel/tires. FuelSystem is a 10gal. Fuel cell with 1/2"steel line. The pump is an elec. High vol. With an ajustable regulator at the carb. The prev. Owner has it set at 6psi. The tires are street tires 265/50/15.....ScampTramp,He never took it to the track and the nimrod sold it to buy a 86 trans am. The rear susp. Is some kind of ajustable,I haven't figured it out yet? There is also something mounted up front for the fuel line called a "COOLCAN"?
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It would help you alot if you ran a sticky tire, make sure the fuel system is keeping up, this is "vital", especially with BBs, make sure the pressure doesn't start falling off when you lay into it, especially in high gear.

You mentioned it felt like the brakes were applied, have you pushed the car on flat ground to check rolling resistance?

What kind of car is it?
 
The statement it feels like the brakes are applied worries me. When the case is cracked from a bad sprag it feels like this. I dont know if anyone has told you this but never do your burnouts in first gear and let off or the over running clutches suffer damage.The previous owner may have damaged the trans. Years ago I did this and it felt like hanging brakes. If the wheels are all free I would have the trans checked for safety. Search the exploding torqueflites thread here. lots of good info.
 
Ok guys, I got the cam out and I think I've been had! The gear drive has 3 marks on it and 1 on the cam. The one on the cam was lined up with the mark right of center. Also there is a # stamped into the cam between the lobs 292. Isn't that the cam size? And between the carb and intake is a thick plate with 4 holes way smaller than the prim./secd. On the carb! What's up with that?
 
I just had a gut feeling the cam was apart of the problem. Like I said, the cam had no lope to it. Yes, the paper work said the cam specs. Were 475/475-308/308 it just didn't sound like it. With 3"pipes I should of heard a lope?
 
475 is that lift and 308 is duration?


Also if your are looking for a cam you can't just pick one and buy. You have to match it with your gear ration, tranny and many many more.
 
Roger Price said:
Ok guys, I got the cam out and I think I've been had! The gear drive has 3 marks on it and 1 on the cam. The one on the cam was lined up with the mark right of center. Also there is a # stamped into the cam between the lobs 292. Isn't that the cam size? And between the carb and intake is a thick plate with 4 holes way smaller than the prim./secd. On the carb! What's up with that?
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Sounds like your timing chain is the type with advance and retard options. They may have installed it advanced or retarded. Hard to guess which since I don't have the timing set to look at. If you could post a picture of it maybe we can tell more.

If the spacer holes were smaller than the carb. holes it definitely isn't right. Sounds like that spacer was made for a small carb. such as a 600 cfm. So many times guys don't pay attention to what their installing. You need to get rid of that thing as it is restricting you.

The 292 stamp on the cam may mean something and maybe not. Look on the back end of the cam and see if anything there is stamped that'll identify it.
 
Roger Price said:
Ok guys, I got the cam out and I think I've been had! The gear drive has 3 marks on it and 1 on the cam. The one on the cam was lined up with the mark right of center. Also there is a # stamped into the cam between the lobs 292. Isn't that the cam size? And between the carb and intake is a thick plate with 4 holes way smaller than the prim./secd. On the carb! What's up with that?
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Why can't you post some pictures of some of this stuff? Some of the stuff you describe, like the rear suspension "I don't know what it is" and the fuel system, make this rig sound like an all out strip car

WHAT DO YOU MEAN "a thick plate" "holes way smaller"

OF COURSE that will slow the car down!!!!!!!!!!!!!!!!!!!!!!!!!!

Have you even done the BASICS?

WHAT IS the total ignition timing????

DOES the carburetor even open all the way????
 
I did some reserch on that pete jackson gear drive and it does have Retd/Adv.marks.Iwas also told gear drive takes away 8-10hp! So I'm replacing it with a good double roller. And ya,that spacer is gone! Now,to formulate the right thumpstick.
 
Roger Price said:
I did some reserch on that pete jackson gear drive and it does have Retd/Adv.marks.Iwas also told gear drive takes away 8-10hp! So I'm replacing it with a good double roller. And ya,that spacer is gone! Now,to formulate the right thumpstick.
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Curious Roger, what were the diameter size of the holes in the spacer, and what are the hole sizes of the bottom side carb base.
 
daredevil said:
I wonder if the restrictor plate made it seem like it needed a bigger carb?
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To answer that question. "YES", that would explain why it was restricted, Thats why i said he didn't need a bigger carb, problems were elsewhere.
 
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