I think Danny has some pretty good info on sizing your fuel system, If I'm not mistaken, he runs pretty fast on a 5/16 line, but you should confirm what he has to say too.
On the exhaust manifolds. The only difference on the left ones are the flange orientation. The pipe will match right up between the 67 and 68, but the flanges are at about 90 degrees apart.
If you want, I can go look at my 440 with hp manifolds, I would assume that if there is at least an inch under them, then you will have enough room. You are just dealing with a lower block height.
Tek, there also should be an assembly date stamped on the block some where. I'm not familiar with 383 too much, but it should be there.
For fuel flow, it is recommended to have roughly 0.5 lbs of fuel per hp. There is roughly 6.3 lbs of fuel per gallon, so you need roughly 40 gallons per hour (gph) to support 500 hp. I like to double that number for losses (fuel pumps are rated for free flow). Aftermarket mechanical fuel pumps are typically rated between 80 to 120 gph. Problem with the mechanical pumps is that the higher the rpm the lower the flow output (I can send you some trial data on that if you are interested). I don’t believe you will support the hp you are targeting with a stock pump.
My daughter’s car ran a best of high 13.80’s at 96 mph. My HP calculator says actual 300 hp – the calculator is pretty accurate for my race car.
When I put the 440 in, I replaced the stock 5/16” fuel line with a 3/8’ line and installed a Carter 120 gph mechanical pump. The car did not want to pull past 4000 rpm. Checked everything and found no issues. Bad pump.
Replaced the pump under warranty and the second pump was better until the engine warmed up and then was running out of fuel. I installed a fuel pressure gage and the pressure would drop below 1 psi under full acceleration and hot. Started at 6 psi, and the hotter it got the worse it was. I insulated everything and bottom line never got it to work. I asked around the vendors at the Nats and pretty much all agreed what I was seeing was a common issue with these pumps – some succeed with them and others like me never do. Returned the pump to get my money back.
I did not want to drill any holes in my chassis in order to mount an electric pump (want to be able to return car to stock condition as it is a rust free nice car). My solution was an Aeromotive 175 gph pump mounted to the tank. See pics for my solution. No more fuel starvation problems.
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ws27 Wrote:I think Danny has some pretty good info on sizing your fuel system, If I'm not mistaken, he runs pretty fast on a 5/16 line, but you should confirm what he has to say too.
On the exhaust manifolds. The only difference on the left ones are the flange orientation. The pipe will match right up between the 67 and 68, but the flanges are at about 90 degrees apart.
If you want, I can go look at my 440 with hp manifolds, I would assume that if there is at least an inch under them, then you will have enough room. You are just dealing with a lower block height.
HI, the 'flanges are at about 90 degrees apart' part..Has me scratching my head. Can I trouble you for a photo of what you mean here..My issue right now, I do NOT have the new manifolds yet, and my LOG TYPE ones are now off the heads obviously. ANd on top of that we found a very small crack in one of the bolt holes on one manifold. So they are NOT going back on no matter what.
So at some point pretty soon I need to pull the trigger on a solution for exhaust manifolds/extractors.
Of course my 'keep it looking stock' plan goes out the window if I have to get extractors.
Also @markz, thanks for that info. I am going to add it to the list of things to consider.
I don't believe this engine is destined to be anywhere close to 500HP. I actually hope it won't. I think we are aiming around the 350 to maybe close to 400HP mark. It's hard to say.
The more I can keep looking original the better it will be.
Tek, I might be able to describe it with out a photo. Pretend the flange on the pipe is loose. The position of the flange is rotated about 90 degrees on the pipe like you are rotating or spinning the flange on the pipe. The 67 ones have the flange almost 90 degrees to the length of the manifold, the 68 ones, the flange is closer to being in line with the length of the manifold.
Course, in my mind this make perfect sense. Let me know if you need pictures.
TekHousE Wrote:Also @markz, thanks for that info. I am going to add it to the list of things to consider.
I don't believe this engine is destined to be anywhere close to 500HP. I actually hope it won't. I think we are aiming around the 350 to maybe close to 400HP mark. It's hard to say.
The more I can keep looking original the better it will be.
That cam is not crazy, but the heads should help hp quite a bit. I agree 500 hp is probably a stretch but I would not be surprised if it made over 400.
I also wanted to keep my daughter's car original when I put the 440 in so I kept the 383 log manifolds. It was hell making the 440 HP 2 1/2 inch exhaust in without cutting the pipes, but I did it. It has a very mild hydraulic cam in it. I ended up with major reversion issues, to the point that the carb and the air cleaner lid were totally black. I assumed that the root cause was the manifolds, so I installed 1 3/4 inch headers.
Well come to find out my engine builder really messed up the valve train and some valves weren't closing and others weren't opening enough. Lost the fan belt and the engine temp got a tad beit hot and 2 push rods fell out on that one run, and the car flew on that run compared to all previous runs. So I am no longer convinced that the manifolds were the issue for the reversion.
On top of that, there was not huge gains at the track between the manifolds and headers. Hard to tell for sure because of the valve train issues, but maybe in the 3 tenths (0.3) range. May not be worth the gains for you.
Depending on which manifold is cracked, I may be able to help you if that 's the way you want to go. I have several sets of good manifolds for my 65 Fury and one of those is the same as a 67 Coronet 383. Even have one NOS one. A 67 440 hp manifold might be the right answer for you, but I don't really know.
As far as the fuel, the best course of action is a fuel gauge. It will tell you if you are running out of fuel or not.
HI,
One of my guru friends has just said there is no reason the 68 and later HP manifolds won't fit. So I might just take the chance. I have one more guy doing a check for me as well..
The headers will flow better than the HP manifolds, but the difference is slight.
As for HP, over 400 might be nice, I'm not expecting it though, but I would not complain..
Thank you so much for taking the time to post back, I really appreciate it mate.
TekHousE Wrote:HI,
One of my guru friends has just said there is no reason the 68 and later HP manifolds won't fit. So I might just take the chance. I have one more guy doing a check for me as well.
I poked around some on another site and others agree that it should not be a problem - some have said they have done it. So it sounds like you will be fine with these manifolds.
Always learning.........
That's what I am here to do as well mate!