Does anybody know, when to have a Port job done on a .030 over bored 455, how much HP do you gain. It's on a cast iron intake and heads. Looked all over the Internet can't find the answer or maybe there isn't one? VET (Navy)
There are much smarter people than me who can properly answer this. But the bottom line is a port job by itself won't automatically grant you X amount of HP. It's a matter of what your combination is. A port job on a stock motor may likely hurt more than help. But if you have a lot of modifications the port job will help you get the most out of the the other mods. So it's not surprising you can't find someone saying a port job will get you X HP.
Great reply, I agree with you. Here are my 455 engine mods as I bought the car 2 1/2 years ago. (1) Bored .030 (462). (2) Kenny Bell pistions, 10.5 to 1. (3) Comp Cam Hydraulic street version. (4) Oil enlargement done. (5) MSD ingnition system. (6) Port Matched, cast iron intake, heads and exhaust (7) Stage 1 iron heads. (8) Holley 750 cfm, with mechanical secondaries & electric choke. (9) TH400 trans with shift kit. (10) Posi. (11) 2 1/2 inch exhaust. (12) Go fast water. Hope this info helps. Vet
Update: I found an article on YouTube that says, for a port job to be effective and add more HP, your cam needs to have a .500 in lift. My cam is close but no cigar. Intake lift .478 Exhaust lift .495 Does this all make since? Maybe I can add 1 to 5 HP gain??? Vet
Something with a larger intake valve,good bowl work,and a valve job will be great for your application. Simple but effective.
I don't understand, larger intake valve? I have the large Stage 1 valves now, how can I get a larger intake valve in the head? Both valves almost touch each other now. The valve job that was done by a Buick engine builder on this forum was done just 3,500 miles ago. When you say bowl work, I assume you are talking about the combustion chambers? That is something I do want to get done. I did some work on my SB Chevy engine years ago and I think it did add more performance. But, without a flow bench machine and a dyno to see the results of the work, it's just a guessing game. I just turned 75 on Jan 1, so i'am not going to the strip to see if a gained a tenth or 2. Lol. I was thinking about adding tube headers but that can sometimes be a headache. Sometimes they fit and sometimes they don't. I'am not a fan of bashing in an exhaust tube to make it fit. Thank you for the advise, please explain to me what I don't understand. Appreciate your help. Vet
Brian is stating "larger valve" as a general statement, your St1 valves check that box. You have port matched intake/heads (as stated in your documentation), "Bowl work" is working the areas behind the valves in the head to clean up around the valve guides, and blending the bowl radius areas to improve flow without "hogging" out a giant pile of metal on the floor of the shop that kills power. Sometimes in head work "less is more", but a flow bench and someone very well versed in the actual heads being worked on is critical to getting power or getting robbed. And Buicks are different in a lot of things. Buick engineers designed the heads to flow high velocity since the nailhead. So, having someone that specializes in Buick BB heads is important in your search for concrete answers. You can realize "up to"* 50 HP with proper head work. But in your case, maybe 25HP is not unreasonable, and unless you get specific with cam/valve train work, you likely will not see more. In the end, how much do you want to spend, and home much more time do you want to have your car in someone's shop? For about 10% increase, the cost, time and risks involved may not be in your favor.
For Aluminum aftermarket TA heads, porting will increase the intake flow from around 300 cfm (OOB) to approx 330 cfm (in my case). That 30 cfm increase approximates to a roughly 60 hp increase, assuming the setup can use all of the 330 cfm.
Thanks Trunkmonkey for the indepth explanation. I do not want to put my Buick back into a shop for any long length of time or spend a ton of money on labor costs. The Stage 1 heads have been reworked by a Buick expert, valve job, port job, ect. Maybe I don't need to spend more money or time to try and get a little more HP. My original question was since my heads and intake are Port Matched, how much additional HP does that add over stock configuration. I realize this is a subjective question and appears additional HP to be minimal at best. With no real way to measure this additional modification, I guess I can't get a real answer. If I was going for hog wild, I would just buy some really good aluminum heads and be done with it, because it sounds like putting in a lot of labor time for a shop to do this work isn't worth the $$$$. Just go big ot go home. Maybe the wise thing to do is leave well enough alone. Vet
Thanks, now I get it, in order to utilize all the 330 cfm, a larger cam than what i'am using comes into play. It kind of like blowing into a straw. If your valves can't take in all the cfm, then you can't extract it either. This is where I hurt on engine building. Many years ago, I built a SB Chevy. But, I used all factory high performance parts with the exception of the carb and intake manifold. It was somewhat of an easy build. Start with a Corvette 327 block with very few miles in it, no need to bore it out. Install 11 1/4 to 1 pistons. Same pistons that Chevy put in this engine from the factory. Install the 30/30 solid lifter cam. That came with the Corvette engine. Install aftermarket beehive valve springs. Install HD Corvette oil pump. Install (a trick here) a 409 mechanical fuel pump. Fits nicely. Install perfect Circle rings (Chrome Molly). Install original forged crank. Install a new at the time, Holley 650 spread bore double pumper. Originally, Chevy used a 625 Carter AFB. Installed, as an experiment an offenhauser low profile tunnel ran manifold. This is the copy of the manifold that Chevy ran in their 302 Cam Am cars. The exception is, I only ran a single 4 barrel not two 4 barrels like the 302's did. Installed a set of Headmen headers. Accel ignition. Installed 456 Zoom rear gears. Installed Borg Warner T 10 4-speed. Installed fiberglass Flex fan. One can see this was a pretty easy and simple build, 85% factory parts over the GM counter. All this in a light weigh 56 Chevy 2 door Belair. It was fast 12.2 in the quarter mile. Now with the Buick, to do the same thing, I would have to replicate the Stage 1 engine with a few upgrades. Alum intake Alum heads Tube headers Bigger cam to match the heads. Port Match heads/intake. Better posi gears. Wonder if I could run a 12.2 et? Just a thought. Vet
Biggest bang for the bucks, definitely put a bigger cfm carburetor on it. At least an 850…. Better yet a 1000 cfm. You are giving up hp with the tiny 750. Buicks love big carbs.
Please realize a lot more BS about effort vs end results exists. It has taken almost as many years since the 60s/70s of performance cars until now for people to realize the truth of it all. What really works, vs the "urban legends" and all that. I came from a background of real world drag racing and innovation from the 50s/60s and 70s, and then later encountered the world of "Automakers Muscle Cars, and the reality of what Detroit was producing, what people were buying and what others were able to massage on their own, both with sanctioned parts/procedures and "Do It Yourself" individuals taking it further. Nearly 80 years of history and four generations. The take away? There is no "magic path" to HP and real world results. It takes knowledge, science, testing and verification, blood, sweat, tears and a fukkton of money to get results that matter. A lot of the former has been put out there, and the smartest people take the best of all of it and make short work to produce real results. Others chase elusive "Holy Grails", and such fool's errands trying to get an "instant fix", similar to those going after "get rich quick" schemes. Math is math. And no one ever cheats math and wins. I am not trying to be a complete A**hole (some parts are missing), but at this time in your life, you should accept the fortune of the car you have, and enjoy it, rather than spending precious time chasing for some "perfect ideal number" of HP/Torque and miss the best that what you already possess can provide for you. However, if you do have the time and money to pursue a specific dream, clarify it, figure out the the "end" you want and write it in indelible ink. Then get on it without taking half assed bunny trails and powder puff paths, but set the mark and press hard to get to the end. No one you encounter has all the answers, we are a sum total of experiences and direct knowledge. It is not ethical nor moral to say things that simply confirm a bias you might have or want, but provide all the information and advice, both desired and contrary, so you do not waste precious time, energy, resources in foolish journeys where you are disappointed after investing those things. If you want a specific purpose built car to produce an exact ET and MPH in the 1/4. This can be realized and a "recipe" provided by several here. But, it will cost you. Math is math. Total weight at the starting line. Time and Distance. (Standing 1/4 mile) What is required to fulfill the desired outcome. What you have to work with (right now). (Total weight, HP/Torque, gearing, suspension, car's potential/ability proven, driver's capability etc.) How far away from what you can achieve currently and what you desire to realize. The difference is what it will take to get there. And those numbers get crazy faster than the number you are chasing. Drag racing is unforgiving and harder to "please" than an unhappy wife. There is no room for feelings. And no trophy for second place. Either you are driven to win, or you are suited to sit on a park bench feeding pigeons. There is no middle ground where one is content. Hope that is helpful. It is certainly not intended to be hurtful.
Thanks Guy. I hear that all the time from Buick friends. Wish I would have known that Before I bought a new carb. I'am amazed Buicks can go this big on carbs when you see how small the combustion chambers. My old SB Chevy 327 had the same size chambers. How in the world is the Buick able to burn all that gas effectly? Vet
Trunkmonkey, you are wise beyond your age. You are 100% correct, to meet a goal, one has to define what all must accomplished to meet that goal and is the math worth doing it? At my advanced age, it's not worth the time, energy or fuckton money to get there. Thank you for clarifying my Thought process. I just now realized i'am living in the past and trying to makeup for 50 years I had family, wife, children, home, and work responsibilities to attend too. You're dead on, you can't fool math. Thanks, Vet (Navy)
On your application you are the point of diminishing returns....500lift thing is irrelevant.....a nice set of heads with low and mid lift improvements will add power to your combo..how much....25 maybe 35....enough to spend 4k doing the swap??? I think not Carb on your application you won't see an improvement....I prefer the 750s on the street driven stuff..they are snappier...the difference between your carb...a 800qjet and 1000cfm thermoquad for example...MAYBE 1.5mph at most....that worth the $400 to $1k it would take to upgrade?? Not in my opinion especially seeing how you will lose throttle response The only way you make an improvement that validates the money spent is a new combo..more compression..more cam..more cfm...headers..etc...playing with a little change on the same base engine if it's running well is most always a waste of money
With most any head where talking about here up to .300" lift or so all the air flow that gets into the chamber is governed by the valve job, not the size and shape of the main runner of the port. If your running a .500" lift Cam then .300" lift is where 60% of your valve open time is spent, so in this. .100" to about.300" lift range is very important that it be a very well researched and efficient valve job. The simple formula to find out how high in valve lift the valve size your using is impacted by the valve job is simple. It's D x .18, so for a 2.00" valve all the way up to .360" lift is where this effect fades off. Number 2 in this valve job chart is a single angle valve job. As you can see once you get a good well researched 3 angle valve job in place there is not much more improvement to be found, in fact in terms of flat out heads used for racing I am of the opinion that the implementation of a 5 angle valve job is more for controling high lift port velocity then it is for added air flow. Installing larger valves in stock heads allows the use of a very nice 3 angle valve to be utilized.
Port-matching or gasket-matching will have zero effect if there is a bottleneck in front,behind,or both. I just won’t do anything by itself,if the other areas are not addressed.
So since we're on the subject of valves when I had my 455 heads rebuilt the valves needed replaced so I purchased an had installed TA regular stock size stainless swirl polished valves with a 3 angle valve job. I figured since the stainless valve set from TA really wasn't that much more cost I would be better off with the stainless valves. My question is even with stock diameter valves did I make the right decision. My Machinist really liked the looks of the valves and he reassured me with a three angle valve job there definitely would be an improvement. Any thoughts? Jim
