ENGINE - I need more top in.

[Guest]

As I explianed my situation in the General forum section on my little run with a new T/A, I need more top in on this engine. The lowend is there I just want longer legs so to speek. I could'nt pull away from this guy and wanted to badly. So any ideas? I'm working on some different heads for the engine, but what would be a quick change that would net me more top in without sacrifising to much lowend torque?

 

Jon.

[Ian]

You could put a overdrive in it. Or lower number gears. I would go for the overdrive as it would be the best of both worlds.

 

Ian

 

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http://web.tampabay.rr.com/iann/monte.html

[Guest]

Clock, aren't you running a dual plane intake on the motor? I can't remember which one you have, at this time the choice is limited to the edelbrock performer, performer rpm, and the super victor. If you have the standard performer swap up to the rpm manifold it will give you more power up to 6500 where the performer peaks at about 5000 normally.

Don

[Guest]

Don,

I have an airgap rpm performer on right now. I was thinking that a single plane would net me alittle more on the top in. Since I have vortech heads on the engine right now they kinda limit me to my intake options. I'm just going to wait until I get the set of heads, and go from there. I already have a torker single plane intake in the basement that I've kept just in case I'd go back to the conventional heads. I'm planing on hitting the junk yard and installing an electric fan or fans. I can get some good fans cheap. I'm also looking at a trans from an 80's SS Monte with a lower first gear and overdrive, but thats down the road aways. My focus is on the heads right now. I think these vortech heads are good lowend torque heads but the valve size just chokes the engine at higher engine speeds. They seem to start to fall off where most performance heads are still picking up flow on the lift. I'm thinking of heads now though.

 

Jon.

[Ian]

If you change heads, are you going to sell the vortec heads and if so how much do you want for them. I need a set of heads for my drag car it has a set of open chamber smog heads on it now an they suck

 

Ian

[chuckash]

Before you go spending lots of cash, you need to decide what you really want to do with this vehicle. If you want to run around the freeways at 100+ mph, the best way to do that is put in an overdrive transmission and install a higher (numerically lower) gear. These two things would get you into the 140's or 150's no problem, but acceleration out of the hole will suffer with a higher gear.

 

Since I rarely see anything above 70, I geared mine to accelerate quickly. But with 3.73 gears, my top end is likely only 110 to 115 (with a TH350 trans and 1:1 final drive ratio.) But, that isn't where I spend any time driving.

 

The only reason the T/A could run you at those speeds is because it does have an overdrive transmission. You are probably making more HP and more torque than the T/A, and probably weigh about the same since it was a ragtop.

 

It is really all about compromises. If you want to run those speeds and really crank up the engine, consider changing the cam to get the HP up higher in the RPM range. It is tough to have your cake and eat it too with top end power and streetable power down low.

 

What I need to constantly remind myself is that no matter how fast I make my rides, there is always somebody out there faster.

[Guest]

Chuckash has it right. You gotta deside what you are going to do with the car. Most of us want a compromise.

I want a relatively quick car but it must be streetable (including the highway).

I have 3.73 gears with a TH400. This is about the lowest a gear (highest number) that I would recommend for street use. A 4.11 is quick but the engine will be screaming at 70 mph on the highway.

My feeling is lean toward quickness. That is where you have the most fun. Blasting off from lights and getting to 80 mph quickly.

These cars do not handle well even when all the suspension components are brought up to new standards. Going 150mph in a 30 year old car is a bit scary in my book.

That's my 2 cents...

 

 

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Dave Kase

"Desmo888"

'70 SS454

always collecting info on the Monte Carlo SS454, questions always welcome.

[Guest]

I totally agree with you guys, but with a 400 s/b you need the absolut largest heads you can get on there. There's little room for compromise I understand and I'm not wanting to get into to many mods, but these vortecs are choking this engine at highway speeds no doubt. Heads are always a key factor to Horsepower, and and overdrive can only make it more fun. I could just stick in a high lift long duration cam to get the power band into the upper rpm range but then your looking at a new stall converter ect. Also I figure a larger cam would help but would still be restricted from the smaller heads. Thats why I've decided to start with the heads and go from there. All great advise though. I am planing on an over drive tranny, Hmmmmm 150 in a 30 yr. old car. Sounds like fun! My front end was rattling alittle at 120mph, it got interesting. Thanks everybody!

 

Ian, as far as the vortech heads I'm going to take off, you'll have first shot at them. I'm setting to buy a set of heads from Don(rice racing), so I'll keep them on the engine for now until I have everything in place for the swap. I don't know how long it'll be so I just wanted to let you know. The vortecs are set up for a larger spring. They have a single spring and damper on them right now. I think they' good up to .500 lift. I can get the matching inner springs to make them a dual spring that are good up to .650 lift. They've had a valve job, guides are excellent, they have screw in studs and guide plates. No port work has been done and not recommended for them. Would you also be interested in the intake also? It's a brand new Edelbrock RPM Air Gap.

 

Jon.

[chuckash]

I may be interested in that RPM Air Gap intake. That would work nicely on my 400 sb with 215 cc Dart Iron Eagles.

 

If nobody else is intersted, let me know how much.

 

Thanks,

 

Charlie

[Guest]

Chuck, the airgap that clock has won't work on anything but the vortec heads, different bolt pattern. and remember regardless of what you read in the rag's oops mag's, the 400 is not just a overgrown 350. the 400 wants more of everthing compared to 350's even the 383's don't like what the 400's like. things that are race only on a 350 or 383 will normally work on a seriuos street 400. take the heads for example, as clock has found out even tho the vortec's flow like a ported bowtie head they have no top end power in a 400. they flow good but only when the velocity in the runners is not to high. yes it is possible to have to much velocity in the ports, when air speed reaches 450 feet per second, not cfm, the air reaches a point in which it becomes its own restriction, just like in a exh system.

the 400's like more port volume as well as flow. mild 400's run good with a single plane like a holley strip dominator or a edelbrock victor jr. no they don't cost you mid range and low end though. most of the time they are equal from idle to 3500 then the singles take over and kill the dual planes.

Don

[chuckash]

Don,

 

I forgot that the vortech heads required a specific intake. Thanks for the heads up.

 

I still kick around which intake I should be running. Right now it has a Performer. Since I drive it pretty much exclusively on the street, I'm not sure if the extra money for another intake will be worth the investment. I want to be able to feel the difference when a modification is complete, by being sucked into the seat harder.

 

Thanks again,

 

Charlie

[Guest]

Charlie, I've ran the RPM non air gap on my other 400 and it's a very good intake, and at 130.00, I think they are well worth the money. Just my opinion.

 

Jon.

[Guest]

Charlie, what heads do you have? are you running a square flange holley or a Q-jet? one of the best dual plane maniflds for street driving is the holley part# 300-36, it will only work with holley flange carbs, but have run them on 400's up to 6500 rpms and still making good power. low end and throttle response is very good also. if you are running dart heads the tops of the runner pairs will need to be cut down a little to fit under the lip from the raised vc rail. have seen this intake for $120 in summit and PAW adds before. think about this for a moment, you guy's all seem to be thinking that edelbrock has the world beat on manifolds etc, is this because of the advertising they do? A friend of mine that works in the advertising field told me once that the products you see advertised a lot don't sell themselves well, makes sense so if edelbrock advertises all the time whats that tell you? some of their stuff is good but a lot of it is targeted at the street rod crowd, you now looks and some sound but real performance not that important. what I am saying is don't base things on advertisements and magazine articles, ask around and see what the cars that run hard are useing. to be honest the new super victors from edelbrock are the first maniflods from them that have worked well for me in a long time.

Don

 

[This message has been edited by Rice Racing (edited 03-22-2002).]

[chuckash]

Don,

 

Thanks for the input. I'm running a setup somewhat similar to what you described in your post elsewhere, but a few differences. I'm using an Edelbrock performer intake with a 650 holley square bore. That is feeding Dart Iron Eagle 215 cc heads with 72 cc chambers, no porting. I cant remember if I gasket matched the intakes or not! The cam is an Extreme energy 268, degreed in and installed straight up. The pistons are mounted to stock 400 rods, they are Sterling hypereutetic, 10.25:1 Cr. Block bored 0.030 over, and rods/mains 0.030 under. Long, ugly story on the crank. This is all being lit up by an HEI with the MSD coil, MSD ignition module, Taylor wires, and the AC Delco high dollar plugs.

 

What I cant decide for myself is whether the investment is worth changing the intake. Will a change make a noticeable difference, you know, seat of the pants? Or would my money be better spent on a looser converter? Not exactly sure what converter is in it now, I was told that it was about 1000 rpm looser than stock. This thing has 3.73 gears, no overdrive and mainly street duty.

 

The carb thing also has me a bit confused. Everybody seems to want to stick on a 750, but the Holley tech line suggested something in the 650 range. Fortunately, I had a 650 sitting on the shelf, so they didn't make a sale! It is a vac. secondary carb.

 

I guess what I really need is a driveshaft loop first, even though I dont run slicks.

 

Charlie

[Guest]

Charlie, the intake change will make a difference but a little more carb will help, a stock Q-jet was 750 cfm. the rpm airgap or the dart kool can will help. right now you have way more cylinder head than a standard performer can feed, remember 15 years ago nascar was running a 190 cc runner 23 deg head and making 650 hp.with that 650 I personally would switch manifold. what you have is choking the air flow down. besides the port exits on that performer are way smaller than the port entrance in the head, when you run a set up that way you create a dead spot at that point and the air slows down and causes turbulence. which cuts the air flow even more, this may sound wrong but it works, put a holley 300-25 strip dominator, victor jr or a # 7530 team g weiand on it. both this manifolds have very good low end torque better than some single planes. the victor jr port matched to the heads with 650 should make more power and better throttle response. the 400's don't loose bottom end power with the single plane like 350's and 383's do, because the bore size of the 400 it has a lot better draw on the intake tract and can tolerate way more breathing. try the strip dominator "300-25 holley" once you retune to that manifold you will like it. then later swap on a larger carb. I have set this up on very similar combos engine wise with a 3.31 gear in a 70 before, the holley strip dominator, a 750 carb and run 12.90's at 106 mph on radials thru the exh, set up for daily driving.

Don

 

[This message has been edited by Rice Racing (edited 03-23-2002).]

 

[This message has been edited by Rice Racing (edited 03-23-2002).]

[chuckash]

Don,

 

Thanks for the input. When I replaced the cam last year, I did notice the difference in port size between the intake and the heads. This was really noticeable, in fact the difference was so much that I had to be extremely careful installing the intake for fear of an intake leak. I could still see the blue parts of the felpro gaskets at some ports!

 

Maybe I'll give another intake a try. Since used performer intakes usually sell quickly, it wouldn't cost too much to make this change.

 

Before I restored this car, it ran 13.60's with the 3.73 rear, Q-jet, performer intake, crappy mufflers, stock heads, and stock ignition (on some sticky tires). Since spending a small fortune on the restoration, I've been too scared to run it down the strip. Maybe some day.

 

I just looked at the specs on that Holley 300-25. The RPM range they advertise is 4500 to 7500. Was 300-25 the part you were thinking of? I would have thought that would be way too much intake for my setup, but if you have run this successfully on the street, I would be inclined to go with experience over advertising!

 

Charlie

 

[This message has been edited by chuckash (edited 03-25-2002).]

[Guest]

That power band is based on a 327-350 cube motor like super stock racer with a lot of cam. It actually works better than a victor jr does on a 400+ ci motor. I have run dyno test with some combos close to what you are running with the E manifolds, the H manifolds and the W manifolds, both dual planes and single planes, the 300-25 from idle to 3500 ran neck in neck with the best dual plane but really kicked the dual's collective behinds from there on up. on a 350 or a 383 the results are wat different, they don't run well with the single's, not enough motor to pull air with. don't pay too much attention to these power band numbers in these adds, they are all based on 350 ci max with stock heads.

Don