455 performance... what next?

the car is really running as good as can be expected really. if you can get your timing straight it'll pick up some I'm sure. you'll want about 32 total.

the best bang for your buck will be a decent converter along with a good exhaust.

 

All timing issues were solved last year with the help of Larry. That part is excellent right now.

I do feel that with the current installed parts that this car is running as good as it can today. So what's the next best step? I've heard headers, cam, exhaust and stall converter. If I enlarge exhaust will it matter much with this 268 cam and stock exhaust manifolds? Or is the bottle neck likely the cam? If I put in a better cam, am I only increasing HP by 25hp like TAperformance states with the 284 or is that comp 268 a real turd that's in there now?

 

Valve springs appear to be putrid OEM items. They were weak for "high" RPM with the stock cam. I'm surprised to see them with the cam you have. When you upgrade the cam, you're going to need springs and retainers, too. Make sure the retainers (keepers) are compatible with the multi-groove valve stems you probably have. Not real enthused about the rocker arms, either, but as long as they're not worn, I guess you'll get by.

I've heard good things about air bags in lower-power cars. I heard they're a problem with higher-power/faster/quicker vehicles but I have no experience with them at all. "MY" A-body has No-Hop bars. Again, some folks like 'em, some don't. They seem to be useful down to the 11s anyway. They're wonderfully invisible, too. The big question here is "do you suffer from wheelspin at the track?" If wheelspin isn't a problem, you don't need a solution...yet. I'd be looking at ALL the suspension bushings, front and rear. Polyurethane is your friend up front, and on the lower arms in back, but rubber may be better on the angled upper rear arms due to suspension binding. Or consider the "Jonny-Joint" upper arms that supposedly fix the binding, yet still have eliminated the mushy rubber bushings.

One of the best things I ever did to my "A" body was to replace all the body bushings. Made the whole car much more rigid. Now the suspension works instead of the body/frame flexing. VERY RECOMMENDED.
http://www.chevelles.com/techref/body_bushings.html

Of course, rear sway bar, front sway bar upgrade, possible brake upgrade, faster-ratio steering box upgrade, assure all ball-joints, tie rod ends, Idler arm, etc. is in good shape--all of this gets the vehicle ready to handle more power safely.

 

Yes it is running it in a Buick engine.


Derek

 

If you want to start out simple and work up from there, I'd put a set of headers on it and change the converter from the stock 13 incher to a 10 inch converter and about 2200-2400 stall. I'd bet your MPH would go up to 96+ and ET would drop to high 13s. I agree with others that your compression is closer to 9:1. In 1971 and later the piston dish was deeper than on the '70 10.5 motors.

 

Headers, timing, convertor.

 

It would surprise me if one could top even 370 real world HP thru the stock Exh Manifolds with out having over 11.5 comp!

 

I think you're leaving a half second on the table with either the cam, tuning, or driving. I'm in the high 13s with iron manifolds, 2 1/4" duals, and 2.93 gears. My converter is very close to stock, too, and shifting at 52-5300 I'm running 95 in the quarter. There may be some gain in your carb (be sure your secondaries are fully open at WOT), maybe go up on jets and rods, tinker with the secondary spring tension. In my opionion though you need a weekend at the track where you can change one thing at a time (shift point, total advance, launch rpm, etc, maybe even swap carbs or parts in yours) to see what helps. When you have all those things down, think cam, converter, and 2 1/2" exhaust.
Patrick

 

Very good. I had the wrong throttle cable on last year and now secondaries are 100% open. Spring tension is just about perfect. I had stage 1 needles in and that helped. Went up to the next thinner and didn't notice a difference in time at the track.

 

So it looks like cam, converter and exhaust would be the first steps.

2-1/2 inch exhaust- has mixed comments for what I have now for the motor. But any engine upgrades I do will need the bigger exhaust. Will heads, cam and exhaust manifolds be the bottle neck and likely no improvement with exhaust if I don't change other things?

Converter - what stall should I be looking at with my current setup? Also, would it be the same converter if I get up to 400+ hp some day? How about 450 or 500 hp? I really want good street manners. And I want to try and avoid doing things twice if possible.

Cam - suggestions appreciated. And with the cam you recommend, what application is it best for? So far I've heard taperformance 212 and 284. What's a typical cost for installation? Springs and retainers? Any other thoughts?

Much thanks,

Matt

 

As mentioned I'd at least shim the tired stock valve springs. Just a .030 shim can do wonders with valve sealing and reving. You should be able to rev to 5500.

 

I think I remember that the 212 can use stock components. Never had a cam put in for me, but I would guess that a shop would charge about 4-6 hours (WAG) because they have to remove the front cover (cover, distributor, fuel pump), intake manifold w/rocker & pushrods (to remove lifters) and radiator (to name a few items). After that you have to break-in the new cam & lifters.

 

Being told you bought the "correct" distributor doesn't do it for me.

Consider listing your
initial advance
Centrifugal advance number of degrees and RPM to begin, and max-advance
Vacuum advance number of degrees and vacuum needed to begin, and max-advance
for those of us too lazy to trace down old threads.

 

14 initial
16 mechanical
30 total

That's all I have for now. I've put in super light springs to figure this out last year and I confirmed the advance on the distributor that I purchased.

 

I strongly suggest my Stage 1 9.5" converter.. will grow with your combo, positive/tight light throttle feel, about 2800 stall with your current setup with slicks on the drag strip. Many satisfied customers on this board with that exact converter.

The strong 2.1 Stall torque ratio is what makes these converters wake up even stock setups. Once you launch, the 18 lbs rotating weight reduction from your current converter helps the engine rev faster.

Likely will be the single biggest improvement for your strip time, and best bang for your buck..

And you don't have to take the motor apart..

Order it today, and you will very likely have it before the Holiday weekend.

$620 to your door...

JW

 

Thanks Jim. Isn't the 2800 a little high for me and wanting good street manners?

 

Unless that cam is a horrible choice (don't know; never used it) or it's installed wrong (was it degreed or just dots lined up), you should be a little quicker than you are. Try 32* total, then 34*. Try getting up on the converter before launching. Go up or down 200 rpm on shift points. Unless it's the cam or its install, or possibly valve springs, nothing about your combo now should hold you out of the 13s. Get there first, or find out for sure why it won't do it, before buying upgrades.

 

I don't know what's a worse job, crawling under the car and dropping a trans or leaning under the hood and changing a cam?!

But yeah, a converter is something that would help a lot, pair that with a cam change and you'll have something.

Exhaust can be changed later, do one change at a time and make a record on the improvements, perhaps here in a thread so you'll have access to it for as long as this website is online. For your power level, somewhere in the very low 300 HP or even less, the what may seem small to some, 2 1/4" ex. isn't holding you back yet. An X-pipe would help though as mentioned before.

Un-ported factory heads probably with the small valves and exhaust manifolds with a factory intake, I would say that engine was assembled to see how low the HP can be made in a BBB. I had a sbc Vortec 305 that ran low 14.2s in the QM in a '64 Skylark weighing 3,400 lbs, any BBB should beat the flock out of that time, even 375 lbs heavier! It just goes to show how horrible that Comp 268 is in any Buick engine big or small.

If you don't want to do things twice then perhaps you can skip the flat tappet cams and get a roller cam right out of the gate when you get rid of the Comp 268 out of there. JW has a real nice Stage 1 roller grind that would work really well with ex. manifolds, even if you upgrade to aluminum heads later. Would be even better with headers, if you can force yourself to get rid of those restrictors. If plans are for aluminum heads eventually consider the Stage 2 SE heads and upgrade to the Stage 2 headers at the same time.

When you upgrade the ex. as well go with 3" if your plans are eventually for aluminum heads. Roller rockers would be a good idea as well so you're not limited to .500" or lower lifts with the factory rockers on a roller cam. Higher lifts with lower durations help get the valve in the max flow range quicker and keep it there longer to fill the cylinder while maintaining good street manners.

Upgrades can snowball if you don't establish a goal then make a plan for the upgrades and stick to it. Upgrading over time is easier on your wallet as well. Perhaps you can buy one of the used flat tappet cams that go up for sale here for this engine and get a 455 core to build from bottom to top taking your time? That way you would know the bottom end would hold up to the top end upgrades.


Derek

 

Lot of experimenting last year with timing and going to 32-33 didn't really change anything at the track. I've shifted the car myself and let it shift itself and I don't recall seeing much difference there.

Perhaps a real cheap tinker would be to shim the valve springs or new springs?

 

I drive mine with a 2800 stall and it is fine for every day driving.