[gtome]

There has to be a good shop down there that could check things out for him! Anyone know of any?? Or maybe a fellow PY'er that could look it over? Its a real shame that he spent some good money...and in the right places...to have this performance.

[Stuckinda60s]

It does look like you've got some really low compression. However, it seems as though the engine is still not doing what it's capable of.

I would confirm top-dead center to make sure the dampener hasn't slipped. The other thing I would do, if you're not already doing it, is make sure you're using manifold vacuum for your vacuum advance.

[tr709]

Originally Posted by gtome

There has to be a good shop down there that could check things out for him! Anyone know of any?? Or maybe a fellow PY'er that could look it over? Its a real shame that he spent some good money...and in the right places...to have this performance.

Wish some of you lived closer, for those nearby that can take a look, plenty of food and beer will be provided.

And as for the money spent, amen brother!

All of this great input will help in putting together a plan. Thanks so much!

[screamingchief]

IIRC that's up in the Dallas/Denton area,so yeah there should be some place (or someone) that is'nt real far away that can handle that sorta work.

From where I'm at that's like 250 miles (3+ hr's one way),so ya'll can pretty much count me out.

I dont even make it to the swap meets or races up there much anymore,just too damn broke these days.



Bret P.

[amcmike]

Yeah, I have to believe there are shops in the Dallas/Arlington/Fort Worth area that can help even if there are no board members closer. A bit far, but worth it if you can get good references. Have you tried checking on the firstgenfirebird.org website? There's a bunch from TX, but mostly Houston I think.

[chiphead]

That engine has good parts and good port work. It should be pretty fast.

Post cranking compression numbers from all cylinders.

What is manifold vacuum at idle?

What are engine temps at cruise?

At 9.x:1 compression it should not detonate. The timing curve is too quick. Other things to check are sparkplugs may be too hot a heat range. Cam may be installed incorrectly. Valves may be too tight.

Engine needs re-tuned, but the answers for above will help narrow it down.

[amcmike]

Also post your fuel pressure both at idle and a neutral sweep.

[Sun Tuned]

Depending on how good the shop was that worked the dist and the springs they used to get it in by 2500, some portion of the curve may be in already UNDER the idle speed.

Can quickly check that by checking initial timing at idle and replacing only the dist springs with some original "hood springs" (heavy dist springs), and recheck initial, any change in original number is that many degrees you don't actually have on the total number you thought you had.

Just one more thing to check.

[jakeshoe]

I'm local

Give us a shout, we can look it over, get the dialback timing light on it, check compression, and see where the power is hidden.

[tr709]

jake,

If you read through this post (especially my 1st post with my current combo) it will give you some background and lots of good input too. I'll try and give you sometime today. Thanks!

[gtome]

See....thats why I love this place! Pontiac guys stick together!!

[vidguy]

That's a nice gesture Jake.

[jakeshoe]

I don't feel this is an ideal combination with the gearing, converter, engine setup, etc HOWEVER I've seen much worse combos run pretty decent.

I don't think this engine needs a cam swap or even exhaust changes to achieve what Tony is trying to achieve.

Gearing is ALWAYS critical, it is one of the best bang for the buck seat of the pants improvements we can do, however 2.93 is an acceptable ratio for a cruiser. This is not a drag car, it doesn't need 3.73, 3.90, 4.10's or deeper.

The gearing and converter could be improved but this combo should still launch effectively on the street.

Stock manifolds are not killing the engine bottem end enough to make it feel this weak.

There is undoubtedly a tuning issue involved. We can find that without huge expense.
We will find it, tune it, and I'm sure make a noticeable difference in the performance of the vehicle.

Once we get it close to optimized, then we can "throw parts at it" if it's still not as stout as he wants.

[gtome]

Awesome! I have a few friends down your way, I will be sure to send em to you when they need work done!

[GAGuy]

tr709,

with the exception of two things (cam & exhaust manifolds), I really like your combination, especially for a street driven cruiser! I like your gears and stall speed for a cruiser. Only after you sort out why your current combination is so down on its potential power would I resort to changing parts to optimize your car. A lot of good advise here as far as getting down to basics to find out why your motor is not putting out any real power. No sense in throwing $$$ at more parts when most likely something basic is not right with what you have now.

If it were my car, I would only look at changing your exhaust manifolds to some cast iron "D" port Ram Air headers with some mandrel bent down pipes and I would also ditch your current camshaft. I too have my own tale horror of installing an XE series camshaft only to find the car was slug. Cliff said it best, the cam was an absolute TURD! I ended up installing a custom cam with much less duration and a wider lobe seperation, the difference was night and day.

Just for giggles I ran your engine combination through an engine simulator and came up with 357HP -428lbs tq. Changing the exhaust manifolds and going with a milder cam (218/224 on a 114 lobe sep) the numbers were 409HP - 462lbs tq. The cam by itself added 22HP, the exhaust by itself added 32HP. These figures are all net peak power numbers, taking into consideration a full exhuast system, and engine driven accessories. Gross power (open exhaust, no accessories) with the changes computed as 458HP - 496lbs tq.

Just my 2-cents worth......by the way awesome car, I really like the color. Good Luck!

[mechanic17]

I'm among those who suspect simple ignition timing. It's either set retarded in the first place or not all coming in. Someone said to be sure to use MANIFOLD vacuum for the advance. You would be running too much advance at idle that way (hence, set retarded to compensate--have seen this many times.) That should be PORTED vacuum (will only move a vacuum gauge when the motor is revved, but not at idle.) This problem is usually diagnosed by your buddies as "needs a better carb/rebuild," but since Cliff checked it, they can't say that. Call me a caveman, but I'd try the "power brake seat of the pants timing" method. Put one of those guys to work holding the gas pedal at a high idle (2000 rpms or whatever it will do) in gear against the brakes, while you advance the timing by hand (CLOCKWISE on a Pontiac, remember). You'll either hear pinging (back off) or the tires will start spinning (celebrate). If you fear injury, you can gently nose the car up to a wall so it can't go anywhere (a towel will protect the nose). Hey, it's free, and requires no special knowledge. Or you could just try a borrowed distributor. Advance springs/weights can stick. Good luck.

[tr709]

All,

Working on getting the car to Jake asap for him to look at it. Agree with trying to make sure the car is performing to its potential given the current setup and if I want more go from there.

GAGuy - Thanks for the compliments, I only wish my car was making 357hp (feels more like 257)

Timing has been checked many times, unless of course the balancer is off, making any setting moot. Pretty sure the vacuum advance is hooked up to the carb. I'll double check that.

Someone previously asked about the plus. They are NGK6945, probably not what I would have picked. But if that is an issue, even I can change spark plus

Thanks agian for all the replies!

[mechanic17]

The carb has both a manifold vacuum AND a ported vac connector. The one you need is on the right (toward the throttle linkage) if memory serves. Needs to be checked to see if it's working right.

[amcmike]

Originally Posted by tr709

Someone previously asked about the plus. They are NGK6945, probably not what I would have picked. But if that is an issue, even I can change spark plus

Friend of mine had problems similar to yours. Turns out the plugs he used were incorrect for the head, and didn't seat deep enough (way up from the combustion chamber) Changed them, and it really woke up the engine. Something else to look at.

[screamingchief]

Originally Posted by tr709

Someone previously asked about the plugs. They are NGK6945, probably not what I would have picked. But if that is an issue, even I can change spark plus

Those are too hot a plug for a high performance engine IMHO,they are an NGK 4 heat range.

Only plug hotter from NGK is a 2,and those typically are for lawn mowers and such.

And they're an extended tip plug to boot (makes them act a bit hotter for the given heat range).

Not to mention an extended gap (.060") plug.

Originally Posted by amcmike

Friend of mine had problems similar to yours. Turns out the plugs he used were incorrect for the head, and didn't seat deep enough (way up from the combustion chamber) Changed them, and it really woke up the engine. Something else to look at.

This is the opposite problem here.

What he has is a tapered seat plug,this in heads ('71 #96) that are meant for use with a gasketed seat plug.

That is a deal breaker,and here's why.

Understand that the plug reach on the tapered seat plugs is all wrong for those #96 heads as well.

NGK 6945 plug reach is 11mm (7/16" or .437"),and the early ('67-'71) gasketed seat plug reach is 3/8" reach (thus .375"),so you likely have the end of the plug hanging out into the chamber some with those NGK plugs in there.

That is not a good thing!

So those are way,way wrong plugs for those heads.

Most guys use a heat range up around 6 or 7 for an NGK plug in a healthy performance oriented pontiac engine,as the NGK heat range the higher numbers are the cooler plugs,opposite of brands like A-C or Autolite where the higher numbers are the hotter plugs.

And I see absolutely no reason to run the bigger gaps,never have.

I use .045" gap as the max for the most part,often .035" works just fine,usually I just split the difference and use .040".

Plugs I would use for something like this:
(all are extended tip/resistor plugs except as noted)
Autolite #85
Denso #W20PR-U
A-C #R43S
NGK racing #R5670-6 (non-resistor)

Gap @ .035" to .040".

So that would be a good place to start IMO,you can put the right plugs in there when you go ahead and do the compression testing.

HTH

Bret P.