[tarzan]

Hi brahs!

I kinda a newbie when it comes to old cars, but last year I bought a GTO 69 Convertible. The car hadn't been running for 7 years and there was a lot of stuff to fix, install a new cam, a new converter etc etc. Well my and a friend have been working with the car the last 5 months and now it's out on the streets!! However I'm kinda dissapointed with how it performs, I've tried to get informationa about every part in the car and according to the specs the car should perform really nice with the current setup. As I said the car is a 69 but it came with a block and heads from a 67 (all orginal parts were included in the deal, however). This is the current setup:

Engine block: 400cui (YE 104920)
Heads: #670 (E297 Right Front, F027 Left Front)
Carburetor: Holley Dominator 750cfm
Intake: Warrior
Converter: ?? Mechanic said it stalls at about 2500rpm
Exhaust system: Custom built 3" (with cross pipe)
Roller Arms: Crane Gold Race (0750)
Cam: Crane RAM AIR III blue print??(968 CR, 540-33, K125)
Ignition: MSD 6AL
Transmisson: TH400 (with a manual gearhouse)

Well if you heven't figured it out yet, I'm telling you I'm not american, I'm Swedish. That's way I might use the wrong terms here and there... [img]smile.gif[/img]

The problem is that it feels like there's no low end torque. When I'm going in 55mph, putting it in second gear and hit it, it runs pretty good uptil 90mph but from 0-50mph it feels like there should be more, a lot more.

The car will be running on the streets and occasionally on the strip, i.e. it's more important to outrun those BMW's and Mercedes on every redlight than ultimate performance on the strip! [img]smile.gif[/img]

Any help would be nice!

Regards,
Max

[tarzan]

Hi brahs!

I kinda a newbie when it comes to old cars, but last year I bought a GTO 69 Convertible. The car hadn't been running for 7 years and there was a lot of stuff to fix, install a new cam, a new converter etc etc. Well my and a friend have been working with the car the last 5 months and now it's out on the streets!! However I'm kinda dissapointed with how it performs, I've tried to get informationa about every part in the car and according to the specs the car should perform really nice with the current setup. As I said the car is a 69 but it came with a block and heads from a 67 (all orginal parts were included in the deal, however). This is the current setup:

Engine block: 400cui (YE 104920)
Heads: #670 (E297 Right Front, F027 Left Front)
Carburetor: Holley Dominator 750cfm
Intake: Warrior
Converter: ?? Mechanic said it stalls at about 2500rpm
Exhaust system: Custom built 3" (with cross pipe)
Roller Arms: Crane Gold Race (0750)
Cam: Crane RAM AIR III blue print??(968 CR, 540-33, K125)
Ignition: MSD 6AL
Transmisson: TH400 (with a manual gearhouse)

Well if you heven't figured it out yet, I'm telling you I'm not american, I'm Swedish. That's way I might use the wrong terms here and there... [img]smile.gif[/img]

The problem is that it feels like there's no low end torque. When I'm going in 55mph, putting it in second gear and hit it, it runs pretty good uptil 90mph but from 0-50mph it feels like there should be more, a lot more.

The car will be running on the streets and occasionally on the strip, i.e. it's more important to outrun those BMW's and Mercedes on every redlight than ultimate performance on the strip! [img]smile.gif[/img]

Any help would be nice!

Regards,
Max

[Dave A]

Hi Max,

The most likely culprit noticeable from the info you gave is the Warrior intake - my understanding is that this is a rather large runner single-plane intake, intended for use with heavily ported heads in a higher RPM range (especially on a 400). The stock heads become very flow restrictive on a 400 (in my experience) around 5500 RPM.

Also, the dominator carburetor is a double-pumper, mechanical secondaries, race oriented carb. Your GTO is a heavy car, and I am not sure what gearing you have - but you may very well be better off with a vacuum secondaries carb.

I would suggest trying an Edelbrock performer or factory ram air type intake manifold with the vac secondaries carb (or try a good Q-jet). A good comprimise for the rear end gearing for a decent launch with decent top end would be 3.55's. If the converter is a good 2500 RPM stall converter, it should be fine.

I am not sure of the cam specs either, but a RAIII spec cam should run well in your engine.

Definitely check the ignition advance curve as well (use a timing light and 'map' it out versus engine speed to see what the mechanical advance is).

Best of luck!

[A455GTO]

I agree, go back to a dual plane intake - factory or Edelbrock Performer RPM. That should give you back some of that famous Pontiac low end torque! Happy wrenching

[WARPed]

I agree with Dave. The main problem is your intake manifold. Switch to a dual plane design like a factory unit or Edelbrock Performer/RPM Performer and you should see a big improvement. Naturally the carb will also have to go but replace it with a similar size (CFM) unit that will properly match the replacement intake.

[tarzan]

Thanks a lot!

I understand that the Warrior is a pure race intake which performs at it's best in the higher RPM's but still I thought that it would perform good on low RPM's as well. Obviously this is not the case?

How about a Holley Dominator intake? found one on Ebay: http://cgi.ebay.com/ebaymotors/ws/eB...tem=1841609754

Or you guys recomend the Edelbrock Performer RPM intake?

How about the carburetor is that also to race oriented? Or do I just have to change it since it will not fit on the Edelbrock intake? (A lot of questions here, bear with me [img]smile.gif[/img] )

If I would go for a new intake and carburetor, what would be a decent price for the Warrior intake and the Dominator carburetor?

Mahalo!

Max.

[Rholmes]

Max I bought a 68 GTO about 7 years ago with your exact combination.The car had no bottom end.I replaced the warrior intake with an edelbrock performer intake and traded the 750 mech for a 750 vac sec.Timing was set at 16 deg initial with a total of 36 at 2600 rpms, and with a set of 3 tube hedman headers,2.5 exhaust, and 390 rear gears,this car went 8.58 in 1/8 miles.Later you may want to port the 670 heads and install the RAIV cam.Hope this help.

[tarzan]

Thanks for all the good tips!

I think I will go for a Edelbrock Performer RPM and a new carburetor.

Anyways, I found this wicked man in Sweden not far from where I live who has built two crazy Pontiacs and I will meet him this afternoon to see what he has to say! Check out his page at: http://www.osterlen.com/alf/ (it's in swedish but the pictures and specs speak for themselves)

Again, thanks for the help!

Max.

[Dave A]

I would suggest even taking a look at the regular Performer intake - believe it or not, sometimes 'less' is 'more'. The performer RPM likes mildly to moderately ported heads, and will probably not give you much power over the performer in your rev range while possibly sacrificing a little low end torque still over the performer.

The 'matching' Edelbrock 750 CFM carb would be a good choice, or a Holley 750 vacuum secondaries carb, or a decent Q-jet.

Can't comment on fair prices for the Warrior/dominator combo, other than (as you know) they were $$$$ (expensive) to begin with! I would think the sale of these used in good condition should come close to covering the purchase of the new intake and carb (??).

Nice cars!

[GTOPhil]

I'll add another opinion...all you need is a factory cast iron intake with your combo. Why spend the money for an Edelbrock RPM if you don't need it?? Hard to beat the Pontiac cast iron manifold for most street applications.

[Will]

I agree with all that these guys have said here concerning intakes. A factory iron 4-bbl intake from '67 - '72 will be a great intake for your engine. If you can't find one of these, a regular Performer intake (not the RPM) will function just like the factory intake.

The RPM intake is a good intake for the larger engines (455s) but not the best choice for a 400 unless you have ported heads and a pretty big cam.

What you need to understand about this is that velocity through the intake tract is what helps the engine make good low-end torque. With large-runner intakes like the Performer RPM or single-plane intakes like the Holley Street Dominator or Warrior you lose that velocity and thus your low-end torque. You also need to match the intake to the type of cam being used.

I'm also curious about your camshaft. According to the Crane Cams website they offer three different factory blueprint cams, the "N", "S", and "T" grinds. These grinds are now more commonly known by the last three digits of their factory part numbers. The "N" grind (Crane blueprinted 9779066, commonly referred to as the "066 grind") is very mild and a good choice for stock rebuilds/grocery getters. The "S" grind (Crane blueprinted 9779068) could be considered a "RAIII" cam but that is not it's usual designation. This is a good cam for low-end and midrange torque but because of it's relatively short duration and low lift won't work well with large intake manifolds and carburetors. The "T" grind (Crane blueprinted 9779041) is the "Ram Air IV" cam and is a pretty big cam for a street 400. That cam would work good with an RPM or Holley Street Dominator intake, but you'd need more stall converter behind it and reasonably steep gears for optimum performance.

So, looking at the cam you're running, which is probably the 068 duplicate and which is also a relatively small cam for a 400, a stock intake or regular Performer would really be the best choice.

Good luck with your new toy! It's always fun to hear about Pontiacs overseas.

Cheers,
-Will