[ScumOne]

Ok, I got home with my 69 Firebird 400 I just acquired. Thank God the factory A/C worked like it should!

The pile of receipts is immense, as in 4-5 inches thick, with a DVD of the before/during/after restoration pics. The car got 13.3 mpg at 70 mph with the A/C on. I was turning 3000 RPM to get that 70 mph, so I think the rear gears have to be 3:55 - 1 or close.

In any case, the motor is just not accelerating like it should IMO. I found the rebuild specs from Chandler Speed Shop (Chandler, AZ, now out of business).

They put in dished 9:5 - 1 pistons, and did the balancing, etc to the motor.

There was a spec sheet for the cam, a Melling SPC-8. From a little googling on the net it seems this is the 041 Ram Air IV spec camshaft. It looks like I have 62 (or 6X)-8 heads on a YT 400/330HP original 400 block from 69.

Now that the CR has been lowered to 9:5-1, I'm figuring this RA IV cam is likely too big for this engine, or it needs more carb CFM or something to make it more responsive.

My question is whether to just put in a new camshaft with better street manners/acceleration and not mess with the rebuild of the block, or to have the heads ported/flowed and put the 10.75 - 1 pistons back in and let it roar.

From what I'm reading the speed shop put in hardened valve seats, etc so it seems it's all setup for a nice low compression build that will chew any type of gas (I'll still use premium 91-93 octane).

But there has to be a better cam for this to wake it up. Any suggestions?

Here's a recap of the engine specs.

1969 400 YT 330hp block, now with 9:5-1 pistons (how much HP did I lose?)
62 or 6X-8 heads (stock)
Pontiac cast iron intake manifold
14" single inlet air cleaner (stock chrome setup)
Rochester Q-Jet rebuilt w/electric choke
HEI distributor
Stock exhaust manifolds, stock exhaust pipes
Dual exhaust out to dual mufflers, then joined to a resonator in front of the gas tank, then dual pipes out.

I can see removing the resonator from the exhaust system for sure, but that's not going to make it accelerate a bunch faster unless it has some more HP.

Going to drive this one on the street, but I don't want it to bog down when I need to go!

Open to suggestions to improve the performance, so let them fly!

Thanks!

Jim
ScumOne

[70f400]

First thing determine what heads you have. My guess would be 62 with 72 cc chambers. This would be why they put in hardened seats and dished Pistons. 6x-8 would already have hardened seats and would be to large of chambers 101 cc.

[70f400]

Before you change the 041 cam do some reading on rhoads lifters they will give you better vacuum at idle and better low end throttle response. They have a solid lifter noise at idle but it did not bother me on my last combo. That cam in a 400 would do better with 10:1 compression but you may be surprised at what the rhoads would do for it.

[b-man]

The original heads should be # 62. The standard 330 HP 400 engines all came with the 9779067 cam, a much milder cam than the radical 041 RAIV.

Since someone used some common sense in choosing to put dished pistons in your engine be thankful and leave them there. Swap to the 400 HO cam that Pontiac used that year, the 9779068 cam.

Chances are your gears are 3.23, factory A/C Firebirds in 1969 didn't come with 3.55s. I owned an all original 4-speed 1969 330 HP Firebird 400 with factory A/C and it had a 3.23 rear end.

[grivera]

Look at the center exhaust ports on your heads to determine the number. If #62's, the chambers are likely 75cc unless they've been shaved some. Perhaps I missed it in your post, but is the car an automatic or 4 spd? I

[tom s]

Just get the brakes done and drive it for awhile.You have all winter to spen money on it!Tom

[ScumOne]

Originally Posted by 70f400

First thing determine what heads you have. My guess would be 62 with 72 cc chambers. This would be why they put in hardened seats and dished Pistons. 6x-8 would already have hardened seats and would be to large of chambers 101 cc.

Ok, I looked closer and they are 62 heads with the 72cc chambers. I also read up on the Rhoads lifters and they seem to specifically address what my issues are with the 400 & 041 cam.

I guess the next question is whether 1.65 rockers are needed, or just stick with the factory 1.5 ratio rockers?

[grivera]

#62 heads were advertised as 72cc but usually measure at 75cc unless shaved.

[tom s]

You would need to pull the heads to get them clearanced for 1.65s.Tom

[ScumOne]

Originally Posted by b-man

The original heads should be # 62. The standard 330 HP 400 engines all came with the 9779067 cam, a much milder cam than the radical 041 RAIV.

Since someone used some common sense in choosing to put dished pistons in your engine be thankful and leave them there. Swap to the 400 HO cam that Pontiac used that year, the 9779068 cam.

Chances are your gears are 3.23, factory A/C Firebirds in 1969 didn't come with 3.55s. I owned an all original 4-speed 1969 330 HP Firebird 400 with factory A/C and it had a 3.23 rear end.

I had a 69 Firebird in 1977. It came with the 6cyl OHC and 3:55 gears (pretty certain of that). It ran 2800 rpm at 65 mph, that's why I'm thinking 3000 rpm at 70 mph would be 3.55 in this one. But I could very well be misremembering due to age! When I get it on a lift I'll see if I can find the axle codes, or just spin the driveshaft and count the revs.

Originally Posted by tom s

Just get the brakes done and drive it for awhile.You have all winter to spend money on it!Tom

Ha ha! You're probably right about that, sir. But who wants to wait?

The car has a TH400 automatic tranny, forgot to mention that.

Originally Posted by tom s

You would need to pull the heads to get them clearanced for 1.65s.Tom

Ah, well....that might be a deal killer.

Almost seems like the easiest solution would be the Rhoads lifters if they'd improve the low end torque and idle. tom s, is it possible you could email me pics of your water temperature sender and wiring harness? The previous owner put in the Trans Am dash/gauges/etc (aftermarket from Classic Industries) but they don't seem to read right. The oil PSI was at 60, but it must have failed during the drive back to So Cal, cuz now it reads 80 psi all the time.

And the water temperature sender starts at 210, and floats up to 225-230 and stops. It never is below 210, and I'm thinking the sender is toast. There are two female spade terminals next to the temperature sender, but only one is attached. Not sure if I need the dual male spade terminal verson of the temp sender or not. Let me know if you can decipher that for me, OK?

Thanks so much for all the help everyone!

[tom s]

I have aftermarket gauges.Get a lazer temp gun.Get the car up to temp and take readings at the water X over where the sender screws in and know where your at.Also while your at it take readings at the timing cover where the water goes in and where it goes out of the block.Tom

[70f400]

I need to add while I had the 041 cam with rhoads in my 455 and it was very street able, in a 400 CI motor even with the rhoads lifters it may require more converter than stock. Big cubic inch motors handle the extra duration better. Not to say that it would not be a fun combo. It depends on what your needs are from the car. b man suggestion of the 068 cam would be a good cam for your compression ratio.

[b-man]

The RAIV cam 'likes' free-flowing RAIV long-branch exhaust manifolds or headers. It doesn't particularly work well with the restrictive standard log exhaust manifolds.

The RAIV cam also likes compression. A compression ratio of 9.5:1 is okay for a 455 with the RAIV cam, but really not enough in a 400 engine. The Rhoades will help the situation, but they don't necessarily make the RAIV cam suitable in your 9.5:1 400.

The RAIV cam likes low gears. No RAIV 400 car was ever delivered with a ratio numerically lower than 3.90, most came with 4.33s. No RAIV 400 car ever was available with A/C, the RPMs the RAIV could quickly spin up to combined with stiff rear gearing wasn't friendly to A/C compressors.

I'd swap the cam.

[Steve C.]

Ditto with Tom, post #6

Rhoads lifters
Pulling heads.
Changing cams.
???

Go have fun. If close to 9.5 CR, enjoy under all the conditions with piss gas, weather, etc.

Later when the time comes a proper converter will be the best bang for your buck. Similar to a tight 10-inch like a Contental. Good stall, coupled on the road.

[ScumOne]

The receipts are so numerous for this car it's nuts. After digging through more of them, it seems the TH400 was rebuilt with a shift kit and the torque converter was modified/rebuilt or replaced, too. Of course, there's not any specific specs on the tranny rebuild & converter, so I'm not sure what exactly is in there.

I did ask the previous owner what he spent on the restoration of the car, and he said he was totaling up the receipts one day. He got to $22k, and stopped adding...can't say as I blame him for that.

I'll do some more digging and see what else is going on with this, and post what I find. Maybe that will help clarify what needs to be done going forward.

Thanks, once again, for all of the replies and suggestions!

Jim

[STEELCITYFIREBIRD]

How,How far and How often you plan to drive it should determine your plan.... and how much $ and time you got!
As seems to be the majority consensus.
For you a cam change,seems easiest solution.
If you want max performance, then you'll need to go into the short block and add some gear, and a converter.
Some carb/ignition tuning and a set of rhoads lifters may make it acceptable to you with current cam.
I'd match the cam to what your current static compression and gear want.

Where is the 9.5:1 static # coming from? Calculated?
Any mention of the block being zero decked or what head gasket was used?
A piston part #?

[ScumOne]

Originally Posted by STEELCITYFIREBIRD

How,How far and How often you plan to drive it should determine your plan.... and how much $ and time you got!
As seems to be the majority consensus.
For you a cam change,seems easiest solution.
If you want max performance, then you'll need to go into the short block and add some gear, and a converter.
Some carb/ignition tuning and a set of rhoads lifters may make it acceptable to you with current cam.
I'd match the cam to what your current static compression and gear want.

Where is the 9.5:1 static # coming from? Calculated?
Any mention of the block being zero decked or what head gasket was used?
A piston part #?

The speed shop invoice (I'm missing the 1st page) on page 2 says the engine received dished 9:5 - 1 pistons, balanced the rotating assembly, line hone, bore, hone, Vat, ?turn Crank, resize rods, press pistons on rods, Valve Job, Install Hardened Seats, Guides, Surface.

Tranny was rebuilt, shift kit installed (I can feel that) and new torque converter (no specs on it), new Lokar S/S braided tranny dipstick cable and filler tube.

R&R engine from car, tranny R&R w/Bendix steel lines, 180 degree thermostat.

My goal is to have a reasonably quick car with a decent idle, and not die at stoplights due to the A/C being on. It will get driven to the usual cruise nights and club outings, or somewhere for the weekend. Not going to drag the car, I prefer longer drives with some curves and wide open spaces to let it gradually exceed the speed limit (or not so gradually!).

[74Grandville]

that cam is going to want that engine to spin to make power. there is a reason the factory put 3.90/4:11 rears in RAIV cars.

Rhoads would help, but changing to a smaller cam might be a wiser choice.

Maybe before you do anything, verify it's a RAIV cam. maybe degree it with a valve cover off and tape on the balancer.

[ScumOne]

Originally Posted by 74Grandville

that cam is going to want that engine to spin to make power. there is a reason the factory put 3.90/4:11 rears in RAIV cars.

Rhoads would help, but changing to a smaller cam might be a wiser choice.

Maybe before you do anything, verify it's a RAIV cam. maybe degree it with a valve cover off and tape on the balancer.

There is some timing degree tape on the balancer and on the block as well,
so that would help. The only other thing I've got is this pic of the pistons
being installed supplied by the speed shop during assembly.



Definitely will see exactly what cam I've got before getting too frisky with the credit card.

[72LuxuryLeMansLa.]

Originally Posted by ScumOne

The speed shop invoice (I'm missing the 1st page) on page 2 says the engine received dished 9:5 - 1 pistons, balanced the rotating assembly, line hone, bore, hone, Vat, ?turn Crank, resize rods, press pistons on rods, Valve Job, Install Hardened Seats, Guides, Surface.

Tranny was rebuilt, shift kit installed (I can feel that) and new torque converter (no specs on it), new Lokar S/S braided tranny dipstick cable and filler tube.

R&R engine from car, tranny R&R w/Bendix steel lines, 180 degree thermostat.

My goal is to have a reasonably quick car with a decent idle, and not die at stoplights due to the A/C being on. It will get driven to the usual cruise nights and club outings, or somewhere for the weekend. Not going to drag the car, I prefer longer drives with some curves and wide open spaces to let it gradually exceed the speed limit (or not so gradually!).

I'm no expert but given your stated driving situations B-Man is DEAD ON with the factory 068 cam suggestion. You want it to spin the tires but idle well (AC) at lights and drive it a bunch so that's that in my mind. Now, when they list pistons as being 9.5:1 Compression, that is useless information. The piston is one of five or six things that determine the Static Compression Ratio..........https://en.wikipedia.org/wiki/Compression_ratio#Formula