[gto19]

I’m curious to know what was different between the 67 ho motor versus the 67 ram air motor ? Cam ? Pistons ? Heads Etc.

[Jerry H.]

Heads and camshaft.

[gto19]

So did the ram air use the 670 head that’s on my HO gto ?

[muscle_collector]

modified with taller valve springs some were ground and stamped 997

[lust4speed]

My 1967 service manual lists valve lengths at 5.06 intake and 5.05 exhaust for standard GTO, H.O. and Ram Air. Was a taller valve installed in the 1967 Ram Air heads?

There seems to be a discrepancy in the listed in open heights in the manual, but right below that the installed height is within .004" across the board.

Regardless, the same 670 casting would have been used. Early RA still marked 670 and later 997 stamped as stated above.

[gto19]

Thanks guys
I’m not a engine rebuilder . Could you run the ram air cam with the stock 670 heads ?

[lust4speed]

The old non-RA springs won't be up to the task, and it's time to go with new one piece valves. A good machine shop will also update the valve guides for Viton seals and insure all the new parts play nicely with each other. The 1967 Ram Air cam is very mild in lift and duration compared to what is available, and if the budget allows it a change to a hydraulic roller will give more power with no loss in street manners. Just pick the cam and lifters and have the shop give you an cost estimate for the head work and parts to support the change.

In the 1980's I ran a large solid roller with .660"/.666" lift on the street with my original 670 heads. Now those same heads have duty in my street GTO and still running .622" lift with a hydraulic roller cam a little larger than the Old Faithful. Longer valves allow much more lift and I'm running the Ferrea 6000 RAIV length valves. Again, just need to match the valve train for whatever cam combination you decide on.

[Jerry H.]

Originally Posted by muscle_collector

modified with taller valve springs some were ground and stamped 997

Exactly. I've only see one 67 RA engine in the original car. The center exhaust port of the head was ground flat and '997' was stamped there. Car sounded wicked with open headers!

['ol Pinion head]

Originally Posted by gto19

I’m curious to know what was different between the 67 ho motor versus the 67 ram air motor ? Cam ? Pistons ? Heads Etc.

Besides the cyl head differences, the bottom ends were different. the only real deal '67 XS coded RA GTO engine I've examined, disassembled, had factory 4 bolt main caps, an armasteel crank, & Morraine 400 bearings. the original '67 400 HO's (WS & YZ) had 2 bolt blocks, nothing special on the cranks, just some of the first nodular iron 3.75" stroke cranks.

[Jerry H.]

Originally Posted by 'ol Pinion head

Besides the cyl head differences, the bottom ends were different. the only real deal '67 XS coded RA GTO engine I've examined, disassembled, had factory 4 bolt main caps, an armasteel crank, & Morraine 400 bearings. the original '67 400 HO's (WS & YZ) had 2 bolt blocks, nothing special on the cranks, just some of the first nodular iron 3.75" stroke cranks.

I had forgotten about the bottom end.

[Kenth]

I have found:

1:st 1967 RA engine has a #670 head machined for taller single valve springs (same as 1966 RA) and polished valves.

Ram Air engines released after May, 1967 (starting with Motor Unit No. 646616) were updated with either cast #997, or cast #(9)7 heads with taller dual valve springs, and polished "nail head" valves.

2:nd 1967 RA engines got either a #670 head machined for taller dual valve springs and polished valves. To identify it the factory ground off the "6" and the "0", leaving the cast "7". Then stamped the #9 replaced the "6". The casting number then became "97". The other version was cast #997, which appeared on the side of the head, just to the right of the center exhaust ports, and below the #4 or # 5 spark plug hole.

All of the 1967 (and 1966) Ram Air engines uses the #744 camshaft.

None of the 400 blocks were 4-bolt in 1967, including Ram Air.
Service Replacement Ram Air blocks however got 4-bolt mains.
Some will say VERY late production Ram Air blocks got the 4-bolt mains.
The original owners may know?

[gto19]

Great info !

Does anyone know if the cam is stamped with a letter ? And if so where is it stamped ?

[johnta1]

It would have a 'H' stamped on the nose of the cam.


Cam Codes

[gto19]

Ok cool
So they are stamped from the factory

[johnta1]

Yes.

[gto19]

These are the cam specs I got from Ames .
Comparing the HO cam versus the ram air am . Do you guys see a big difference in the two cams ?

N524 is the HO cam

N525 is the ram air cam

[Kenth]

Enough difference 1967 Ram Air GTO´s got 4.33:1 rear gears from factory as standard.

[PontiacJim1959]

I did not see mention of the 1967 RA exhaust manifolds with the left manifold unique to 1967.

The valve lengths for the 670 and RA heads were all the same, AMA Specs dated 8-26-1966 show:

5.0625"/Int. & 5.0515" Exh. for all 670 & RA head.

670 head Intake Valve, 4 Bbl & HO all transmissions:
Outer Spring Pressure/Length - Closed 59-65 lbs @ 1.586"
Outer Spring Pressure/Length - Open 128-138 lbs @ 1.176" for 4 bbl; 1.172" for the HO engine.

670 head Intake Valve Inner Spring:
4 bbl & HO - Manual trans - Closed 47.5-52.5 lbs @ 1.566"
4 bbl & HO Auto trans - Closed 28-34 lbs @ 1.566"
4 bbl & HO Manual trans - Open 111-121 lbs @1.156"
4 bbl & HO Auto trans - Open 93-99 lbs @ 1.156"

Ram Air -
Outer Spring Pressure/Length - Closed 97-107 lbs @ 1.586"
Outer Spring Pressure/Length - Open 231-247 lbs @ 1.173"
Inner Spring - None
Exh. Spring Pressure/Length - Closed 97-107 lbs @ 1.586"
Exh. Spring Pressure/Length - Open 231-247 lbs @ 1.173"
Later heads used dual springs.

Camshaft:
4 bbl Auto - 066 Cam Stamped N
4 bbl Manual - 067 P
HO Auto - 068 S
HO Manual - 068 S
Ram Air - 744 H also used on 1966 389 XS engine and RA III


Trans & Rear Axle Ratio - Manual 4-speed close ratio or TH-400 with 4.33:1 gears.

[Kenth]

Looks like the AMA Specs dated 8-26-1966 does not include the 2nd type Ram Air engine with serial number 646616 and up and with cast #997 cylinder heads.

The 2nd type Ram Air engine uses swirl polished intake valves #9792316 length 5.065" and swirl polished exhaust valves #9792313.

Also for the 2nd type Ram Air engine inner valve springs
#9785999 39-46lb@1.642" installed height
and outer valve springs
#9785998 76-81b@1.712" installed height were used.
(Same as early 1968 Ram Air engines).
The taller installed spring height was due to milled spring seats.

And, no GTO used the 066 camshaft, except in 1973 w/AT.

[PontiacJim1959]

Originally Posted by Kenth

Looks like the AMA Specs dated 8-26-1966 does not include the 2nd type Ram Air engine with serial number 646616 and up and with cast #997 cylinder heads.

The 2nd type Ram Air engine uses swirl polished intake valves #9792316 length 5.065" and swirl polished exhaust valves #9792313.

Also for the 2nd type Ram Air engine inner valve springs
#9785999 39-46lb@1.642" installed height
and outer valve springs
#9785998 76-81b@1.712" installed height were used.
(Same as early 1968 Ram Air engines).
The taller installed spring height was due to milled spring seats.

And, no GTO used the 066 camshaft, except in 1973 w/AT.

Yes, no later RA specs, just the earlier specs. You are also correct on the 066 cam. It may have been what they had planned on using, but did not, but it is shown. The optional 8.6 low compression 2 bbl 255HP 400CI used the "254" cam.

Thanks for your info.