[HO LEMANS]

OK I really need an answer to something that I have been told the answer to several times but it seems to be a conflicting answer each time!!!
Are the #48 heads on my 350 HO a smaller cc than the #48 heads on a R/A III
I have been told that they are exactly the same and I have been told that the 350 has a 66 cc and that the 400 has 72 cc I have looked obviously not in the right places for this answer so I turn to you guys for the CORRECT answer thanx
HO

[PaulatFast]

My best educated guess is they are the same. Look at how many different casting numbers were used on essentially the same heads. In 68-9 we had 16,62,31and 48's. It would seem crazy to think they then made two different 48 heads. The only way I could see the chambers being different sizes is if they milled the heads destined for the 350 more than the 400 heads. If so, they are still the same head.

[SWEETJUDGE]

i would say the same, but did they actually put a ram air III on a 350???? is there a 46 casting?

[RicksGTO]

a lot of good info in this post, pretty long:

http://forums.maxperformanceinc.com/...=48+heads+66cc

[HO LEMANS]

The engine that came out of my Lemans which is indeed the original vin# confirms that- is an 350 H.O. XU block with the #48 heads turbo 400 3.30 saf-t-trac all original bucket seats column shift ---- but anyway the heads are in really rough shape since someone stole the carb and put a sleeping bag over the engine the mice used the 350 for a condo and pi$$ed all over in the ports of the heads which = rust, the little didn't do the pistons any good either !!!!!
What I am worried about is not being able to save the heads --- and if I can't am I looking @ two sizes of #48 or just one size #48 thanx
HO

[north]

The fact that there was only one part number and that they used the same casting number makes it almost certain that they are the same.

[69 RA GTO]

When it comes down to it, the only 100% sure way to know HO Lemans is to pull off one of the heads and then have it measured. Off hand I do not remember exactly what cc GTO 48 heads are but I am sure someone will chime in with the answer. If you do this is would also help us out with the answer because I know I have been curious for years about this and it sounds like you may be able to help us all out with what you find. Just my 2 cents. Good luck with the motor and lets hope the dam mice did not screw up your motor.

Tim

[HO LEMANS]

Unfortunately 69 RA I already have the engine torn down and the little s have made quite the mess of the heads and even a couple cylinders I think the block will be ok but man the heads are rusty in the ports even to the point of the cast flaking a little and in the combustion chamber I'm not sure a person could get an even measurable clean surface ---- guess I need to find somewhere to send them and get them looked at to see if there's any hope --- no place around here close since this is a dirt track community and small block chevy hell most guys wouldn't know a Poncho engine if ya dropped it on them -------but anyway I guess that question is one that can and will be answered yes there are two different ones and no they are both the same but someone somewhere has the correct info to settle this ----PLEASE STEP FORWARD WE ARE WAITING!!!

[Rocky Rotella]

There's a few places in Omaha that can help assess your engine's condition. Are you going to rebuild the 350 HO to stock specs?

[Region Warrior]

Saw a set off a 400 GP once, but didnt get to check'm.
Visually they were smaller then 16's and 62's.
Looked the same size as 12's.

[HO LEMANS]

Hey Rocky how are ya I saw ya at the show in Gretna didn't make it over to talk though
anyway I would like to put the H.O. back to stock yes -- any recommendations on who to talk to in the big city ???? thanx for the help
HO

[Rocky Rotella]

I suggest Chuck Willard at Willard Auto Machine. 402-573-8984

[HO LEMANS]

Well much to my surprise in the May 2010 issue of H.P.P. on page 82 under the heading Cylinder Sleeve Salvation I happened to notice a 350 Poncho block that looked VERY familiar and completely NOT the same as the engine in the article is the very one that I was talking about earlier in this thread --- I delivered it to Chuck at Willard Auto Machine in Omaha Nebraska under the suggestion of Rocky Rotella (thanks Rocky) and Chuck has done an absolute wonderful job of turning this poor rusty mess into something of pure Pontiac beauty

[U47]

All 69 350" 2bbl heads are cast #47. The valve sizes are 1.96 and 1.66 ( the intakes are larger than 60-61SD's (389's) and 63-66 H-O's (389 @ 421's) at 1.92.
The # 48 head for the 400" are 2.11-1.77 and the chamber volume is 72cc. with a compression of 10.75 to 1. The 350 # 48 has a compression of 10.5 to one. To me that means the 350 # 48 head has a different chamber volume than the 48 400" head, just look at the bore size difference 4.12 vs 3.88 ! That dosen't equate .5 in compression.

Don

[David Jones]

I'd bet that neither engine had the advertised CR either.

[U47]

David, only a fool would bet you on that one.

Don

[70KGOLD]

The 350 HO came with the 48 heads. I owned a 1969 Lemans with that combo.

[U47]

Originally Posted by 70KGOLD

The 350 HO came with the 48 heads. I owned a 1969 Lemans with that combo.

We know 48's are a given, it's the cc question we are trying to find out. I am a original owner of a 69 350 H-O LeMans, and even though the original engine is not more than fifteen feet from me I'll be damned if I want to pull one of the heads to cc a chamber.

Don

[Jim Robertson]

I have played with a few #48s over the years and yes we have found two different combustion chamber volumes. 66ccs and 72ccs. No question about the originality of the heads. The difference is in the depth of the chamber and the scallop on the spark plug side of the chamber. In all my searching and buying I have only found one set of #48s that measured 72 ccs all others measured 66cc. Definitely a difference in the machining operation when produced. If you place one of each side by side you can see the difference. The 48s pictured on my website have the 66cc chamber - about 5ccs due to milling.
Jim
www.racev8s.com

[bulletpruf]

HO - if the heads are off the engine, take them to a machine shop to be cc'ed or cc them yourself. You can get a nice cc kit for $100 or a budget one for about $25. Check Summit. Will take you 5 minutes to do a chamber.

Scott