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section 8 08-31-2012 10:40 PM

gee mr peabody....350 engine
I have a question about compatability of front timing covers and timing marks. I have a 69 350 and a 67 400 cover and balancer. I set it at 6btdc and it feels lethargic pull it up to where it feels freed up and my timing mark looks to be an inch or better adv from the whole timing lug. And to comment on 350's, this one seems to do pretty good with a cranecam if I remember correctly 215/228@050 454/470 and #47heads, an old square bore p4b manifold and a edelbrock carb. I am planning a stroker engine for the 68 and have a 67 400 block w 061 heads. What is your opinion of the chamber design? And who has accurate information on head casting #'s I've seen many dif variations. And seems nobody has an accurate number on chamber size 72-80cc's and would you have to dish the pistons to run pump gas? I have 2 other 400 blocks 70/72 and a pr of #13 heads ive been reading jim hands book and its a wonderful source of information.

cdminter59 09-01-2012 01:46 AM

head chamber size
You cannot go by what is on the internet. You will have to cc the chambers to have an accurate measurement. You will have to have this measurement to figure compression ratio. Check out KB's compression calculator it will show all the measurements needed to figure static compression ratio. United Engine & Machine Co. Incorporated On pistons you will find a set that the head volume added in on the calculator with the rest of your info will give you 9:1- 9.5:1 compression ratio. This with that correct quench should be good to run pump gas. On your timing of your 350 use a timing light with advance. Unplug the vacuum line from the distributor and plug. Set the knob on the back of the Timing light at 16* to start. Shine it at the timing scale and move the distributor until you get to "0" this means you have now set the initial at 16* BTDC. Next set the knob to 0 and idle the engine to 3000 rpms take another reading this time turn the knob on the timing light until you reach 0 again. The reading on the back of the timing light should be at 36-38* Total. This is minus the initial is your mechanical advance. Read this article it is great information.

section 8 09-01-2012 02:22 AM

section 8
Thank you for response, was wondering what 5 or 6sp would live behind it

section 8 09-01-2012 02:37 AM

section 8
Thank you for response, was wondering what 5 or 6sp would live behind it

Mr. P-Body 09-01-2012 08:22 AM

Section 8,

That's correct. All published numbers regarding chamber volumes, etc. are "nominal", and not necessarily exact. This is not unique to Pontiac, either. One must do the "leg work" to be certain. A very good database for Pontiac stuff is at

Wallace Racing-Drag Racing Pontiac powered Firebirds,Trans Ams and Dragsters

I've never run that particular cam, so I can't really "say". It's a nice dual-pattern grind, and follows the trend to more exhaust duration. In a 350, it will be a nice mid-range and upper-end cam. Hydraulics usually run out of breath in the 5,800-6,000 range. If you plan such revs, replace the connecting rods!!! Even the least expensive forgings "out there" are better than ANY factory rod, possible exception of the 421SD rods (too rare to consider).

The P-4B is a decent intake, but not "optimum". Edelbrock "split" the dual plane designs into Performer and RPM for several reasons, the least of which was NOT marketing. 350 "likes" Performer, even for mid-level performance applictions. 350 does not "like" RPM (too "big"). P-4B might hamper low-end a bit, but is better on the high-end than Performer for 350. Use a 650 carb for best results.

The 061 heads are quite unique. They have a chamber similar (but not exact) to Ram Air IV heads. They also share the good intake runner profile with 670, a very popular performance head ('67 350 HP 400s and "up"). Scott's '68 Firebird managed 11.90s with a 406, 061 heads lightly ported, Performer, AED 750, XE274H on 93 octane. The car has a good rear suspension, 3.90 gears and is fairly light, so keep it in perspective. Still, they'll easily support 400 HP, well over 500 if properly ported. They need the pressed studs removed, the holes HeliCoiled and screw-in studs installed. No geometry changes are needed. I have a couple pairs stashed. I like 'em.

Very little of what we "do" to make 350 perform applies to 461 ("stroker"). Completely different animals. Don't let anyone convince you 455 is "better" than 461. It's not. The 455 block is weaker than the 400. NOT an opinion. Fact. The crank is the strong point (no need for the larger mains). Don't waste a nickel on a 4-bolt block. Many blocks were "drilled" for 4-bolt caps but shipped with 2-bolt caps installed. Be aware some sellers may try to "advertise" a 4-bolt. Unlike a small block Chevy, 4-bolt mains aren't needed until power goes WAY beyond "street" levels. VERY important you understand Pontiacs and Chevys are not similar. Each engine family has it's strengths and weaknesses, and they're different from each other.


Mr. P-Body 09-01-2012 08:29 AM

Sorry, got carried away...

The '67 timing cover and balancer are fine. The later style water pump ('69-up) is more efficient, and you should collect the parts you need for that conversion, 'cuz the old style won't cut it when the 461 goes in. Pulleys will be the biggest challenge. They're readily available "new", but not cheap.


section 8 09-03-2012 10:51 PM

section 8
That's exactly what I was looking for mr p-body..I. intentionly spelled it peabody as in mr peabody and sherman he always has the answer an from what I've read you know what your talking about. The cam I'm running is only good to 5400 along with the smaler valves and bottleneck pressed in studs I didn't want to have issues. the 350 is impressive for what it is. I feel sorry for all the guys that swapped chevy engines into their first gen firebirds they don't know what they're missing. And its pulled a chevelle with a 454 though only inching it was definately going in the right direction.

section 8 09-03-2012 11:05 PM

section 8
I would also like to thank cdminter59 for his imput as well although I haven't had a chance to locate that particular type of timing light. This past weekend was eventful between between races at stanton and car show in lansing, mi. Id also like to add section 8 is a multi persons group of foreign and domestic cars. John

section 8 09-03-2012 11:43 PM

section 8
Id also like to add when I was playing w the bbc I was shifting @3800 because the secondary jets are too small. I swapped the 95 out for the 98 that were in the primary an now I get 70 from 2nd @5100 ..its fun to play with, I started small because it was a 350 car from the factory (4-1-68) with a wide ratio m20 and 10 bolt 3:36 safe-t track and no ps/pb and drums on all 4 so its fast enough as it is. The 461 will be added after I figure out how I'm going to stop it and what kind of(stick) transmission to use with it ...........john

Mr. P-Body 09-04-2012 08:10 AM

The "handle" Mr. P-Body is a "play" on Mr. Peabody and his pet boy "Sherman" (not to forget the "way back machine"). Mix that with the "P-body" (Fiero), the "purest form" of Pontiac (no other GM division used the platform), and viola... And I DO have an '88 GT!!

The mythology surrounding the Pontiac V8 and Chevy's greater popularity has little to do with overall performance. Afterall, GTO didn't get a reputation for losing... In the '60s, when GTO came out, people left Chevy and Ford in droves, flocking to the superior "stock" performance of the Pontiac (Catalinas had been completely dominant up to '64). Where they went "wrong" was in their approach to making power with the ol' Injun. Smokey said it best: "Don't rev it up, GEAR it up!" aimed at taking advantage of the massive low-end power the design is capable of. Instead, big cams, "high rise" intakes, etc., and gearing them "to the teeth" just as with the small blocks, led to LOTS of catestrophic failures. The Pontiac got an unearned reputation as a "grenade". If done correctly, a VERY potent power plant. Put good connecting rods in them, and darn near bullet-proof!


section 8 09-04-2012 08:19 AM

section 8
did you read the article where smokey made a fiero 4cyl turbo ..instead of cooling the charge he heated it starting at the base of the carb and continuing thru the turbo to fully vaporize the fuel... 0 to 60 in less than 6 and 30mpg

section 8 09-04-2012 08:28 AM

section 8
did you read the article where smokey made a fiero 4cyl turbo ..instead of cooling the charge he heated it starting at the base of the carb and continuing thru the turbo to fully vaporize the fuel... 0 to 60 in less than 6 and 30mpg

spinn 09-04-2012 01:16 PM

Boost is a incredible way to get the acceleration you desire. My 305 c10 has an e force supercharger/blower unit pressing 6 psi. Really gets a heavy thing to move. The 305 is a notorious bomb, but add 5-10 psi and it is dynomite.

A performer sbc intake yeilded better results on mild cammed engines under 350" for me. The RPM intake worked for larger inch small block engines around 400+ inches. For larger cammed engines above 400 inches the open plane intake and 3600 stall combined to get the strongest all out pull. Big block performer intakes are made with larger ports than the small block already .

Stock rods going over 5500rpms should be peened. They will hold with arp fasteners.

Does the timing cover match the engine. Using a drivers side marked chrome cover in place of a 12' o clock oem orientation cover would retard the hell out of it. Use a piston stop find true tdc. Make your own indicator from a wire hanger. Use a dial back light and set your timing to verify correctness.

section 8 09-04-2012 04:04 PM

section 8
I am planning a 461 kit for the 400 that was in the fb when I purchased it, originally a 350 car I wanted to stick with that. I've been looking for a few years for a so called #matching block and haven't been able to locate one. One day on craigslist I found a block someone started. The machine work was done and assembled, I located a pr of #13 head that were also done. Then I purchased a cam recommended by a local speed shop and noticed on the cam card that max rpm rating was 5400. Thinking that was a little low I started lookin for another cam to get the full potential out of the 350. I also wanted to find a oil pan and timing cover. I located a 350 eng, thinking that thousands have been scrapped during the "cash 4 clunkers" I better start grabbing up what I can,anyway I purchased it for $100.00 (thanks Ed) it turned out to be a new rebuilt 350. Being that I didn't know the grind of the cam and it having a 2bbl intake I pulled the cam (lucky I did the 1st cam bearing was stuck to the cam) so I bought a set of bearings and making sure the notches were lined up used the stuck bearing to install the new bearing(not recommended but worked) installed the cam and an old p4b dual plane edelbrock intake. I had Dan at Clutchdynamics in Lansing,Mi put a clutch together for my application, and it hooks up great! (Thanks again dan and jerry you guys do awesome work) I put it all together an fired it up. During the break in I noticed antifreeze on the floorboard and found some a** hole had poked a hole in the dr side freezeplug on the back of the head with a pick. But I still have a fresh block and heads and accumulated another complete 350( purchased for the alt/ps brackets and pullys and 2 other than the original 400 I pulled out and that's what brought me to this site as I was trying to figure which 400 block to use and found Mr P-Body to quite knowlegeable in this field. And again thanks to everyone who has responded to this post.........john

Thumpin455 09-04-2012 06:00 PM


Originally Posted by section 8 (Post 1588279)
did you read the article where smokey made a fiero 4cyl turbo ..instead of cooling the charge he heated it starting at the base of the carb and continuing thru the turbo to fully vaporize the fuel... 0 to 60 in less than 6 and 30mpg

Funny you mention that. Its one of the things I am working on with my 70 GTO, but not with gasoline because gas needs the 450F temps to fully vaporize. The turbo was more to keep the fuel from evaporating out of the carb than to add more air. You need some pressure to keep it in the carb and a turbo does that. 450F means exotic parts and more expense, so I am using a fuel that fully vaporizes below 200F to achieve the same thing. The other difference is I will eventually be using EFI. Pontiac engines work great for this because of the high velocity ports and great torque production. I'll let you know how it works out once I get the rest of the car up to date and legal.

If you build the Pontiac to maximize its bottom end and midrange you can keep the highway gears, drivability, and economy while still making it move. The number of sbc and bbc cars that I have beaten with grocery getter engines shifting under 5800 is growing, its been quite a few. They tell me it sounds like I am headed to the store for a loaf of bread. You can build them to RPM, but there is no need on the street unless you want to run single digits in the 1/4. What Jim says works great, his engines run pretty damn hard and long. When you get around to the 400 block he has some really good info.

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