Topic: 1970 XH 400 with # 13 heads, good or bad?

[80 Formula]

I just bought a 79 WS6 with a 1970 XH 400 with # 13 heads motor in it. According to the yearone site, it is a 350HP motor. The guy I bought the car from said that it was from a 1970 Grand Prix and it has about 10,000 miles on a rebuild. The car has not been licensed since 1999.

The car had sat for a few years, I put 87 octane gas in it, and a battery, it started right up, and I drove it home. It seems to run pretty good, it does not burn any oil. It really needs a good tune up.

I would like to put a cam in it, headers, and a different carb, (it has one of the edelbrocks on it) it runs real rich.

Is this motor and heads worth keeping, is the compression ratio (not sure what it is for that year with the #13 heads) to high for the street?

I will post pics as soon as the weather gets a little warmer.


Mike

[bluebyu64gp]

On premium you should be fine...I run three different 400's with #13 heads.  Stock out of the box, they are "supposedly" 75 CC chambers putting you roughly in the 9.3-9.5:1 compression on a 400....Answer to your question, good.

[80 Formula]

Thanks for your response David, I read somewhere that motor had 10.5 to 1 CR. The engine sounds really healthy, it just needs the carb gone thru and a major tuneup. I see your from Egwood, I live over here in eastern washington (kennewick). I will contact you about your engine builds.
I went thru alot of posts, and never really saw that anybody was using them.

Thanks
Mike

[Mr. P-Body]

   The reality is propbably right at 10:1.  Is it a good engine? Among the best. A slight "dish" in the piston and it will be a very good "pump gas" engine. Using a modern cam grind and a well-done Q-Jet will bring it "to life".

   You might consider replacing the connecting rods, if you plan on "pounding" on it, and your budget can stand it.

Jim

[72blackbird]

I'm running a set of ported no.13's on the 455 I'm starting to build this spring. I'll also be using forged Icon (KB) dish pistons and Tomahawk 4340 I-beam rods along with the stock crank- it should be a nice running 455 since these heads kicked butt on a 400.

Geno

[bluebyu64gp]

Geno, you running race gas?  Or doing the 22 cc dish to the pistons to run pump gas?

[80 Formula]

I would like to not tear it down if possible (other than a cam). I am going to do the tuneup and try out one of my many q-jets that I have collected over the years. I do have a new holley 750 with vacuum secondarys also.

The next question is what cam? How much will I really gain from porting the heads? This car will be a driver, hopfully I can get it the high 13's with a cam, and some 3.42 gears that I have laying around.

Thanks for the input.

Mike

[72blackbird]

No race gas- crappy SoCal 91 octane. I opened up my no.13's to 82cc's, deburred all sharp edges and rolled back the valve shrouding- that's what will let me get away with running a 15cc dish in a +.030 455. I'll be running a Crower 60919 w/ 1.65 roller rockers- not a radical or unknown cam to run w/ a 455, but you need to have good heads that can flow to help this classic profile make power.

No. 13's on a 400 will need more than just 91 octane, since the SCR is around 10-10.5:1 w/ flat tops. You'll need to run dished pistons as Jim stated, or open up the chambers as I did to bring the compression down. I would definitely get the heads ported too- these no.13's on a 400, 750 Holley v/s on an e-performer, Crane 284H, 1.5 roller rockers, built TH-350 w/ 2500 stall and 3.08 posi helped my 'Bird run 13.0x's @ 102-104 mph, and that's on street tires.

I'll be very surprised if these heads on a 455 didn't run at least low-mid 12's with the same combo on the car now.

Geno

[80 Formula]

Geno, do you recommend the "750 Holley v/s on an e-performer, Crane 284H, 1.5 roller rockers" with the head porting?

Mike

[72blackbird]

Mike,
The Holley setup works, but so would a Q-jet on the stock intake if it was tuned and rejetted- it would also probably do a little better than the 14-16 mpg I pulled down with the Holley as well. The Crane 284H worked well but is a single pattern cam and an older design- the newer dual-pattern cams will work even better so go with one of those.The Crane Energizer 284H  is still listed with a part no. on JEG's website, but I doubt it's still available.

If I were looking for a cam for that 400 now I'd run a Crower 60916 or 60242 w/ 1.5 roller rockers- be sure to run the Crower 68404 or 68405 valve springs with either cam. This cams have a little lope, but nothing too radical and are still suitable for a driver. A switch to 1.65 roller rockers will also help, but don't forget to get the pushrod holes elongated for the pushrod clearance.

Geno

[80 Formula]

Geno, I just found a Q-Jet carb in my shop. It is part #7040240, I decoded it as 800 cfm, application 1970 buick 455, will this be a direct fit to the original 1970 400 intake? I guess I should re-phrase what I meant by "driver", It will be a weekend cruiser, with a occasional trip on the freeway to work or the strip.

Will I get more performance from the 60242 w/ 1.5 roller rockers, or the 60916 with the stock rockers. I do not mind spending the extra money.

Do you port your own heads?

Thanks again
Mike

[72blackbird]

Mike,
You can't go wrong with a Q-jet, just make sure to have it rebuilt properly- it will also fit the stock intake perfectly. Either cam has it's powerband in the 1800-4800 rpm range, the 60242 is just the newer computer-optimized version. I would recommend going with the full roller rocker whether you run a 1.5 or 1.65 ratio, as the roller tip still generates heat at the fulcrum and the full roller version reduces alot more friction.

I do port my own heads, but oddly enough a Chevy guy taught me how to do it. I did however get a copy of H-O Racing's Blueprinting and Assembly guide, read that a few times cover-cover before I attempted to start grinding on my own heads (this was back in the early 90's before Jim Hand and Jim Lehart came out with their current Pontiac book). My Chevy buddy questioned my methods, but I can't argue with the results- all of the best information on porting Pontiac heads works.

Geno

 

[80 Formula]

Thanks again for the info. One thing, what do you recommend for plugs, and plug wires?

Mike

[bluebyu64gp]

Mike, asking me about engine building will just be repeating what I have learned on this site for the most part.  Mr. P who answered on this posting is the expert here.  He has also, as stated before, written some of Jim Hands book.  I have done nothing special to my heads or 400's as of yet.  That said, I did turn a couple of mid 14's in the upper 90's in my 76 T/A this past fall.  

What you must know about this engine is that the whole thing cost me $200.  It came out of a Public Storage auctioned unit.  My original stock 400 in the T/A was bad, so Dad and I installed this one.  We could tell it was .030 with forged pistons and Comps Extreme Energy 268H cam with stock converter in a T350 with 2.41 rear gears.

I am now building a 428, with Mr. P, Geno's, and others help from this site.  It will be a .035 over with Chevy Eagle H-Beam 4340 6.8 rods, Ross Pistons, solid roller cam with a Torker II intake and AED 850 Holley.  Probably start with my #13 heads and then eventually upgrade to a nice set of E heads.  I am using the stock crank and 2 bolt mains with the Rod Journals turned down for the 6.8 rods.

Also installing a pretty stout T400 with Continental 3500 stall, upgrading the rear end to a Detroit Locker, Moser Axels, Moser C Clip eliminators and Richmond 3.42:1 ring and pinion in a bigger 10 bolt 8.5 housing.

This will be a street/strip T/A and hoping to get in the lower 12's or high 11's.  I don't want to roll-cage this car.  I have a 64 Lemans that will become full time trailer race car that will get all that stuff.

[72blackbird]

David,
Sounds like the makings of a nice 428 build- the solid roller , 6.8 BBC rods and 4" stroke will make that rev like a SBC, and make big numbers too. If your no.13's are ported right they will surprise you with awesome numbers, even more so on a 428 or 455.

I built a 455 years ago using a T-II and 850 DP, ported no.64's and the good old Crower 60919- that engine ran low 12's on street tires with a TH-350 w/ 2500 stall and 3.08 posi, and got into the 11's on slicks and pizza cutters. I'm looking forward to this upcoming 455 build, and with the good pistons and rods it should rev alot better than a stock 455 too.

Mike- I'd have to go see what plugs are on my 406 w/ no.48's now, but they're the same ones I use w/ the no. 13's. Use whatever spiral-core suppression wire you like- Taylor, MSD, Accel, etc.- they're all pretty good.

Geno