[69SJ4SPEED]

on the 428 in my 69 Grand Prix 4-speed.
Rod is sticking right through the oil pan. I just had the original heads reworked and put on March under-drive pulleys. Man this car is costing me!


Two questions:

1. Am I better off putting a 455 short block in and will the heads fit and be practical?

2. Where can I get a Superman deal at a Clark Kent price for a short block? I want the most power I can get on 93 Octane without pinging -- and not be a problem with power brakes and A/C.


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[69SJ4SPEED]

on the 428 in my 69 Grand Prix 4-speed.
Rod is sticking right through the oil pan. I just had the original heads reworked and put on March under-drive pulleys. Man this car is costing me!


Two questions:

1. Am I better off putting a 455 short block in and will the heads fit and be practical?

2. Where can I get a Superman deal at a Clark Kent price for a short block? I want the most power I can get on 93 Octane without pinging -- and not be a problem with power brakes and A/C.


------------------
Its nice to be important -- but more important to be nice!


My Wheels ** My Maniacal Ravings ** Yankee Judge @ a Texas Chili Cookoff ** Rednecks

[Bill Lake]

Is the block damaged? Or just a rod through the pan? If you are looking for a correct block there are a nuimber of places in Hemings that list blocks. 428 was it a 370HP or 390HP? HO blocks are harder to come by. If you do mot care about correct block 455 blocks are easy to come by most are already drilled and tapped for 4 bolt caps and heads from 428 will interchange. There a number of engine builders listed in High Performance Pontiac Mag. that will send you a crate engine making 390+Hp for around $3000-3800.

[GP-K]

Dave,

What happened????? Too much compression on 93 octane gas? I can't remember what cylinder heads you have on that car, but if you had the originals on it, you would have been running more than 10:1, and you most likely would have had a detonation problem if you ran it hard at all...

If the block isn't windowed (or otherwise damaged) you may want to rebuild the engine, but use some good forged rods, and drop the compression down some. You may want to use a wilder camshaft to reduce the dynamic compression (but don't go too far, or you will have problems with your vacuum power accessories, like the power brakes)


But never the less, since the car isn't original anyway, I'd go ahead and put in a 455 (with forged rods, either the eagles, or crower's), and put the high compression 428 heads back on the shelf. If you are going to stick with stock manifolds, I would suggest using '71 or '72 400 heads, or the 6x's. Shoot for around 9:1 compression, and you should be ok.

Sorry to hear about the oops....

Good Luck,

K.

[69SJ4SPEED]

I'll pull the engine out next week and tear it apart to see what happened.
The short block was alleged to have been a stock 69 428 with later model low compression heads. I never verified this -- but will need to (I'll need to find some material on how to decode the block) as the a$$hole who sold me the car lied about it being a factory 4-speed.

I received the (alleged) original bare block (the crank was broke and not worth throwing in the truck) and heads with the car. I thought the car to be too slow for a 428 and mentioned it on this board. A couple people (I forget who -- and it doesn't make a difference) said that I needed ditch the low compression heads and to put the 69 heads back on. So I had them rebuilt and threw them on. That's when I started getting a denotation after the thermostat opened. I drove the car less than 10 miles with easy acceleration (would only denotate when jumping on it a little) while trying to play with the timing to get rid of the denotation. I finally mixed 1/2 racing gas with 1/2 93 octane and the denotation went away. I still hadn't put 50 miles on the car.

I put the March serpentine system with Sandin A/C compressor on it -- but before I could take it out for a test drive I screwed up my clutch knee sliding into 2nd base and needed an operation. Last week I was at the point where I could drive a stick again and decided to take the car for a ride. I barely got to 4th under moderate acceleration when all Hell broke loose.

I heard a bang, lost power and it felt like I broke a driveshaft. I looked under the car (although it was high grass on the shoulder and my knee still keeps me from kneeling) and saw oil and antifreeze pouring out but the driveshaft was still up.

I walked home and got my truck and trailer. That was another adventure -- but not Pontiac related.

When I got the car on the trailer where I could take a quick look at it, I saw a rod peeking through the oil pan. I haven't really had a chance to look at it as I needed to hurry up and shower for a PTA meeting that I was running late for and have been swamped with mini-crisis ever since. My guess is that the block is trashed since anti-freeze was also pouring out. I have what is alleged to be the original block. How can I tell?

The Billet HEI, Heads, March serpentine, etc.. are all new. So what would you suggest? Have a lower compression short block for the high compression heads or higher compression short block for the lower compression heads.

As most of you know I'm more experienced in MOPAR and just learning about swinging a wrench on a Pontiac. Any suggestions will be greatly appreciated.

I don't get high performance magazine, can't say that I've even seen it on the magazine rack. I guess I need to go to a real newstand.

Dave


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['ol Pinion head]

Dave, I hope your block survived the loose rod. If not, feel feel & e-mail, I have an SR 428 4bolt block & numerous std-std 428 cranks. Could even deliver to Dallas, possibly further south.

[Bill Lake]

The two engines that were offered in 1969 in the SJ Grand Prix with a 4-speed were a 10.5 compression 370hp 428 that had an engine code "WF" and #62 heads. The other 428 was a HO engine with 10.75 compression and with an engine code of "WL" and #62 heads. The changes in the two engines were in the cams the std. 428 had a #67 cam while the 428HO had a #68 cam. Hope this info helps.

[Bill Lake]

I have a 70 GP SJ 4-speed car, the car has a 455 and am using #16 heads with a #9779068 cam, alum. intake and origional carb. Car runs low 14s on street tires, when I can get her to hook up,500ftlbs of torque will melt most tires. I combat the detonation problem with a good grade of 93 oct. and a oct. booster. The rebuilding of your heads may have contributed to your engines demise if you increased the compression and the short block was not up to the increase(ie. alot of miles on engine, low compression 428 block....)Much luck with your project!!!

[Bill Lake]

PS-in regard to how to tell if you have an origional block - on the left side of the engine as you are facing it look slightly below where the head and the block meet. There should be a two letter code "WF","WG" etc.. and there will be a multi digit number, the number on the engine should match the cars vin number, also on the block at the rear at the dist. there are numbers that will tell you when the engine was manufactured month/year. Hope this helps.

[Alex]

I know this is off the topic,but

Bill,this is exactly the combination I was considering.455 #16 heads
Questions are What pistons are you using and what is the compression??

[69SJ4SPEED]

Thanx for the replies -- and sorry for taking so long to get back. The last two weeks have been from Hell.

Still haven't pulled the engine yet -- bigger fish to fry. Hope to do so late next week.

Thanx for the offer for a 428 block o'l Pinion head -- I feel certain I must have trashed the block -- but won't know for a week or so.

Who puts out quality short blocks for a 428/455?


------------------
Its nice to be important -- but more important to be nice!


My Wheels ** My Maniacal Ravings ** Yankee Judge @ a Texas Chili Cookoff ** Rednecks