[joeg]

I just went through this on my 421 rebuild. I could not find any info on the TRW pistons you have, they look flat.

Generally speaking if you increase the bore .030 and put flat top pistons with the same deck height and keep the 093 (68 CC) heads stock, the compression ratio will increase above 11:00 / 1.
Not so good for today's pump gas.

Joe

[65WJ]

If you could, please take a picture of the back of the block. Look for a casting of 157. We are having a discussion on Petes book and why the Wx blocks have the casting and the Yx blocks do not.
I am doing research on rebuilding the 400 in moms GTO Using a 4in stroke and #62 heads i came up with a 14 cc dished piston to keep the compression around 9.5.

patrick

ps here is the thread

http://forums.maxperformanceinc.com/...d.php?t=648143

[b-man]

Definitely plan on installing some dished pistons if you intend to run the 421 on a steady diet of premium pump fuel.

I'm currently in the planning stages of a +.030 428 build, I want to run some 72cc 1964 389/421 9770716 heads on it along with a '64 Tri-Power setup.

With the standard 12cc dished forged replacement TRW/Sealed Power pistons it would end up at near 10.3:1 compression. Increasing the dish to 20ccs would give me a 9.6:1 engine that should be okay on 91 octane fuel. If there's any possible way to put in a dish of say 22cs or more in those 428 pistons, I'll do it.

I plan to use a Crower 60916 cam (221/229 @ .050, .455"/.470" lift with 1.5:1 rockers), a great street cam that is actually fairly mild in a 421 or 428 but a step up in performance compared to the 068 (212/225) or 2801 (214/224) cams. My car ('64 LeMans convertible) has factory A/C and an auto trans so I want a fairly smooth idle, the 60916 will be perfect.

The XE-series cams build too much cylinder pressure, I wouldn't use one in your 421 even with only 9.5:1 compression.

BTW, love the greasy 421 pics. Should be a great build.

[nmoreilly]

OK, so heres what I am getting form this: With the "stock" pistons, the XE cam will not work. At the moment, no plans to change the pistons or heads, so with that in mind, what are the choices.

What is the issue with the XE cam? is it the lower intake center line? has anyone actually used this cam or similar and come back with a bad experience?

Thanks again for all the input on this

[b-man]

No matter what cam you choose you'll have too much compression to run any unleaded premium pump fuel straight from the pump. You will be buying a few gallons of expensive race gas and mixing it in with a tankfull of premium, or you'll have to run E85 instead of premium unleaded gasoline.

Do a search in the Street forum, plenty has been written about the pros and cons of the XE-series cams. Look for replies from Cliff R and see what a well-known tuner and carb guru has to say about them:http://forums.maxperformanceinc.com/...d.php?t=625841

The XE cams work best in low-compression engines. They are not the best choice for a high-compression 421, especially one that's pushing a heavy full-size Pontiac around.

[nmoreilly]

Originally Posted by b-man

Definitely plan on installing some dished pistons if you intend to run the 421 on a steady diet of premium pump fuel.

I'm currently in the planning stages of a +.030 428 build, I want to run some 72cc 1964 389/421 9770716 heads on it along with a '64 Tri-Power setup.

With the standard 12cc dished forged replacement TRW/Sealed Power pistons it would end up at near 10.3:1 compression. Increasing the dish to 20ccs would give me a 9.6:1 engine that should be okay on 91 octane fuel. If there's any possible way to put in a dish of say 22cs or more in those 428 pistons, I'll do it.

I plan to use a Crower 60916 cam (221/229 @ .050, .455"/.470" lift with 1.5:1 rockers), a great street cam that is actually fairly mild in a 421 or 428 but a step up in performance compared to the 068 (212/225) or 2801 (214/224) cams. My car ('64 LeMans convertible) has factory A/C and an auto trans so I want a fairly smooth idle, the 60916 will be perfect.

The XE-series cams build too much cylinder pressure, I wouldn't use one in your 421 even with only 9.5:1 compression.

BTW, love the greasy 421 pics. Should be a great build.

Bman,

Interesting thoughts, thanks for sharing. Dont really want to change the pistons, will run 93 with octane supreme 130 - I have really good luck with this stuff in my stock L89corvette. For those who care, the L89 was an L71 with aluminium heads. IMHO, Chevy guys definiteluy dont dig as deeply as Pontiac guys do on all the cam events.

But I digress, what is the right cam here, I need to get this right the first time

[Indian Fixer]

A couple pics of the block numbers, castings at the rear and stampings at the front.

Looking at the old greasy head.....can we relieve the chamber in that area above the spark plug and smooth up the sharp edge below the valves? Just a stray thought on losing some CR.

[64gp4spd]

I had that cam in a 9.5 to 1 455 and had to mix Av Gas with the 93 Octane Pump Gas. Cam did really perform nice and idle nice.

[nmoreilly]

Originally Posted by 65WJ

If you could, please take a picture of the back of the block. Look for a casting of 157. We are having a discussion on Petes book and why the Wx blocks have the casting and the Yx blocks do not.
I am doing research on rebuilding the 400 in moms GTO Using a 4in stroke and #62 heads i came up with a 14 cc dished piston to keep the compression around 9.5.

patrick

ps here is the thread

http://forums.maxperformanceinc.com/...d.php?t=648143

OK so our block is a 9782611 which is correct I think. I read through the link, what does this prove?

[joeg]

Your block number is correct 9782611, I don't think we are trying to prove anything, just trying to understand the cast number in question. The number is located on the back of the block to the left of the rear main journal. My 66' YK does not have it.
I opted using 428 dished pistons, 093 heads and the stock 068 cam.
What a coincidence where we have two 421's assembling nearly within the same time frame..
I'll continue my tread dated 8-22-10 named "421 rebuild" soon with updated photos.

Joe

Originally Posted by nmoreilly

OK so our block is a 9782611 which is correct I think. I read through the link, what does this prove?

[65WJ]

look at the picture in post number 4. See the casting 157 on the left could you post a picture of your block of this area? We are not sure what it means. My thought was these blocks may have some extra nickle for the weight of the fly wheel vs the torque converter.
So the engine builders would put a fly wheel on the crank and not a flex plate.
Just my thought.
thanks
patrick

[Heybuck]

I see this topic is changing somewhat but just going back to the cruise control, I have this niggling thought in the back of my mind that the entire brake pedal assebly is somehow different to accomodate the vacuum release switch.

I have all my cruise stuff in a shed about 80 miles from here but I'm going down to the shed on Tuesday. I'll drag it out and take some photos.

I'm just saying all this here in case you get rid of the donor car and don't realise you might need the brake assembly. I might be wrong, but its best to be sure....

Ian

[nmoreilly]

Originally Posted by joeg

I just went through this on my 421 rebuild. I could not find any info on the TRW pistons you have, they look flat.

Generally speaking if you increase the bore .030 and put flat top pistons with the same deck height and keep the 093 (68 CC) heads stock, the compression ratio will increase above 11:00 / 1.
Not so good for today's pump gas.

Joe

Joe,

Would you mind giving me the full spec on the 068 cam? Which manufacturer did you use?

Thanks,

Noel

[Deadhead]

Check the Melling SPC-7 kit. That is the 068's original manufacturer. It is going to be hard to run the 093 heads without dished pistons regardless of cam.

[joeg]

Noel,

I have always used Crane Blueprinted Cams,
Grind number 9779068
See attached.
If you need anything else let me know.

Joe

Originally Posted by nmoreilly

Joe,

Would you mind giving me the full spec on the 068 cam? Which manufacturer did you use?

Thanks,

Noel

[nmoreilly]

Thanks Guys

[nmoreilly]

Spent a lot of time over the last week or so going through the forum on cams, static compression, dynamic compression. Got it narrowed down to either the 068 or 744. As far as fuel octane is concerned, this will not be a daily driver and if I have run higher octane using the supreme 130 with the 093 heads and current pistons I can live that. Will also try lowering the total mechanical per Jim Hands suggestions with in the context of zero deck height.

The static compression comes in right at 11.00. The dynamic compression with 068 comes in at 7.85, the DCR with the 744 comes in at 7.3240.

Will the 744 work with automatic and 3.08 rear end? Is there any vacuum issues?

[Deadhead]

I am running a 744 cam in a YK421, but I have 96 heads. I love this cam for what it is. It is right on the edge of streetable. I have 9.5 comp and no real issues with the vacuum. I put a gauge on it and it runs within the acceptable range. 3.42 rear. A 3.23 would be better with a TH400 IMO. 1st gear gets you about 50'. But if you are not going on the HWY for very far with it then it is not an issue. I would love to try a 3.08 with my combo, but don't have one.

The 744 is just a fun cam to have in a car. Sounds like 'BAMF' when you are sitting at a light.

[Al T.]

I'm not trying to hi-jack your thread, but hopefully you can answer a quick couple of questions. I've got a 66 421 YJ in my 64 GTO. The YJ is preceeded by an "X" on my stamp pad. Does anyone happen to know what the "X" denotes?
I'm also likely converting from the ST-300 to a Muncie this winter. I was curious as to whether the crank in your engine was drilled for a pilot bearing?

Thanks in advance!

Al T.

[nmoreilly]

No X on the eblock that I have seen. If you go back through previous post there are a number of picture sof the engine block, ehads etc