I was given a set of 350 heads with a 73 casting on them. They were shaved some and I wanted to know how much. My later brother left me a burette and I decided to give it a try. The stock 71 350 heads spec'd out at the expected 58cc. 73 castings came back as 54cc. That works out to about .3 points of compression. If it builds like I'm measuring, a 0.040 head gasket will make the 58cc heads 8.75:1 CR and the 54cc heads 9.11:1 CR. Will iron heads run 9.11:1 with 87 octane using a TA 284H-88 cam?
It should be ok. Start with initial timing at 8 advanced. I would not run a stock converter with that cam. 2400 for small block (2800 for general rating) . That cam really likes to be advanced 4 degrees. Which gives a strong lower end . Probably about.020 milled off heads.
She's a stick car with 3.08 rear and 2.98 first in the M23Z. Should be able to launch like 3.64 rears and still cruise nicely.
I would keep an ear open just in case, detonation has more factors than just compression. Engine load is a big factor also, and typically an automatic transmission does not load the engine as much as a manual transmission due to the torque converter. I’m at 11 to 1 with iron heads, no detonation, but I’m At .005 in the hole, and have a JW 9.5 3000 stall converter, so my combo doesn’t see a huge load on the engine.
I would like to suggest something to you while you have the heads off. These chambers in the SB heads leave a lot to be desired. There lack of squish area and how far the chamber is layed back on the plug side is to me a nightmare. a perfect way to 1) speed up the burn rate , 2) reduce detonation, 3) run less timing and yet make more power also is to run a long plug with a extended tip . Doing this adds a little bit of the effect of having a modern Heart shaped chamber with there plug being closer to the center of the chamber. Here are two pictures of what I mean. This long plug can not go in as deep as it should because its not a flare seat type plug, it uses a gasket . The next picture shows it in the chamber, but it’s still 1/4” shy of how much it should stick out off of the roof of the port. The plug you use for this should be one heat range colder for starters then what you would normally run. you should also roll over/ flatten out and of the plug threads that stick out into the Chambers so they do not become hot spots at wide open heavy throttle.
IIRC I cc’d the heads and they were 53/55 cc’s they were milled .030 80 years ago I’m going to cc them again before I reassemble. The Auto TEC pistons I had them made for 11.1 .005 in the hole Head gaskets are standard Fel Pro
It’s a real shame that TA couldn’t produce the heads. They won’t pay machinists thier worth so they will never be successful. Heck they don’t have a proper inventory system. Let er buck
A note here to the OP. Even if you where to have a 9.5 to 1 compression I say you are shooting yourself in the foot with that 284 cam! your going to wish you where running Rhoads lifters with that Cam unless you have a 4 speed and 3.90 rear gears or better. even if you where at 10.5 compression I would want 3.55 rear gears. The main power band of that can just starts to kick in at 3200 rpm with a 350 cid motor , so unless 75% of your driving time will be at or above 3200 I would drop down to a cam in the 270s advertised duration range . The rule of Thumb for cams even when just bracket racing, no less running on the street is to err on the small side! Then you can always change over to higher ratio rockers to take advantage of the over the nose duration that they add,plus the added lift if you find that you want more top end power. I would respectfully ask those on this board who are running this 284 can with flat top pistons and post 1969 heads to post up what there cranking compression is. If it’s under 160 psi in a fresh motor then that’s just not going to be making the most of what that cam can do for you, period!
I don’t see a problem with the 284-88 cam. Brother has a 430 with the cam advanced 4 degrees. Great power with a 2700 converter and 87 octane. 3.42 gears and a 2.75 first gear in trans. I would do some clean up Porting on heads. Bowl work , not necessarily gasket matching. I see no reason to run rhoades lifters on such a tiny cam
The 284 cam is a dog unless you have well over 10:1 compression. Several members have been disappointed with the 284 and 9:1.
Hmm, I've not bought any cam as of yet. I run a TA-212 in my Stage 1 motor and I like it a lot. I may go with the 212 in the 350. The TA-284 gives a DCR of 7.61. The TA-212 of 7.72 if I run stock cc heads instead of the 54cc set. The 350 car is a stick, it will have the M-23Z, which is a 1st gear of 2.98. It came with an M-21 with a 2.20 1st gear. Changing the trans will make those 3.08s launch like an M-21 with 4.11s and still cruise decently at 70MPH turning 2600 RPM.
Of course it runs better its a 430 not a350 At least a 355 gear and you need 10.0 comp at least and yes these 350's with any cam do not get going till 3200 rpm. If you cannot get a 1.80 60 ft time out of the hole you will lose the race, even at 1.90 it is tough 2.00 you might as well forget it. You do a 1.80 60 ft you will be out front and by then you will be turning 3500 rpm and rolling. If you are anywhere close to stock or at 9.1 comp 212 is the biggest to go slap a 75 shot of nitrous and you will get a 1.60 60ft time I know I did it not the 212 but a Lunati Pop Mechanics cam. 507-502 I,E. 230-245 @.050 116lsa
I see no one’s taken me up on posted cranking compressions yet! Might it be that they where a bit shocked at how low it was with that 284 cam?
