429Cj help!!!!!!

[429CJ]

I recently purchased a 429 Cobra Jet, it has DOOE-R heads(large intakes), four bolt main. The motor had been bored 60 over when I bought it. I installed a Clay Smith solid cam and lifters, and also installed roller rocker. The piston's are flat top's with valve reliefs. I'm trying to figure out what octane gas to run. I know that a stock 429CJ came 11.3.1 from the factory. Should I run premium with aviation fuel, or just premium. I don't want to detonate(explode) this motor all over the river like I did the last one. Any help will be appreciated.

[spectras only]

429CJ, run premium plus gas,and make sure the ign timing is max 36 degrees at WOT.No need to go aviation fuel since boats have plenty of water for cooling to keep detonation at bay, compared to cars with a closed cooling system.

[429CJ]

Thanks Spectra for the info. What I'm worried about is the compression on pump gas. I was told with the motor being 60 over, I'm probably looking at 12.1 compression. Do you still think pump gas is ok. Now, if you will, tell me what you think I should set the timing at idle? You said no more than 36 deg at wot... I'm just worried like I said before about blowing this thing all over the river. I have spent to much money on this one. Once again thanks for the help.

[058]

Try a 50/50 mix of 110 racing and pump 92. Works fine in my 12.8 to 1 514" BBF

[Eat me & die]

With flat tops your motor is only about 9.5 The ford will not have that much as the pistons dont even come to the top of the block.if you want more power put a 460 crank in the block and you will have a 472. The way you have it set up pump gas will work fine for now.

[spectras only]

If you mix 50/50 as 058 suggest,you'll be fine.Here the Chevron premium plus is 94 octane.I set the timing at 36 max with the flyweights fully open.

[429CJ]

Thanks everyone for the info, going to try pump gas for now and see what happens. Where I live Av gas is cheaper than Chevron 94, but will try the pump first. Thanks again for the info

[mister460]

A 429 has about 11.3-1 comp from the factory, give or take a bit. .060 over will only bump compression up .1 or less. 92 octane will run just fine. And like Spectras said keep the timing below 36 max. Good idea, especially on a boat. Stick with the 429. You can rev it higher than a 460. They both make about the same amount of torque, the 429 just does it a little higher. And the pistons do come all the way up in the bore(maybe not zero deck hieght but close), if they didn't, they wouldn't come close enough to the quench area and you'd detonate even if you were running 8-1 ratio and 130 octane gas. Don't want an argument with anyone, but that's the truth. All in all, use good pump gas and you'll be fine.

[429CJ]

Once again thanks everyone for the info. Now it's to the boat ramp to break the motor in. Yes the boat ramp, it's nice living at the river. No out of towners on the weekdays. Thanks everyone for the info, I appreciate it.

[Eat me & die]

I just went out in the shop and miked a block. If this were to be true than why on a 429 block do we have .315 from the ring line to the top of the block? I can tell you its because that is where the top ring stops.The top of the piston stops short of the deck by .090 This block is a 429CJ .060 just the same as the one he is asking about. If you want more comp, deck the block on a ford it`s a cheep way to get it.mister 460 if you want to see what I`m telling you I can send you a pic of the block .

[jroos]

I`ve never heard of a bigger bore giving you more compression? I did the same, had .020 shaved off the heads and .015 off the deck, don`t know what the compression is. 460

[rivercrazy]

I could be wrong here but it would seem reasonable that if you bore the cylinders larger your compression would increase. You have more volume of air to compress in a fixed space (assuming your pistons still travel the same distance up and down and you didn't fuss with head porting or cam).

[RiverDave]

RiverCrazy, this is true but you just made that Fixed space larger to when you opened up the cylinders. It shouldn't affect compression at all or atleast very minimally.
RD

[058]

429 and 460s had 3 deck heights: 10.300" -10.310" and 10.320" The 10.300" was used from 1968 thru 71. The 10.310" block was used for a short time in 71-72 The 10.320" block from 72 and later. All these deck heights was to lower compresson ratios. And boring a cylinder will increase the swept voluume of that cyl. and with out changing the combustion chamber voluume will result in slightly higher compresson ratio.

[429CJ]

Ok guys, I took my boat to the ramp and started the new motor. Sounds very healthy, but there is one little thing missing...................OIL PRESSURE!!!!! When we first fired it up it had 20 pounds, after about ten minutes it went down to 5 pounds, that's when I said to my self...Self, you should shut this thing off. When I bought the 429Cj it had been rebuilt and never started. It sat in this guys garage for 6-7 years, bagged up. Do you think the pressure relief valve is stuck open on the oil pump, or is it something I really don't want to hear(plugging ears) Ok, just tell me, be blunt. Hope you guys can help.

[lakecrazy]

Did you check to see if your oil galley plugs were all installed? If I remember correctly, there are two plugs in the lifter valley, two behind the cam sproket and one near the fuel pump\timing cover area. I don't know if there are two at the back of the block on either side of the cam plug. sorry, my memory is not what it used to be! Also, one at the rear of the intake where most oil senders are mounted.
[This message has been edited by lakecrazy (edited July 19, 2001).]

[skijake]

For you guys that fuel up in California, a heads up.
Starting in August the octane on premium fuel will drop from 92 octane to 91 octane, this is to avoid a legal but unethethical patent that Unocal put on all reformulated gasoline (I do not buy Unocal, they caused gas prices to rise roughly 6 cents due to their patent)
Also running a mixure of 50/50 110 octane and 92 octane is probly a waste of good money for most engines, even blown with high boost. but remember it is always better to error on the high side when it comes to detentanation.
Good luck

[429CJ]

All the oil galley plugs are in. I was thinking, I had a 460 in my boat before the 429. When I pulled the 429 oil pan it did not have a windage tray. My 460 pan did. I put the 460 pan with the windage tray on the 429. Could the oil pick up tube be the wrong one and the oil pick up is to close to the bottom of the pan. The guy who built the motor is a very well known builder where I live. Everyone I've talked to says they doubt if he put the wrong main bearings in, and it's not a clearance problem. They seem to think it's a oil pump problem. Need to figure it out, the summer is slipping by.

[058]

429CJ, When you pull the engine check the main bearing clearance. I had a problem with F/M mains that were boxed and stamped as .010" under but were .017" under, F/M had aknowleged that they had a run of bad bearings and if it was assembled without checking the clearances on all journals then this can easily slip by. We chased a low oil pressure problem similer to yours, 30-35 lbs cold and 5-10 lbs hot running on a 460 in a car. One last thing, not all bearings were .017" under, only 3 pairs and both upper and lower were the same size.

[429CJ]

Thanks for the info 058 I had planned to check the bearings when I get it back out of the boat. What a pain in the @#$ this is. I'm hopeing it's not the mains, but will find out when the pans off.

[429CJ]

Thanks for the info 058 I had planned to check the bearings when I get it back out of the boat. What a pain in the @#$ this is. I'm hopeing it's not the mains, but will find out when the pans off.