Jeep Strokers

Alright,

Heres the deal.

I have built a OBD-I 4.7l stroker. I used the.060 over KB-2229 pistons with the 4.2L Rods and crank to get to this displacement. The deck height is .020 and I am using a Lunati cam part number 63500. I have a 62 mm throttle body with #24 injectors. I am currently running a stock fuel pressure regulator. I am afraid that the DCR is too high for High Test as I am hearing a metallic noise at part throttle from the engine. What can I do to lower the DCR.......Increase the combustion chamber volume in the head or retard the cam or both. Also, do I need the Hesco fuel pressure regulator for this set up? Help a confused jeeper out please.

First I would triple check the indexing of the distributor. Second I would invest in a wideband air fuel ratio gauge. It will allow you to see what is exactly happening with the fueling.

Use the calculator (http://www.jeepstrokers.com/calculator) to determine your static and dynamic compression ratios.

SilverXJ wrote:First I would triple check the indexing of the distributor. Second I would invest in a wideband air fuel ratio gauge. It will allow you to see what is exactly happening with the fueling.

X2 on both counts. I suspect that your engine may be running lean but you won't know for sure until you've checked the AFR.

Looks like 10:1 SCR and 8.7:1 DCR. I dont have a Wide Band on it yet. WIll try to get one installed soon. Based on this, do you think the DCR is too gross for 93 octane? I will check the distributor indexing again, but I am pretty sure that I have that right.

fast65 wrote:Looks like 10:1 SCR and 8.7:1 DCR. Based on this, do you think the DCR is too gross for 93 octane?

No, an 8.7:1 DCR should be OK for premium gas but you could try some octane booster and see.

OK,

Well, if, with a A/F gauge, i find that I am running lean, what are the next steps to correct this?

MAP adjuster.

http://www.angelfire.com/my/fan/MAP_adjuster.html

Ill give it a shot and keep you posted. Thanks

Cheromaniac wrote:

fast65 wrote:Looks like 10:1 SCR and 8.7:1 DCR. Based on this, do you think the DCR is too gross for 93 octane?

No, an 8.7:1 DCR should be OK for premium gas but you could try some octane booster and see.

Whats the DCRs for each octane gas. What ranges of DCR use what octane gas?

Slim357 wrote:Whats the DCRs for each octane gas. What ranges of DCR use what octane gas?

There aren't any hard & fast numbers 'cause there are several other factors that'll determine an engine's resistance to detonation, but a higher DCR definitely correlates with the need for higher octane gas.

Just indexed the distributor again. I have the rotor pointing slightly past 5 o'clock and I have 3 cm between the edge of the cam position sensor's rubber plug and the rotor. As I read Dino's instructions this should be correct. I will button everything back up and try it out. It may take me a while to get the wideband on. I'll keep everyone posted. Thanks so much.

Re-indexed Dizzy again and not difference. Still waiting on wide band. The noise the engine makes is hard to describe. I have a 62 mm TB with a conical filter on top, no tube or anything. Could this be the cause of my sound? I just thought of that last night when i read that there can be a whistling sound with machined throttle bodies. Anyone else have this issue?

Mine whistles under light load when I had my home brew cold air intake on it almost sounded turboed.

Hey Tank,

No whistle at idle or full throttle?

My strokedjeep throttle body on my XJ never whistles, but my other bored throttle body on the ZJ does. Never at idle or WOT, but at part throttle. The cone filter right on top of the TB may have something to do with it.