Jetting my 250 B&M and 1050 Carb...
03-22-2011, 12:06 PM
#1
Jetting my 250 B&M and 1050 Carb...
Ok, I know many of guys on here have ran similiar combos with this blower. I went thru both carbs and freshened them up. They currently have 96 jets F&R, and 6.5PV front and rear. They were on my buddies 509s with the 250 blowers setup running 3psi of boost and max rpm of about 5000. His plugs were tan.
My setup, is 468ci, dart aluminum heads, roller cam, 8.4:1, 2 circuit 1050. will be turning 5300-5500RPM and about 6-7psi. For some reason, from all the different setups i see jetting ranges from 92's all the way to 102's on similiar setups. Stock jets in the merc 525SC motors were 98's squared, but i dont believe they ran a pv in the rear? I know they were setup pretty fat from merc.
I have a feeling the setup i have now in the carbs would be close, but I am thinking of starting with 98's or 102's and then going down from there if needed. I'd rather start rich and drop them down after doing some runs.
Any suggestions or similar setups?? I know air bleed sizes come into play here too, so I need to measure them and see what i have.
My setup, is 468ci, dart aluminum heads, roller cam, 8.4:1, 2 circuit 1050. will be turning 5300-5500RPM and about 6-7psi. For some reason, from all the different setups i see jetting ranges from 92's all the way to 102's on similiar setups. Stock jets in the merc 525SC motors were 98's squared, but i dont believe they ran a pv in the rear? I know they were setup pretty fat from merc.
I have a feeling the setup i have now in the carbs would be close, but I am thinking of starting with 98's or 102's and then going down from there if needed. I'd rather start rich and drop them down after doing some runs.
Any suggestions or similar setups?? I know air bleed sizes come into play here too, so I need to measure them and see what i have.
03-22-2011, 10:10 PM
#2
Charter Member # 55
Charter Member
The 525SC's had 6.5PV's in the primaries and secondaries.
Forgot to get back to you on the email. The #98 jets are yours if you want them. Just Paypal me the $10 with your shipping info.
Forgot to get back to you on the email. The #98 jets are yours if you want them. Just Paypal me the $10 with your shipping info.
03-23-2011, 12:11 PM
#5
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I tuned my setups with a LM2. 470 cid, 177cfm merc blowers, 9.5:1 compression, 5psi. 98s all around with 4.5 pv got me 11.8-9 a/f at wot. Right where I want it. I changed to 100 all around and went to 6.2psi but now am back at 5psi to be safe. My burn in the chambers after teardown this winter I'd say is perfect. A touch rich, but right on. Your's should be very similar in all regards. Mine are 1050s too.
03-24-2011, 07:10 PM
#6
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you think i should richen my jetting with my new build from stock 330, to bob m cam, 781 heads, 9.25:1, airgap intake and 750 holly?
Also will new hydrulic roller rockers fit under short gm valve covers? Thanks guys
Also will new hydrulic roller rockers fit under short gm valve covers? Thanks guys
03-25-2011, 01:44 AM
#7
Charter Member # 55
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You will have to grind off the oil drip tabs on the underside of the valve covers and may need to grind off the corners of a couple rocker arms depending on what brand you get.
