Intake swap, poss gains?

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OldmanRick said:
Have you considered going to a flat tappet solid? You definitely have to consider lift with the 1.7 rockers.....as in piston to valve clearance.

With the 4.56's, a little more cam, and possibly a little larger carb, will bring your top end in line. I am assuming this is a all or mainly a track car.

I'll sniff around for a grind that give you some duration, but doesn't put your lift over the top.....If I see something that looks decent, i'll post it up.
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It's a street strip car, I could careless about driveability, it doesn't get driven far. Performance> driveability.
 
1980volare said:
Have 5psi fp at wot.
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Not near enough! Add 2 psi.

Jetting up that much is another indication of insufficient fuel delivery. Plus, it slowed down so it may be way too fat if it actually is getting enough fuel.

I'd go back to the factory baseline, maybe +2 jets on each end if you have a spacer, up fuel pressure if you can and see where it falls.
 
crackedback said:
Not near enough! Add 2 psi.

Jetting up that much is another indication of insufficient fuel delivery. Plus, it slowed down so it may be way too fat if it actually is getting enough fuel.

I'd go back to the factory baseline, maybe +2 jets on each end if you have a spacer, up fuel pressure if you can and see where it falls.
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Can't up fuel pressure, using a holley mechanical high flow. Time for an electric?
 
Cracked is right about the jetting. That size carb has to be really be fat running those numbers. I understand about the mechanical only deal. I'd take the time to inspect the lines from the tank to the pump, just to make sure you don't have any kinks or older hose pieces that could be collapsing and hurting the volume of fuel.
 
1980volare said:
Holley high flow mechanical pump. 650 double pumper with a proform main body. My wideband o2 took a crap, but it likes a fatter jet. Last Friday I had it at 74 and 87 now it's at 78 and 92 with a 6.5 pv
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The large jets doesn't surprise me with a 650dp that has had a Proform main body added. My carb is the exact same thing (started with a 650 dp, and added a 750 Proform main body), and my jetting I normally don't post because people jump all over me and tell me I have WAY too much jet...but I've done a LOT of testing and my car makes the most power with my current setup (82/92 with pv or 91 square without pv). With all that said, you might have too much jet, but here is the best way to find out.

Go to the drag strip, set your jetting back to what came with the main body kit and make a pass (which is 72/84 if I recall), looking only at MPH at the stripe. Repeat just to get a good baseline. Jet up 2 sizes (74/86) and make another pass. If your MPH goes up then keep jetting up until it slows down, then back up to the best MPH jetting and you're good. If it slows down right off the bat, then go the other way (take away 2 sizes until it slows).

I think the reason this carb setup uses so much jet has to do with the size of the air bleeds on the Proform main body...but I could be wrong (I'm not a carb expert).

Good luck....by the way, I'm still using that carb, works great on my 10 second street car.
 
Got a carb built the same way 650 DP with a ProForm main body. Think I got 82/92 in it.
 
Since i haven't used a Proform body before, i didn't realize how big the bleeds were? You guys with that knowledge need to take it from here...i'm out.
 
Use Proform main bodies on 750 dp.....had 73/81 jets in them.....
 
Think mine had 36 or 37 hi speed bleeds in it. 33 or 34 would probably bring the jetting down to a more average size.
 
Get a solid flat tappet. Comp Xtreme Energy Solid lobe #6056 intake and exhaust ground on a 106 LSA with 4* advance.

242* @ .050
.580 lift with 1.7 rockers
 
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