My friend gave me a Quick Fuel 950 carb with E85 metering blocks. I am planning on running gas so I need to replace the blocks. I was looking at the QF replacements blocks but not sure which ones to get. Do I need the same block on the front and back? Any advice greatly appreciated. I have been looking at these:

https://www.summitracing.com/parts/qft-34-10qft/overview/

Thanks,

Steve

Check with Dominic Thumper. He has his own made by BLP. Think they already have lowered IFR's. And he can set you up with a calibration.

Call them for the best answer on what they build them with
BTW, you may need more than the metering blocks, E85 requires a lot bigger fuel flow throughout the entire carb.

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Dom can also help you to make sure no their changes are needed as cab pointed out.

The boosters MAY need to be changed as well but not 100% till you either ask QF or measure em yourself and if that's the case, I'd sell it and get what you need or someone can build to you needs............ As far as BLP building the blocks w/lower ifr's, Mark W I believe pushed em in that direction and I buy a bunch so now they whip em up for who ever likes those changes..........

Thanks for the info. I'm not sure what "ifr's" are; I will do some research, call QF and look into the BLP blocks.

I talked to my friend and its a gas center and he added e85 blocks so the boosters should be gas. It probably didn't run good so that is why he gave it to me :-).

Its this main body (actually a Proform):

https://www.summitracing.com/parts/pro-67108c

Thanks again,

Steve

I'd get the 34-105 kit which comes with a pair of blocks.

Several years ago I built a few "HP750's" out of the original ProForm bodies.
Back then I just used std metering blocks for a Holley 4779(750dp), along with std base plates.
Those carbs worked pretty well....... So I thought I'd do another one with the new style parts. I used the Holley HP body for this one, along with the aluminum qft bowls, billet baseplate, and the 34-105 metering block kit.

Unfortunately, I haven't run it on anything yet, so I can't comment on the performance.

I must be the only guy who can't my junk to run with the IFR's down low. My car hates the IFR's low. I've tried it many times and I can never make it happy with them down.

you will also need to change the air bleeds (idle and high speed) on the main body...they are different size went using e85 compared to gas.

Dwayne it looks like I have the same main body and base plate only mine is a 950 so that might be the way to go.

I now know what IFR (idle feed restriction) is but I'm not sure why it should be lowered. Is lowering it a race carb technique? I should mention this carb is intended for a street/strip car (mostly street) so I would like a reasonable idle quality.

FYI, looks like all Quick Fuel products are on sale 10% on Summit if anyone needs anything.

Thanks,

Steve

the low IFR is supposed to have a more consistent feed and therefore better idle characteristics, probably particulalry in low vacuum ocmbinations.

thanks for the explanation. I would probably benefit from lowered IFRs. Are there any general rules on IFR settings based on vacuum levels?

I would trade that one for a gas carb, there are always guys looking to switch to e85.

My understanding is that it is a gas carb and the metering blocks were just switched to e85 (never correctly converted to e85 and probably didn't run that good). That said I don't think e85 guys would want it either. My thinking is all I need to do is get a good set of gas blocks for 100 to 150 rather than buying a new carb for 700/800. Trying to be cheap/thrifty and I'll probably regret it later.

Thanks,

Steve

The qft blocks have the ifr in the upper position.
I wouldn't worry about moving them until you determine your combo can't seem to be made to run right with them in the upper position.

You told us it's a gas carb with E85 metering blocks.
You told us the guy who put it together didn't like the way it ran and gave it to you. You are a lucky guy!

Simply sell the E85 metering blocks and buy gas metering blocks from vendor of your choice. Or trade. Someone who wants to go E85 might be willing to swap straight across. Look for blocks from a carb the same cfm. Billet blocks are preferred because everything is more precise.

I'm making an assumption here that the guy who gave you the carb didn't mess with things like air bleeds and flow restrictors.

Thumper is a board member and has his own metering blocks made.
He has a very good reputation here and would be more than willing to get your carb set up right. You could ship him the carb for a reconversion. He could check air bleeds, etc.

If I had your problem I would change one thing at a time (unless having an expert pitch in). You are getting some pretty specialized advice here which may be good in the end but I think you need a baseline.

So put down the drill and pick up the telephone! Good Luck!

R.

I have ~8 inches of vacuum at idle and my carb doesn't like low IFR's. I've never been able to nail it down but I'm assuming the low idle vacuum wants high IFR's.

I'm sure Dom and Mark have better thoughts on it than I do.

I have 5 and no problem at all so your idle circuit needs some help but easy enuff to fix imo...........My # is down below and if the op needs help,