I am putting an 86 model 302 in my car. It will has a stock roller cam, edelbrock performer rpm intake, hooker 6901 headers. I am putting in 4.11 gears. I want it to be a street strip car. I am planning on buying a new carberator pretty soon. I was thinking of getting a holley 600 double pumper ut that might be to much. Any help would be appreciated
I don't think it would be too much. I don't think you want to go any smaller or you would be buying another carb when you change the cam and convertor and try to make the car faster. And believe me, if you take it too the strip you are going to want to go faster.
I question the use of 4.11 gears with a stock cam. I've tried that before with a 4v 351c and even that high winding engine couldn't use 4.11 gears (26" tires) with a stock cam and dual plane intake. Also, I had issues with a Performer RPM being able to keep up with the same 4.11 gears, in the same car, with a 306 built to rev high. It used a Torker 289, and would rev FAST and cleanly. I swapped on an RPM intake and it just became dog lazy and the 4.11s brought the revs up so soon that the intake just couldn't keep up. I put the single plane back on and it was fast again. Remember though, this 306 was cammed and built to rev. The same car and gears, with a bone stock 4v Cleveland drove like a dumptruck because it wasn't able to rev as fast as the 4.11s demanded. You may have this issue with a stock cam and/or dual plane intake. You could use taller rear tires to tame the gears, but then what is the purpose of having the gears??? Btw: I have used 600, 700, and 750 DPs on 302s (well 306s) and had good luck. My personal fav is the 700 when using a DP. If you get a Holley, just make CERTAIN that the bowls use umbrella valves in the accel pumps. The older BB style bowls are less responsive. I have also seen them have problems with corrosion and catching junk in the valve.
I just posted a thread about my 600 dp. It seems like it is running lean, and I so far have jetted it from 65 to 76 on the primary circuit, and still running lean. My engine is a 308 with a fairly high lift cam. I am thinking I need 700 or 750. So at least go bigger than the 600. If someone can send me a 750 to try for a few days, I will send you the 600 to try.
What PV are you running? The power valve must open to enrich the main circuit during crusing. If your PV doesn't match the vacuum level created by your cam while cruising, you can run lean or rich depending on which way it's off. IIRC, I have run as large as 74 front and 82 rear on a T289/DP Holley combo.
Power valve is 6.5, I run 12 mmhg vacuum at idle. It would be cheap to try a lower valve. What is next, 5.5? Going to rejet tomorrow, so I could swap the valve while I am in there. Currently, I am running 76 primary jets, and only 74 secondary. It runs fine full throttle, just not at part throttle on the primary circuit.
The vac at idle method is considered a 'rule of thumb'. The most accurate way of measuring is to run a vacuum line into the cabin, attached to a vac gauge. Then, with your passenger (for obvious safety reasons) attentively watching the gauge, you should drive around for a few miles. During the drive, you should make various driving situations occur, and should should do some full throttle accellerations from stop, and from various speeds. You should also do various throttle runs on different terrain, like up and down hills. Your passenger should record the lowest vacuum the gauge ever sees. In each situation, if the vac reading is lower than the last, it should be recorded. The lowest vac reading reached during your entire trip is the one you need. Now is where my memory is shot. I can't remember if Holley recommends adding 1 digit, subtracting 1 digit, or using the exact number... to get your PV rating. It is a minor detail that shouldn't be hard to google or pick out of a Holley manual.
Hey Ratio!!! Thanks for the advice. I have a vacuum gauge, and since I just put in the second seat, this gives me an excuse to MAKE the wife go for a ride with me!!!:bananaman Would it work to disconnect the vacuum line to the transmission and hook up the vacuum line there, and drive it like that?
No if that is the only manifold source you have use a TEE. I use the cruise vacuum as a reference for the power valve number.
I have a tee there, going to the trans and to the vacuum system that controls my heater doors. I can disconnect the heater door tube and hook up the vacuum gauge there, while leaving my trans connection in tact.
